JP3384982B2 - Ladder legs such as stepladders - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ladder-like leg such as a stepladder, a ladder, and a workbench. 2. Description of the Related Art A ladder-like leg such as a stepladder is composed of a pair of side frames on both sides and a step crossed at required intervals in the longitudinal direction between the side frames. If the length is long, the strength of the side frame is a major problem.To improve the strength of the side frame, conventionally, the side frame is called a main side frame,
A proposal has been made in which a secondary side frame for reinforcement arranged along this side and a plurality of connecting pieces connecting the both side frames are formed. [0003] In the production of the side frames reinforced as described above, for example, a rectangular cylindrical aluminum extruded material is used for each of the main side frame and the sub side frame, and the side frames are connected. Since short pieces of suitable aluminum extrusions are used for the parts and they are joined together by welding, the number of processing steps by welding increases, and it takes much time and effort to manufacture the side frame. There was a problem that it was time-consuming and costly. Accordingly, the present invention can improve the strength of the side frame, and requires a small number of processing steps, is easy to manufacture, and is a ladder-like leg such as a stepladder having a lightweight and good design in the side frame. The purpose is to provide the body. [0005] The invention according to claim 1 is:
In a ladder-like leg such as a stepladder, which comprises a pair of side frames 5 and 5 on both sides and a step 6 which is laid between the side frames 5 and 5 at a required interval in the longitudinal direction, each side frame 5 is a pair. together they are formed by aluminum extrusion consisting of parallel tubular portions 7 between the two tubular portions 7 a connecting plate portion 8 Prefecture, number of openings 9 are opened in the plate portion 8, each Stepping Pier 6 is a
Formed by extruded luminium
The plate-like portion 8 and the tubular portions forming the both-side frames 5, 5
7, 7 are formed to conform to the shape of the outer surface,
Both ends of the step 6 contact the plate-like portion 8 and each
To engage with the tubular portions 7, 7 and engage with the tubular portions 7, 7
Characterized in that both ends 15 of the step rail 6 are joined by welding . FIG. 1A is a front view showing a tripod with a three-point support structure in a folded state, and FIG. 1B is a side view thereof. 2 is a side view of the tripod in the use state. This tripod stepladder has a ladder-like leg 1 which is opened in a substantially U-shape as shown in FIG. 1A, and a rod-like support leg which is arranged on the rear side of the ladder-like leg 1. 2 and
The upper end of the ladder-like leg 1 is fixed to the top plate 3, and the upper end of the bar-like support leg 2 is pivotally connected to the top plate 3 so as to be openable and closable. In use, as shown in FIG. 2, a stopper 4 such as a chain is used in a state where both legs 1 and 2 are opened at a required angle back and forth.
Thus, the two legs 1 and 2 are held. As shown in FIG. 1A, a ladder-like leg 1 is provided with a pair of side frames 5, 5 arranged on both sides in a substantially C-shape.
And a plurality of steps 6 laid horizontally on both sides of the frame 5 at a required interval in the longitudinal direction. As shown in detail in FIGS. 1B and 2 and FIGS. 3 to 4, each side frame 5 has a pair of tubular portions 7, 7 extending in parallel at regular intervals, and both tubular portions 7, 7. Are formed by an aluminum extruded material comprising a plate-shaped portion 8 connecting the two, and a large number of openings 9 are opened in the plate-shaped portion 8, and are punched and formed by, for example, a punching press device. Each tubular portion 7 has a substantially cylindrical shape. As shown in FIGS. 4 (A) and 4 (B), the tubular portion 7 of the extruded aluminum material forming each side frame 5 has, on its outer peripheral surface, a ridge portion 7a and a concave ridge portion extending in the longitudinal direction. 7b are provided alternately in the circumferential direction. As can be seen from FIG. 3, the opening 9 of the plate-shaped portion 8 is formed in a triangular shape with rounded corners, and each opening 9 is formed with an adjacent opening 9.
Are formed in a line in the plate-like portion 8 in such an arrangement that the right and left are alternately reversed. Note that the shape and arrangement of the openings 9 are merely examples, and the openings 9 can be formed in the plate-like portion 8 in any shape and arrangement. If the dimensions of the extruded aluminum material forming the side frame 5 are shown for reference, the total length L is, for example, 22
00 mm, the width Wa is 85 mm, the width Wb of the plate portion 8 is 42 mm, its thickness is 2 mm, the outer diameter of the tubular portion 7 is about 20 mm, and its wall thickness is about 1.5 mm. The length of one side of the triangular opening 9 formed in the plate portion 8 is about 40 mm, and for example, about 50 openings are formed in the plate portion 8. The side frame 5 having the above structure is cut to a predetermined length (for example, 2200 mm), and is cut in FIG.
As shown in (1), the upper end is fixed to the top plate 3 by welding or the like, and the wide grounding member 10 is fixed to the lower end.
