JP2002013595A - Cogged belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cogged belt which can prevent generation of cracks in a cog valley. SOLUTION: The present invention relates to the cogged belt A provided with a cogged part 4 formed at least in a compression rubber layer 1 by arranging alternately a plurality of cog hills 2 and cog valleys 3 in the longitudinal direction of the belt. A curved line of a bottom of the cog valley 3 appeared on the cross section taken along the longitudinal direction and in the depthwise direction of the cogged belt A is formed by the curve in which arcs of a plurality of curvatures continues. Thereby, the stress caused when the cogged belt A bends is prevented from being concentrated at one location of the bottom of the cog valley 3 and can be distributed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cogged belt provided with a cog portion.

[0002]

2. Description of the Related Art As a power transmission belt, at least a compression rubber layer of a compression rubber layer and an extension rubber layer is provided with a cog portion in which a large number of cog peaks and cog valleys are alternately arranged along the longitudinal direction of the belt. There are cog belts known as low edge single cog belts or low edge double cog belts.

FIG. 1 shows an example of a cogged belt A known as such a low-edge single cogged belt. An inner peripheral side compression rubber layer 1, an outer peripheral side extension rubber layer 10, and both rubber layers 1 are shown. Adhesive rubber layer 11 between 10 and 10
And a core wire 12 embedded in an adhesive rubber layer 11, and has a V-shaped (inverted trapezoidal) cross section. The compressed rubber layer 1 is provided with a cog portion 4 formed by alternately arranging a large number of cog peaks 2 and cog valleys 3 along the belt longitudinal direction. By providing the cog portion 4 including the cog peak 2 and the cog valley 3 in this manner, the cog belt A can be easily bent at the cog valley 3 and can be used for a small-diameter pulley. It becomes.

Therefore, when the cogged belt A bends,
Stress concentrates on the bottom of the cog valley 3 of the cog portion 4. Therefore, during the operation of the cogged belt A, a crack may be generated at the bottom of the cog valley 3 due to the repeated stress on the cog valley 3 and the belt may be damaged. Further, since the stress is concentrated on the bottom of the cog valley 3 as described above, the cog belt A easily generates heat when bent, and a crack is more easily generated due to a rise in temperature due to the heat generation.

Therefore, as shown in, for example, Japanese Patent Application Laid-Open No. 2000-2300, a crack-preventing rubber containing short fibers oriented in the longitudinal direction of the belt is provided at least in the cog valley 3 so as to be laminated. Conventionally, measures have been taken to reinforce the cog valley 3 to prevent cracks.

[0006]

SUMMARY OF THE INVENTION As described above, Cog Valley 3
Can prevent cracks in the cog valley 3, but it is necessary to use a separate material such as a crack-preventing rubber for reinforcement and also requires a step of laminating the crack-preventing rubber. I do. For this reason, cog belt A
It has been desired to be able to prevent cracks in the cog valley 3 by devising the shape of the above.

[0007] The present invention has been made in view of the above points, and it is an object of the present invention to provide a cogged belt which can prevent a crack from being generated in a cog valley by devising a shape of a bottom portion of the cog valley. Things.

[0008]

According to a first aspect of the present invention, there is provided a cog belt comprising a plurality of cog peaks and a plurality of cog valleys alternately arranged on at least a compression rubber layer along a longitudinal direction of the belt. In the cogged belt A provided with the portion 4, a curve of a bottom portion of the cog valley 3 which appears in a cross section obtained by cutting the cogged belt A in a thickness direction along the belt longitudinal direction is formed by a curve in which arcs having a plurality of curvatures are continuous. It is characterized by having.

Further, according to the present invention, among the plurality of arcs having a plurality of curvatures, the arc forming the deepest curve at the bottom of the cog valley 3 is formed to have the smallest curvature, and the side surface of the cog peak 2 is formed. Is characterized in that the curvature of an arc forming a curve close to is large.

