JP2992235B2 - Ladder with adjustable hanging angle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ladder which can be hooked freely, and more particularly to a ladder which can be hung on a framed scaffold or the like.

[0002]

2. Description of the Related Art A ladder, particularly a ladder for hanging on a narrow limited place such as a framed scaffold, usually has a single girder material, and a plurality of treads or tread bars are fixed to parallel girder on both sides. I was

A ladder having a plurality of parallel treads is hung at an inclined angle at which the treads become horizontal by a predetermined angle between the girder material and the treads, and is generally used in a place where the inclination is gentle. Was.

[0004] A ladder having a plurality of parallel treads or a narrow tread has been used in a place where it is hooked at a nearly vertical angle.

[0005]

However, the conventional ladder has a problem in that a plurality of treads are fixed to the girder members, respectively, and the treads cannot be horizontal unless the ladder leans at a fixed hanging angle. . Therefore, the hanging angle is limited by the ladder, and there is a problem that the ladder cannot be used safely in some places.

In particular, when installing a ladder in a narrow limited space such as a framed scaffold, there are various subtleties such as a case where the ladder must be hooked at a right angle and a case where a worker wants to use the ladder safely at a gentle inclination. Angle was required. For this reason, conventionally, a frame scaffold had to use a plurality of ladders in order to enhance safety. Further, depending on the construction site, if the object on which the ladder is hung is the building base, the height and the hanging space may change depending on the time, and it was necessary to respond quickly to that.

[0007] Also, when the ladder is hung at an angle close to the vertical, there is also a problem that the worker becomes unstable when the stepping portion is a treadle and the danger is high.

Further, when lifting a heavy object, it is necessary to more reliably fix the hanging angle of the ladder.

[0009]

In order to solve the problem, one girder is composed of two upper and lower girder members provided with a U-shaped cross section in a columnar shape with a U-shaped opening facing outward. A hook is provided at the upper end of the lower girder material, two girders are provided in parallel with each other, and a plurality of treads are erected in parallel between the parallel girders. A plurality of girder members parallel to each other in a freely angled ladder, each of which is rotatably hung between a plurality of girder members and a fixing member below a handrail frame is detachably provided on each girder. An anti-smudge device is provided between two upper and lower girder members parallel to each other so as to have an acute angle opposite to the acute angle formed by the anti-smudge device. One end is rotatably connected to the end of the plate with a bolt, and the other end is rotatably connected to the other girder. The tie plate has a tie plate, and the slide plate is slidably provided within the interval between two stop bolts protruding from one of the beam members, and after determining the latch angle of the ladder, the eye nut is rotated. The present invention proposes a ladder with a freely adjustable angle, wherein the angle between the tie plate and the slide plate is fixed by tightening a bolt, and the slide plate is fixed to one of the girder members so that the angle can be freely fixed.

The first girder is composed of two upper and lower girder members provided with a U-shaped opening facing outward with a columnar body having a U-shaped cross section, and the lower girder member is an upper girder member. The width is wider than the material, and the upper end is provided with a hook. Two spars are provided in parallel with each other, and a plurality of treads are laid in parallel between the parallel spars. In the ladder which is rotatably bridged between a plurality of girder members at each of the girder members and has a fixing member at the lower part of the handrail frame provided on each girder so as to be freely detachable, a plurality of girder members having parallel tread plates are provided. An anti-fog device is provided between two upper and lower girders parallel to each other so as to have an acute angle opposite to the direction of the acute angle formed by the anti-fog device, and the anti-fog device is slidable in the groove of the wide lower girder material. , One end of the slide plate is rotatably connected with the end of the slide plate and a bolt, and the other end is The slide plate is slidably provided within the interval between two stop bolts protruding from the lower girder member, and the ladder has a fixed angle. After that, the angle between the tie plate and the slide plate is fixed by rotating the eye nut and tightening the bolt, and the slide plate is fixed to the lower girder material so that the mounting angle can be freely fixed. Suggest a ladder.

