JP2010047924A - Stepladder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a stepladder closing operation from being inhibited by a collision between rungs of front and rear legs, when the stepladder closing operation is performed, and to make the rung as wide as possible. <P>SOLUTION: A movable rung 42 of the front leg 11 is connected to a rear edge of a fixed rung 41 of the front leg 11 in such a manner as to be swingable on a swing axis line C elongated in parallel with an opening/closing axis line O, and a movable rung 42 of the rear leg 11 is connected to a front edge of the fixed rung 41 of the rear leg 11 in such a manner as to be swingable on the swing axis line C elongated in parallel with the opening/closing axis line O. The closing motion of shifting both the legs 11 to a closing attitude from an opening one is performed. Thus, the movable rungs 42 of the rungs 23 of both the legs 11 are brought into contact with each other and pushed to swing upward. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a stepladder used for work at a high place, for example.

  This type of stepladder has front and rear legs that are connected to each other so as to be openable and closable. Each leg has a pair of left and right support columns spaced apart from each other in the left and right direction and a step that is passed to both support columns. What is equipped with a gap is known.

  When using a stepladder, the wider the step, the easier it is to perform stable work. In many cases, the stepladder is assembled in such a manner that both the left and right ends of the step are inserted into the two columns, and both are fixed to each other. In that case, the width of the step must be less than or equal to the width in the front-rear direction of the column, and there was a limit to increasing the width of the step.

  On the other hand, in order to widen the width of the step, except for the left and right ends of the step, which are inserted into the column, the middle of the step is projected from either side of the column to either the front or back side. There is also an example in which an extended portion is provided, and the width of the step is increased by the amount of the extended portion.

  However, even in this example, there was a limit to increasing the width of the step. The reason is as follows. When the stepladder is in a closed state, it is preferable that the lower end portions of the front and rear legs are brought into contact with each other for the convenience of transportation and storage of the stepladder. In this case, if the width of the step is made too wide when the stepladder is closed, the tips of the extension portions of the front and rear legs collide with each other and the lower ends of the front and rear legs are completely brought into contact with each other. It becomes impossible to do.

  An object of the present invention is to provide a stepladder that can prevent the stepping action of the front and rear legs from colliding with each other when the stepping action is closed, thereby preventing the stepping action and making the width of the stepping step as wide as possible. It is in.

  The stepladder according to the present invention includes front and rear legs that are connected to each other so as to be openable and closable around an open / close axis extending in the left-right direction, and each leg includes a pair of left and right support columns spaced from each other in the left-right direction; Steps for each leg consist of a fixed step and a movable step, and the left and right ends of the fixed step for each leg are on the left and right sides The movable leg of the front leg is at the rear edge of the stationary leg of the front leg, and the movable leg of the rear leg is at the front edge of the stationary leg of the rear leg, parallel to the opening / closing axis. Centering on the extended swing axis, they are connected to each other so that they can swing, and by moving the both legs from the open position to the closed position, the movable steps of the steps of both legs come into contact with each other and When pressed, the movable step on both legs swings upward Possible are those that are.

  In the stepladder according to the present invention, with the closing operation of both legs, the movable steps of the front and rear legs are brought into contact with each other and pressed to be swung upward. Therefore, when the stepladder closing operation is performed, it is possible to prevent the stepping of the front and rear legs from colliding with each other and hindering the leg closing operation. Therefore, the width of the step can be increased.

  In addition, a stopper is provided for restricting the downward swing of each leg of the movable step, and when the legs are opened, the downward swing of the movable step is restricted by the stopper. If the top surface of the stationary step and the top surface of the movable step can be held flush, a wide tread surface can be stably secured when the stepladder is used.

  In addition, when the downward swing of the movable step of each leg is restricted, the tip of the movable step of both legs comes into contact with each other when performing the closing operation from the open position of both legs to the closed position. And if it is made to press, the movable step of both legs can be rock | fluctuated upwards stably and reliably.

