JPH0893372A - Ladder - Google Patents

Abstract

PURPOSE: To make it possible to prevent a fit-in part of a post in an extended state from clattering in the diametral direction of the fit-in part by expanding corner parts of a sliding ring to each fit-in part of the post and pushing forcibly a sliding face-to-face area in the radial direction. CONSTITUTION: When a sliding ring 40 is mounted, there is formed a substantially triangle-shaped void between an inside of a corner and a grooved circular bottom 51 of a ring mounting groove 50. Them, the sliding ring 40 is housed in the ring groove 50 and each corner part 55 of the sliding ring 40 is pushed and fitted into the groove, thereby producing a fit-in state where a thrust force is exerted on a face-to-face area. Therefore this construction prevents the clattering of the parts and increases a manufacturing tolerance in a proper range of elastic deformation. The sliding ring 40 is extended in the peripheral direction by expanding the corner parts when they are fitted in but the elongation is absorbed by a void produced at a cut section. When the sliding ring 40 is installed to the fit-in part of a post 4 at two locations separated from each other, this serves to reinforce stability against bending.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ladder, and more particularly to a retractable ladder.

[0002]

2. Description of the Related Art As a conventional expandable / contractible ladder, there is Japanese Patent Application No. 5-157911 proposed by the applicant of the present application.
As shown in FIG. 3 to FIG. 5, the schematic structure thereof is a pair of pillar portions 4 and 4 which are arranged in parallel at a distance and have a hollow inside.
And a horizontal rail portion 6 provided between the upper ends of both of the columns.
Multiple members consisting of and (a number that is approximately equivalent to the number of ladder steps)
Are formed by sequentially changing the thicknesses of the support columns 4 and 4,
In both of the pillar portions of the thickest member 2a of the pillar portion,
Thin members 2b, 2c, 2d, ...
2n is slidably fitted from above so that the horizontal rail portions 6 of the respective members are brought into contact with each other in the vertical direction in a shortened state (the state shown in the lower half of FIG. 3), and The crosspiece 6 is formed so as to be in an extended state (a state shown in the upper half of FIG. 3) in which the crosspiece 6 is appropriately separated and the support post is fitted. The respective members are firmly coupled and formed so that the pair of support columns 4 and 4 and the horizontal cross-piece 6 are integrated. Then, as shown in FIGS. 4 and 5, the members other than the uppermost member 2n are provided in the horizontal rail portion 6 so as to project into the hollow portions of both of the columns 4 and 4 by the biasing means 12. The projecting body 10 and the supporting holes 4 and 4 fitted in the hollow portion are formed of the engaging holes 8 with which the projecting body 10 projects and engages in the extended state to maintain the extended state. An engaging portion 11 and an operating portion 36 corresponding to the engaging portion 11 are provided so as to project downward from the horizontal rail portion 6, and the operating portion 36 is pushed up to release the protruding body 11. This is a configuration in which the means 14 is provided.

The projecting body 10 of the locking means 11 is a rod-shaped body, and is composed of a body portion 16, a neck portion 18, and an end portion 20.
The body portion 18 is slidably supported in the through hole 24 formed in the inner support wall 22, and the tip end 28 of the body portion 16 is formed of protective rubber. The urging means 12 projects into the support column 4 from a guide hole 26 formed in the guide 25. The biasing means 12 is the support wall 2
2 is a coil spring 31 arranged in a compressed state between the spring receiving washer 30 provided in the body portion 16. Unlocking means 1
Reference numeral 4 denotes a lever that rotates about the rotary shaft 32, one end 34 of which is engaged with the neck portion 18 of the projecting body 10 and the other end of which is an operating portion 36. Reference numeral 36 denotes a state in which the projecting body 10 projects and is fitted into the engaging hole 8, and projects downward from the lower edge of the horizontal cross-piece 6 as seen in FIG. When the operating portion 36 is pushed up to the lower edge 6a of the horizontal rail portion 6, as shown in FIG. 4, the projecting body 10 retracts and comes out of the engaging hole 8. In the lowermost member 2a, the support columns 4 and 4 are slightly extended downward, the lower end is provided with a non-slip rubber plug 37, and a reinforcing horizontal bar 38 is provided.

In the shortened state, this ladder is in a state in which the horizontal rail portions 6, 6, ... Are in contact with each other vertically as seen in the lower half of FIG. Further, in the extended state, as shown in the upper half of the figure, the horizontal cross-sections 6, 6, ... Are separated to form each step of the ladder, and the locking means 11 is seen as shown in FIG. The projecting body 10 is projectingly engaged with the engaging hole 8 and the operating portion 32 of the locking releasing means 14 is projecting below the horizontal rail portion 6. To change from the extended state to the shortened state, the operating portion 36 of the locking releasing means 14 projecting downward from the horizontal rail portion 6 of the member 2a is pushed up, and the locking of the support columns 4 and 4 of the member 2b is released. Therefore, the member 2b descends due to the weight of the member itself and the members above it, and the supporting columns 4 and 4 of the member 2b are deeply fitted into the supporting columns 4 and 4 of the member 2a so that the respective horizontal crossbars 6 and 6 are formed. It comes into contact. At this time, since the operating portion 36 of the unlocking means 14 of the member 2b is relatively pushed up by the cross rail portion 6 of the member 2a, the locking of the member 2c thereon is further released, and the member 2c and itself are lifted. The member 2 d is lowered by the weight of the member, and thereby the locking of the member 2 d is released. In this way, the locked state is sequentially released from the lower one to the upper one, and the shortened state is brought about by its own weight.