According to a third aspect of the present invention, the curve in which the plurality of arcs having a plurality of curvatures are continuous is continuously formed such that the curvature increases sequentially from the deepest portion at the bottom of the cog valley 3 to the side surface of the cog hill 2. It is characterized by being formed by a series of curves of changing arcs.

[0011]

Embodiments of the present invention will be described below.

As shown in FIG. 1 described above, the cogged belt A includes an inner peripheral side compressed rubber layer 1 and an outer peripheral side expanded rubber layer 10.
And an adhesive rubber layer 11 between the two rubber layers 1 and 10 is formed in a laminated and integrated structure, and a core wire 12 is embedded in the adhesive rubber layer 11 in the longitudinal direction of the belt. And compressed rubber layer 1
A cog portion 4 formed by alternately arranging cog peaks 2 and cog valleys 3 along the longitudinal direction of the belt is provided on at least the compressed rubber layer 1 of the stretch rubber layer 10.

Here, the compression rubber layer 1, the extension rubber layer 10,
Examples of the rubber forming the adhesive rubber layer 11 include natural rubber, butyl rubber, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, alkylated chlorosulfonated polyethylene, hydrogenated nitrile rubber, hydrogenated nitrile rubber, and unsaturated carboxylic acid. A composition of a rubber material alone such as a polymer mixed with a metal salt or a mixture thereof can be used. And the compression rubber layer 1 and the extension rubber layer 1
It is preferable that 0 is used by mixing fibers. As the fibers, fibers such as aramid fibers, polyamide fibers, polyester fibers, and cotton can be used. The fiber length varies depending on the type of fiber, but short fibers of 1 to 10 mm are used. For example, aramid fibers of 3 to 5 mm and polyamide fibers, polyester fibers and cotton of about 5 to 10 mm are used. The adhesive rubber layer 11 may contain fibers, but preferably does not contain fibers.

As the core wire 12, a cord obtained by treating a cord of polyester fiber, aramid fiber, glass fiber or the like with an RFL solution can be used. Further, a reinforcing cloth may be laminated on the surface of the compressed rubber layer 1 or the surface of the stretched rubber layer 10. As such a reinforcing cloth, a canvas made of cotton, polyester fiber, nylon fiber, or the like woven in a plain weave, twill weave, satin weave, or the like can be used.
After the treatment with the FL solution, the rubber composition is used as a rubber-coated canvas subjected to fiction coating. R
The FL solution is an initial condensate of resorcinol and formalin, chloroprene, styrene / butadiene / vinylpyridine terpolymer, hydrogenated nitrile rubber (H-NBR), NB
It is mixed with latex such as R.

In the cogged belt A formed as described above, the cog peak 2 and the cog valley 3 of the cog portion 4 are each formed in a circular shape in a side view, and the cog belt A is formed along the belt longitudinal direction. When cut in the thickness direction (inner and outer directions), the top of the cog valley 2 appears as a convex curve on the cut surface, and the bottom of the cog valley 3 appears as a concave curve. This concave curve at the bottom of the cog valley 3 is generally formed by a single arc having a single curvature as shown in FIG. It is smoothly connected to the side of. However, when the concave curve at the bottom of the cog valley 3 is formed by an arc having a single curvature as described above, the stress at the time of bending is applied to the deepest portion at the bottom of the cog valley 3 where the thickness of the cog valley A becomes the thinnest. Is easily concentrated, and the bending fatigue caused by the concentration of stress causes cog valley 3
Cracks are likely to occur in the deepest portion at the bottom of the steel.

Therefore, in the present invention, the concave curve at the bottom of the cog valley 3 is formed as a curve in which arcs of a plurality of curvatures are continuous. The stress is prevented from being concentrated, the bending fatigue is reduced by dispersing the stress, and the occurrence of cracks in the cog valley 3 is prevented.

