JP2001336614A - Toothed pulley - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toothed pulley capable of reducing a coefficient of fluctuation of rotation regardless of the magnitude of installing tensile force of a belt. SOLUTION: In this toothed pulley having a curved tooth, a radius of curvature of a part 11 between a tooth tip part 10 and a pressure surface 12 is set large for reducing interference with a belt tooth caused when starting to mesh with a toothed belt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toothed pulley having curved teeth.

[0002]

2. Description of the Related Art In recent years, toothed belts and toothed pulleys used in so-called OA equipment and the like have adopted curved teeth in order to improve stop position accuracy.

However, in the conventional meshing between the belt and the pulley, as shown by the symbol X in FIG. 12, the tooth of the belt B and the tooth tip R of the pulley P (code p1) at the beginning of the meshing.
Interference occurs between them, and there is a problem that meshing vibration that causes an increase in the rotation fluctuation rate occurs.

In the conventional meshing between the belt and the pulley, as shown by reference numeral Y in FIG. 13, just before the belt B and the pulley P are completely meshed, the tooth bottom b1 of the belt B and the tip of the pulley P There is also a problem in that the portion P2 comes into pressure contact with the portion P2 to generate a meshing impact that causes an increase in the rotation fluctuation rate. The occurrence of the meshing impact is caused by the fact that the belt tooth bottom has a glass cord directly under the canvas and has little cushioning effect at the time of meshing.

Accordingly, in the industry of manufacturing and selling OA equipment which requires high stop position accuracy, a toothed pulley capable of reducing the rotation fluctuation rate regardless of the magnitude of the belt mounting tension has been developed. I'm waiting for you.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a toothed pulley capable of reducing the rotation fluctuation rate regardless of the magnitude of the belt mounting tension.

[0007]

Means for Solving the Problems (Invention of Claim 1)
The present invention relates to a toothed pulley having curved teeth, in which a radius of curvature of a portion between a tooth tip portion and a pressure surface is increased to reduce interference with a belt tooth that occurs at the time of starting engagement with a toothed belt. It has been set.

In the toothed pulley according to the present invention, the radius of curvature of the portion between the tooth tip and the pressure surface is set to be large,
Since interference with the belt teeth, which occurs at the start of meshing with the toothed belt, is reduced, the occurrence of inducing meshing vibration is suppressed, and the rotation fluctuation rate is reduced. (Invention of Claim 2) The present invention relates to the invention of Claim 1, and reduces the pressure contact force between the tooth bottom of the toothed pulley and the tooth tip of the toothed pulley just before the toothed belt is completely engaged. To achieve this, the depth of the pulley tooth groove is set shallower than the height of the belt tooth portion attached to the pulley tooth groove.

In the toothed pulley according to the second aspect of the present invention, the tooth depth immediately before the toothed belt is completely meshed with the toothed belt is set by setting the depth of the tooth bottom of the pulley to be shallower than the height of the tooth portion of the belt attached thereto. The contact force between the tooth tip of the toothed pulley and the tooth bottom of the toothed pulley is increased, so the impact force between the tooth bottom of the toothed pulley and the tooth bottom of the toothed pulley with poor cushioning properties is suppressed. . Therefore, when this toothed pulley is employed, the rotation fluctuation rate decreases.

The toothed pulley function of the present invention will be described in the following embodiments of the present invention.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings showing embodiments. (Embodiment 1) FIG. 1 shows a comparison between the shape of a toothed pulley according to an embodiment of the present invention and the shape of a conventional toothed pulley. FIG. 2 shows a toothed belt attached to the toothed pulley. FIG. 3 shows a test machine S for measuring a rotation fluctuation rate in rotation transmission. [About the shape of the toothed pulleys 1a and 1b and the conventional toothed pulley] The toothed pulleys 1a and 1b of the embodiment of the present invention include:
The portion 11 between the tooth tip 10 and the pressure surface 12 (in the industry, tooth 11) is shown by the solid line in FIG. 1 and compared to the conventional toothed pulley shown by the two-dot chain line in FIG. The radius of curvature of the point R (referred to as “Hasaki R”) is set large. In FIG. 1, reference numeral 13 denotes a tooth bottom.

