JP3420052B2 - Steps - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step for mounting on the wall surface of a concrete product.

[0002]

2. Description of the Related Art Most of concrete boxes such as manholes and handholes are constructed by carrying in a factory prefabricated hollow unit to the site. Steps are installed on the inner surface of these concrete boxes so that the boxes can be moved. When providing a step on the inner surface of a concrete box, incorporating it when prefabricating in the factory is
Since there are many problems in the shape of the durable formwork, its removal, etc., and it takes time and labor, it is often installed inside the box when the box is assembled on site.

As shown in FIG. 12, a conventional step 90 is used.
Has a substantially U-shape, and support arms 96 extend substantially vertically from both ends of the tread 94, and a tip portion 96a of the support arm 96 becomes a portion to be embedded in a concrete box, and unevenness 98 is formed. . This conventional step 9
0 is the tip portion 96a so that it can be embedded in concrete.
The iron material is exposed, and the other part is entirely covered with a resin such as vinyl chloride. In this step 90, the tip 96a is inserted into a hole provided in advance on the wall surface so that the tip 96a is inserted, and further, mortar is filled and fixed in the gap between the step 90 and the hole.

[0004]

In this step 90, when it is mounted on a concrete wall, the mortar filled in the gap between the hole and the tip of the step cannot be used until it completely hardens, and it takes a considerable time to harden it. . For example, in winter it is necessary to leave the step for two days or more before it can be used.

For this reason, it is conceivable that a fixing plate having a hole for attachment is provided at the tip of the supporting arm of the step and the bolt is fixed to a screw hole previously provided in the concrete wall by an insert or the like by using a bolt. ing. Also,
In such a step, it is convenient to remove the bolt and remove the step from the box. Further, since the mounting is performed only by tightening the bolts, the time required for that is short and the curing period of the filler and the like is not required, so that it can be used immediately after mounting.

However, in such a step, the post-treatment of the portion where the fixing plate is welded to the tip portion of the support arm is troublesome. At the welded part, the connection part and the welding traces around it are uneven, and the appearance is not good. Further, if the irregularities have an acute angle, there is a possibility of damaging a worker or a user, and therefore it is necessary to use a grinder or the like to smoothly finish the welded portion and the surface around it. Further, since the fixed plate must be adhered to the wall surface of the concrete, after the processing such as welding, the process to flatten taking the distortion of the fixing plate also requires the support arm perpendicular to the wall surface of the concrete In order to be able to attach it, a laborious work is required. In this way, equipped with a fixed plate
The steps are easy to install, but are expensive to manufacture because they are laborious to manufacture. Further, since the amount of manual work using a grinder or the like increases, mass productivity also decreases.

Therefore, it is an object of the present invention to provide a step which can be supplied at a low cost and which can be easily and quickly mounted on the inner surface of a concrete box. Furthermore, it is an object of the present invention to provide a highly durable step.

[0008]

Therefore, in the step of the present invention, the resin is applied so as to cover the welded portion and its vicinity, which are the boundary between the support arm and the fixed plate, in a state where the post-treatment of the welded portion is omitted. I am trying to use it for molding. That is, the steps of the present invention include a substantially U-shaped metal footrest part in which the supporting arms extend substantially vertically from both ends of the step rod, and a metal fixing plate extending substantially vertically from the tip of the supporting arm. has the door, comprising the steps of mounting holes are open to the fixing plate, the fixing plate and the supporting arms are connected by welding, the welded parts and the vicinity thereof of at least the support arms and the fixed plate, the welded parts It is characterized by being molded with resin without post-treatment . In the step of the present invention, the periphery of the portion where the support arm and the fixing plate are connected by welding is molded (molded) with resin into an appropriate shape and covered with the molded resin with an appropriate thickness. Even if there are irregularities due to welding, they do not appear on the surface of the molded product. Therefore, it is possible to provide a step having a smooth surface without performing a post-treatment (work) such as a grinder. Therefore, it is possible to provide, at low cost, a step including a fixing plate that can be screwed and attached to an insert or the like that is provided in advance on a concrete wall. Further, as the resin, a plastic material such as vinyl chloride, ABS, or polycarbonate can be used.

