JP2000337448A - Transmission belt and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of noise and to keep specified side pressure resistance and friction resistance in any running direction, in a transmission belt mixed with short fibers. SOLUTION: Aramid short fibers 8 protruding from the side 11 of the V-rib 7 of a V-rib belt are formed in a curled state. The root part of the aramid short fiber 8 is erected from the side 11 of the V-rib 7. The tip part of the aramid short fiber 8 is curved in a direction different from the curving direction of an intermediate part. The protrusion parts 15, 15... of the aramid short fibers 8, 8... are differed in a curving direction in a manner to be dispersed throughout a multi-direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power transmission belt and a method of manufacturing the same, and more particularly to a power transmission belt such as a V-ribbed belt or a V-belt in which short fibers are mixed in a bottom rubber portion, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Publication No.
As disclosed in Japanese Unexamined Patent Publication No. 7 (1999) -74, Japanese Unexamined Patent Publication (Kokai) No. 7-4470, and the like, the object is to improve the lateral pressure resistance and wear resistance of the friction transmission portion of the belt and to prevent abnormal noise during belt running. A transmission belt is known in which a short fiber group is mixed into a bottom rubber portion while maintaining the orientation in the belt width direction, and a part of the short fiber group is projected from the surface of the bottom rubber portion. .

[0003] However, even in the case of a power transmission belt in which a part of the short fiber group is protruded, if the area of the protruding part of the short fiber group occupying the surface of the bottom rubber part is small, the rubber and the pulley directly contact each other. Since the contact area increases, the wear resistance does not improve much.

In order to increase the exposed area of the short fiber group on the surface of the bottom rubber portion, Japanese Patent Application Laid-Open No. 1-164839 discloses an aramid mixed in the bottom rubber portion 100 as shown in FIG. The projecting length of the short fiber 101 is set to 0.
There has been proposed a power transmission belt in which the length of the transmission belt is set to 065 mm to 0.13 mm, which is longer than the conventional one, and the protruding portion 102 is bent in a fixed direction 103 along the driving surface of the belt.

[0005]

However, Japanese Patent Application Laid-Open No.
In the transmission belt disclosed in JP-A-164839, although the exposed area of the short fiber 101 increases, the protruding portion 102 is bent from the root, so that the protruding portion 102 of the short fiber is It will be almost flush. Therefore, there is a problem that it is difficult to form surface irregularities which are considered to be effective in suppressing abnormal noise, and the effect of preventing abnormal noise cannot be sufficiently obtained.

Further, since the short fiber projecting portion 102 is bent in one direction 103 along the surface of the bottom rubber portion 100, if the running direction is reversed, the characteristics of the belt greatly change. Therefore, in order to obtain the designed belt characteristics, it was necessary to carefully check the running direction when attaching the belt. Further, the belt could not be used for a device in which the running direction was appropriately switched.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power transmission belt which is excellent in abrasion resistance, hardly generates abnormal noise, and has no dependence on the running direction. Is to do.

[0008]

In order to achieve the above-mentioned object, according to the present invention, a protruding portion of a short fiber is deformed into a curl shape.

Specifically, the power transmission belt according to the present invention comprises:
A short fiber group is mixed in the bottom rubber part so as to be oriented in a predetermined direction, and a transmission belt in which a part of the short fiber group protrudes from the surface of the bottom rubber part. It is set up from the surface of the bottom rubber portion and is curved.

According to the above-mentioned matter, since the protruding portion of the short fiber is curved, it has a sufficiently large exposed area with respect to the surface of the bottom rubber portion. As a result, the wear resistance of the rubber bottom portion is improved.
In addition, since the short fibers rise from the surface of the bottom rubber portion, the root portion of the short fiber rises from the surface of the bottom rubber portion.
As a result, microscopic irregularities having a convex portion at the base of the short fiber are formed in the bottom rubber portion, so that generation of abnormal noise is suppressed.

Further, it is preferable that the protruding portion of the short fiber bends in one direction from the root toward the tip and then in a direction different from the direction.

