JP4874190B2 - Ladder stepladder - Google Patents

Description

  The present invention relates to a ladder and stepladder in which upper end portions of a pair of front and rear ladder-like legs are rotatably connected.

  6 (a) is a side view showing the use of the conventional stepladder / ladder B in the stepladder state, (b) is a sectional view taken along line XX of (a), and (c) is a ladder of the stepladder combined with step B. FIG. It is a side view which shows the use in a state. In this conventional ladder-supporting stepladder B, both rotations of a rotating metal fitting 11 formed by pivoting ear pieces 12o, 13o projecting from the upper inner edge of a pair of flat plate-like rotating members 12, 13 by pivot pins 4 are provided. The upper ends and the lower ends of the members 12 and 13 are respectively attached to the outer surface upper end portions of the pair of front and rear legs 5 and 6 by a plurality of rivets 7, 7, 8, and 8, whereby both legs 5 and 6 are attached. It is formed by pivotally connecting the upper end portion of the. Each of the front and rear legs 5, 6 is composed of a pair of left and right support columns 9, 9 and a plurality of step bars 10 laid across between the support columns 9, 9.

  FIG. 7 shows in detail the positional relationship between the rotary metal fitting 11 and the rivets 7 and 8 when the conventional ladder combined stepladder B is used in the ladder state. The rivet 7 is a rivet in which the upper ends of the rotating members 12 and 13 are respectively attached to the upper end portions of the outer surfaces of the legs 5 and 6, and the rivet 8 is the lower end of the rotating members 12 and 13. , 6 are rivets that are attached to the upper end of the outer surface.

  When the ladder and stepladder are used in the ladder state, the place where the load is most applied to the column 9 of each leg 5, 6 is the central portion of the ladder. As shown in the figure, if the load in the vertical direction with respect to the support column 9 is P2, this load P2 is applied to the edge portions 15 and 16 where the left and right rotating members 12 and 13 turn and the upper end portions meet each other. Become. Thus, due to this load P2, the struts 9 of the legs 5 and 6 are centered on the end Q of the butted end edges 15 and 16 of the rotating members 12 and 13 opposite to the pivot pin 4. Destroyed in the farthest and weakest places. Usually, the rotating metal fitting 11 of the aluminum alloy ladder and stepladder 11 is composed of rotating members 12, 13, struts 9, rivets 7, 8. The weakest place is the end Q on the opposite side of the pivot pin 4. This is a place with a mounting hole (not shown) for the rivet 8 which is the farthest from the center.

  However, referring to FIG. 7 showing the positional relationship between the rotary metal fitting 11 and the rivets 7 and 8 of the conventional ladder-supporting stepladder B, a plurality of lower members of the rotary members 12 and 13 are attached to the legs 5 and 6 side. Since the rivets 8 and 8 are not aligned on the circumference C1 having the radius R1 from the center Q, when a load P2 in the vertical direction is applied to the column 9 on the condition that they are all fixed with the same rivet, The rivet 8 (especially 8a) on the circumference C1 having the radius R1 farthest from the center Q receives the load P2 and is broken.

  When the rivet 8a on the circumference C1 with the farthest radius R1 is broken, the rivet 8 at the second furthest position, that is, the rivet 8 inside the circumference C1 (on the circumference C1 with the radius R2 from the center Q) In particular, 8b) is destroyed. Since radius R2 is closer than radius R1, it will be broken with a lower load than rivet 8a. If rivet 8a is broken, rivets located closer to it will be broken one after another. Become.

  In view of the above problems, an object of the present invention is to provide a ladder and stepladder having a structure capable of withstanding a breaking load when used in a ladder state.

Means for solving the above-described problems will be described with reference numerals in the embodiments described later. The invention according to claim 1 projects oppositely from the upper inner edge of each of the pair of flat plate-like rotating members 2 and 3. By attaching both rotating members 2 and 3 of the rotating metal fitting 1 formed by pivoting the ear pieces 2o and 3o with the pivoting pin 4 to the upper side of the outer surface of the pair of front and rear legs 5 and 6, respectively. In the ladder and stepladder formed by pivotally connecting the upper ends of the bodies 5 and 6,
Both the rotating members 2 and 3 of the rotating metal fitting 1 are attached to the upper end portions of the legs 5 and 6 by the plurality of rivets 7, 7, 8, and 8, respectively. At the same time, the plurality of rivets 8 and 8 which are attached to the lower ends of the rotating members 2 and 3 are rotated by the rotating members 2 and 3 while the ladder is in use, and the upper end edges 15 and 16 abut each other. its thrust together with the edge portions 15 and 16, wherein the pivot pin 4 is arranged on the circumference C of a predetermined radius R around the end portion O of the opposite, both rotating members of the rotating tool 1 when the 2 and 3, respectively, on the lower ends of the outer edges, on a circumference C having a predetermined radius R centered on the end O opposite to the pivot pin 4, and perpendicular to the outer edges of the rotating members 2 and 3. Displacement stoppers 17 and 18 which are bent and locked to the outer end surfaces 19 of the legs 5 and 6 are provided .