[Specific conventional toothed pulley and its shape] The conventional toothed pulley has a tooth pitch of 2.0 mm, the number of pulley teeth is 16, and the outer diameter of the addendum circle is 9.68 mm. Then, as shown by the two-dot chain line in FIG. 1 (mostly overlapping with the solid line), the intersection of the center line CL of the tooth space and the addendum circle AC is defined as the origin (X, Y) of the coordinates (X, Y). (0, 0), it is formed by a curve drawn by the coordinates (X, Y) of the center of the arc and the radii R1, R2, R3, R4 shown in Table 1. The tooth space depth is 0.750 mm.

[0013]

[Table 1]

"Specific toothed pulleys 1a, 1b and their shapes" The toothed pulleys 1a, 1b are, as shown by the solid lines in FIG.
It has almost the same shape as the conventional toothed pulley, except that the tip R is R4 'having a larger radius of curvature than R4, and there is no R3. Table 2 shows the coordinates (X, Y) and radii of the arc centers of R1, R2, and R4 '. Note that the tooth groove depth is the same as that of the conventional toothed pulley.

[0015]

[Table 2]

[About the shape of the toothed belt 2] The toothed belt 2 has a tooth pitch of 2.0 mm and a belt circumferential length of 384 m.
m, the number of belt teeth is 192. Then, as shown in FIG. 2, the intersection of the center line CL of the belt teeth and the bottom line BC is defined as the origin (0, 0) of the coordinates (X, Y).
Then, it is formed by arcs indicated by BR1, BR2, and BR3. Table 3 shows the coordinates (X, Y) and radii of the arc centers of the BR1, BR2, and BR3. Note that the tooth height is 0.750 mm.

[0017]

[Table 3]

[Configuration of Test Machine S] This test machine S
As shown in FIG. 3, a conventional toothed pulley mounted on the shafts 30, 31 or the toothed pulley of the embodiment of the present invention.
The toothed belt 2 is stretched between 1a and 1b, and the toothed pulley 1a is driven to rotate by a motor (not shown), and the rotation fluctuation rate of the toothed pulley 1b is measured by a non-contact speed unevenness meter 32. [Comparison of Rotational Fluctuation Rate with Toothed Pulley and Toothed Belt Mounted on Testing Machine S] As shown in FIG.
a, 1b respectively attached, said toothed pulley 1a, 1b
The toothed belts 2 were attached to each other under the following tension, and the rotation fluctuation rate was measured.

"The belt installation tension is set to 4.7 N (0.4
8 kgf) ". In this case, as shown in FIG.
The meshing frequency was 53.3 Hz, and the rotation fluctuation rate was 0.355%. In addition, when the conventional toothed pulley is used, as shown in FIG.
It was 59%. That is, when the toothed pulley according to the embodiment of the present invention is employed, the rotation fluctuation rate is reduced by about 0.1% as compared with the case where the conventional toothed pulley is employed.

"The belt mounting tension is 9.4 N (0.9
6 kgf) ". In this case, as shown in FIG.
The meshing frequency was 53.3 Hz, and the rotation fluctuation rate was 0.297%. In addition, when the conventional toothed pulley is used, as shown in FIG.
It was 49%. That is, when the toothed pulley according to the embodiment of the present invention is employed, the rotation fluctuation rate is reduced by about 0.15% as compared with the case where the conventional toothed pulley is employed. (Embodiment 2) The toothed pulleys 1c and 1d of this embodiment
This is indicated by the solid line in FIG. 4, and the pulley tooth groove depth is set to be slightly shallower than that of the toothed pulley of the first embodiment indicated by the two-dot chain line in FIG. 4. That is, the toothed pulleys 1c and 1d have almost the same shape as that of the first embodiment, but R1 of the first embodiment is replaced with R1 '. The R
Table 4 shows coordinates (X, Y) and radii of the center of the arc of 1 ', R2, and R4'. The tooth space depth is 0.730 mm.

[0021]

[Table 4]

Here, as shown in FIG. 3, the toothed pulleys 1c, 1d are attached to the testing machine S, and the toothed pulleys 1c, 1d are attached.
The toothed belts 2 were attached to each other with the tension shown below, and the rotational fluctuation rate was measured.