According to the above, when the belt is wound around the pulley, the short fiber exerts a restoring force like a leaf spring on the pulley, and the tension fluctuation accompanying the running of the belt is absorbed by the restoring force. Therefore, the transmission performance is stabilized. Further, when the surface pressure is large, the pressure applied to the short fiber also increases, but the force applied to the root portion is reduced by the restoring force of the curved portion of the short fiber. Therefore, the short fibers are prevented from coming off from the bottom rubber portion, the wear resistance is improved, and the life of the belt is extended.

[0013] It is preferable that at least the tip of the protruding portion of the short fiber is formed flat.

According to the above, the surface area of the short fibers is increased, and the wear resistance of the belt is improved.

The protruding portion of the short fiber may have a tear at the tip.

According to the above, the surface area of the short fibers is increased, and the wear resistance of the belt is improved.

It is preferable that the protruding portions of the short fiber group have mutually different curving directions so that the protruding directions are dispersed.

According to the above-mentioned matter, since the bending directions of the projecting portions of the short fiber group are different from each other and the projecting directions of the projecting portions are dispersed, the abrasion resistance of the belt becomes uniform in any direction. Therefore, even if the running direction of the belt is reversed, its characteristics do not change, and the direction dependency of the belt is eliminated.

The short fibers are aramid short fibers, and may be para-aramid fibers or meta-aramid fibers.

According to the above, a suitable short fiber can be obtained.

A method of manufacturing a power transmission belt according to the present invention is a method of manufacturing a power transmission belt in which a group of short fibers protrudes from the surface of a bottom rubber portion, wherein the short fibers are mixed so as to be oriented in a predetermined direction. The method further includes a step of grinding the bottom rubber portion with a grindstone having superabrasive grains protruding from 50% to 95% of the abrasive grain size.

According to the above-mentioned matter, since the protruding amount of the superabrasive grains is large, direct contact between the bond portion of the superabrasive grains and the bottom rubber portion of the transmission belt is prevented, and the generation of frictional heat is suppressed. Therefore, the grinding process can be performed under a wide range of conditions such as increasing the speed of grinding. In addition, it is easy to increase the amount of the short fiber projecting from the surface of the bottom rubber portion, and it is easy to curve the projecting portion.

Another method of manufacturing a power transmission belt according to the present invention is a method of manufacturing a power transmission belt in which a group of short fibers protrudes from a surface of a bottom rubber portion, wherein the short fibers are oriented in a predetermined direction. Abrasive grain density of 3.5%
The method includes a step of grinding with a grindstone having super-abrasive grains of about 55%.

According to the above-mentioned matter, the chip pocket becomes large due to the small abrasive grain density, and the grinding chips are easily discharged. For this reason, clogging due to cutting chips is unlikely to occur, so that an increase in grinding load and heat generation on the ground surface due to clogging are suppressed. Therefore, the grinding process can be performed under a wide range of conditions. In addition, since the short fibers protruding from the bottom rubber portion are not easily cut, it is easy to form a protruding portion having a long protruding length or to curve the protruding portion.

Another method of manufacturing a power transmission belt according to the present invention is a method of manufacturing a power transmission belt in which a group of short fibers protrudes from a surface of a bottom rubber portion, wherein the group of short fibers is oriented in a predetermined direction. The mixed bottom rubber part is 50% to 9% of the abrasive particle size.
The method includes a step of grinding with a grindstone having superabrasive grains with 5% protruding and having an abrasive grain density of 3.5% to 55%.

According to the above-mentioned matter, since the protruding amount of the superabrasive grains is large and the abrasive grain density is small, the increase in the grinding load and the heat generation on the ground surface are suppressed, and the grinding process can be performed under a wide range of conditions. In addition, it becomes easy to form a long projecting portion of the short fiber projecting from the bottom rubber portion and to curve the projecting portion.

[0027]

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

FIG. 1 shows a sectional shape of a transmission belt 10 according to an embodiment of the present invention. The power transmission belt 10 is a V-ribbed belt used for a driving device of an auxiliary device of an automobile and other general industrial uses.

Tensile members 2 extending in the belt length direction are embedded in the adhesive rubber layer 4 at equal intervals in the belt width direction (the left-right direction in FIG. 1). On the upper surface side of the adhesive rubber layer 4, that is, on the outer surface side of the belt, a canvas layer 5 is provided. On the lower surface side of the adhesive rubber layer 4, that is, on the inner surface side of the belt, a plurality of V-ribs 7 extending in the belt length direction are provided in the belt width direction. The V-rib 7 corresponds to a “bottom rubber portion” in the present invention. Adhesive rubber layer 4
And V rib 7, for example, chloroprene rubber, H-NBR
It can be formed from rubber, CSM rubber, natural rubber, SBR rubber, butadiene rubber, EPM, EPDM, and the like.

The V rib 7 has a plurality of aramid short fibers 8,
Are buried while maintaining the orientation in a predetermined direction. Specifically, in the present embodiment, the aramid-based short fibers 8
Are buried while maintaining the orientation in the belt width direction. The aramid short fiber 8 may be a para-aramid fiber or a meta-aramid fiber. That is, polyparaphenylene isophthalamide or polymetaphenine isophthalamide may be used. Specifically, Kevlar (trade name of DuPont), Technora (trade name of Teijin Limited), Toalon (trade name of Enca), etc. can be used as the para-aramid fiber. Nex (trade name of Teijin Limited),
Nomex (trade name of DuPont) or the like can be used.

As shown in FIG. 2, a part of the aramid-based short fibers 8, 8,... Embedded in the V rib 7 protrudes from the side surface 11 of the V rib 7. Aramid staple fiber 8 projections 15,15, ...
Are curved so as to increase the apparent volume and cover the side surface 11 of the V-rib 7. Aramid staple fiber 8,
Are not curved in the same direction, but are irregularly curved in multiple directions so that the bending directions are different from each other. That is, the plurality of protrusions 15, 15,.
Are distributed and curved in various directions, so that the wear resistance of the V-ribbed belt 10 is uniformly improved in any direction. Thus, the direction dependency of the belt is eliminated, and the V-ribbed belt 10 exhibits the same performance in any running direction.

Next, the shape of the protruding portion 15 of each aramid short fiber 8 will be described in detail with reference to FIG. The root 12 of the protrusion 15 of the aramid short fiber 8 stands from the side surface 11 of the V-rib 7. In other words, the root 12 of the aramid-based short fiber 8 is substantially upright with respect to the side surface 11 of the V-rib 7. The intermediate portion 13 of the protrusion 15 is curved from the root 12. The distal end portion 14 of the protruding portion 15 is curved in a direction different from the bending direction of the intermediate portion 13. For example, in the aramid-based short fiber 8 shown in FIG. 3, the distal end portion 14 is curved in a direction opposite to the curved direction of the intermediate portion 13. In other words, the aramid-based short fibers 8 are curved in two stages, specifically, a so-called curled shape that curves once in a predetermined direction from the root to the tip, and then curves in the opposite direction. Is formed. As a result, the aramid-based short fiber 8 is entirely lifted from the side surface 11 of the V-rib 7 and is formed in a curl shape, so that it exhibits a restoring force like a leaf spring. Also, on the surface of the V rib 7,
Micro unevenness having the root 12 as a projection is formed.

The length of the protrusion 15 of the aramid short fiber 8 is
It is preferably 50 μm or less.

The aramid-based short fibers 8, 8,... Have a flattened shape due to friction with a grinding stone during the later-described grinding process, and have cracks at their tips as shown in FIG. Things are also included.

Next, a method for manufacturing the V-ribbed belt 10 will be described.

First, an unvulcanized rubber sheet serving as the adhesive rubber layer 4, a cord serving as the tensile member 2, an unvulcanized rubber sheet mixed with aramid short fibers, and the like are sequentially laminated, and these are heated and vulcanized. To obtain a cylindrical belt molded product.

Thereafter, as shown in FIG. 5, the belt molding 19 is moved to the main roll 22 and the tension roll 23 of the drive mechanism 20.
And run by the drive mechanism 20.
Then, while the grindstone 21 is rotationally driven and pressed against the running belt molded body 19, the belt molded body 19 is ground. At this time, the mixed aramid short fibers 8
Is difficult to cut due to the large Greig tensile modulus,
A part thereof projects from the side surface 11 of the V-rib 7.
Specifically, the stress generated on the fiber surface due to interference between the aramid-based short fiber 8 and the abrasive grains is released, and the aramid-based short fiber 8 undergoes plastic deformation, and its tip is curved.

At this time, the length, shape and degree of flatness of the protruding portion of the aramid-based short fiber 8 and the state of tearing of the tip are adjusted by adjusting the kind of the grinding stone 21 and the pressing force of the grinding stone 21. It is possible to

As the grinding wheel 21, a disk-shaped grinding wheel 25 is used.
It is preferable to use a structure in which the diamond abrasive grains 24 are fixed to the peripheral surface by electroplating, brazing, baking or the like. However, the abrasive grains are not limited to diamond abrasive grains, and other superabrasive grains such as CBN can be used. FIG. 6A is a diagram in which a part of the peripheral surface of the grinding wheel 25 is projected from the vertical direction, and FIG. 6B is a cross-sectional view taken along line AA of FIG. 6A. These FIG. 6 (a)
And (b), the grinding wheel 25 (see FIG. 5)
An adhesive (metal bond, nickel bond, etc.) is thinly stretched and applied on the peripheral surface of
Are formed.

The diamond abrasive grains 24 are uniformly arranged on the bonding portion 26 and adhered. The grain size of the abrasive grains 24 is preferably # 30 to # 200, and in the present embodiment, the grain size is # 1.
It is set to 40. The amount of protrusion of the abrasive grains 24 from the bond portion 26 is preferably set to 50% to 95% of the total height of the abrasive grains 24. In this embodiment, the protrusion amount of the abrasive grains 24 is 80
% Is set. The abrasive density of the abrasive grains 24 (the ratio of the surface area of the abrasive grains to the ground surface) is preferably 3.5% to 55%, and is set to 45% in the present embodiment.

In the grinding process, five grinding wheels 25
It is preferable to rotate at a peripheral speed of 00 to 2000 m / min, and in the present embodiment, the peripheral speed is set to 1000 m / min. The grinding speed ratio Vs / Vw, which is the ratio of the peripheral speed Vw of the belt to the peripheral speed Vs of the grindstone 21, is 0.002 to 0.04.
Is preferable, and in this embodiment, it is 0.004.

-Effects of this embodiment- As described above, in the present V-ribbed belt 10, since the protruding portion 15 of the aramid short fiber 8 is plastically deformed and curved,
The apparent area of the aramid short fiber 8 with respect to the side surface 11 of the rib 7 is large. Therefore, the V-ribbed belt 10 has high wear resistance.

Further, the surface area of the aramid short fiber 8 is further increased due to the flatness of the aramid short fiber 8 or the occurrence of a crack at the tip thereof. Therefore, the wear resistance of the V-ribbed belt 10 is further improved.
In addition, if the tip of the short fiber is fibrillated, the original strength of the short fiber may be impaired, but the aramid short fiber 8 of the belt 10 is in a state where a fissure has occurred without fibrillation. That is, the tears of the aramid-based short fibers 8 in the belt 10 are more macroscopic than the fibrillation. Therefore, the original strength of the aramid short fibers 8 is not impaired.

Since the aramid short fibers 8, 8,... Are curved in multiple directions, their performance can be exhibited without depending on the running direction of the belt 10. Therefore, when the belt 10 bites into the pulley or separates from the pulley, the belt 10
A stable sliding resistance can be obtained on the sliding surface between the pulley 10 and the pulley. As a result, the fluctuation of the sliding resistance is small, and the running of the belt is stabilized. Therefore, the V-ribbed belt 10 exhibits the same lateral pressure resistance and wear resistance in any direction.

Intermediate part 13 of protrusion 15 of aramid short fiber 8
In addition, since the distal end portion 14 is curved and the bending direction of the intermediate portion 13 and the bending direction of the distal end portion 14 are different, the aramid short fiber 8 has a restoring force like a leaf spring.
Fluctuations in the pressure applied to the ribbed belt 10 are absorbed by the restoring force. Therefore, the running of the belt is further stabilized, and the power can be transmitted stably. Further, the force applied to the root 12 of the aramid short fiber 8 is reduced by the restoring force. Therefore, the aramid-based short fibers 8 are prevented from coming off, and the deterioration of the V-ribbed belt 10 is suppressed.

Since the root 12 of the aramid short fiber 8 stands on the side surface 11 of the V-rib 7, the root 12 becomes a convex and microscopic irregularities are formed on the side 11 of the V-rib 7. Is done. Therefore, generation of abnormal noise can be effectively prevented.

In the method for manufacturing a V-ribbed belt according to the present embodiment, the bonding portion 26 is used to form 50% to 95% of the abrasive particle size.
Since the grinding process is performed using the super-abrasive grains protruding, contact between the bond portion 26 and the V rib 7 during grinding is less likely to occur.
Therefore, heat generation due to friction is small. Therefore, the grinding process can be performed favorably. In addition, since diamond having relatively high thermal conductivity is used as the superabrasive, heat generation can be effectively suppressed.

Since the abrasive grain density of the superabrasive grains is relatively coarse, ie, 3.5% to 55%, the gap between the abrasive grains, that is, the chip pocket becomes large. For this reason, clogging due to chips is less likely to occur during grinding. Heat generation due to clogging of chips is less likely to occur. Therefore, the grinding process can be performed favorably.

By using the grinding wheel 25 provided with super-abrasive grains having a large amount of protrusion and a small abrasive grain density, the aramid-based short fiber 8 can be made to protrude from the side surface 11 of the V-rib 7 for a comparatively long time. Has become easier. Also, the protrusion 15
Can be easily formed into a curled shape in which the root portion 12 stands upright.

Next, a performance comparison test in which the present V-ribbed belt 10 is compared with a conventional V-ribbed belt will be described. As a conventional V-ribbed belt, a belt in which aramid short fibers extend linearly was used. The test was performed as shown in FIG.
A weight of weight W is hung on the sample belt 32 via the guide roller 33, and the tension T1 on the tension side of the belt and the tension T2 on the loose side of the belt are detected by detecting the load cell value of the load cell 31. Ratio) T1 / T2 was calculated by calculating the change over time. Note that the tension ratio T1 /
T2 indicates the coefficient of friction μ = (1 / π) ln (T1 / T2).

As a result, as shown in FIG. 8, it has been clarified that the variation of the tension ratio T1 / T2 in the V-ribbed belt 10 according to the present embodiment is smaller than that in the related art. Also,
As shown in FIG. 9, when the tension ratio T1 / T2 after running continuously for 24 hours was compared, the V-ribbed belt 10
It was clarified that the fluctuation of the tension ratio T1 / T2 was smaller than in the conventional case. That is, it was found that the V-ribbed belt 10 not only has excellent initial performance but also has excellent performance at the time of running deterioration as compared with the conventional V-ribbed belt.

The reason is considered as follows. That is, in the conventional V-ribbed belt, since the inclination direction of the aramid short fiber is one direction, the sliding resistance in a predetermined direction is stable, but the sliding resistance in the opposite direction is high. Tended to be. Therefore, when the direction of the tension fluctuates from the above-described one direction to the opposite direction, the sliding resistance greatly changes with respect to the minute tension fluctuation, and as a result, the tension fluctuation tends to increase. However, in the present V-ribbed belt 10, the aramid-based short fibers 8, 8,... Are irregularly curved in multiple directions, so that there is little change in sliding resistance with respect to minute tension fluctuation.
Therefore, it is considered that the tension fluctuation is not increased and the tension ratio is stable.

By the way, if the fluctuation of the sliding resistance is large, a so-called belt squeal is likely to occur. Therefore, a performance comparison test was also performed on a belt squeal at the start using a belt in which aramid short fibers were bent in a certain direction as a conventional V-ribbed belt. Depending on the environment of use, water and oil may be used between the V-rib and the pulley, so the squealing noise is measured not only in the initial state of the belt but also during water injection. Was. As a result, as shown in FIG. 10, it was found that the V-ribbed belt 10 had a much lower squealing sound than the conventional V-ribbed belt. The main reason is, as mentioned above,
It is considered that the fluctuation of the tension ratio in the ribbed belt 10 is small.

In the conventional belt, the squealing noise is remarkably increased at the time of water injection.
Then, the squealing sound is very low even at the time of water injection. The reason is considered as follows. That is, in the present V-ribbed belt 10, the protrusions 15 of the aramid-based short fibers 8 are formed in a curl shape and the roots 12 thereof stand up. Flow through the gaps between the base portions 12 of the web. Therefore, the moisture is
It is hard to stay on the side surface 11 of 7, and it is easy to drain well. For such a reason, it is considered that the generation of squealing noise is suppressed in the present V-ribbed belt 10 even when moisture is mixed in as compared with the related art.

-Variations- The application of the present invention is not limited to the above-described V-ribbed belt 10, but may be other types of V-ribbed belts. For example, a combined V-ribbed belt 10A as shown in FIG. 11 may be used. Further, another transmission belt such as a V-belt may be used.

[0056]

As described above, according to the present invention, since the protruding portion of the short fiber is curved, the exposed area of the short fiber with respect to the surface of the bottom rubber portion can be secured large, and the abrasion resistance of the belt is improved. Performance can be improved. Further, since the protruding portion of the short fiber rises from the surface of the bottom rubber portion, micro unevenness can be formed on the surface of the bottom rubber portion, and generation of abnormal noise can be effectively suppressed.

By forming the protruding portion of the short fiber so as to bend once in one direction from the root to the tip and then bend in a direction different from that direction, the short fiber has a restoring force like a leaf spring. As a result, it is possible to effectively absorb the fluctuation in tension due to the running of the belt. Therefore, power can be transmitted stably. In addition, the restoring force reduces the force applied to the base of the protruding portion of the short fiber, and prevents the short fiber from coming off from the bottom rubber portion. Therefore, the short fiber hardly deteriorates, and the life of the belt is extended.

By forming the protruding portion of the short fiber so that at least its tip is flat, the surface area of the short fiber can be increased, and the wear resistance of the belt can be further improved.

Also, by forming a tear at the tip of the protruding portion of the short fiber, the surface area of the short fiber can be increased, and the wear resistance of the belt can be improved.

By making the bending directions of the projecting portions of the short fibers different from each other, the bottom rubber portion of the belt exerts the same lateral pressure resistance and wear resistance in any direction, The direction dependency of the belt can be eliminated.

By forming the short fibers with para-aramid fibers or meta-aramid fibers, a suitable specific structure can be obtained.

The bottom rubber portion, in which the short fibers are mixed so as to be oriented in a predetermined direction, is ground by a grindstone having superabrasive grains protruding from 50% to 95% of the abrasive grain size, thereby obtaining superabrasive grains. Contact between the bond portion and the bottom rubber portion of the transmission belt can be prevented, and generation of frictional heat can be suppressed.
In addition, it is possible to easily manufacture a power transmission belt in which the short fibers rise from the surface of the bottom rubber portion and are curved.

By grinding the bottom rubber portion in which the short fibers are mixed so as to be oriented in a predetermined direction with a grindstone having superabrasive grains having an abrasive grain density of 3.5% to 55%, abrasive chips are formed. A large pocket can be secured, and clogging of the swarf can be suppressed. In addition, it is possible to easily manufacture a power transmission belt in which the short fibers rise from the surface of the bottom rubber portion and are curved.

The bottom rubber portion in which the short fibers are mixed so as to be oriented in a predetermined direction is mixed with super-abrasive grains having an abrasive grain size of 50% to 95% and an abrasive grain density of 3.5% to 55%. Grinding with a grindstone can suppress the generation of frictional heat and can suppress the clogging of the grinding chips. In addition, it is possible to easily manufacture a power transmission belt in which the short fibers rise from the surface of the bottom rubber portion and are curved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a V-ribbed belt according to the present invention.

FIG. 2 is a sectional view near the surface of a V-rib.

FIG. 3 is a schematic view showing a protruding portion of an aramid short fiber.

FIG. 4 is a schematic view showing a tip of a protruding portion of an aramid short fiber.

FIG. 5 is a schematic configuration diagram of a V-ribbed belt grinding apparatus.

FIG. 6A is a plan view showing a part of the peripheral surface of the grinding wheel in an enlarged manner, and FIG. 6B is a cross-sectional view taken along line AA of FIG.

FIG. 7 is a schematic configuration diagram of a test apparatus for a performance comparison test.

FIG. 8 is a performance comparison diagram showing a change in a tension ratio in an initial state.

FIG. 9 is a performance comparison diagram showing a change in a tension ratio after continuous running for 24 hours.

FIG. 10 is a performance comparison diagram regarding a squeal.

FIG. 11 is a sectional view of a combined V-ribbed belt.

FIG. 12 is a view showing a projection state of aramid short fibers of a conventional power transmission belt.

[Explanation of symbols]

 2 Tensile body 4 Adhesive rubber layer 7 V-rib (bottom rubber part) 8 Aramid staple fiber 10 V-ribbed belt 11 Side (surface) 12 Root part 13 Intermediate part 14 Tip part 15 Protrusion part 21 Grinding stone 24 Super abrasive grain 25 Grinding wheel 26 Bond part

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Miyoshi Kuroshimi 3-2-15 Meiwadori, Hyogo-ku, Kobe-shi, Hyogo F-term (reference) in Bando Chemical Co., Ltd. 4F213 AA29 AA45 AB25 AD16 AG16 AH12 WA53 WA74 WB01

Claims (9)

[Claims] 1. A transmission belt in which a group of short fibers is mixed into a bottom rubber portion so as to be oriented in a predetermined direction, and a part of the group of short fibers protrudes from the surface of the bottom rubber portion. The protruding portion of the power transmission belt rises from the surface of the bottom rubber portion and is curved. 2. The power transmission belt according to claim 1, wherein the protruding portion of the short fiber is curved in one direction from the root toward the tip, and then curved in a direction different from the direction. 3. The power transmission belt according to claim 1, wherein at least the tip of the projecting portion of the short fiber is formed flat. 4. The power transmission belt according to claim 1, wherein the protruding portion of the short fiber has a tear at the tip. 5. The power transmission belt according to claim 1, wherein the projecting portions of the short fiber groups have different bending directions of the projecting portions of the short fibers so that the projecting directions are dispersed. 6. The power transmission belt according to claim 1, wherein the short fibers are formed of para-aramid fibers or meta-aramid fibers. 7. A method for manufacturing a power transmission belt in which a group of short fibers protrudes from a surface of a bottom rubber portion, the method including: A method of manufacturing a power transmission belt, comprising a step of grinding with a grindstone having 50% to 95% of super-abrasive grains protruding. 8. A method of manufacturing a power transmission belt in which a group of short fibers protrudes from the surface of a bottom rubber portion, wherein the bottom rubber portion mixed so that the short fibers group is oriented in a predetermined direction, is provided with an abrasive density A method for producing a power transmission belt, comprising a step of grinding with a grindstone having 3.5% to 55% of superabrasive grains. 9. A method of manufacturing a power transmission belt in which a group of short fibers protrudes from a surface of a bottom rubber part, wherein the bottom rubber part mixed so that the group of short fibers is oriented in a predetermined direction is formed with an abrasive particle size. A method for producing a power transmission belt, comprising a step of grinding with a grindstone having superabrasive grains having 50% to 95% protruding and having an abrasive grain density of 3.5% to 55%.