Further, the connection portion between the support arm and the fixing plate is a portion where stress is concentrated, but in the step of the present invention, the stress is dispersed by the resin molded around the welded portion , so the strength is also increased. Increased durability.
Furthermore, because the connection part that is welded and easily corroded is thickly covered with the molded resin,
It is possible to prevent the connecting portion from corroding. Therefore,
Also in this respect, a highly durable step can be provided. Therefore , since the load of the connecting portion can be supported by the concrete wall surface, the strength is increased, and it is possible to provide a step with less shaking and distortion when a load is applied to the footrest portion. In this way, the steps of the present invention include a fixing plate and can be attached to the inner surface of the concrete box in a short time.
It is a step that can be removed. Further, by molding with a resin, it is possible to omit the post-treatment of the connecting portion, which requires a lot of man-hours, so that it is possible to supply the material with high mass productivity and at low cost. Furthermore, by molding the connecting portion, a step having high strength and durability can be provided.

In the step of the present invention, it is desirable that the periphery of the fixing plate is also made of synthetic resin. Even if there are distortions, burrs, and the like when the fixing plate is welded by molding with a resin including the fixing plate, the fixing plate does not appear on the resin-molded surface, and a flat and smooth fixing plate can be obtained. Therefore, it is possible to provide a step including a fixing plate that can be attached in close contact with a concrete wall by omitting grinder processing of the fixing plate and work for removing distortion. In addition, it is possible to supply steps with no burr or unevenness on the fixing plate, which is safe and good-looking at the time of transportation or installation, at low cost. Furthermore, even if the accuracy of the connecting portion between the fixed plate and the support arm is somewhat low, it is possible to provide a highly accurate step as a whole .

Further, it is more desirable that the entire step including the foot rest and the fixing plate is made of resin. Since the entire step is resin-molded, not only the connecting portion or the fixing plate but also the foot rest portion is covered with the thick resin, so that it is possible to omit the work such as the surface treatment of the step rod or the supporting arm. Therefore, it is possible to provide steps that can be mass-produced and can be supplied at low cost.
Further, since the entire steps are resin-molded, it is possible to finally provide a resin-molded step with high accuracy as a molded product even if there are manufacturing tolerances in the processing accuracy of the fixed plate, the connection portion, and the like. Furthermore, by resin-molding the entire steps, the entire steps can be rustproofed, and highly durable steps can be supplied. In addition, if resin molding is used, painting can be dispensed with and molding can be performed in any desired shape. For example, it is possible to form a non-slip with unevenness on the tread, or to make the corners of the step into a curved surface, and the surface is beautifully finished. In terms of rust prevention, it is possible to form the entire step with stainless steel, but since it takes time and labor for processing the shape, welding and subsequent processing, mass productivity is low and the cost is high.
Further, the process of providing the non-slip unevenness is troublesome.

Even in the conventional step as shown in FIG. 12, by forming the other part of the support arm with the resin except for the tip part of the support arm where the iron material is exposed so that it can be embedded in concrete, It can prevent the generation of rust. However, due to the expansion and contraction of the mortar filled in the gap with the hole provided on the wall surface due to the temperature change, the adhesion of the tip part is reduced and rust occurs, or rust occurs from the boundary part with the coating. Cannot be prevented. Further, since the tip is embedded, it cannot be immediately attached or detached as in the step of the present invention.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows how the steps according to the present invention are installed inside the handhole. The handhole 10 is a box-shaped concrete product having a square shape and a hollow interior, and is assembled by connecting several units vertically. The uppermost unit is provided with a circular entrance / exit 11 so that a worker can enter and exit the box. Wall 1 inside the box
In FIG. 2, a plurality of inserts 14 are embedded in advance at intervals so that steps can be attached. Then, if step 20 of this example is used, step 20 can be fixed with bolts 40 by selecting an appropriate pair from these inserts 14, and the worker can move up and down inside the handhole 10.

FIG. 2 shows the steps according to the present invention in an enlarged scale. Step 20 of this example is a step in which the whole is molded with resin 50, and is a substantially U-shaped footrest portion 30 provided with a step rod 32 and support arms 34 extending substantially vertically from both ends thereof, Tip 35 of foot rest 30
And a substantially flat rectangular fixed plate 36 connected to the. On the surface of the stepping rod 32, a non-slip concave-convex shape 60 is formed, and a fixing plate 36 is provided with a mounting hole 38 penetrating the fixing plate 36 at one position near each end 37. Therefore, in step 20 of this example.
As shown in FIGS. 1 and 2, the bolt 40 can be passed through the mounting hole 38 provided in the fixing plate 36 and screwed to the insert 14 previously embedded in the inner wall 12 of the handhole 10. ing. Similarly, when the bolt 40 is loosened and removed, the step 20 can be removed from the inner wall 12. Thus, step 20 of this example is a step that can be easily attached to and detached from a concrete wall, and is a step that can be used immediately after being attached.

