JPS6052073B2 - sheave for elevator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sheave for an elevator, and particularly to an improvement in the shape of a sheave groove that is effective in obtaining a stable and large frictional driving force and preventing wear and tear on a rope.

It is generally known that rope-type elevators use a friction drive system in which the rope is driven by the frictional force between the rope and the sheave to move the car up and down.

This type of elevator requires a large amount of friction between the rope and the sheave, and if the rope were to slip, the car would not be able to stop in the designated position, which could lead to a serious accident. This will be explained based on the diagram.

In FIG. 1, a rope 2 is wrapped around a sheave 1,
A car 3 and a counterweight 4 are suspended from both ends of the rope 2. In addition, generally on the counterweight 4 side,
A pulley 5 is used to maintain a constant distance from the car 3. Therefore, when the sheave 1 is rotated by an electric motor or the like,
The rope 2 is driven by the frictional force between them, and the car 3 moves up or down to transport passengers. In this way, a large frictional force is required between the rope 2 and the sheave 1, so
A sheave 1 is provided with a groove into which a rope 2 is fitted. In general, the V groove and the second
An undercut round groove 6 having an undercut portion 7 shown in the figure is known. Furthermore, recently, in order to prevent a decrease in frictional force due to groove wear, an undercut V groove 8 having an undercut portion 9 as shown in Fig. 3 has been proposed and has already been put into practical use. As shown in Figure 3A, the groove 8 initially functions as a V-groove with a particularly large frictional force, and as the sheave 1 wears out, it becomes a round groove with an undercut as shown in Figure 3. 6, and has the effect of preventing a decrease in the frictional force.By the way, as is well known, the transferable frictional force between the rope 2 and the sheave 1, that is, the groove, is expressed by the true coefficient of friction between the two being μ. Then, due to the wedge effect of the groove on the lobe 2, the friction coefficient μ apparently increases to μ″.

That is, if the coefficient indicating the wedge effect of this groove is taken as the groove coefficient, it is expressed as follows.

This groove shape coefficient differs depending on each groove shape, and is given by (1) when the undercut round groove 6 and (2) undercut groove 8 are worn out [Figure 3].

Here, as shown in FIGS. 2 and 3, 2β is the angle of the groove, 2α is the undercut angle, and 2γ is the contact angle.
On the other hand, as is clear from equations (2) and (3), the groove coefficient represents the magnitude of the component force acting on the contact surface when the lobe 2 bites into the groove of the sheave 1. In other words, increasing the channel coefficient and increasing the apparent friction coefficient μ'' means increasing the contact pressure between the lobe 2 and the sheave 1. Therefore, as is clear from equation (3), In a groove having undercut portions 7 and 9, the larger the undercut angle 2α and the contact angle 2γ, the greater the groove shape coefficient becomes.In other words, the contact surface pressure between the sheave 1 and the lobe 2 increases, and as a result, , the apparent friction coefficient μ″ increases, and the frictional driving force of the lobe increases. For this reason,
Conventionally, studies have been made to increase the undercut angle 2α and the contact angle 2γ as much as possible. However, since the contact angle 2γ does not exceed 1800 at most, the undercut angle 2α must be made as large as possible in order to increase the apparent friction coefficient μ'' and increase the safety factor against lobe slippage. .On the other hand, undercut angle 2α
I made it too big. If it is too much, the lobe 2 will sink into the undercut portions 7 and 9 from the beginning. Therefore, there is a limit to how large the undercut angle 2α can be, and the limit is generally set at around 2α=1100. As explained above, in a lobe type elevator, a large frictional force is required between the lobe 2 and the sheave 1 in order to prevent the lobe 2 from slipping.There are other ways to compensate for this, but the sheave 1
A large part of this depends on the groove shape.