[0005]

In such a retractable ladder, the locking means 11 is in the locked state in the extended state, and the vertical movement between the supporting columns is restricted, so that the conventional ladder is Can be used as well. However, in use, there is a problem that a slight gap in the fitting portion causes rattling with respect to the acting force in the bending direction between the support columns, which gives an unstable feeling. For this reason, it is conceivable to provide a sliding ring on the fitting part of the strut, but in that case, the groove bottom diameter of the ring groove for mounting the sliding ring, the pipe inner diameter forming the strut, and the thickness of the sliding ring. The rattling cannot be prevented unless the manufacturing tolerances such as the size and the like are made extremely small. If the manufacturing tolerances are too tight, it will be difficult to manufacture, and this will cause the cost to increase. It is an object of the present invention to provide a ladder in which rattling in the diametrical direction of the column portion in the extended state is removed.

[0006]

According to the means of the present invention, in the above-described expandable / contractible ladder, the strut on the small diameter side of the fitted portion of the strut in the extended state has a ring groove on the outer periphery. A sliding ring that is formed and has a polygonal shape with a substantially uniform thickness made of synthetic resin and is divided into parts in its ring groove is attached with small gaps remaining in the divided parts. It is characterized in that it is fitted in the portion via the sliding ring. In the above-mentioned means, the sliding ring is provided in the vicinity of both ends of the fitted portion of the column portion in the extended state.
It is better to install them separately in different places.

[0007]

Since the sliding ring in the means of the present invention has a polygonal shape having a substantially uniform thickness, a substantially triangular void is formed between the inside of the corner and the groove mounting groove bottom in the mounted state. Also, an arcuate space is formed between the outer side of the straight part and the inner peripheral surface of the column part. Now, assuming that the sliding ring is housed in the ring groove and is fitted into the circumscribing circular hole having an inner diameter slightly smaller than the circumscribing circular hole of the sliding ring, each corner of the sliding ring is fitted in a state in which it is expanded. . Therefore, if the diameter of the circumscribing circular hole is determined so that the respective corners are spread out within the range of elasticity of the synthetic resin, a fitting state in which a pressing force is applied between the fitting surfaces by the sliding ring is obtained, The rattling is eliminated, and the manufacturing tolerance can be increased in an appropriate range within the range of elastic deformation. The sliding ring extends in the circumferential direction when the corners are pushed apart during fitting, but the extension can be absorbed by the gap at the dividing point. When the sliding ring is provided at two separate positions in the fitting portion of the column, stability against bending is enhanced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, the sliding ring 40 and the retaining portion 41 are provided on the conventional ladder described above with reference to FIGS. Except for the sliding ring 40 and the retaining portion 41, they are the same as the conventional ladder described above, so only these will be described.

The sliding ring 40 is similarly provided on the supporting columns 4 of the members 2b, 2c, ..., 2n other than the lowermost member 2a, and one supporting column of one of the members 2b. Part 4
Will be described as an example. As shown in FIG. 1A, in the extended state, the lower end portion of the column portion 4 of the member 2b is fitted into the upper end portion of the column portion 4 of the lowermost member 2a, and the locking means 11 of the member 2a is formed.
The projecting body 10 is protruding and engaged with the engaging hole 8 of the member 2b. In this extended state, two ring grooves 50 are provided vertically apart from each other on the small diameter side of the parts fitted to each other, that is, on the outer periphery of the lower end portion of the column 4 of the member 2b, and the sliding ring 40 is provided in the grooves. They are installed respectively.

The sliding ring 40 is made of acetal resin, has a 15-sided polygonal shape and has a predetermined thickness t as shown in the plan view of FIG. Is provided, and a gap having a gap angle α (4.8 °) is formed at the dividing position while being circumscribed on the groove bottom circle 51 of the ring groove 50. The 15 corners 55 of the sliding ring 40 are formed in the same manner, as shown in an enlarged view in FIG.
In the figure, θ is 24 ° in the range of one corner. Figure 2
Indicates a state in which the sliding ring 40 is mounted in the ring groove 50 and is not fitted in the inner hole of the support column 4, and a flat, substantially triangular gap 52 is formed between the sliding ring 40 and the groove bottom circle 51. Ring 4
When a circumscribed circle 53 is drawn with respect to 0, a gap 54 is created. The inner diameter D1 of the column portion 4 of the member 2a is slightly larger than the diameter d1 of the groove bottom circle 51 plus 2t, which is twice the thickness of the sliding ring 40, and slightly smaller than the diameter D of the circumscribed circle 53. .
When it is assembled in the state of FIG. 1A, it is press-fitted, and the sliding ring 40 is elastically deformed and the gaps 52 and 5 are formed.
4 becomes smaller, the clearance angle α also becomes smaller, and an elastic pressing force acts between the fitting surfaces.