FIG. 3 shows a cross-sectional view of the steps of the present invention. Step 20 of the present example includes a strength member 30a of a footrest portion 30 formed by bending an iron rod-shaped member into a U shape, and the entire strength member 30a has the outer shape as step 20. It is covered with the resin 50 having a sufficient thickness to be formed. That is, step 3 of step 20
The center 2 is a strength member 32a made of iron, and the periphery thereof is molded with a resin 50. For example,
The periphery of the strength member 32a having a diameter of about 16 mm is molded with the resin 50 to form the footrest portion 32 having a diameter of about 25 mm. Similarly, the support arms 34 on both sides have a strength member 34a made of iron at the center, and the periphery thereof is molded with a resin 50. Further, the fixing plate 36 is also the same, and the fixing plate 36a made of iron, which serves as a strength member, is the supporting arm 3
4 is attached to the tip 35a of the strength member 34a of No. 4 by welding, and a connecting portion 39 between the strength member (hereinafter, a support arm member) 34a of the support arm and the strength member (fixed plate member) 36a of the fixed plate 36 is also provided. The entire fixing plate 36 including it is molded with resin 50.

FIG. 4 is an enlarged view of the connecting portion 39 of step 20. A connecting portion 39 between the supporting arm member 34a and the fixed plate member 36a is fillet welded, and a beat 39a is formed in the connecting portion 39. Immediately after the welding of the connecting portion (welding portion) 39 to be welded, the surface of the welding beat 39a has irregularities and the surface is rough. Further, since the welding spatter 39b is scattered around the welded portion, the surface around this is also roughened. Then, in step 20 of this example, the connection portion 39
It is commercialized by resin molding in the state just after welding. Conventionally, the welded connection part is welded beat 3
It is necessary to carry out a post-treatment work for smoothing the welding spatter 39b scattered around 9a and its surroundings by a grinding process or the like. By this post-processing work, the unevenness and burrs caused by the welding beet 39a and the welding spatter 39b are removed to form a smooth flat surface, and the appearance is adjusted, and the unevenness and burrs of these welding marks prevent the operator and the user from being injured. This is because. Further, since these surfaces are usually coated, such post-treatment is also effective as pre-treatment for coating. Further, since the fixing plate member 36a may be distorted by performing fillet welding, when the distortion is large, a work for removing the distortion may be performed by heat treatment or the like.

On the other hand, in the step 20 of the present invention, the connecting portion 39 between the fixed plate member 36a and the support arm member 34a.
The whole is molded by the resin 50 in a state where the fillet welding is performed and the state is almost the same. Since the resin-molded connection portion 39 is covered with the resin 50 having an appropriate thickness, the irregularities and burrs caused by the welding beat 39a and the welding spatter 39b are covered with the resin mold. Resin 5
It does not appear on the surface of step 20 molded with 0, and step 20 having a smooth outer surface or an outer surface trimmed into a predetermined shape can be manufactured. Therefore, it is possible to omit the post-treatment that is performed after welding to remove unevenness and burrs at the welded portion. Therefore, in step 20 of this example.
Can reduce the labor required for manufacturing, and
When processing the connecting part, post-processing that is performed manually using a grinder etc. is omitted, so mass productivity is also high,
It can be provided at low cost.

Further, the connection portion 39 between the support arm member 34a and the fixed plate member 36a is a portion where stress is concentrated, but by molding the periphery of the connection portion 39 with the resin 50 as in step 20 of this example. The effect of distributing the stress is also obtained. Therefore, it is possible to provide a step having high durability against repeated stress applied each time the step is used. Further, since the connecting portion 39 which is in a state of being easily corroded by processing such as welding is thickly covered with the molded resin 50, it is possible to prevent the connecting portion 39 from being corroded. Therefore, it is possible to provide a step having high strength and durability against corrosion.