Here, among the arcs of a plurality of curvatures forming the concave curve at the bottom of the cog valley 3, the curvature of the arc forming the deepest curve at the bottom of the cog valley 3 is formed to be the smallest. Is preferred. The curvature of the arc having the smallest curvature may be zero. In the embodiment shown in FIG. 2A, the curvature of the arc forming the deepest curve at the bottom of the cog valley 3 is formed to be the smallest, and the curvature gradually increases as approaching the side face of the cog valley 2. Each of the arcs is formed so as to be larger, and the plurality of arcs are smoothly connected to form a continuous curve. Both ends of the curve are smoothly connected to the side surface of the cog mountain 2.

In the embodiment shown in FIG. 2B, the curvature of the arc forming the deepest curve at the bottom of the cog valley 3 is formed to be the smallest as described above, and the deepest portion at the bottom of the cog valley 3 is formed. The curve is formed by a series of circular arcs that continuously change so that the curvature gradually increases from the side to the side surface of the cog mountain 2, that is, a spline curve.

As described above, of the plurality of arcs of curvature forming the concave curve at the bottom of the cog valley 3, the curvature of the arc forming the deepest curve at the bottom of the cog valley 3 is formed to be the smallest. When the cogged belt A is bent, stress can be prevented from being concentrated at the deepest part of the cog valley 3 and the stress can be dispersed to the periphery thereof. That can be prevented. In addition, since the bending stress can be dispersed in this manner, heat generated when the cogged belt A bends can be reduced, and cracks can be prevented from easily occurring due to a temperature rise due to the heat generation. As shown in FIGS. 2A and 2B, the change in the curvature of the arc having a plurality of curvatures is represented by the cog valley 3.
Is preferably sequentially increased from the deepest portion toward the side surface of the cog peak 2, so that a high stress dispersing effect can be obtained.

Further, when the cog valley 3 is formed only by a circular arc having a small curvature which forms the deepest curve at the bottom of the cog valley 3, the width of the side surface of the cog valley 3 is increased and the side of the cog valley 3 is formed. Although the area becomes large and the thickness of the side surface of the cog peak 2 becomes thin and the cog peak 2 becomes small, the curvature of the arc is increased from the deepest part of the cog valley 3 to the side surface of the cog peak 2 as described above. Cog valley 3
Can be minimized to prevent the Cog peak 2 from becoming smaller.

[0021]

Next, the present invention will be described specifically with reference to examples and comparative examples.

(Comparative Example) FIG. 3 shows a cut end face when the cog belt A is cut in the thickness direction along the longitudinal direction of the belt. In the comparative example, the cog valley 3 of the cog portion 4 is shown.
Was designed by CAD as shown in FIG. That is, the curve at the bottom of the cog valley 3 appearing on the cut end face is represented by θ ₁ =
The arc is formed as a circular arc having a curvature radius of 1.6 mm in the range of 163 °, and both ends of the circular arc are connected to the side surface of the cog peak 2. In addition, Cog mountain 2 appearing on the cut end surface described above
Is formed by an arc having a curvature radius of 3.2 mm, the height of the cog peak 2 (the height from the deepest part of the cog valley 3 to the top of the cog peak 2) is 6.8 mm, and the half of the cog peak 2 5.1 pitch
It was formed to 5 mm. In FIG. 3, L indicates the center of the core wire 12, and the cog valley 3 is located from the center L of the core wire 12.
Was formed to a depth of 3.1 mm, and a thickness from the center L of the core wire 12 to the surface of the stretched rubber layer 10 was set to 3.3 mm.