Further, the upper and lower spar 1 is a columnar body having a U-shaped cross section and provided with the U-shaped opening facing outward.
The lower girder is wider than the upper girder and has a hook at the upper end. Two girders are provided in parallel with each other, and between the parallel girder. A plurality of treads were installed in parallel, each tread was rotatably bridged between a plurality of girder members at each of both side ends, and a fixing member below the handrail frame was detachably provided on each girder. In a ladder having a freely adjustable hanging angle, an anti-smudge device is provided between two parallel upper and lower girder members so that the tread plate has an acute angle opposite to an acute angle formed by a plurality of parallel girder members. A slide plate guide provided in the groove of the wide lower girder, a slide plate slidably provided in the slide plate guide, and one end rotatably connected by an end of the slide plate and a bolt, A tie plate that pivotally connects the other end to the upper girder The slide plate is slidably provided within the interval between the two stop bolts protruding from the lower girder, and after determining the ladder's locking angle, turning the eye nut and tightening the bolt. The present invention proposes a ladder with a freely adjustable angle, characterized in that the angle between the rate and the slide plate is fixed, and the slide plate is fixed to the lower girder member so that the mounting angle can be freely fixed.

[0012]

[0013]

[0014]

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION
First, FIG. 1 showing a side surface of a ladder according to the first embodiment,
FIG. 2 showing the front, FIG. 3 showing the plane of one tread plate, FIG. 4 showing the side of the fixing member below the handrail frame, FIG. 5 also showing the front, FIGS. And a description will be given based on FIG. 7 in a state where the tightening screw is tightened.

The ladder comprises a girder 1, a step board 2, a handrail frame 3, a latching section 4 and a base section 6.

The spar 1 is composed of a plurality of parallel spar members 5 on each side of the spar 1. In this embodiment, the one spar 1 is composed of two parallel spar members 5. The two parallel beam members 5 are rotatable at two longitudinal end portions of a mounting bracket 20 provided on the side portions of the plurality of tread plates 2 and at both longitudinal end portions of a base portion 6 provided at the lowermost portion of the beam. To form a single-sided spar 1 and one spar 1 is composed of two spar members 5
Keep parallel while changing the distance between The beam member 5 is a columnar body having a U-shaped cross section, and is provided with the U-shaped opening facing outward.

The two girders 1 are provided in parallel on both sides of the plurality of treads 2. The plurality of treads 2 are rotatably attached to the two girder members 5 at the attachment brackets 20 on both sides in the longitudinal direction. In the embodiment, the length of each girder member 5 is 2290 mm, the distance from the mounting position of the lowermost base portion 6 to the mounting position of the lowermost tread plate 2 is 300 mm, and the distance between the plurality of tread plates 2 is the same. Is 300 mm. The number of steps 5 is seven.

A hook 4 is provided at the upper end of a beam 5 below each beam 1. The hook 4 is made of a gripping metal and is fixed to the upper end of the beam 5 so that it can be hooked on a horizontal rod or the like of a framed scaffold.

A base portion 6 is provided at the lowermost end of each spar 1. The base portion 6 is an angle having an L-shaped cross section, and is rotatably attached to the lowermost ends of the two girder members 5 in the same manner as the attachment bracket 2a of the tread plate 2 by both longitudinal portions of the upright portion.

In this embodiment, the step board 2 has a length of 4 mm.
A metal plate having a thickness of about 50 mm, a width of about 240 mm, and a thickness of about 30 mm.
0 is provided. The mounting bracket 20 has a trapezoidal portion in a side view projecting upward from the thickness of the tread plate, and is attached to each of the two girder members 5 at two end portions of the trapezoidal portion so as to be rotatable.

The handrail frame 3a of the first embodiment is detachably provided on each of the beams 1 on both sides. One handrail frame 3a has an upper handrail section 30 and two handrail sections 30 provided below the handrail section 30.
A pillar 31 of a book, and a fixing member 32 provided below the pillar 31
Consists of

The handrail portion 30 is formed of a horizontal rod formed by bending the front and rear parts downward in a semicircular shape, and the pillar 3 is perpendicularly downward from the horizontal rod.
1 is provided. A second horizontal rod is fixedly provided at an intermediate portion between the two pillars 31.

A fixing member 3 connected and fixed to the lower part of the pillar 31
2 is an outer member 32a formed by connecting two hollow prismatic members side by side and connected by a plate portion, and an inner member 32b formed by connecting two hollow prismatic members side by side and connected by a plate portion. And a connecting portion 32c for connecting the two portions at the top, and a fixing bolt 32d for tightening the outer member 32a and the inner member 32b.