"The belt mounting tension is set to 4.7 N (0.4
8 kgf) ". In this case, as shown in FIG.
The meshing frequency was 53.3 Hz, and the rotation fluctuation rate was 0.267%. Therefore, when the toothed pulleys 1c and 1d of the second embodiment are adopted, the rotation fluctuation rate is reduced by about 0.19% as compared with the conventional toothed pulley, and the rotation fluctuation rate is reduced by about 0.19%. It turns out that it reduces by about 0.09% in comparison.

"The belt mounting tension is 9.4 N (0.9
6 kgf) ". In this case, as shown in FIG.
The meshing frequency was 53.3 Hz, and the rotation fluctuation rate was 0.128%. Therefore, when the toothed pulleys 1c and 1d according to the second embodiment are employed, the rotation fluctuation rate is reduced by about 0.32% as compared with the conventional toothed pulley, and the rotation fluctuation rate is reduced by about 0.32%. It can be seen that it is reduced by about 0.17% in comparison.

FIG. 5 showing the results of the first and second embodiments.
FIG. 11 is a bar graph of FIG. 10 to FIG. As is apparent from FIG. 11, it is apparent that the use of the toothed pulley of the present invention reduces the rotation fluctuation rate regardless of the magnitude of the belt installation tension.

[0026]

The present invention has the following effects since it has the above-described configuration.

As is clear from the description of the embodiment of the present invention, a toothed pulley capable of reducing the rotation fluctuation rate regardless of the magnitude of the belt mounting tension was provided.

[Brief description of the drawings]

FIG. 1 is a front view comparing a toothed pulley according to a first embodiment of the present invention with a conventional toothed pulley.

FIG. 2 is a front view of an embodiment of the present invention and a toothed belt stretched over a conventional toothed pulley.

FIG. 3 is a conceptual diagram of an apparatus for measuring a rotation fluctuation rate in rotation transmission.

FIG. 4 is a front view comparing the toothed pulley according to the second embodiment of the present invention with the toothed pulley according to the first embodiment.

FIG. 5 is a graph showing a rotation fluctuation rate when the toothed pulley according to the first embodiment is employed and a belt attachment tension is set to 4.7N.

FIG. 6 is a graph showing a rotation fluctuation rate when the toothed pulley according to the second embodiment is employed and a belt attachment tension is set to 4.7N.

FIG. 7 is a graph showing a rotation fluctuation rate when a conventional toothed pulley is employed and a belt mounting tension is set to 4.7N.

FIG. 8 is a graph showing a rotation fluctuation rate when the toothed pulley according to the first embodiment is employed and a belt mounting tension is set to 9.4N.

FIG. 9 is a graph showing a rotation fluctuation rate when the toothed pulley according to the second embodiment is employed and a belt attachment tension is set to 9.4N.

FIG. 10 is a graph showing a rotation fluctuation rate when a conventional toothed pulley is adopted and a belt mounting tension is set to 9.4N.

FIG. 11 is a bar graph summarizing the graphs of FIGS.

FIG. 12 is an explanatory diagram showing a state in which a tooth tip R of a conventional toothed pulley and a belt tooth have started to mesh with each other.

FIG. 13 is an explanatory view showing a state immediately before the conventional toothed pulley and the toothed belt are completely meshed.

[Explanation of symbols]

 1a toothed pulley 1b toothed pulley 1c toothed pulley 1d toothed pulley 10 tooth tip 11 tooth tip R 12 pressure surface 13 tooth bottom 2 toothed belt

Claims (2)

[Claims] 1. A toothed pulley having curved teeth,
A toothed pulley, wherein a radius of curvature of a portion between a tooth tip and a pressure surface is set to be large in order to reduce interference with belt teeth at the time of starting engagement with the toothed belt. 2. In order to reduce the pressing force between the bottom of the toothed belt and the tip of the toothed pulley immediately before the toothed belt is completely engaged with the toothed belt, the depth of the groove of the pulley tooth to be attached to the toothed belt is reduced. The toothed pulley according to claim 1, wherein the pulley is set to be shallower than the height.