  In addition, when the closing movement from the open position of both legs to the closed position is performed with only the movable step of one leg of both legs restricted by the stopper, If the tip and the bottom surface of the other movable step are in contact with each other and pressed, the stepladder can be closed regardless of the posture of the other movable step when closing the stepladder. it can.

  Moreover, when the escape for avoiding interference with the tip of one movable step is formed on the bottom surface of the other step, the stepladder can be smoothly closed.

  Each strut has a U-shaped cross section and has opposing front and rear walls extending in parallel with each other, and both struts of each leg are arranged so that the front ends of the front and rear walls are opposed to each other. The left and right ends of the fixed step are inserted between the front and rear walls of both struts of each leg, and the movable step is projected backward from between the tips of the rear walls of both front struts. It is preferable that a movable step is projected forward from between the front ends of the front walls of both pillars of the rear leg.

  According to the present invention, there is provided a stepladder in which the width of the step is made as small as possible so that the steps of the front and rear legs do not collide when the stepladder is closed.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the following description, the direction indicated by the arrow A is referred to as the front and the opposite side is referred to as the rear, and the left and right are the left and right sides when viewed from the front.

  As shown in FIG. 1, the stepladder is connected to the front and rear legs 11 and the tops of both sides of the legs 11 respectively, and the legs 11 are connected to each other so that the legs 11 can be opened and closed around an opening / closing axis O extending in the left-right direction. A pair of rotating metal fittings 12 and a pair of opening metal fittings 13 respectively passed to both side surfaces of both legs 11 at positions immediately below the two rotating metal fittings 12.

  Both legs 11 have the same structure, although the front and rear directions are opposite. Hereinafter, the front leg 11 will be described, and portions corresponding to the front leg 11 of the rear leg 11 will be denoted by the same reference numerals and description thereof will be omitted. In the following, description for identifying the front and rear legs is omitted unless particularly necessary.

The legs 11 are passed to both struts 21 at a position below the top plate 22 and a pair of left and right struts 21 spaced apart from each other, a top plate 22 passed to the tops of both struts 21 As shown in FIG. 1, only the upper step 23 is shown in FIG. 1, but one step 24 is also passed to the lower step (FIGS. 4 and 5).

  Each support column 21 is made of an aluminum extrusion mold material having a U-shaped cross section, and is formed with opposing front and rear walls 31 and 32 extending in parallel with each other and one of the opposing edges of the front and rear walls 31 and 32. It consists of a communicating side wall 33. Both struts 21 are arranged so that the front ends of the front and rear walls 31 and 32 are opposed to each other.

  Each step 23 includes a fixed step 41 and a movable step 42 connected to the rear edge of the fixed step 41 so as to be swingable up and down. Both the fixed step 41 and the movable step 42 are made of an aluminum extrusion mold. The swing axis C of the movable step 42 extends parallel to the opening / closing axis O.

  The fixed step 41 has a length equal to or less than the distance between the side walls 33 of both struts 21 and a width equal to or less than the distance between the front and rear walls 31, 32 of each strut 21. .

  The left and right ends of the fixed step 41 are inserted between the front and rear walls 31 and 32 of the column 21 on the corresponding side. In this state, both the struts 21 and the fixed step 41 are fixed by rivets (not shown).

  The movable step 42 has a length equal to the distance between the tips of the front and rear walls 31 and 32 of both columns 21.

  2 and 3 show in detail the cross sections of the fixed step 41 and the movable step 42. FIG. 2 shows a state where the movable step 42 is located at the lower limit of the swing range, and FIG. 3 shows a state where the movable step 42 is located at the upper limit.

  The stationary step 41 has a substantially square cylindrical shape close to a square cross section, and includes a top wall 51, a rear wall 52, a bottom wall 53, and a front wall 54.

  Similar to the stationary step 41, the movable step 42 includes a top wall 61, a rear wall 62, a bottom wall 63, and a front wall 64, but has a rectangular cylindrical shape close to a cross-sectional triangle.