The fixing member 32 has a gap 32 between the outer member 32a and the inner member 32b which is about 1 mm wider than the width of the girder member 5.
g. In this embodiment, the width of the beam 5 is 2
5 mm, gap 32 between outer member 32a and inner member 32b
The width of g is 26 mm. Outer member 32a and inner member 3
2b is connected and fixed by a connecting portion 32c, which is a U-shaped member that opens downward at the upper portion. Outer member 3
The plate-like member 2a is provided with through holes 32e vertically separated from each other, and the plate-like member of the inner member 32b at a position corresponding to each through-hole 32e is provided with two fastening holes 32f provided with female screws inside. .

When the ladder is hooked and the hook angle is determined, the fixing member 32 sandwiches the upper and lower girder members 5 above the girder 1 so that the upper and lower girder members 5 are sandwiched in the gap 32g from above. And push it in until it stops. Further, two fixing bolts 32d, which are butterfly bolts, are respectively attached to the outer portions 3
It penetrates through the upper and lower through holes 32e of 2a, passes through the gap 32g, and is screwed into the upper and lower fastening holes 32f of the inner portion 32b. One fixing bolt 32d is located between the upper and lower beam members 5, and the other fixing bolt 32d is located below the lower beam member 5.

When the hanging angle of the ladder is determined, the handrail frame 3a is provided with a fixing member 32 on the upper part of the spar 1 on both sides.
Secure by tightening 2d.

In the ladder, since the two girder members 5 and the plurality of tread plates 2 and the base portion 6 on both sides are rotatable, the ladder can be hung at a free angle while keeping the plurality of tread plates 2 horizontal. In order to lock the ladder at the desired angle on the site such as a framed scaffold, and to fix the locking angle, the handrail frame 3 is used.
This is done by fixing a to the digits 1 on both sides. Since the fixing member 32 of the handrail frame 3a is attached to the two girder members 5 and the interval between the two girder members 5 is fixed by tightening the fixing bolt 32d, the angle between the girder 1 and the tread plate 2 is fixed.

Next, FIG. 8 showing a side surface of a ladder according to a second embodiment of the present invention, FIG. 9 showing a front surface thereof, FIG. 10 showing a side surface of a handrail frame, and FIG.
1, FIG. 12 and FIG. 3 showing an enlarged side view of the anti-fog tool.
FIG. 13 showing a partial side surface of the ladder according to the embodiment, FIG. 14 showing a partial side surface of the ladder according to the fourth embodiment, and FIG. 15 being a perspective view of a hooking portion of the ladder according to the fifth embodiment. It will be described based on the following.

A ladder according to a second embodiment of the present invention comprises:
It is composed of a girder 1, a step board 2, a handrail frame 3b, a hook 4, a base 6, and an antifog device 7.

The girder 1 has a plurality of parallel girder members 5 on each side, and in this embodiment, one girder 1 comprises two parallel girder members 5a and 5b. The two parallel girder members 5a and 5b are turned at two longitudinal end portions of the mounting bracket 20 provided on the side portions of the plurality of tread plates 2 and at the longitudinal end portions of the base portion 6 provided at the lowermost portion of the girder. The spar 1 is constituted by being movably attached, and one spar 1 is kept parallel while changing the interval between the two spar members 5. The beam member 5 is a columnar body having a U-shaped cross section, and is provided with the U-shaped opening facing outward.

In the ladder of the third embodiment, since the length of the beam 5 is relatively long (3790 mm in length), the two beams 5
The width of the lower beam 5b is wider than that of the upper beam 5a.

The two girders 1 are provided in parallel on both sides of the plurality of treads 2. The plurality of treads 2 are rotatably attached to the two girder members 5 at the attachment brackets 20 on both sides in the longitudinal direction. In this embodiment, the length of each girder 5 is 2290 mm, and the lowermost tread plate 2 is moved from the mounting position of the lowermost base portion 6.
Is 300 mm, and the interval between the plurality of treads 2 is also 300 mm. Although the number of the treads 2 is seven in this embodiment, the number of the treads 2 is 4 when the length of the girder 5 is 1390 mm (not shown).
When the length of the sheet member 5 is 3790 mm, the number of the tread plates 2 is 12 pieces. Depending on the length of the beam 5,
From about 1 to about 15 treads 2 are possible.

A hook 4a is provided at the upper end of the beam 5 below each beam 1. The hook 4a is formed by fixing a gripping metal to the girder member 5, and can be hooked on a horizontal rod or the like of a framework scaffold.