(Embodiment 1) FIG. 2 (a) shows a cog belt A
2 shows a cut end surface of the cog valley 3 when the slab is cut in the thickness direction along the longitudinal direction of the belt. In Example 1, the bottom of the cog valley 3 of the cog portion 4 is shown in FIG. As designed by CAD. That is, a curve at the bottom of the cog valley 3 appearing on the cut end face is formed into an arc formed at the deepest part of the cog valley 3 with a curvature having a radius of curvature of 2.8 mm in a range of θ ₂ = 34.6 °, and this arc Θ ₃ = 6 on both sides of
An arc formed with a curvature having a radius of curvature of 1.0 mm within a range of 4.2 ° is formed as a continuous curve, and the arcs on both sides are connected to the side surface of the cog mountain 2. Other dimensions were designed in the same manner as in FIG. FIG. 2 (a)
The dashed line indicates the curve at the bottom of the cog valley 3 of the comparative example.

(Embodiment 2) FIG. 2B shows a cogged belt A.
2 shows the cut end surface of the cog valley 3 when the slab is cut in the thickness direction along the longitudinal direction of the belt. In the second embodiment, the bottom of the cog valley 3 of the cog portion 4 is shown in FIG. As designed by CAD. That is, the curve at the bottom of the cog valley 3 appearing on the cut end face is formed by a curve that smoothly connects points indicated by black points by spline curves. Is a continuous curve of circular arcs that continuously changes so that the curvature gradually increases toward the side surface. Other dimensions were designed in the same manner as in FIG. The chain line in FIG.
The curve at the bottom of the cog valley 3 of the comparative example is shown.

With respect to the cogged belt A in which the bottom of the cog valley 3 of the cog portion 4 is designed as in the comparative example and the first and second examples, the stress generated in the cog valley 3 when the cog belt A is bent is analyzed by the finite element method. Verified by. FIG. 4 (a)
Indicates a finite element method analysis model, and includes rubbers 1, 10, and 11 composed of eight-node secondary plane strain elements;
It is composed of a core wire 12 composed of two-node truss elements. The truss at the portion of the cord 12 has a larger Young's modulus than that of the rubbers 1, 10, and 11, and the cogged belt A bends around the portion of the cord 12. This model is arranged for two pitches from Cog Mountain 2 to Cog Mountain 2, and is constrained in the plane with both ends as symmetry planes. As shown, the right side was rotated clockwise to bend the cogged belt A. Here, the Young's modulus 3 of the rubber 1,10,11 portion
9 N / mm ² (4 kgf / mm ² ), Poisson's ratio 0.49
9 (uncompressed), Young's modulus of the core wire 29420N / mm
^{2 (3000kgf} / mm ^2), Poisson's ratio of 0.3, to set the cross-sectional area 0.785 mm ^2, cogged belt and A θ ₄ = 3
It was bent at an angle of 0 °. The average radius of curvature at the center of the core wire 12 is 39.3 mm.

The stress applied to the left cog valley 3 of the two cog valleys 3 of the model shown in FIG. 4A when the cogged belt A is bent as described above was determined by the finite element method analysis using nonlinear analysis. At this time, since the cog valley 3 is compressed at the time of bending, the stress applied to the cog valley 3 is determined as the minimum principal stress, and the results are shown in FIGS. FIG. 5 shows the analysis results of the comparative example of FIG. 3, FIG. 6 shows the analysis results of the embodiment 1 of FIG. 2 (a), and FIG. 7 shows the analysis results of the embodiment 2 of FIG. 2 (b). The absolute value of the minimum principal stress is the largest at the part indicated by the arrow in each figure. FIG. 8 is a graph comparing the absolute values of the minimum principal stress in the comparative example and the first and second examples.

It is considered that the greater the absolute value of the minimum principal stress, the greater the damage due to bending fatigue and the easier the occurrence of cracks.
And in FIG. 5 of the comparative example, the minimum principal stress is one place,
In FIG. 6 of the first embodiment and FIG. 7 of the second embodiment, the minimum principal stress is dispersed at two places, and the stresses at the two places have substantially the same value. Also, from the results of the graph of FIG. 8, the minimum principal stress of Example 1 is 1 to the absolute value of the minimum principal stress of Comparative Example.
4.3% and the minimum principal stress of Example 2 are 17.6%, which are small. Therefore, Example 1,
In the case of No. 2, it is confirmed that the stress at the time of bending can be dispersed at the bottom of the cog valley 3 to prevent a large stress from concentrating and acting, and to prevent the occurrence of a crack in the cog valley 3. Is what is done.