In terms of durability and strength, stainless steel can be used to form a step that looks substantially the same as step 20 of this example. However, since welding and post-treatment of stainless steel requires more work than the post-treatment of the usual iron material (carbon steel) described above, the cost is high and the mass productivity is low. Further, it is difficult to apply a non-slip process to a step rod or the like, and the shape of the step is also limited.

FIG. 5 shows a state in which the support arm member is connected to the fixed plate member by a method different from this example. The connecting portion 39 has a through hole formed in the fixed plate member 36a, and is connected by welding the support arm member 34a from both sides of the front surface 28a and the back surface 28b of the fixed plate member 36a after passing through the tip portion 35a of the support arm member 34a. ing. In order to attach the step 20 to the wall surface 12, the back side 28b of the fixing plate 36a needs to be processed into a flat surface without unevenness so that it can be closely attached to the inner wall 12. As shown in FIG. 5, in order to increase the strength of the welded portion 39, the support arm member 34a is combined so as to penetrate the fixed plate member 36a, and fillet welding is also performed on the back side 28b of the fixed plate member 36a. The front end portion 35a of the support arm member 34a and the welding beat 39a project to the back side 28b, and the back surface 28b is not flat. Therefore, it was difficult to adopt the connection method as shown in FIG. On the other hand, in the case of step 20 of the present invention, the back surface 28b of the fixed plate member 36a is
Even if the tip 35a of the support arm member 34a slightly protrudes or the welding bead is present, the entire connecting portion 39 including the back side of the fixing plate member 36a is molded with the resin 50. For this reason, the step 20 having a smooth surface which is covered with the molded resin 50 and does not appear on the back surface 33 of the fixed plate 36 can be realized because the portion protruding from the back surface 28b or the unevenness of the back surface 28b is covered. As described above, in step 20 of the present invention, it is possible to employ a connection method in which unevenness remains on the surface of the strength member, and it is possible to provide a step with high durability. it can.

FIG. 6 schematically shows a process of manufacturing the steps of this example. As shown in FIG. 6A, the strength member 30a of the U-shaped footrest portion and the fixing plate member 36a having the mounting holes 38a opened near both ends 37a are connected to each other.
9 is welded and the strength member 20a of step 20 is manufactured. Next, as shown in FIG. 6 (b), the manufactured strength member 20a is installed inside the mold 70 for molding,
The molding resin 50 is injected into the mold 70. As a result, the entire step-shaped strength member 20a is molded with the resin 50, and the molded step 20 having a shape conforming to the shape of the mold 70 is manufactured. At this time,
The sleeve 72 is installed in the mounting hole 38a. The periphery of the mounting hole 38a is also molded with the resin 50 having an appropriate thickness to form the mounting hole 38 having an appropriate diameter. When the injected resin is cured, as shown in FIG. 6C, the step 20 is released from the mold 70 and molded with the resin 50. In this way, the periphery of the mounting hole member 38a is also covered with the thick resin 50, and further, the fixed plate member 36a and the support arm member 34a.
The resin 50 covers the welding beat 39a of the connection portion 39, the distortion caused by welding, etc., and the step 20 having a smooth surface molded into a predetermined shape is completed.

As described above, in step 20 of the present example, since the entire step is resin-molded, the pickling process for removing the dirt on the surface is not performed as described above, ie, the post-treatment such as the grinding of the connecting portion 39 is not performed. The step 20 can be molded by setting the mold 70 to some extent. Therefore, since it is possible to omit the labor-intensive post-treatment of welding, mass productivity is high and it can be provided at low cost.

Further, since the entire strength member 20a welded into a substantially step shape is molded by the resin 50, there is no problem as a product even if the assembly tolerance of the strength member 20a is a little large. Can be provided. For example, the support arm member 34a and the fixed plate member 3
Even if the processing tolerance of the connecting portion 39 of 6a is somewhat large,
It is covered with the molding resin 50, and the shape of the molded step can be manufactured to have a predetermined tolerance. Therefore, also in this respect, it is possible to save the labor for manufacturing.

Further, since the entire step including the mounting hole 38 into which the bolt 40 is inserted when mounting the step 20 on the wall surface is molded with the resin 50, the strength member 20a made of iron can be protected from water and rust occurs. Can be completely prevented, and rust prevention coating can be omitted. Therefore, it is possible to provide the step 20 which is low in cost, has high durability, and can be used even in a place where the groundwater level is high. Further, since it is molded with the resin 50, the shape of step 20 or the pattern of the surface of step 20 can be freely selected. For this reason, it is possible to provide the step 32 of the footrest portion 30 with the non-slip processing 60 such as unevenness, or to provide a step with a curved corner portion and a safe appearance that is good-looking at low cost.