The ladder engaging portion 4b of the fifth embodiment shown in FIG. 15 is used when the member to be engaged is a square member having a right-angled corner. It is a plate-like body bent at a right angle having an inner shape of a concave right angle, which has a shape corresponding to the convex right-angle surface of a square bar. The hook portion 4b is provided on a plate-like body fixed to the upper end portion of the girder member 5 so as to be rotatable vertically, and is angle-fixed by an angle fixing bolt 40b. After the hook 4b is hooked, it is detachably fixed to the hook member A by the fixing bolt 41b.

A base 6 is provided at the lowermost end of each spar 1. The base portion 6 is an angle having an L-shaped cross section, and is rotatably attached to the lowermost lower ends of the two beam members 5 in the same manner as the attachment bracket 20 of the tread plate 2 by both sides in the longitudinal direction of the upright portion.

In this embodiment, the step plate 2 has a length of 4 mm.
A metal plate having a thickness of about 50 mm, a width of about 240 mm, and a thickness of about 30 mm.
0 is provided. The mounting bracket 20 has a trapezoidal portion in a side view projecting upward from the thickness of the tread plate, and is attached to each of the two girder members 5 at two end portions of the trapezoidal portion so as to be rotatable.

The handrail frames 3b are detachably provided one by one on each of the girders 1 on both sides. If the girders 5 are long, two or two or more are provided. When the length of the girder member 5 is short, a shorter handrail frame (not shown) is provided. One handrail frame 3 b includes an upper handrail section 30, two pillars 31 provided below the handrail section 30, and a fixing member 33 provided below the pillar 31.

The handrail portion 30 is formed of a horizontal rod formed by bending the front and rear downwards into a semicircular shape, and the pillar 3 is perpendicularly downward from the horizontal rod.
1 is provided. A second horizontal rod is fixedly provided at an intermediate portion between the two pillars 31. The length of the beam 5 is 1390m
m, in the case of a handrail frame (not shown) provided on a ladder having four tread plates 2, the semicircular portion before and after the handrail portion 30 is only one side, and the other side is a right angle having a horizontal rod with a radius. To form a pillar 31 as it is.

The fixing member 3 connected and fixed to the lower part of the pillar 31
3 is provided with two plate-shaped members 33a arranged in the width direction of the ladder and fixed to the pillar 31 via a connecting member 33b having a U-shaped cross section. The plate-like body 33a is provided such that the fixing groove 33c is opened to the side surface of the plate-like body with the interval between the two sheets being substantially equal to the width of the girder member 5. Although two fixing grooves 33c are provided in the length direction,
As the angle between the ladder and the horizon increases, the interval between the parallel girder members 5 also increases, but a width interval corresponding to the width between the girder members 5 is provided.

A fixing bolt 33d is provided in the fixing groove 33c from the opening side. In this embodiment, the fixing bolt nut 33d is made up of a press wing bolt and a nut, and tightens the bolt to narrow the interval between the parallel plate-like bodies 33a and fix the beam member 5 therebetween.

The anti-smudge device 7 includes two parallel beam members 5.
a and 5b, and are provided outside the left and right girders 1, respectively, but may be provided on only one girder 1. When the ladder of the present invention is mounted, the angle between the ladder and the ground plane B differs depending on the hook angle of the ladder, and the angle formed with the ground plane B is an acute angle and an obtuse angle except when the ladder is hooked vertically. The respective angles between the girder 5 of this ladder and the ground plane B are the respective angles of the girder 5 and the tread plate 2. The anti-smudge device 7 is attached so as to have an acute angle opposite to the acute angle formed by the girder member 5 and the tread plate 2. That is, the anti-fog device 7 is provided between the girder members 5 parallel to the direction intersecting with the direction of the tread plate 2, and the mounting angle is changed depending on the hook angle of the ladder. The direction of the acute angle between the beam 5 and the footboard 2 is opposite.

In the second embodiment, the anti-smudge device 7a
Is composed of a tie plate 70, a slide plate 71, a bolt 72 capable of rotatably connecting and fixing the two plates 70, 71, and an eye nut 73 screwed to the bolt 72. The tie plate 70 has a hole 74 at the end opposite to the connecting portion side with the slide plate 71, and a fixing pin 75 is fitted into the hole 74 to be rotatably attached to an appropriate position of the upper beam 5a. . Slide plate 71
Is slidably attached to the lower beam 5b. The two stop bolts 76 protrude from the lower spar member 5b at a position where the slide plate 71 is slidably attached to the slidable mounting position of the tie plate 70 below the ladder. It is provided so as to be slidable within the interval range. After determining the hook angle of the ladder, the anti-smudge device 7a turns the eye nut 73 to the bolt 72 and tightens the tie plate 70 and the slide plate 71.
Are fixed to each other at a fixed angle, and the slide plate 71 is fastened and fixed to the beam 5b.