For this reason, attempts have often been made to make the undercut angle 2α of the groove of the sheave 1 as large as possible. However, the larger the undercut angle 2α, the higher the contact surface pressure with the lobe 2, which generally accelerates the friction of the cast iron sheave 1, causing the problem that the sheave 1 wears out and needs to be replaced sooner. . To deal with this problem, attempts have been made to increase the hardness of the sheave 1 material to improve its abrasion resistance, but in this case, this accelerates local wear of the rope 2, resulting in the formation of the lobe 2. A problem occurred in that the wires caused by the strands were broken early, and the life of the lobe 2 was significantly shortened. The purpose of the present invention is to address the above-mentioned conventional problems, and to provide stable and high frictional driving force.
The purpose of the present invention is to provide a sheave groove shape that extends the life of the lobe.
At the starting point of the undercut portion, or in other words, at the position from the groove around which the lobe is wound to the undercut portion, a third surface consisting of a convex curved surface or a flat surface spanning both sides is formed.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG. Fourth
Figure A shows the initial state in which the sheave 1 is not worn.The fact that it has an undercut portion 11 and a groove angle of 2β is similar to that of the conventional undercut V-groove 8.
is the same as However, a particular difference from the conventional method is that a third convex curved surface 12 is formed at the undercut starting point (section Q in FIGS. 2 and 3). This third convex curved surface 12
has a curvature of radius R, and is configured to be continuous with V and the undercut surface. The characteristics of the improved undercut groove 10 are made clear from the structure of the lobe 2.

As shown in FIG. 4A, the lobe 2 with a diameter D is made up of several strands 2A twisted together, and each strand 2A is similarly made up of several strands 2a twisted together. . Therefore, although the cross section of the lobe 2 is generally expressed as a round shape, strictly speaking, each strand 2A
It has a polygonal shape, and further a complicated polygonal shape composed of each strand 2a. Therefore, when the undercut angle 2α is increased in the undercut groove 8 as shown in FIG. will be subjected to high surface pressure. In this case, if the hardness of the sheave 1 is increased to prevent wear, the contact surface of the lobe wire 2a that comes into contact with the undercut starting point Q will be plastically deformed due to the high contact pressure, and the surface will be work hardened. It becomes brittle and eventually fatigue cracks develop, leading to wire breakage. This phenomenon is also supported by the fact that there are many wire breaks particularly in the lobe 2 where the diameter D is narrow or where the diameter D is partially narrow. Therefore, if the third convex curved surface 12 made of a curved surface with a curved surface radius R is formed at the undercut starting point Q as in this embodiment, no matter how the polygonal lobe 2 enters the groove 10, Since the strands 2a do not come into local contact with the sheave 1, plastic deformation of the lobes 2 is prevented, and the problem of early strand breakage is solved.
For example, ■Groove angle 2β is 300 and undercut angle 2α
With undercut of 110 degrees ■Groove 10, diameter D is 1
According to an experiment using a lobe 2 of 2w0n, the third surface 1
2 curved surface radius R in 3 or more order, that is, 114J for the lobe diameter D)). If it is set upward, the number of test strokes until breakage occurs in the strand 2a of the lobe 2 will increase by 1.5 times compared to the case without the third convex curved surface 12, and the limit number of strand breaks will be increased. The effect was that the number of test strokes required to reach 100% was approximately doubled.

Therefore, the curved surface radius R of the third convex curved surface 12 is the lobe diameter D
It is preferable to set the ratio to 1 to 4 or more, but even if it is lower than that, the effect will be obtained although it will not be significant. Furthermore, since the hardness of the sheave 1 can be increased, the wear resistance of the sheave 1 can be improved and its life can be extended. Furthermore, as shown in Figure 4, in the early stages of wear of the sheave 1, since the third surface 12 is a curved surface, it is the same as increasing the undercut angle 2α, and the apparent friction coefficient μ'' increases. Therefore, the effect of increasing the frictional force can also be obtained.