FIG. 7 shows the appearance of the steps of a different example of the present invention. In the step 20 of this example, the entire resin 50
It is the step 20 molded by. In step 20 of this example, the support arms 34 are bent vertically upward, and the two fixing plates 36 are connected so as to overlap in parallel with the tip portions 35 of the respective support arms 34. There is. Each fixing plate 36 is provided with a mounting hole 38 through which a bolt can pass, and in the step 20 of this example, the step of mounting and detaching the inner wall such as a hand hole with the bolt can be performed in the same manner as the step 20 described above. Is. The same parts as those in the above steps are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 8 shows the connection portion 3 of step 20 of this example.
9 is shown enlarged. In the connection portion 39 of this example, the periphery of the vertically curved tip portion 35a of the support arm member and the overlapping portion of the fixed plate member 36a are welded, and a wide welding area can be secured, so that the step has high welding strength. ing. Furthermore, since the entire portion including the connecting portion 39 is molded with the resin 50, the post-treatment of the connecting portion 39 can be omitted. In addition, the corrosion resistance is high, the mass productivity is excellent, and it is possible to obtain the same effects as those of the above-described steps such as supplying at low cost.

In FIG. 9, the whole is molded with resin 50.
The steps taken are shown. In step 20 of this example, as shown in FIG. 10 by enlarging and showing the connecting portion 39 of step 20 of this example, the fixing plate member 36a extending vertically by pressing and bending the tip 35a of the support arm member 34a. Is formed. When the fixed plate member is manufactured by such press working, the bending radius R of the bent portion 39c (connection portion 39) of the fixed plate member 35a and the support arm member 34a becomes large. Further, since the fixing plate member 36a is pressed,
If it is left as it is, there will be problems such as burrs and danger, or a flat surface that cannot be installed vertically. Therefore, in order to use it as a step in a pressed state, it is necessary to carry out post-processing by a grinder and strain relief, and therefore, it is time-consuming and mass-productive as with the step of welding. In addition, since the bending radius R of the bent connecting portion 39c is large, a gap is generated on the wall surface, which is weak in strength and causes shaking or distortion when placed on a step.

On the other hand, in step 20 of the present example, since the whole of the fixing plate member 36a including the fixing plate member 36a is molded with the resin 50, even if the fixing plate member 36a is distorted or burred, the surface is not formed after the molding. Can provide a flat and smooth step 20. Therefore, similarly to the steps described above, it is possible to omit the grinder work for eliminating the burr and the distortion caused by the press. Further, even if the thickness of the fixing plate member 36a varies due to the pressing, the step 50 having the substantially flat fixing plate 36 having a predetermined thickness can be provided because it is molded with the resin 50, and the concrete wall 12 can be provided. Can be attached closely.

Further, paying attention to the bent connecting portion 39c, the bending radius R of the connecting portion 39c is large, but the periphery of the connecting portion 39c is molded by the molding resin 50 into a shape having a flat surface that can be brought into close contact with the wall surface. ing. That is, the gap generated between the connecting portion 39c and the wall surface is filled with the mold resin 50 so that the connecting portion 39c does not float from the wall surface when the step 20 is attached to the concrete wall surface. Therefore, step 2 of this example
At 0, since the connection portion 39c is also supported by the wall surface, the strength is high, and further, the step does not shake or distort when it is placed on the step.

Further, it is difficult to make the angle of the fixing plate 36a vertical for bending and to align it with another fixing plate, but in step 20 of this example, the outer shape of the fixing plate 36 is the mold resin. Since it is formed by 50, it is possible to provide a high-quality step with no problem in accuracy even if there is some tolerance in the angle or position of the fixing plate 36a.

Also in step 20 of FIG . 11, the resin 50 is entirely used.
Is a step molded by the connecting part 3
9 is formed by pressing the tip 35a of the support arm member 34a. In step 20 of this example, the vertically extending fixing plate member 36a is molded with the resin 50 to mold the substantially disc-shaped fixing plate 36. As described above, the fixing plate 36 is not limited to the quadrangle described above, and can be formed into an appropriate shape by resin molding. Of course, the shape is not limited to a circle, and various shapes such as an ellipse, a triangle, a pentagon or more polygon, and a star shape can be selected.