  The effect of the invention by the above solution will be described with reference numerals of the embodiments described later. According to the invention according to claim 1, the lower end portions of the rotating members 2 and 3 of the rotating metal fitting 1 are respectively connected to both legs 5. , 6, when a plurality of rivets 8, 8 are attached to each other when the upper end edges 15, 16 of both rotating members 2, 3 face each other in use in a ladder state, 16 is arranged on a circumference C having a predetermined radius R with the end O on the opposite side of the pivot pin 4 as the center, so that a plurality of rivets 8 and 8 can disperse the breaking load and withstand the structure. Therefore, the durability of the rotating metal fitting 1 is improved, and the service life of the ladder-supporting stepladder A can be greatly extended.

Further , according to the present invention, since the displacement stoppers 17 and 18 are provided, even when the lower end side of each of the rotating members 2 and 3 is pulled inward when a vertical load P2 is applied to the support column 9, By receiving the tensile force by the displacement stoppers 17 and 18, it is possible to prevent the rivets 8 from being displaced at the lower ends of the rotary members 2 and 3.

  A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 (a) is a side view showing the use of the stepladder and stepladder A according to the present invention in a stepladder state, and FIG. 1 (b) is a ladder state. It is a side view which shows the use in. In this ladder combined stepladder A, like the conventional ladder combined stepladder B shown in FIG. 6, the ear pieces 2o and 3o projecting from the upper inner edge of each of the pair of flat plate-like rotating members 2 and 3 are pivotally attached to the pin 4 A plurality of rivets 7, 7, 8 are respectively connected to the upper and lower ends of the pair of front and rear legs 5, 6. , 8, the upper ends of both legs 5, 6 are pivotally connected, and each of the front and rear legs 5, 6 is placed between a pair of left and right struts 9, 9 and both struts 9, 9. It is composed of a plurality of pedestals 10 to be mounted.

  When this ladder combined stepladder A is used in the ladder state, the place where the most load is applied to the supports 9 of the stepladders 5 and 6 is the center of the ladder as shown in FIG. 2, and the vertical downward load at this time is P1. The At this time, as shown in FIG. 3, if the load in the vertical direction with respect to the support column 9 is P2, the load P2 is rotated by the left and right rotating members 2 and 3, and the edge portions 15 and 16 where the upper end portions meet each other. (Mating surface). Due to this load P2, the struts 9 of the legs 5 and 6 are weakest farthest from the end O on the opposite side of the pivot pin 4 of the butted end edges 15 and 16 of the rotary members 2 and 3. Destroyed in place. Usually, the circumference of the rotary metal fitting 1 of the aluminum alloy ladder and stepladder is constituted by the rotating members 2 and 3, the support 9 and the rivets 7 and 8, and the weakest place is the end opposite to the pivot pin 4. This is a place where the mounting hole 8o (see FIGS. 4 and 5) of the rivet 8 located farthest from the portion O is located.

  Under the conditions as described above, the position where the ordinary ladder and stepladder is the weakest in strength is determined, and the ladder and stepladder A according to the present invention has a structure capable of withstanding the breaking load at one place.

  That is, in the ladder-supporting stepladder A according to the present invention, the rotating metal fitting 1 protrudes from the upper part of the inner edge of each of the pair of plate-like rotating members 2 and 3, similarly to the conventional rotating metal fitting 11 shown in FIGS. 6 and 7. Ear pieces 2o and 3o are pivotally attached to each other by means of a pivot pin 4, and both rotary members 2 and 3 have upper end portions and lower end portions, respectively, that are upper end portions on the outer surfaces of the columns 9 of both legs 5 and 6. A plurality of upper end rivets 7 and 7 and lower end rivets 8 and 8 are attached to the side, and the lower ends of both rotary members 2 and 3 are attached to the legs 5 and 6 respectively. The rivets 8 and 8 of the above-described rivets 8 and 8 are the pivots of the end edges 15 and 16 which are abutted when the rotating members 2 and 3 are turned and the upper end edges 15 and 16 abut each other. Arranged on a circumference C having a predetermined radius R centered on the end O opposite to the contact pin 4 It is, has become thereby withstand and distribute the breaking load of a plurality of lower end rivet 8,8 structure.

  In addition, the lower end portions of the outer edges of both the rotating members 2 and 3 of the rotating metal fitting 1 are on a circumference C having a predetermined radius R centered on the end O and perpendicular to the outer end edges of the rotating members 2 and 3. By providing the slip stoppers 17 and 18 which are bent and locked to the outer end surface of the support column 9, the slip stoppers 17 and 18 together with the rivets 8 and 8 can withstand a breaking load. The displacement stoppers 17 and 18 support the tensile force on the outer end surface 19 of the column 9 because the lower ends of the rotary members 2 and 3 are pulled inward when a vertical load P2 is applied to the column 9. Thus, the rivets 8 and 8 at the lower ends of the rotating members 2 and 3 are prevented from being displaced.