  First, the fixed tread 41 will be described in detail. The top surface of the top wall 51 forms a tread surface, on which a plurality of parallel non-slip ribs 71 are formed. A cross-sectional semicircular arc-shaped fitting groove 72 is formed in a rearward direction at a corner where the top wall 51 and the rear wall 52 intersect. On the upper edge portion of the fitting groove 72, an engagement convex portion 73 is provided downward. The front end surface of the engaging convex portion 73 is a convex arc surface. The swing axis C of the movable step 42 passes through the center of the arc formed by the distal end surface of the engagement convex portion 73. The bottom surface of the fitting groove 72 is formed in a concave arcuate surface centered on the swing center C.

  At the corners where the rear wall 52 and the bottom wall 53 intersect, a substantially inverted L-shaped stopper protrusion 74 having a transverse cross section that protrudes rearward and downward is provided. A complementary groove 75 is formed above the base of the stopper protrusion 74. In front of the base of the stopper protrusion 74, a guide wall portion 76 that extends in an arc shape around the swing axis C of the movable step 42 is provided.

  Next, the movable step 42 will be described. A parallel anti-slip rib 81 is formed on the top surface of the top wall 61 corresponding to the tread surface of the fixed tread 41. The front wall 64 is substantially equal to the height of the rear wall 52 of the fixed step 41 and is made to be opposed thereto. At the corner portion where the top wall 61 and the front wall 64 intersect, a fitting protrusion 82 having a substantially T-shaped cross section fitted in the fitting groove 72 is provided in a forward protruding manner. At the base portion of the fitting protrusion 82, an engagement recess 83 is formed upwardly in which the engagement protrusion 73 is engaged from the front. Near the lower end of the front surface of the front wall 64, a complementary protrusion 84 corresponding to the complementary groove 75 is provided. The bottom wall 53 includes a flat portion 85 and a concave arc portion 86 connected to the rear edge thereof. A convex arc-shaped cover wall portion 87 is provided continuously to the front edge of the arc portion 86. The center of the arc formed by the cover wall portion 87 is aligned with the swing axis C of the movable step 42. An engaging convex edge portion 88 is provided upward on the front edge portion of the cover wall portion 87. The rear wall 52 is generally flat and is inclined rearward and obliquely downward.

  By sliding the fixed step 41 and the movable step 42 relatively in the length direction, the fitting groove 72 and the fitting protrusion 82 are fitted, whereby the fixed step 41 and the movable step 42 are fitted. Is achieved. In a state where the fixed step 41 and the movable step 42 are connected, the movable step 42 is protruded rearward from the rear walls 52 of both columns 21.

  In FIG. 2, the complementary groove 75 and the complementary protrusion 84 complement each other. The guide wall 76 is covered with a cover wall 87 from below. The front end of the engaging convex edge portion 88 is in sliding contact with the guide wall portion 76. A portion below the complementary protrusion 84 is brought into contact with the rear surface of the front end of the stopper protrusion 74 from the front side, and thereby the downward swing of the movable step 42 is restricted. In other words, the rearward facing surface of the stopper protrusion 74 forms the lower limit stopper 91 of the movable step 42.

  In FIG. 3, an opening that extends greatly downward is formed between the rear wall 52 of the fixed step 41 and the front wall 64 of the movable step 42, and a cover wall portion 87 is covered with this opening. Thereby, it is possible to prevent a finger or the like from being sandwiched between the rear wall 52 and the front wall 64. An engagement convex edge portion 88 is brought into contact with the front end front surface of the stopper protrusion 74 from the rear side, and thereby the upward swinging of the movable step 42 is restricted. In other words, the base end front surface of the stopper protrusion 74 forms the upper limit stopper 92 of the movable step 42.

  Next, the opening / closing operation of the leg 11 will be described with reference to FIGS. 4 and 5, the right side is the front, and the opposite side is the back.