In the above description, the steps in which the whole is molded with the resin 50 are described as an example. However, from the viewpoint of omitting the post-treatment of the welded portion, it goes without saying that even the step in which only the connecting portion is molded with the resin is possible. This is good, but this makes it possible to obtain the resin molding effect related to the above-mentioned connecting portion. Further , since the flat surface can be easily obtained by molding the fixing plate member with resin, it is possible to provide a step that can be easily attached to the concrete wall surface. Of course, by molding the entire steps with resin, many effects as described above can be obtained, and it is possible to supply steps that have high durability, are safe, and have a good-looking appearance at low cost.

Further, the shape of the steps is not limited to the above-mentioned example, and the shape of the non-slip can be freely set. Further, the step of the present invention is not limited to the inner surface of the handhole, but may be a box for connecting cables (such as a common groove and a CC box) set along the road, and further, a manhole or other tanks. And walls
It can be attached and removed anywhere on the wall where the insert is buried.

[0034]

As described above, in the step of the present invention, the connecting portion between the support arm and the fixing plate, and further preferably the fixing plate, and more preferably the entire step is molded with resin. I am trying. In the step of the present invention, at least the periphery of the portion where the support arm and the fixing plate are connected by welding is the post-treatment of the welding portion.
Molded in a suitable shape with resin without
Since it is covered with the molded resin with an appropriate thickness, even if the connection portion has irregularities due to welding, it does not appear on the surface of the molded product, and it is possible to provide a step having a smooth surface. Therefore, it is possible to omit post-processing of a connecting portion such as a grinder. Further, it is possible to mass-produce and supply a step in which a fixing plate that can be easily attached and used by a bolt or the like is provided on an insert or the like that is previously provided on a concrete wall at low cost.

Further, since the step of the present invention is molded with resin, it is a step which can be safely used even in a place having high durability and high humidity or a place where the groundwater level is high.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which a step according to an embodiment of the present invention is attached with a part of a handhole cut away.

FIG. 2 is a plan view showing a state in which the steps shown in FIG. 1 are attached to an inner wall of a handhole.

3 is a cross-sectional view of the step shown in FIG.

FIG. 4 is an enlarged cross-sectional view showing how the support arm and the fixing plate of the step shown in FIG. 1 are welded.

FIG. 5 is a cross-sectional view showing an example of steps in which the support arm and the fixing plate are welded at four points.

FIG. 6 is a diagram schematically showing an outline of a manufacturing process of steps according to the present invention.

FIG. 7 is a diagram outlining different steps of the present invention.

8 is a diagram showing a cross section of a connecting portion of the step shown in FIG.

FIG. 9 is a diagram showing an outline of a step in which a tip portion of a support arm is pressed to form a fixing plate.

10 is a diagram showing a cross-sectional view of a connection portion of the step shown in FIG.

FIG. 11 is a diagram showing an outline of a step in which a tip portion of a support arm is pressed and a fixing plate is formed into a substantially circular shape.

FIG. 12 is a schematic diagram of conventional steps.

   ─────────────────────────────────────────────────── ─── Continued front page       (56) Reference JP-A-9-291549 (JP, A)                 Japanese Patent Laid-Open No. 7-18963 (JP, A)                 54-137259 (JP, U)                 Actual Kaihei 3-78900 (JP, U)                 62-159556 (JP, U)                 Actual Development Sho 61-112058 (JP, U)

Claims (4)

(57) [Claims] 1. A substantially U-shaped metal footrest having support arms extending substantially vertically from both ends of the step rod, and a metal fixing plate extending substantially vertically from the tip of the support arm. Having a step in which a mounting hole is formed in this fixed plate, wherein the support arm and the fixed plate are connected by welding,
At least a welded portion of the support arm and the fixing plate and the vicinity thereof are molded with resin without post-treatment of the welded portion . 2. The step according to claim 1, wherein the periphery of the fixed plate is molded with resin. 3. The step according to claim 1, wherein the entire step is made of resin so as to cover the footrest portion and the fixing plate. 4. The step according to claim 3, wherein a non-slip concavo-convex portion is formed on a surface of a portion formed by resin so as to cover the step rod.