When the length of the girder member 5 of the ladder is long, the width of the lower girder member 50b is increased. A slide plate guide 77 having a small width is provided, and a slide plate 71 is slidably mounted in the slide plate guide 77. Stop bolts 76 are provided at both ends of the slide plate guide 77. Slide plate 71, tie plate 70, bolt 72, eye nut 73
Is the same as in the second embodiment.

As another example of the anti-fog devices 7a and 7b of the second and third embodiments, the anti-fog devices 7a and 7b
It is also possible to provide the beam members 5a and 5b with b upside down. That is, the lower end of the tie plate 70 is rotatably attached to the lower girder 5b, and the slide plate 71
Is slidably attached to the upper beam 5a.

The anti-foging device 7c according to the fourth embodiment shown in FIG. 14 is a rectangular plate-like body, and has a plurality of fixing recesses 70c in the longitudinal direction, which are opened on both upper sides.
The lower end is rotatably attached to the lower girder 5b by a pivot pin 74c. The anti-fog device 7c of the fourth embodiment includes a fixing recess 70c corresponding to an appropriate position depending on the angle at which the ladder is hooked, and a fixing hole 72c of a fixing plate 71c fixed to the upper beam 5a. Are fixed and the fixing bolt 73c is tightened.

As another example of the anti-smudge device 7c of the fourth embodiment, a plurality of fixing plate-like members 71c are mounted upside down and the upper end is rotatably mounted on the upper beam member 5a. The fixing recess 70c can be detachably fixed to the lower beam member 5b.

In the ladder, since the two girder members 5 and the plurality of treads 2 and the base portion 6 on both sides are rotatable, the ladder can be hung at a free angle while the plurality of treads 2 are kept horizontal. Then, the ladder is hung at a desired angle at a site such as a framed scaffold or the like, and in order to fix the hung angle, the handrail frame 3b is fixed to the spar 1 on both sides, and the sliding portions of the anti-smudge devices 7a and 7b are provided. The side is fixed to the lower beam members 5b and 50b, and the anti-fog 7c is achieved by fixing the fixing recess 70c to the upper beam member 5a.

[0049]

Therefore, according to the present invention, the step plate can be kept horizontal regardless of the angle at which the ladder is hung, and the worker can work safely and reliably. Therefore, it is possible to immediately respond to sites having different heights.

In particular, when installing a ladder at a construction site such as a framed scaffold, the ladder can be hooked with one ladder according to the size of the space where the ladder is required, and the ladder can be installed at an angle close to a right angle or a gentle inclination angle. The work efficiency at the site can be greatly improved because it can be hooked at any angle. In addition, since one kind of ladder can be used at various sites, it is easy to carry and store the work.

[Brief description of the drawings]

FIG. 1 is a side view of a ladder showing a first embodiment of the present invention.

FIG. 2 is also a front view

FIG. 3 is a plan view of one tread plate.

FIG. 4 is a side view of a fixing member below a handrail frame.

FIG. 5 is also a front view

FIG. 6 is a plan view of the same.

FIG. 7 is a cross-sectional explanatory view showing a cross section taken along the line AA of FIG. 5 and showing a state where fixing bolts are tightened.

FIG. 8 is a side view of a ladder showing a second embodiment of the present invention.

FIG. 9 is also a front view

FIG. 10 is a side view of the handrail frame of FIG. 8;

FIG. 11 is a plan view of the anti-fog tool.

FIG. 12 is a side view of the anti-fog tool.

FIG. 13 is a partial side view of a ladder showing a third embodiment of the present invention.

FIG. 14 is a partial side view of a ladder showing a fourth embodiment of the present invention.

FIG. 15 is a perspective view of a hanging portion of a ladder showing a fifth embodiment of the present invention.