Although the third surface 12 of the undercut starting point Q portion was shown as a curved surface in the above embodiment, it is not limited to this curved surface, and as in the embodiment shown in FIG. 15
may be composed of a plane. Third surface 15 according to this plane
In this case, if the angle 2θ of the third surface is set to ■groove surface with an even smaller opening angle following the V-groove 13 by setting β>0≧β/2 to the groove angle 2β, the same element as above is obtained. It has been confirmed through experiments that the effect of wire breakage is 15 times or more greater. However, even if the angle 20 of the third surface 15 is less than that, the effect is still obtained although it is not significant. What you should want is β〉θ
≧β/2 is preferred. In the above embodiments, the undercut V grooves 10 and 13 have been described, but the same applies to undercut round grooves. In FIG. 6 showing the embodiment, since the diameter D of the lobe 2 varies in size, the radius r of the round groove is selected to be large, and generally the radius γ of the round groove is It is selected to be about 1.0 to 1.3 times. Furthermore, when tension is applied to the lobe 2, the diameter D becomes thinner and the difference from the radius r of the round groove becomes larger.
Therefore, although γ is apparently used as the contact angle,
In the early stages of wear of the sheave 1, the lobe 2 and the sheave 1 are in contact only at point contact, that is, at the undercut starting point (Q in FIG. 2). Therefore, a high surface pressure is generated on the lobe wire 2a at the contact portion, and the same problem as described above occurs. Therefore, if the third surface 12 with the curved radius R is provided at the starting point of the undercut 17 as in the embodiment shown in FIG. 6, the same effects as described above can be obtained.

Curved surface radius R of third surface 12 of round groove with undercut 16
It has been confirmed through experiments that, unlike the groove 10 with an undercut, a sufficient effect can be obtained by providing one groove above the lobe diameter. In the above explanation, the third surfaces 12 and 15 of the undercut starting point Q are shown as a curved surface radius R or a flat surface, but without being particular about this, for example, they can be expressed as a parabolic curved surface, or two or three surfaces. A method such as forming a flat surface may also be used, and these are within the scope of the present invention.As explained above, a convex curved surface or a flat surface spanning both the groove where the lobe is wrapped and the undercut is formed. According to the present invention in which the third surface is formed, a stable and large frictional driving force can be obtained, and early wear and tear of the lobes can be prevented, so that the life of the lobes can be extended.

of

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating the structure of an elevator, FIGS. 2 and 3 are groove sectional views showing an example of a conventional elevator sheave, and FIG. 4 is a diagram illustrating an embodiment of the present invention. Similar sectional views, FIGS. 5 and 6, are similar sectional views to FIGS. 3 and 2 showing other embodiments of the invention. 1... Sheave, 2... Robe, 3...
... Cart, 4... Counterweight, 7,
9, 11, 14, 17...Undercut part, 8
, 10, 13... ■Groove with undercut, 6, 16
...Round groove with undercut, 12, 15...
...Third surface, 2β...■Groove angle, 2θ...
... Angle of the third surface, Q ... Undercut starting point, D ... Lobe diameter, R ... Curved surface radius of the third surface.

Claims (1)

[Scope of Claims] 1. A sheave having a groove in which a rope for suspending a car is wound around and driven by friction, and an undercut portion formed at the bottom of the groove, at a position extending from the groove to the undercut portion. . A sheave for an elevator, characterized in that a third surface is formed that is a convex curved surface or a flat surface that spans the groove and the undercut portion. 2. The elevator sheave according to claim 1, wherein the groove is a V-groove, and the third surface is a convex curved surface with a radius of 1/4 or more of the rope diameter. 3. The elevator sheave according to claim 1, wherein the groove is a round groove, and the third surface is a convex curved surface with a radius of 1/12 or more of the rope diameter. 4. The elevator according to claim 1, wherein the groove is a V-groove, and the third surface is a plane continuing from the V-groove and forming a V-groove surface with a smaller opening angle. Sheave for use.