  As described above, the lower end portions of the rotating members 2 and 3 of the rotating metal fitting 1 are brought into contact with each other when the upper end edges 15 and 16 of the rotating members 2 and 3 are in contact with each other when used in a ladder state. The leg portions 15 and 16 have a plurality of lower end rivets 8 and 8 arranged on a circumference C having a predetermined radius R centered on an end O opposite to the pivot pin 4. By attaching to the support pillars 5 and 6, it becomes a structure that can disperse the breaking load with the plurality of lower end rivets 8 and 8, so that the durability of the rotating metal fitting 1 is improved, and the ladder stepladder is also used. The service life of A can be greatly extended.

  4 shows one rotating member 2 of the rotating metal fitting 1. FIG. 4A is a front view, FIG. 4B is a left side view, and FIG. 4C is a plan view. As shown in FIG. 4, the rotating member 2 is provided with, for example, two rivet mounting holes 7o for mounting the rivets 7 on the upper end portion, and rivet mounting holes 8o for mounting the rivets 8 on the lower end portion. For example, two are provided, and the stopper 17 is provided at the lower end of the outer edge of the rotating member 2 in a state of being bent at a right angle. Further, a hole 4o for attaching the pivot pin 4 is provided at the tip of the ear piece 2o. Further, the upper end edge 15 of the rotating member 2 is formed by being bent at a right angle from the upper end of the main body of the rotating member 2 as shown in the side view of FIG.

  5A and 5B show the other rotating member 3 of the rotating metal fitting 1. FIG. 5A is a front view, FIG. 5B is a left side view, and FIG. 5C is a plan view. As shown in FIG. 5, the rotating member 3 is provided with two rivet mounting holes 7o for mounting the rivets 7 at the upper end, and two rivet mounting holes 8o for mounting the rivets 8 at the lower end. Further, a displacement stopper 18 is provided at a lower end portion of the outer edge of the rotating member 3 in a state bent at a right angle. A hole 4o for attaching the pivot pin 4 is provided at the tip of the ear piece 3o. The upper end edge 16 of the rotating member 3 is formed by being bent at a right angle from the upper end of the main body of the rotating member 3 as shown in the side view of FIG.

(a) is a partially enlarged side view showing the use of the stepladder and stepladder according to the present invention in a stepladder state, and (b) is a partially enlarged side view showing the use in a ladder state. It is a whole side view in the ladder use state of the ladder combined stepladder concerning the present invention. Side view showing a state in which a vertical load is applied to the column in the ladder use state of the ladder also used as a ladder, (b) is a partially enlarged view of (a), and is an explanatory view showing in detail the positional relationship between the rotating metal fitting and the rivet. . FIG. 2 shows one rotating member of the rotating metal fitting, in which (a) is a front view, (b) is a left side view, and (c) is a plan view. The other rotating member of the rotating metal fitting is shown, (a) is a front view, (b) is a left side view, and (c) is a plan view. (a) is a side view showing the use of a conventional stepladder and stepladder in the stepped state, (b) is a cross-sectional view taken along the line XX of (a), and (c) is the use of the stepladder and stepladder in the ladder state. FIG. It is explanatory drawing which shows in detail the positional relationship of a rotary metal fitting and a rivet in the use in the ladder state of the conventional ladder combined use stepladder.

Explanation of symbols

A Ladder stepladder 1 Rotating metal fittings 2, 3 Rotating member 4 Pivoting pins 5, 6 Leg body 7 Rivet 8 that attaches the upper end of the rotating member 8 Rivet 9 that attaches the lower end of the rotating member 9 Leg support 15 16 Upper edge 17 and 18 of rotation member Shifting stop B Conventional ladder and stepladder

Claims (1)

A pair of front and rear rotating members 2, 3 of a rotating metal fitting 1 formed by pivoting ear pieces 2 o, 3 o projecting from the upper inner edge of each of the pair of flat plate-like rotating members 2, 3 with a pivot pin 4. In the ladder and stepladder formed by pivotally connecting the upper ends of both legs 5 and 6 by attaching to the upper ends of the outer surfaces of the legs 5 and 6, respectively,
Both the rotating members 2 and 3 of the rotating metal fitting 1 are attached to the upper end portions of the legs 5 and 6 by the plurality of rivets 7, 7, 8, and 8, respectively. At the same time, the plurality of rivets 8 and 8 which are attached to the lower ends of the rotating members 2 and 3 are rotated by the rotating members 2 and 3 while the ladder is in use, and the upper end edges 15 and 16 abut each other. its thrust together with the edge portions 15 and 16, wherein the pivot pin 4 is arranged on the circumference C of a predetermined radius R around the end portion O of the opposite, both rotating members of the rotating tool 1 when the 2 and 3, respectively, on the lower ends of the outer edges, on a circumference C having a predetermined radius R centered on the end O opposite to the pivot pin 4, and perpendicular to the outer edges of the rotating members 2 and 3. ladders and characterized in that the displacement stop 17, 18 for locking the outer end surface 19 of the bent has been leg 5,6 are provided Stepladder.

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