  FIG. 5A shows the stepladder in use, and the front and rear legs 11 are in an open state. The angle θ1 with respect to the horizontal line of the front and rear legs 11 is about 75 °. The steps 23 of the front and rear legs 11 are all horizontal. That is, the top surfaces of the fixed step 41 and the movable step 42 of each step 23 are included in the same horizontal plane. The lower limit stopper 91 restricts the downward swing of the movable step 42.

  When the front and rear legs 11 are closed from the state shown in FIG. 5 (a), the angle with respect to the horizontal line is increased while the top surfaces of both movable steps 42 are included in the same plane. Eventually, as shown in FIG. 5 (b), the tips of the stepping feet 23 of the front and rear legs 11 are brought into contact with each other for the first time. At this time, the angle θ2 formed by the top surfaces of the fixed step 41 and the movable step 42 of each step 23 with respect to the horizontal line is about 13 °. From this state, when both legs 11 are pressed further in the closing direction, the contact point S of the two stepping stools 23 is positioned at a level higher than the swing axis C of each movable pedestal 42, so that it acts on both legs 11. A part of the pressing force to be applied acts to lift the tip portions of the two movable stepping shoes 42 upward.

  As the tips of the two movable steps 42 are lifted, the top surface of the fixed step 41 and the top surface of the movable step 42 are flush with the tips of the two movable steps 42 kept in contact. The angle is gradually narrowed from 180 degrees. In FIG. 5 (c), both legs 11 are parallel to each other. That is, the angle of both legs 11 with respect to the horizontal line is 90 °.

  In FIG.5 (d), both the legs 11 are closed completely and the lower ends of both the legs 11 are made to contact. At this time, the angle θ3 with respect to the horizontal line of both legs 11 exceeds 90 ° by about 7 °. The bottom surfaces of both movable step ridges 42 are opposed to each other in a substantially vertical plane with a slight gap therebetween.

  The above is an explanation of the case where both the movable step 42 are positioned at the lower limit of the movable range when both legs 11 are closed. However, when both legs 11 are closed, both movable step 42 are not necessarily positioned at the lower limit, and at least one of both movable steps 42 is positioned somewhere within its swing range. There is also a possibility.

  FIG. 5 shows that when the legs 11 are closed, the upper movable stopper 42 is restricted from swinging upward by the upper limit stopper 92, and the lower movable stopper 42 is restricted from swinging downward by the lower limit stopper 91. The case is shown.

  FIG. 5 (a) shows a state when the two movable steppers 42 are brought into contact with each other for the first time. The tip of the front movable step 42 is brought into contact with the bottom surface of the rear movable step 42. When both legs 11 are further closed from this state, the bottom surface of the rear movable step 42 is kept in contact with the front end of the front movable step 42 while the bottom surface of the rear movable step 42 is in contact. Accordingly, the tip of the movable step 42 on the front side is pushed up. The situation at this time is shown in FIG. When both legs 11 are finally closed, it is as shown in FIG.

  Here, the manner in which the front movable step 42 moves along the bottom surface of the rear movable step 42 will be examined in detail.

  In FIG. 6, three first to third oscillating axes C1, C2, and C3 are plotted from the front to the rear on the rotation radius R of the oscillating axis C with the opening / closing axis O as the center. Three first to third contact points S1, S2, S3 of the movable step 42 corresponding to the first to third swing axis C1, C2, C3 are shown in order from the bottom. These first to third contact points S1, S2, and S3 are on the arc portion 86. The first contact point S1 is a point where both the movable step 42 first contact each other. The third contact point S3 is a point where both the movable step 42 finally come in contact and leave. The second contact point S2 is an intermediate point between the first contact point S1 and the third contact point S3, and the distances from the first contact point S1 and the third contact point S3 are substantially equal. This means that when the legs 11 are closed, the distance to which the swing axis C1, C2, C3 moves and the tip of the front movable step 42 moves along the arc 86 of the rear stepping step 42. The distances S1, S2, and S3 to be balanced mean that the swing speed of the front movable step 42 is constant at that time. That is, the push-up force that is applied to push up the movable step 42 is constant, for example, due to the friction coefficient and the like, and an unreasonable force cannot be applied to the movable step 42.