As shown in FIG. 1A, the retaining portion 41 is located at a position where the sliding ring 4 is provided in a fitting range in which the supporting column 4 is fitted in the extended state of the ladder. It is provided on the upper side. The retaining portion 41 is an annular convex portion 60 of the inner hole of the member 2a and an annular convex portion 61 of the outer periphery of the member 2b,
The state shown in the drawing is a state immediately before the protrusions 60 and 61 come into contact with each other, and they do not come into contact with each other when the locking means 11 is operating.
This is to prevent the retaining portion 41 from engaging with the support portion 4 if there is a portion where the locking means 11 does not act when the ladder is extended, which is dangerous.

The ladder thus constructed is used in a stretched state when used, as in the conventional case, and is shortened when stored. In the extended state, since the relative movement of the fitting portion in the axial direction of the support portion 4 is locked by the locking means 11 and rattling in the diametrical direction is prevented by the sliding ring 40, there is no unstable feeling. . Lowermost member 2a when shortened
When the operating portion 36 of the is pushed up, the second member 2b from the bottom
Is unlocked and the member 2b and the member above it in the locked state descend together. The descending speed of the sliding ring 40
Due to the presence of the elastic member, elastic pressing force is exerted between the sliding surfaces of the supporting columns 4 which are fitted to each other, so that it is not a sudden one such as a natural fall but is considerably decelerated. The risk of getting your hand caught between 6 and 6 is small. Second member 2
When the horizontal cross-section 6 of a comes into contact with the lowermost horizontal cross-section 6, the third member 2c from the bottom is unlocked and descends,
When the horizontal rail portion 6 of the member 2c comes into contact with the horizontal rail portion 6 of the member 2b, the locking of the member 2c is released, and thereafter, the upper members are likewise sequentially lowered to be in the shortened state.

[0013]

According to the present invention, since the sliding rings are present in the respective fitting portions of the supporting columns of the ladder in a state where the corner portions are spread out and the sliding surfaces are pressed in the radial direction, Even if the deformation range is large and the manufacturing tolerance of the component parts is not made extremely small,
It can eliminate the rattling and provide a stable ladder.

[Brief description of drawings]

FIG. 1A is a vertical side view showing a main part of an embodiment of the present invention, and FIG. 1B is an enlarged plan view of a sliding ring.

FIG. 2 is a partially enlarged view of FIG. 1 (b).

FIG. 3 is a partially omitted front view of a conventional telescopic ladder.

FIG. 4 is an enlarged vertical cross-sectional front view of a main portion showing a conventional unlocked state of the ladder.

FIG. 5 is an enlarged vertical sectional front view of a main part showing a locked state of the conventional ladder.

[Explanation of symbols]

 2a member (bottom) 2b member (second from bottom) 2c member (third from bottom) 2n member (top) 4 strut part 6 lateral beam part 8 engaging hole 10 projecting body 11 locking means 12 biasing means 14 Lock Release Means (Lever) 32 Rotating Shaft 36 Operating Unit 40 Sliding Ring 55 Corner

Claims (2)

[Claims] 1. A plurality of members, each of which is composed of a pair of pillars, which are arranged in parallel at a distance from each other and are hollow inside, and a horizontal crosspiece provided between the upper ends of both of the pillars, are sequentially arranged. The columns are formed with different thicknesses, and the thin members of the column parts are sequentially slidably fitted into the both column parts of the thickest member of the column parts from above so that the horizontal cross section of each member is The horizontal rails of each member are formed so as to be in a shortened state and the horizontal rail portions of the members are appropriately separated to be in an extended state in which the support columns are fitted. Inside the crosspiece, there is a locking means for holding the extended state, and an operation part corresponding to the locking means and projecting downward from the horizontal crosspiece, and the locking is released by pushing up the operation part. In a ladder provided with an unlocking means, the support columns are fitted in the extended state. The strut part on the small diameter side of the part has a ring groove formed on the outer circumference, and a sliding ring that is made of synthetic resin and has a polygonal shape with a substantially uniform thickness is partly divided in the ring groove. A ladder characterized in that the ladder is mounted in a state in which a small gap remains, and is fitted in the large-diameter side strut through the sliding ring. 2. In the means, the sliding ring is
A ladder, wherein the ladder is provided separately at two locations near both ends of the fitted portion of the column in the extended state.