In addition, a reinforcing bar 11 is appropriately attached between the side frame 5 and the top plate 3. The grounding member 12 is also attached to the lower end of the rod-shaped support leg 2 as a matter of course. As described above, each side frame 5 of the ladder-like leg 1
Is formed by an aluminum extruded material consisting of a pair of parallel tubular portions 7, 7 and a plate-shaped portion 8 connecting the two tubular portions 7, 7, so that the two tubular portions 7, 7 and the plate-shaped portion 8 connecting these are formed. As a result, the strength of the side frame forming the ladder-like leg 1 can be sufficiently improved, and no welding work is required to manufacture the side frame 5, so that the number of processing steps can be reduced as much as possible, and the manufacturing cost can be reduced. Can be greatly reduced. Further, since a large number of openings 9 are formed in the plate-like portion 8 connecting the two tubular portions 7, 7, the weight can be reduced by the amount of the openings 9, and the ladder-like leg 1 can be reduced. In addition to reducing the weight, the opening 9 can improve the design. In particular, various excellent design effects can be obtained depending on the shape of the openings 9 and the arrangement relationship thereof. FIG. 5 exemplifies a short step 6 on the upper side of a plurality of steps 6 laid between a pair of side frames 5 on both sides, and shows a plan view thereof. 5 is a sectional view taken along the line Y-Y in FIG. 5, and FIG. 7 is a plan view showing a state where the end of the step 6 is welded to the side frame 5. The step 6 is formed of an aluminum extruded die, and as shown in FIG. 6, a pair of square tubular portions 13, 13 and both square tubular portions 13, 1 are provided.
3 and a support plate portion 14 connecting the surfaces 3 in a plane. At the end of the step 6, a double-sided cylindrical portion 13,
Engagement recesses 15, 15 having a substantially semicircular shape in plan view for engaging the end of 13 with the tubular portions 7, 7 of the side frame 5 are formed. On each of the upper surfaces of each of the rectangular cylindrical portion 13 and the support plate portion 14, an uneven anti-slip portion 16 is provided in the longitudinal direction of the step bar 6, and the support plate portion 14 has an anti-slip effect. A plurality of openings 17 for reducing the weight are provided. As shown in FIG. 7 , in order to hang this step 6 on a pair of side frames 5, 5, the end of the support plate 14 is applied to the inner surface of the plate portion 8 of the side frame 5. At the same time, the substantially semicircular engaging recess 15 formed at the end of each of the rectangular tubular portions 13 is engaged with each of the tubular portions 7 of the side frame 5 so that the contact portions and the engaging portions are formed. Aluminum is welded and joined to obtain a state as shown in FIG. As described above, when the end of the step 6 made of the extruded aluminum material is joined to the side frame 5 by aluminum welding, the joining operation is simpler than the joining by screws or the like. 5 can be easily and easily traversed, whereby the manufacturing cost of the ladder-like leg 1 can be further reduced. Of course, the present invention uses screws, rivets,
Alternatively, it does not exclude that the step 6 and the side frames 5 and 5 are joined by crimping or the like. In the above embodiment, only the case of a tripod with a three-point support structure has been described. However, the present invention is not limited to this tripod, but may be a ladder-like leg such as a normal quadruple stepladder, a ladder, a workbench or the like. Is applied. According to the first aspect of the present invention, each side frame of the ladder-like leg is formed by an aluminum extruded material comprising a pair of tubular portions and a plate-like portion connecting the two tubular portions. Thus, the strength of the side frame forming the ladder-like legs can be sufficiently improved by the two tubular portions and the plate-shaped portion connecting them, and in order to manufacture the side frame having such improved strength. Since no welding operation is required, the number of processing steps can be reduced as much as possible, and the production cost can be reduced. Further, by providing a large number of openings in the plate-like portion connecting the two tubular portions, the weight can be reduced by the amount of the openings, and the weight of the ladder-like leg can be reduced. The design can be improved by the opening, and various excellent design effects can be exhibited, particularly depending on the shape of the opening and the arrangement thereof. Further , according to the present invention, the both ends of the step formed of the extruded aluminum material are brought into contact with the both side frames so as to conform to the outer side surface shapes of the both side frames, and both are joined by aluminum welding in that state. Further, the step can be easily and firmly laid on the both side frames, and the production cost of the ladder-like leg can be further reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a front view showing a tripod with a three-point support structure in a folded state, and FIG. 1B is a side view thereof. FIG. 2 is a side view of the tripod in a used state. FIG. 3 is an enlarged view of a portion indicated by an arrow A in FIG. 4A is a cross-sectional view taken along line XX of FIG. 3, and FIG. 4B is an enlarged view of a portion indicated by an arrow B in FIG. FIG. 5 is a plan view showing a step rail. FIG. 6 is a sectional view taken along line YY of FIG. 5; FIG. 7 is a plan view showing a state where the end of the step is welded to a side frame. [Description of Signs] 1 Ladder-like leg 5 Side frame 6 Step 7 Tubular part 8 Plate-like part 9 Opening

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Claims (1)

(57) [Claims 1] A ladder-like leg such as a stepladder comprising a pair of side frames on both sides and a step crossed between the both frames at a required interval in the longitudinal direction, Each side frame is formed of an aluminum extruded mold comprising a pair of parallel tubular portions and a plate-like portion connecting both tubular portions, and a number of openings are opened in the plate-like portion, and each of the step rails is made of aluminum. Extruded material
, Both ends of which form the side frames
To match the shape of the outer surface of the plate-shaped part and both tubular parts
When both ends of each step are abutted against the plate-shaped part,
Both engage with each tubular part, and engage with this tubular part
A ladder-like leg such as a stepladder , wherein both ends of a step rail are joined by welding .