  As a comparative example, it is assumed that there is no arc portion 86 on the bottom surface of the rear movable step 42 and the entire bottom surface of the rear movable step 42 is flat. As shown in FIG. 7, the positions of the first contact point S1 and the third contact point S3 are the same as those shown in FIG. However, the fourth contact point S4 is shown between the first contact point S1 and the third contact point S3. The fourth contact point S4 corresponds to the second contact point S2, but the distance from the first contact point S1 to the fourth contact point S4 is the distance from the third contact point S3 to the fourth contact point S4. Is bigger than. This means that the front end of the movable step 42 is moved from the first contact point S1 to the fourth contact point S4 at a considerably high speed, and thereafter moved at a considerably slow speed. During this time, it means that an unreasonable force due to friction or the like acting between the two movable steps 42 is applied to the front end of the movable step 42.

  6 and 7, it can be seen that the arc portion 86 forms a relief that does not hinder the smooth swinging of the front movable step 42, so that both movable steps 42 do not interfere with each other. I understand that.

It is a perspective view of the stepladder by this invention. It is a cross-sectional view of the step of the stepladder showing a state where the movable step is located at the lower limit. It is a cross-sectional view of the step of the stepladder showing a state where the movable step is located at the upper limit. It is opening / closing operation explanatory drawing of the stepladder. It is opening / closing operation | movement explanatory drawing which shows an aspect different from FIG. 4 of the stepladder. It is explanatory drawing which shows the opening / closing operation | movement shown in FIG. 5 of the stepladder in detail. It is explanatory drawing corresponding to FIG. 6 which shows the comparative example of the stepladder.

Explanation of symbols

11 legs
21 Prop
23 stepping on
41 Fixed step
42 Movable step
O Open / close axis
C Oscillation axis

Claims (6)

  It has front and rear legs that are connected to each other so as to be openable and closable around an open / close axis that extends in the left-right direction. Each leg is composed of a fixed step and a movable step, and the left and right ends of each leg's fixed step are fixed to the left and right corresponding posts, The movable leg of the front leg is at the rear edge of the stationary leg of the front leg, and the movable leg of the rear leg is at the front edge of the stationary leg of the rear leg, centering on the swing axis that extends in parallel with the opening and closing axis. As shown in the figure, the movable steps of both legs are brought into contact with each other and pressed by causing the closing movement of both legs from the open position to the closed position to be brought into contact with each other and pressed. A stepladder where the movable step can swing upward.   Each leg is equipped with a stopper that controls the downward swing of the movable step. When both legs are open, the downward swing of the movable step is restricted by the stopper. The stepladder according to claim 1, wherein the top surface of the fixed step and the top surface of the movable step can be held flush with each other.   When the downward swinging of the movable step of each leg is restricted, the tips of the movable step of both legs are in contact with each other and pressed when performing the closing operation from the open position of both legs to the closed position. The stepladder according to claim 2, wherein the stepladder is adapted to be used.   When the closing movement from the open position of both legs to the closed position is performed with only one movable step of both legs restricted by the stopper, The stepladder according to claim 2, wherein the bottom surface of the other movable step is in contact with and pressed against each other.   The stepladder according to claim 4, wherein a relief for avoiding interference with a tip of one movable step is formed on a bottom surface of the other step.   Each strut has a U-shaped cross section and has opposing front and rear walls that extend in parallel to each other, and both struts of each leg are arranged so that the front ends of the front and rear walls are opposed to each other. The left and right ends of the fixed step are inserted between the front and rear walls of both struts of each leg, and the movable step is projected rearward from between the tips of the rear walls of both struts of the front leg. The stepladder according to any one of claims 1 to 5, wherein a movable step is protruded forward from between the front ends of the front walls of both legs.

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