[Explanation of symbols]

 1 girder 2 tread plate 20 mounting bracket (of tread plate) 3a handrail frame (first embodiment) 30 handrail portion 31 pedestal 32 fixing member 32a outer member 32b inner member 32c connecting portion 32d fixing bolt 32e through hole 32f tightening hole 32g Air gap 3b Handrail frame (2nd, 3rd, 4th, 5th embodiment) 33 Fixing member 33a Plate 33b Connecting member 33c Fixing groove 33d Fixing bolt and nut 4a Hanging portion 4b Hanging portion 40b Angle fixing Bolt 41b Fixing bolt 5 Girder material 5a Upper girder material 5b Lower girder material 50b Wide lower girder material 6 Base part 7 Smoke prevention tool 7a Smoke prevention tool 70 Tie plate 71 Slide plate 72 Bolt 73 Eye nut 74 Hole 75 Fixing pin 76 Stop bolt 7b Anti-fog tool 77 Slide plate guide 7c Anti-fog Ingredients 70c fixing recesses 71c securing the plate member 72c fixed holes 73c fixing bolt 74c pivot pin

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nagayoshi Nagayoshi 1-10-12 Nihombashi Horidomecho, Chuo-ku, Tokyo Chuo Built Industrial Co., Ltd. (56) References JP-A-6-272466 (JP, A) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) E06C 1/02-1/10

Claims (3)

(57) [Claims] The first girder is a columnar body having a U-shaped cross section and is composed of two upper and lower girder members provided with their U-shaped openings facing outward, and is provided at the upper end of the lower girder member. A hooking part is provided, two 1-spares are provided in parallel with each other, and a plurality of treads are erected in parallel between the parallel girders, and each tread is turned between a plurality of girder members at each of both side ends. While being freely laid,
In a ladder with a freely adjustable hanging angle provided with a fixing member below the handrail frame on each girder, a parallel up and down so that the tread plate has an acute angle opposite to the acute angle of the plurality of parallel girder members. An anti-fog device is provided between the two girder members. The anti-fog device connects a slide plate slidable to one of the girder members, one end of the slide plate rotatably by an end and a bolt, and the other. A tie plate rotatably connecting the end to the other spar, the slide plate being slidably provided within a distance between two stop bolts protruding from the one spar, and a ladder engaging angle; After tightening the bolt, tighten the bolt by turning the eye nut to fix the angle between the tie plate and the slide plate, and fix the slide plate to one of the girder members so that the mounting angle can be fixed freely. Angle free Ladder. 2. The first spar is a columnar member having a U-shaped cross section and is composed of two upper and lower spar members provided with a U-shaped opening facing outward, and the lower spar member is an upper spar. The width is wider than the material, and the upper end is provided with a hook portion, two spars are provided in parallel with each other, and a plurality of treads are laid in parallel between the parallel spars,
Each tread plate is rotatably bridged between a plurality of girder members at each of both side end portions, and a ladder having a freely angled hanging ladder provided with a fixing member at a handrail frame lower portion on each girder, An anti-smoke device is provided between two parallel upper and lower girder members so that the tread plate has an acute angle opposite to the acute angle of the plurality of parallel girder members, and the anti-smudge device is a wide lower girder member. A slide plate slidably provided in the groove of the slide plate, a tie plate rotatably connected to the end of the slide plate and one end by a bolt, and the other end to be rotatably connected to the upper beam. Slide plate protrudes from lower girder 2
It is slidably provided within the interval range of the two stop bolts, after determining the ladder's hanging angle, turning the eye nut and tightening the bolt to fix the angle between the tie plate and the slide plate and lower the slide plate A ladder with a freely adjustable angle, which can be fixed at any angle by fixing to a spar member. 3. The first spar is a columnar member having a U-shaped cross section and is composed of two upper and lower spar members provided with a U-shaped opening facing outward, and the lower spar member is an upper spar. The width is wider than the material, and the upper end is provided with a hook portion, two spars are provided in parallel with each other, and a plurality of treads are laid in parallel between the parallel spars,
Each tread plate is rotatably bridged between a plurality of girder members at each of both side end portions, and in a ladder having a freely angled ladder provided with a fixing member at a lower part of a handrail frame on each girder, An anti-smoke device is provided between the upper and lower two parallel girder materials so that the tread plate has an acute angle opposite to the acute angle of the plurality of parallel girder materials, and the anti-smudge device is a wide lower girder material. A slide plate guide provided in the groove of the slide plate, a slide plate slidably provided in the slide plate guide, and one end rotatably connected to an end of the slide plate and a bolt, and the other end to the upper beam member. The tie plate has a tie plate that is rotatably connected, and the slide plate is slidably provided within the interval between two stop bolts protruding from the lower girder member. Turn to tighten the bolt Hooking angle freely ladders, characterized in that the fixed slide plate an angle between tie and the slide plate can be attached angle securable by fixing under the beam members put.