[0028]

As described above, the present invention relates to a cogged belt provided with a cog portion formed by arranging a large number of cog peaks and cog valleys alternately at least in the compression rubber layer along the belt longitudinal direction. The curve at the bottom of the cog valley, which appears in a cross section cut in the thickness direction along the longitudinal direction, is characterized in that arcs of a plurality of curvatures are formed by a continuous curve, and the cogged belt is bent. The stress at that time can be prevented from concentrating at one position at the bottom of the cog valley, and the stress can be reduced to reduce the bending fatigue, thereby preventing the crack from being generated in the cog valley.

According to a second aspect of the present invention, the curvature of the arc forming the deepest curve at the bottom of the cog valley is formed to be the smallest among the arcs having a plurality of curvatures, and the curve close to the side surface of the cog peak is formed. Since the curvature of the arc to be formed is large, it is possible to prevent the stress from being concentrated at the deepest part of the cog valley when the cogged belt is bent, and to disperse the stress to the periphery thereof, It can reduce bending fatigue and prevent cracks from occurring.

According to a third aspect of the present invention, a curve in which a plurality of arcs having a plurality of curvatures are continuous is a curve in which the curvature continuously changes from the deepest portion at the bottom of the cog valley to the side surface of the cog hill. Since it is formed by a series of curves, when the cogged belt bends, it can prevent stress from concentrating on the deepest part of the cog valley and disperse the stress to the periphery, and there is a bending fatigue of the cog valley This can reduce the occurrence of cracks.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an example of an embodiment of a cogged belt.

FIG. 2 is a diagram showing a cut end surface of a cog valley portion according to an example of an embodiment of the present invention.
(B) shows Example 2 respectively, and the unit of the numerical value of the dimension in FIG. 2 (a) is mm.

FIG. 3 is a diagram showing a cut end surface of a cogged belt according to an example of the related art, and a unit of a numerical value of a dimension is mm.

FIG. 4A is a diagram showing a model of a finite element method analysis,
(B) is a diagram showing a state in which the model is bent.

FIG. 5 is a diagram illustrating a result of a finite element method analysis of a stress applied to a cog valley when a cog belt of a comparative example is bent.

FIG. 6 is a diagram illustrating a result of a finite element method analysis of a stress applied to a cog valley when the cog belt of Example 1 is bent.

FIG. 7 is a diagram showing the result of a finite element method analysis of stress applied to a cog valley when the cog belt of Example 2 is bent.

FIG. 8 is a graph comparing the absolute values of the minimum principal stresses of Examples 1 and 2 and Comparative Example.

[Explanation of symbols]

 1 compressed rubber layer 2 cog peak 3 cog valley 4 cog part

Claims (3)

[Claims] 1. A cogged belt provided with a cog portion formed by alternately arranging a large number of cog peaks and cog valleys at least in a compression rubber layer along a belt longitudinal direction, wherein the cog belt is formed in a thickness direction along the belt longitudinal direction. A cogged belt, characterized in that a curve at the bottom of a cog valley appearing in a cross section cut into a cross section is formed by a curve in which arcs of a plurality of curvatures are continuous. 2. The arc of the plurality of curvatures forming the deepest curve at the bottom of the cog valley has the smallest curvature, and the curvature of the arc forming the curve close to the side surface of the cog valley has the smallest curvature. The cogged belt according to claim 1, wherein the cogged belt is formed large. 3. A curve in which arcs of a plurality of curvatures are continuous are formed by a series of arcs that continuously change so that the curvature increases sequentially from the deepest portion at the bottom of the cog valley to the side surface of the cog hill. The cogged belt according to claim 1, wherein: