JP2022103622A - Toothed belt - Google Patents

Abstract

To provide a toothed belt having favorable positioning performance and responsiveness.SOLUTION: A toothed belt comprises a belt main body having multiple tooth parts which are arranged at a belt internal periphery at constant pitches, and a core wire along a belt length direction, embedded into the belt main body so as to form a spiral shape having a pitch in the belt length direction. The core wire includes carbon fibers having filament diameters of 4 to 6 μm as a constituent, and is formed of twisted yarns of 5,000 to 7,000 pieces of filament including the carbon fibers, the number of times of single twits or the number of times of top twists of the twisted yarns is 4 to 10 times/10 cm, a diameter of the core wire is 0.5 to 0.6 mm, and the pitch of the core wire is 0.70 to 0.85 mm.SELECTED DRAWING: Figure 1

Description

The present invention relates to a toothed belt.

The toothed belt is suitable for applications that require synchronous rotation, and is used, for example, as a belt for synchronously transmitting a crank shaft and a cam of an automobile engine (for example, Patent Document 1).
In addition, for example, it is also used in a belt transmission system that requires synchronous transmission of precision machines such as cameras, computers and copiers, and general industrial machines such as robots.

Japanese Unexamined Patent Publication No. 2004-138239

For example, a toothed belt used in a robot is required to have good positioning property.
Further, in the robot field, in order to reduce inertia, it is required to reduce the weight and size of parts. Therefore, the toothed belt used in the robot is also required to cope with the above-mentioned weight reduction and compactification.
For example, when a toothed belt is used to drive a robot arm, it has been proposed to use a toothed belt with a tooth pitch of 5 mm with a small diameter pulley having a diameter of about 20 mm and a two-axis layout. Further, the toothed belt used in the robot is also required to be capable of high load transmission.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a toothed belt which is excellent in positioning property and can be used for high load transmission.

(1) The toothed belt of the present invention is
A belt body having multiple teeth provided at a constant pitch on the inner circumference of the belt,
A core wire embedded in the belt body so as to form a spiral having a pitch in the belt width direction as well as in the belt length direction.
Equipped with
The core wire contains carbon fibers having a filament diameter of 4 to 6 μm as a constituent material, and is a twisted yarn of 5000 to 7,000 filaments containing the carbon fibers.
The twisted yarn has a single twist count or an upper twist count of 4 to 10 times / 10 cm.
The diameter of the core wire is 0.50 to 0.60 mm.
The pitch of the core wire is 0.70 to 0.85 mm.

According to the toothed belt of the present invention, since the above-mentioned specific core wires are embedded in the belt body at a predetermined pitch, the positioning property is excellent. Further, since the toothed belt uses a core wire containing carbon fiber as the core wire, it can be suitably used for high load transmission applications such as for driving an arm of an industrial robot.
In the present invention, positioning means that when a pulley rotated by a toothed belt is rotated in one direction from a certain position and then stopped at a predetermined position, the pulley is stopped at a commanded target position. The smaller the deviation between the target position and the actual stop position, the better the positioning accuracy.

(2) The toothed belt preferably has a tooth pitch of 5 mm.
The toothed belt provided with the core wire according to (1) above is particularly suitable for improving the positioning property of the toothed belt having such a tooth pitch.

(3) The toothed belt preferably has a flexural rigidity of 7.33 Ncm ² or less.
In this case, since the toothed belt can bend the belt with a small force when the belt winds around the pulley, it is not necessary to apply high tension to the belt and the rigidity of the device can be reduced. Further, the lower the rigidity of the belt, the smaller the power transmission energy loss, and the better the bending fatigue and responsiveness of the belt.

(4) The toothed belt preferably has an elastic modulus of M1.0 (stress at an elongation of 1.0%) of 300 N / mm or more.
In this case, the toothed belt has a belt strength that can suppress the elongation rate of the belt when a load is applied to the belt by power transmission to about 1.0% at the maximum. Therefore, a toothed belt having an elastic modulus in the above range when the elastic modulus is M1.0% can suppress the elongation of the belt with respect to the load when a load is applied, and the toothed belt has good positioning accuracy. Become.

(5) In the toothed belt, it is preferable that the belt body is made of a rubber composition or an elastomer composition having a hardness (JIS-A) of 84 to 94.
In this case, the toothed belt has good responsiveness in addition to positioning.

According to the present invention, it is possible to provide a toothed belt having excellent positioning.

It is a perspective view which shows typically the toothed belt which concerns on 1st Embodiment. It is a front view of the arrow X in FIG. 1. It is the end view of the line AA of FIG. It is a partial cross-sectional view of the belt molding mold used for manufacturing a toothed belt. It is a figure explaining the manufacturing process of a toothed belt. It is a figure explaining the manufacturing process of a toothed belt. It is a figure explaining the manufacturing process of a toothed belt. It is a figure which shows the pulley layout of the belt tester used in the evaluation of the positioning property. It is a graph which shows the relationship between the rotational torque and the displacement amount on the pitch line of a toothed belt acquired by the evaluation of positioning property. It is a figure which shows the pulley layout of the belt tester used in the evaluation of responsiveness. It is a graph which shows the evaluation result of the toothed belt of Example 2, and is the graph which shows the time change of the rotation speed of each of a drive pulley and a driven pulley. It is a graph which shows the evaluation result of the toothed belt of Example 2, and is the graph which shows the time change of the difference in the rotation speed between a drive pulley and a driven pulley.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to these embodiments.
FIG. 1 is a perspective view showing a part of a toothed belt 10 according to an embodiment of the present invention. FIG. 2 is a front view of the arrow X in FIG. FIG. 3 is an end view taken along the line AA of FIG.

The toothed belt 10 is used, for example, for driving a robot arm.
Although FIG. 1 shows only a part of the toothed belt 10, the toothed belt 10 is an endless meshing transmission belt.
As shown in FIG. 1, the toothed belt 10 includes a belt main body 11, a core wire 13, and a reinforcing cloth 14.

The toothed belt 10 is a relatively small toothed belt, and has a belt circumference (belt length in the belt pitch line BL) of, for example, 200 mm or more and 2000 mm or less, a belt width of, for example, 4 mm or more and 30 mm or less, and a maximum belt thickness. For example, it is 3.0 mm or more and 4.0 mm or less. The toothed belt 10 is excellent in positioning even with such dimensions. A toothed belt having such dimensions is also suitable for, for example, miniaturization and weight reduction of a robot.
Of course, the dimensions of the toothed belt according to the embodiment of the present invention are not limited to this range.

The toothed belt 10 has a plurality of belt teeth 12 arranged on the inner peripheral side at predetermined pitch intervals.
The tooth profile of the belt tooth 12 is preferably an arc tooth profile, and among the arc tooth profiles, the S tooth profile is more preferable. The S tooth profile reduces backlash in the gap between the belt tooth portion and the pulley groove, and has a large belt tooth width and belt tooth height. In addition, since the tip of the belt tooth is in close contact with the bottom of the pulley groove and meshes with it, the force on the pressure surface of the tooth that the toothed belt receives is dispersed and uniform, the deformation of the tooth is small, and the design is excellent in positioning accuracy. Because it is suitable for doing.

In the embodiment of the present invention, the tooth profile of the belt tooth 12 is not limited to the S tooth profile, and may be an arc tooth profile other than the S tooth profile, a trapezoidal tooth profile, or any other tooth profile. You may.

In the toothed belt 10, the belt teeth 12 are straight teeth extending parallel to the belt width direction.
In the embodiment of the present invention, the belt tooth 12 may be a tooth tooth extending in a direction inclined with respect to the belt width direction.

In the toothed belt 10, the tooth pitch P of the belt teeth 12 (see P in FIG. 3) is, for example, 2 mm or more and 8 mm or less.
Positioning accuracy is improved by subdividing the tooth pitch. As for the size of the tooth portion, the larger the size, the higher the power can be transmitted. Therefore, from the viewpoint of achieving both good positioning accuracy and high power transmission performance, the tooth pitch P of the belt teeth 12 is preferably 3 mm or more and 5 mm or less, and particularly preferably 5 mm.

The tooth height of the belt teeth 12 is defined by the dimension from the bottom portion 15 between the pair of belt teeth 12 adjacent to each other in the belt length direction to the tip of the belt teeth 12 (see H in FIG. 3), for example. It is 1.7 mm or more and 2.2 mm or less.
Further, in the toothed belt 10, the number of teeth is, for example, 40 or more and 400 or less, the tooth width (dimension in the belt length direction) is, for example, 200 mm or more and 2000 mm or less, and the PLD is, for example, 0.450 mm or more and 0.600 mm or less. ..

The belt body 11 is made of rubber (including erasmer) and has an endless flat band-shaped back rubber portion 11a and a plurality of tooth rubber portions 11b. The plurality of tooth rubber portions 11b are integrally provided on the inner peripheral side, which is one side of the back rubber portion 11a, at intervals in the belt length direction. The belt main body 11 is composed of, for example, an unvulcanized rubber composition in which various rubber compounding agents are blended with a rubber component, which is heated and pressed during belt molding to vulcanize the rubber component.
The constituent materials of the back rubber portion 11a and the tooth rubber portion 11b may be the same or different.

Examples of the rubber component of the rubber composition forming the belt body 11 include hydride nitrile rubber (H-NBR), ethylene-α-olefin elastomer (for example, EPDM and EPR), chloroprene rubber (CR), and chlorosulfone. Examples thereof include chemicalized polyethylene rubber (CSM). The hydrogenated nitrile rubber (H-NBR) may contain an unsaturated carboxylic acid metal salt in H-NBR. Only one kind of these rubber components may be used, or two or more kinds may be used in combination.
The toothed belt 10 may be used, for example, as a toothed belt 10 for driving a robot arm in a robot used in a harsh environment unsuitable for human activities. In this case, the belt body 11 of the toothed belt 10 may be required to have heat resistance, oil resistance, and weather resistance. From such a viewpoint, the rubber component preferably contains H-NBR.

When the rubber component of the rubber composition is H-NBR, the amount of bound acrylonitrile thereof is preferably 20% by mass or more and 50% by mass or less. The iodine value is preferably 5 mg / 100 mg or more and 15 mg / 100 mg or less. Further, the Mooney viscosity at 100 ° C. is preferably 40 ML 1 + ₄ (100 ° C.) or more and 90 ML _{1 + 4} (100 ° C.) or less.

Examples of the rubber compounding agent include a vulcanization accelerating aid, an antiaging agent, a reinforcing material, a plasticizer, a co-crosslinking agent, a cross-linking agent and the like.

Examples of the sulfide accelerating aid include metal oxides such as zinc oxide (zinc oxide) and magnesium oxide, metal carbonates, fatty acids and derivatives thereof. As the vulcanization accelerating aid, it is preferable to use one or more of these, and it is more preferable to use zinc oxide.
The content of the vulcanization accelerating aid is, for example, 3 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the rubber component.

Examples of the antiaging agent include benzimidazole type, aromatic secondary amine type, amine-ketone type and the like. As the anti-aging agent, it is preferable to use one or more of these, and it is more preferable to use benzimidazole-based and aromatic secondary amine-based agents in combination.
The content of the antiaging agent is, for example, 1.5 parts by mass or more and 3.5 parts by mass or less with respect to 100 parts by mass of the rubber component.

Examples of the reinforcing material include carbon black and silica.
Examples of the carbon black include channel black; furnace black such as SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234; thermal black such as FT and MT. ; Acetylene black and the like can be mentioned. These may be used alone or in combination of two or more.
As the carbon black, it is preferable to use at least FEF or HAF.
As the reinforcing material, carbon black and silica may be used in combination.

When carbon black is used as the reinforcing material, its content is, for example, 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the rubber component. The preferable content of the carbon black is 45 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component.
When silica is used as the reinforcing material, its content is, for example, 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the rubber component.

Examples of the plasticizer include a polyether ester, a dialkyl sevacate such as dioctyl sevacate (DOS), a dialkyl phthalate such as dibutyl phthalate (DBP) and a dioctyl phthalate (DOP), and a dialkyl adipate such as dioctyl adipate (DOA). Can be mentioned. These may be used alone or in combination of two or more.
As the plasticizer, it is preferable to use at least a polyether ester.
The content of the plasticizer is, for example, 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the rubber component.

Examples of the co-crosslinking agent include trimethylolpropane trimethacrylate, m-phenylenedimaleimide, zinc dimethacrylate, and triallyl isocyanurate. These may be used alone or in combination of two or more.
As the co-crosslinking agent, it is preferable to use trimethylolpropane trimethacrylate and m-phenylenedimaleimide in combination.
The content of the co-crosslinking agent is, for example, 3 parts by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the rubber component.

Examples of the cross-linking agent include sulfur and organic peroxides. Both may be used alone or in combination.
When only an organic peroxide is used as the cross-linking agent, the blending amount of the organic peroxide is, for example, 2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the rubber component.
When sulfur and an organic peroxide are used in combination as the cross-linking agent, the total amount of the cross-linking agent is, for example, 0.1 part by mass or more and 0.7 by mass with respect to 100 parts by mass of the rubber component. It is not less than parts by mass, and the amount of organic peroxide is 1 part by mass or more and 5 parts by mass or less.

Further, the belt main body 11 is a thermosetting urethane composition in which an uncured thermosetting urethane composition in which various compounding agents are blended with a urethane prepolymer and a curing agent is heated and pressed during belt molding to crosslink the urethane prepolymer. It may be composed of a composition containing a urethane elastomer.
Further, the belt main body 11 may be composed of a thermoplastic elastomer composition in which various compounding agents are blended with a thermoplastic elastomer, which is molded in a mold.

The core wire 13 is embedded in the surface layer on the inner peripheral side of the back rubber portion 11a of the belt main body 11 so as to form a spiral having a pitch in the belt width direction and extend.

The core wire 13 has a core wire diameter of 0.50 mm or more and 0.60 mm or less.
The pitch of the core wire 13 (arrangement pitch in the belt width direction) is 0.70 mm or more and 0.85 mm or less.
When the core wire 13 satisfies these conditions, the toothed belt 10 has good positioning while reducing the bending rigidity of the belt. In addition, it is easy to secure the responsiveness of the toothed belt 10.

In particular, in the embodiment of the present invention, by adopting a core wire containing carbon fiber that can secure sufficient tension even if the core wire is thin, the diameter of the core wire can be reduced to 0.50 mm or more and 0.60 mm or less. , The arrangement pitch of the core wires is narrowed to 0.70 mm or more and 0.85 mm or less.
Therefore, the toothed belt of the embodiment of the present invention has excellent positioning even if it is a relatively small toothed belt.

The core wire 13 contains carbon fiber as a constituent material. The core wire 13 may be composed of only carbon fibers, or may be composed of a composite of carbon fibers and other types of fibers. The carbon fibers may be PAN-based, pitch-based, or both. A sizing agent such as an epoxy resin may be attached to the carbon fiber.
Examples of the other types of fibers include inorganic fibers such as glass fibers and metal fibers, aramid fibers, polyester fibers, PBO fibers, nylon fibers, and organic fibers such as polyketone fibers.

When the core wire 13 contains carbon fibers and other types of fibers as a constituent material, the ratio of the carbon fibers to the total fibers is 50% by mass or more.
The proportion of the carbon fibers is preferably as large as (for example, 90% by mass or more), and may be 100%.

The carbon fiber has a filament diameter of 4 μm or more and 6 μm or less.
By using the core wire containing the carbon fiber having the filament diameter, the toothed belt 10 has good positioning.

The core wire 13 is a twisted yarn of 5000 to 7000 filaments containing the carbon fiber.
By using such a twisted yarn as a core wire, the toothed belt 10 has good positioning.

The twisting method of the core wire 13 is one-sided twisting, various twisting, or rung twisting. Among these twisting methods, one-sided twisting is preferable from the viewpoint of strength, elastic modulus, and adhesion treatment of filaments constituting the core wire.

When the core wire 13 is a single-twisted yarn, the number of single-twisted yarns 13 is 4 to 10 times / 10 cm. If the number of single twists is less than 4 times / 10 cm, bending fatigue is poor and it is not suitable as a core wire for a toothed belt. On the other hand, when the number of single twists exceeds 10 times / 10 cm, the strength and elastic modulus decrease, and the positioning property of the toothed belt using this core wire deteriorates.

When the core wire 13 is a multi-twisted yarn or a rung-twisted yarn, the number of upper twists is 4 to 8 times / 10 cm. If the number of top twists is less than 4 times / 10 cm, bending fatigue is poor and it is not suitable as a core wire for a toothed belt. On the other hand, when the number of top twists exceeds 10 times / 10 cm, the strength and elastic modulus decrease, and the positioning property of the toothed belt using this core wire deteriorates.
When the core wire 13 has various twists or rung twists, the number of lower twists is not particularly limited, but is, for example, 6 to 12 times / 10 cm.

The core wire 13 may be subjected to an adhesive treatment before the production of the toothed belt 10 in order to increase the adhesive force with the belt main body 11.
As the above-mentioned adhesive treatment, for example, one or both of the RFL treatment which is heated after being immersed in the RFL aqueous solution and the rubber glue treatment which is dried after being immersed in the rubber glue, or after being immersed in an aqueous treatment agent containing a rubber latex and a cross-linking agent. A process of drying can be adopted.
The aqueous treatment agent contains rubber latex as a main component. Examples of the rubber latex include those containing at least one selected from the group consisting of nitrile rubber, hydrided nitrile rubber, carboxyl-modified nitrile rubber, and carboxyl-modified hydride nitrile rubber as the rubber component. Be done. The aqueous treatment agent may or may not contain an RFL condensate.
Before the adhesive treatment, the core wire 13 may be subjected to a base treatment of immersing it in an epoxy solution or an isocyanate solution and then heating it.

When the core wire 13 is a single-stranded yarn, the core wire is, for example, a fiber bundle of carbon fibers alone or a fiber bundle of carbon fibers and other types of fibers bundled in one direction (S direction or Z direction). It can be obtained by twisting with the above-mentioned number of single twists.

When the core wire 13 is a multi-twisted yarn, the core wire is, for example, a collection of a plurality of lower twisted yarns in which each of a plurality of fiber bundles including a fiber bundle of carbon fibers is downwardly twisted in one direction (S direction or Z direction). , It can be obtained by top-twisting in the direction opposite to the bottom-twisting direction with the above-mentioned number of top-twisting.

When the core wire 13 is a rung twisted yarn, the core wire is, for example, a collection of a plurality of lower twisted yarns in which each of a plurality of fiber bundles including a fiber bundle of carbon fibers is downwardly twisted in one direction (S direction or Z direction). , It can be obtained by top-twisting in the same direction as the bottom-twisting direction with the above-mentioned number of top-twisting.

In the toothed belt 10, the core wire 13 has an S twisted yarn (in the case of a double twisted yarn or a rung twisted yarn, the upper twisting direction is in the S direction) and a Z twisted yarn (in the case of a double twisted yarn or a rung twisted yarn, the upper twisting direction is in the Z direction). (Things) may be used and may be provided in a double helix so that they are alternately arranged in the belt width direction. In this case, it is suitable for suppressing the deviation of the toothed belt 10 during traveling.
The core wire 13 may be composed of a single S-twisted yarn or Z-twisted yarn.

The reinforcing cloth 14 is attached so as to cover the surface on the inner peripheral side where the plurality of tooth rubber portions 11b of the belt main body 11 are provided. Therefore, in each belt tooth 12, the tooth rubber portion 11b is covered with the reinforcing cloth 14.
In the tooth bottom portion 15, the reinforcing cloth 14 is arranged immediately inside the core wire 13 embedded in the inner peripheral side portion of the back rubber portion 11a of the belt main body 11. The thickness of the reinforcing cloth 14 is, for example, 0.1 mm or more and 0.6 mm or less.

The reinforcing cloth 14 is composed of, for example, nylon fiber (polyamide fiber), polyester fiber, aramid fiber, polyparaphenylene benzobisoxazole (PBO) fiber, woven cloth made of threads such as cotton, knitted fabric, non-woven fabric and the like. There is. Of these, nylon fiber woven fabrics are preferred.
It is preferable that the reinforcing cloth 14 has elasticity, for example, like a woven cloth in which the weft is subjected to woolly processing or the like.

The reinforcing cloth 14 has an RFL treatment that is heated after being immersed in an RFL aqueous solution, a soaking treatment that is immersed in a low-viscosity rubber glue and then dried, and a high-viscosity adhesive treatment for enhancing the adhesive force with the belt body. One or more of the coating treatments in which the rubber glue is applied to the surface of the belt body side and dried may be applied.
Prior to the adhesive treatment, the reinforcing cloth 14 may be subjected to a base treatment of immersing it in an epoxy solution or an isocyanate solution and then heating it.

The toothed belt 10 preferably has a flexural rigidity of 7.33 Ncm ² or less.
In this case, since the toothed belt 10 can bend the belt with a small force when the belt winds around the pulley, it is not necessary to apply high tension to the belt and the rigidity of the device can be reduced. Further, the lower the rigidity of the belt, the smaller the power transmission energy loss, and the better the bending fatigue and responsiveness of the belt. On the other hand, a toothed belt having a large flexural rigidity is inferior in bending fatigue and may not be suitable for use in combination with a small pulley.
The lower limit of the flexural rigidity is not particularly limited, but is, for example, 6.50 Ncm ² .

The flexural rigidity is measured by the following method.
For the toothed belt 10, according to JIS K7106 (1995), the bending stiffness E is obtained by a bending test using an Orzen bending tester, and the bending stiffness E is multiplied by the moment of inertia of area I of the toothed belt 10 to obtain the belt bending rigidity EI. calculate.
Here, for the moment of inertia of area I of the toothed belt 10, the belt width is the width b of the test piece, the belt thickness of the tooth bottom portion 15 is the thickness h of the test piece, and the cross section of the toothed belt 10 is rectangular. The moment of inertia of area is calculated as I = bh ^3/12 . That is, in the present invention, when calculating the secondary moment, the secondary moment is calculated by ignoring the portion of the tooth rubber of the toothed belt 10.

The toothed belt 10 preferably has an elastic modulus of M1.0 of 300 N / mm or more.
In this case, it is more suitable for ensuring good positioning.
The preferable upper limit of the elastic modulus M1.0 is 1000 N / mm.
If the elastic modulus M1.0 is too large, plastic deformation may occur and the strength of the belt may decrease.

In the embodiment of the present invention, the elastic modulus M1.0 of the toothed belt means that the toothed belt is stretched by 1.0% in the direction of the belt length in a tensile test conducted using the toothed belt as a measurement sample. The stress per unit width of the belt.

The elastic modulus M1.0 is measured by the following method using a tensile tester.
First, the toothed belt 10 is cut into strips having a belt length of about 300 mm, and two marked lines separated by about 100 mm are marked on the back surface of the toothed belt 10 to prepare a measurement sample.
Next, both ends of the measurement sample in the belt length direction are gripped by the chuck portion of the tension tester, and the measurement sample is set in the tensile tester.
Then, the measurement sample is pulled in the belt length direction at a tensile speed of 50 mm / min, and the stress when the measurement sample is stretched by 1.0% based on the distance between the marked lines is detected by the load cell.
Finally, the detected stress is divided by the width of the measurement sample to calculate the stress per unit width.
The measurement is performed three times, and the average value thereof is defined as an elastic modulus of M1.0.

In the toothed belt 10, the hardness (JIS-A) of the rubber composition or the elastomer composition constituting the belt body 11 is preferably 84 to 94. If the belt body 11 satisfies this requirement, it is suitable for improving bending fatigue and responsiveness while ensuring excellent positioning.
On the other hand, if the hardness (JIS-A) is less than 84, the positioning property of the toothed belt 10 may be inferior. Further, when the hardness (JIS-A) exceeds 94, the toothed belt 10 may be inferior in bending fatigue and responsiveness.

The hardness (JIS-A) of the rubber composition or elastomer composition is determined by molding the rubber composition or elastomer composition constituting the belt body 11 into a predetermined shape and using this as a measurement sample according to the measurement target. The hardness is measured using a type A rubber meter in accordance with JIS K6253-3 (2012) and JIS K7312 (1996).

The clearance ratio of the toothed belt 10 is preferably less than 30%. In this case, the positioning of the toothed belt 10 becomes better. The gap ratio is more preferably 28% or less.
The gap ratio may be small from the viewpoint of positioning, but if it is too small, the rate of defective products in which the rubber composition is not filled in the tooth rubber portion during manufacturing of the toothed belt may increase. Therefore, the lower limit of the gap ratio is preferably 20%, more preferably 22% from the viewpoint of yield.
The gap ratio means the ratio (%) of the total gap dimension between the core wires in the width direction of the belt to the width dimension of the toothed belt.
The smaller the clearance ratio, the larger the proportion of the core wire in the width direction of the belt.

The toothed belt 10 according to the embodiment of the present invention is wound around, for example, a pair of pulleys, and transmits power from a drive source to the driven side. Here, the outer diameter of the pulley is, for example, 21.32 mm or more and 94.53 mm or less. The belt traveling speed is, for example, 0.1 m / sec or more and 33.0 m / sec or less, and the transmission capacity is, for example, 0.05 kW or more and 20.10 kW or less.

According to the toothed belt 10 according to the present embodiment having the above configuration, the core wire 13 has a specific configuration including carbon fibers, and the core wire 13 is embedded in the belt main body 11 at a predetermined arrangement pitch. Therefore, it has excellent positioning and responsiveness.

Next, a method for manufacturing the toothed belt 10 according to the present embodiment will be described with reference to FIGS. 4 to 7 by taking the case where the belt main body is made of the rubber composition as an example.
The method for manufacturing the toothed belt 10 includes a material preparation step, a molding step, a vulcanization step, and a finishing step.

<Material preparation process>
An unvulcanized rubber composition is obtained by kneading a predetermined rubber component, adding various rubber compounding agents to the kneading, and kneading the mixture. Then, the unvulcanized rubber composition sheet 11'is produced by calendar molding or the like of the obtained unvulcanized rubber composition.

Adhesive treatment is applied to each of the core wire 13 and the reinforcing cloth 14. Further, the reinforcing cloth 14 is formed into a cylindrical shape.

<Molding process>
FIG. 4 is a partial cross-sectional view showing a part of the belt molding die 30.
The belt forming die 30 has a cylindrical shape, and each has an outer peripheral surface in which a plurality of tooth forming grooves 31 formed so as to extend in the axial direction are arranged at intervals in the circumferential direction.

As shown in FIG. 5, a tubular reinforcing cloth 14 is covered on the outer peripheral surface of the belt forming die 30, and the core wire 13 is spirally wound from above.
Then, the unvulcanized rubber composition sheet 11'is wound around the unvulcanized rubber composition sheet 11', and the unvulcanized slab S'is formed on the belt molding die 30. The unvulcanized rubber composition sheet 11'is preferably used so that the columnar direction corresponds to the belt length direction.

<Vulcanization process>
As shown in FIG. 6, a rubber sleeve 32 is put on the unvulcanized slab S'on the belt molding die 30, and the rubber sleeve 32 is placed in the vulcanizing can to seal the vulcanized can. Is filled and held for a predetermined molding time. By pressing the unvulcanized slab S'toward the belt forming die 30 and heating it in this way, the unvulcanized rubber composition sheet 11'is passed between the core wires 13 and the reinforcing cloth 14 is pressed while pressing the unvulcanized slab S'. It is made to flow into each of the plurality of tooth forming grooves 31 and vulcanized. At the same time, the core wire 13 and the reinforcing cloth 14 are compositely integrated, and finally, as shown in FIG. 7, a cylindrical belt slab S is molded.

<Finishing process>
The inside of the vulcanization can is depressurized to release the seal, the belt slab S molded between the belt molding mold 30 and the rubber sleeve 32 is taken out, demolded, and sliced to a predetermined width to form the toothed belt 10. obtain.
By going through such a step, it is possible to manufacture a toothed belt 10 in which the belt body is made of a rubber composition.

Further, the toothed belt 10 in which the belt body 11 is composed of a thermosetting urethane elastomer composition or a thermosetting elastomer composition can be produced, for example, by the following method.
That is,
(1) The core wire 13 is spirally wound around the outer peripheral surface of the cylindrical belt molding die 30 used in the manufacture of a toothed belt whose main body is made of a rubber composition.
(2) Next, the cylindrical belt forming die 31 is housed in a cylindrical outer mold having an inner diameter larger than the outer diameter of the belt forming die 31. At this time, a cavity for forming the belt body is formed between the belt forming die 31 and the outer die.

(3-1) Next, an uncured thermosetting urethane composition containing a urethane prepolymer and a curing agent is injected into the cavity, filled, and heated. At this time, the uncured thermosetting urethane composition is cured while being inserted into the tooth portion forming groove 31, and a cylindrical slab in which the thermosetting urethane elastomer and the core wire 13 are integrated is formed. ..
(3-2) Alternatively, the thermoplastic elastomer composition imparted with fluidity by heating is injected into the cavity, filled, and then cooled. At this time, the thermoplastic elastomer is solidified in a state of being inserted into the tooth forming groove 31, and a cylindrical slab in which the thermoplastic elastomer and the core wire 13 are integrated is formed.

(4) After that, the cylindrical slab is removed from the belt forming die 31 and the outer mold, a reinforcing cloth is attached to the inner peripheral surface (tooth rubber portion side) thereof, and then the slab provided with the reinforcing cloth is sliced. By doing so, a toothed belt 10 is obtained.
By performing such a step, it is possible to manufacture a toothed belt 10 in which the belt body is composed of a thermosetting urethane elastomer composition or a thermosetting elastomer composition.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Examples 1 to 3 and Comparative Examples 1 to 4
Here, a toothed belt having a tooth mold type of S5M (JIS B1857) was produced, and its performance was evaluated.
Each toothed belt was produced by the method described above.
The unvulcanized rubber composition, the core wire, and the reinforcing cloth for forming the belt body (back rubber part and tooth rubber part) were prepared as follows.

(Preparation of unvulcanized rubber composition)
The following rubber compositions A to D having the compositions shown in Table 1 were prepared. In Table 1, the blending amount is shown by mass.
-Rubber Composition A: An unsaturated carboxylic acid metal salt obtained by mixing 45 parts by mass of hydrogenated nitrile rubber (H-NBR) (manufactured by Nippon Zeon Co., Ltd., trade name: ZETPOL 2020) and an unsaturated carboxylic acid metal salt. The base rubber is a rubber mixed with 55 parts by mass of hydrogenated nitrile rubber (manufactured by Nippon Zeon Co., Ltd., trade name: ZSC2195), and zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.) is used for 100 parts by mass of the base rubber. , Product name: Zinc oxide 3 types) 5 parts by mass, Steric acid (manufactured by Shin Nihon Rika Co., Ltd., Product name: Stear acid) 1 part by mass, Dioctyl sebacate (DOS) (manufactured by Dainippon Ink and Chemicals Co., Ltd.) , Product name: Monosizer W280) 10 parts by mass, Carbon Black FEF (manufactured by Tokai Carbon Co., Ltd., Product name: Ester SO) 60 parts by mass, Anti-aging agent (manufactured by Ouchi Shinko Kagaku Co., Ltd., Product name: Nocrack MB) 3 parts by mass, Trimethylol Propanetriacrylate (TMPT) (manufactured by Sanshin Chemical Industry Co., Ltd., trade name: Sunester TMP) 3 parts by mass, Peroxymon F40 (manufactured by Nichiyu Co., Ltd.) 7 parts by mass The unsulfurized rubber composition kneaded in the above was designated as rubber composition A.

The hardness (JIS-A) of the vulcanized product vulcanized under the same conditions as the vulcanization conditions at the time of producing the toothed belt was measured for the rubber composition A and found to be 89.
The hardness of the vulcanized product was measured using a type A durometer in accordance with JIS K6253-3 (2012). The method for measuring the hardness of the vulcanized product of the following rubber compositions B to D is also the same.

-Rubber composition B: Prepared in the same manner as rubber composition A except that the ratio of carbon black FEF was changed.
The hardness (JIS-A) of the vulcanized product vulcanized under the same conditions as the vulcanization conditions at the time of producing the toothed belt of the rubber composition B was measured and found to be 86.

-Rubber composition C: Prepared in the same manner as rubber composition A except that the ratio of carbon black FEF was changed.
The hardness (JIS-A) of the vulcanized product vulcanized under the same conditions as the vulcanization conditions at the time of producing the toothed belt was measured for the rubber composition C and found to be 95.

-Rubber composition D: Prepared in the same manner as rubber composition A except that the ratio of carbon black FEF was changed.
The hardness (JIS-A) of the vulcanized product vulcanized under the same conditions as the vulcanization conditions at the time of producing the toothed belt was measured for the rubber composition D and found to be 80.

(Preparation of core line)
-Core wire A: Carbon fiber (trade name: Toray Industries, Inc. T800HB-6000, filament diameter 5.0 μm, number of filaments 6000) is used, and this is twisted 6 times / 10 cm. The core line A was used. The core wire diameter of the core wire A is 0.55 mm. Two types of core wire A, S-twisted yarn and Z-twisted yarn, were prepared.

-Core wire B: Carbon fiber (trade name: Toray Industries, Inc. T800HB-6000, filament diameter 5.0 μm, number of filaments 6000) is used, and this is twisted 8 times / 10 cm. The core line B was used. The core wire diameter of the core wire B is 0.58 mm. As the core wire B, two types of S-twisted yarn and Z-twisted yarn were prepared.

-Core wire C: A piece made of carbon fiber (trade name: Toray Industries, Inc., trade name: Trading Card T300B-6000, filament diameter 7.0 μm, number of filaments 6000), twisted at 7.5 times / 10 cm. The twisted yarn was core wire C. The core wire diameter of the core wire C is 0.70 mm. Two types of core wire C, S-twisted yarn and Z-twisted yarn, were prepared.

-Core wire D: Carbon fiber (trade name: Toray Industries, Inc., trade name: Trading Card T300B-3000, filament diameter 7.0 μm, number of filaments 3000) is used, and this is twisted 6 times / 10 cm. The core line D was used. The core wire diameter of the core wire D is 0.48 mm. As the core wire D, two types of S-twisted yarn and Z-twisted yarn were prepared.

-Core wire E: Carbon fiber (trade name: Toray Industries, Inc., trade name: Trading Card T300B-3000, filament diameter 7.0 μm, number of filaments 3000) is used, and this is twisted 12 times / 10 cm. The core line E was used. The core wire diameter of the core wire E is 0.53 mm. Two types of core wire E, S-twisted yarn and Z-twisted yarn, were prepared.

-Core wire F: High-hardness glass fiber (high-strength glass cord manufactured by Nippon Sheet Glass Co., Ltd., filament diameter 7.0 μm) is used, and three 200 filaments are collected and twisted 8 times / 10 cm. Eight lower twisted yarns twisted in the direction were collected, and the twisted yarns twisted in the direction opposite to the lower twisting direction with the number of upper twists of 8 times / 10 cm were designated as the core wire F. The core wire diameter of the core wire F is 0.72 mm. Two types of core wire F, S-twisted yarn and Z-twisted yarn, were prepared. The total number of filaments of the core wire F is 4,800.

(Preparation of reinforcing cloth)
The following nylon canvas was prepared as a reinforcing cloth.
Resorcin (manufactured by Sumitomo Chemical Co., Ltd., trade name: resorcinol) and formalin (manufactured by Mitsui Chemicals Co., Ltd., trade name: formalin) are added to a sodium hydroxide solution at a molar ratio of R / F = 1/2. The initial condensate solution thereof was obtained by stirring and mixing. To the obtained solution, hydrogenated acrylonitrile butadiene methacrylic acid ternary copolymer (X-NBR) latex (trade name, ZLX-B manufactured by Nippon Zeon Co., Ltd.) and water are added and mixed by stirring to obtain resorcin. An RFL solution having a mass ratio of formalin and latex of RF / L = 1/8 was prepared.

Next, in this RFL liquid, 80 parts by mass of polytetrafluoroethylene (manufactured by Asahi Glass Co., Ltd., trade name: Fluon AD911, average particle size: 0.25 μm) was blocked with respect to 100 parts by mass of the latex solid content of the RFL liquid. Add 30 parts by mass of isocyanate (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27, bond dissociation temperature 180 ° C.), stir and mix, and further, carbon black (manufactured by Fuji Dye Industry Co., Ltd., product). Name: Fuji SP Black 203) was added and dispersed so as to be 5% by mass of the whole, and a treatment liquid having a solid content concentration of 15% by mass was prepared.

A pair of twill weave fabrics made of 6,6-nylon fiber woolly processed yarn (break elongation 150% or more) with warp 235 dtex and warp 155 dtex are dipped in this treatment liquid and then pulled up. The treatment liquid was adhered to the twill weft woven cloth by passing it between the pressure rolls and squeezing it. At this time, the liquid temperature of the treatment liquid was set to 20 ° C., the immersion time was set to 2 seconds, and the number of treatments was set to 2 times. Further, the clearance of the pressure roll was adjusted so that the basis weight of the RFL coating was about 30% by mass.

A twill weave woven fabric to which the treatment liquid was attached was passed through a heating and drying furnace and dried by heating to prepare a nylon canvas. At this time, the temperature inside the heating / drying furnace (heating / drying temperature) was set to 150 ° C., and the heat treatment time was set to 2 minutes.
This nylon canvas was used as a reinforcing cloth used in Examples and Comparative Examples.

<Example 1>
The above-mentioned manufacturing method (FIGS. 4 to 4) using the rubber composition A as the unvulcanized rubber composition forming the belt body, the core wire A as the core wire, and the nylon canvas as the reinforcing cloth. 7), a toothed belt having a tooth mold type of S5M was manufactured. The belt width was 10 mm and the belt length was 800 mm.
At this time, the core wire A is subjected to an adhesive treatment in which hydrogenated nitrile rubber is the main component, the rubber latex containing no RFL condensate and the cross-linking agent are immersed in the aqueous treatment agent A, and then the core wire A is dried. It was used. Further, the core wire A is provided in a double spiral so that the S twisted yarn and the Z twisted yarn are alternately arranged in the belt width direction and the adjacent core wire pitch is 0.75 mm.
The clearance ratio of the manufactured toothed belt is 26.7%.

<Example 2>
A toothed belt was produced in the same manner as in Example 1 except that the rubber composition B was used instead of the rubber composition A as the unvulcanized rubber composition.

<Example 3>
A toothed belt was produced in the same manner as in Example 1 except that the rubber composition C was used instead of the rubber composition A as the unvulcanized rubber composition.

<Example 4>
A toothed belt was manufactured in the same manner as in Example 2 except that the core wire B was used instead of the core wire A as the core wire.
At this time, as the core wire B, one that had been subjected to an adhesive treatment of being immersed in the above-mentioned aqueous treatment agent A and then dried was used. Further, the core wire B is provided in a double spiral so that the S twisted yarn and the Z twisted yarn are alternately arranged in the belt width direction and the adjacent core wire pitch is 0.75 mm.
The clearance ratio of the manufactured toothed belt is 22.7%.

<Comparative Example 1>
The above-mentioned manufacturing method (FIGS. 4 to 4) using the rubber composition D as the unvulcanized rubber composition forming the belt body, the core wire C as the core wire, and the nylon canvas as the reinforcing cloth. 7), a toothed belt having a tooth mold type of S5M was manufactured. The belt width was 10 mm and the belt length was 800 mm.
At this time, as the core wire C, one which had been subjected to an adhesive treatment of being immersed in the above-mentioned aqueous treatment agent A and then dried was used. Further, the core wire C is provided in a double spiral so that the S twisted yarn and the Z twisted yarn are alternately arranged in the belt width direction and the adjacent core wire pitch is 1.0 mm.
The clearance ratio of the toothed belt is 30.0%.

<Comparative Example 2>
A toothed belt was manufactured in the same manner as in Example 1 except that the core wire D was used as the core wire instead of the core wire A and the following core wire pitch was adopted.
At this time, as the core wire D, one that had been subjected to an adhesive treatment of being immersed in the above-mentioned aqueous treatment agent A and then dried was used. Further, the core wire D is provided in a double spiral so that the S twisted yarn and the Z twisted yarn are alternately arranged in the belt width direction and the adjacent core wire pitch is 0.80 mm.
The clearance ratio of the manufactured toothed belt is 40.0%.

<Comparative Example 3>
A toothed belt was manufactured in the same manner as in Example 1 except that the core wire E was used instead of the core wire A and the following core wire pitch was adopted.
At this time, as the core wire E, one that had been subjected to an adhesive treatment of being immersed in the above-mentioned aqueous treatment agent A and then dried was used. Further, the core wire E is provided in a double spiral so that the S twisted yarn and the Z twisted yarn are alternately arranged in the belt width direction and the adjacent core wire pitch is 0.80 mm.
The clearance ratio of the manufactured toothed belt is 33.8%.

<Comparative Example 4>
A toothed belt was manufactured in the same manner as in Example 3 except that the core wire F was used as the core wire instead of the core wire A and the following core wire pitch was adopted.
At this time, as the core wire F, one which had been subjected to an adhesive treatment of being immersed in the above-mentioned aqueous treatment agent A and then dried was used. Further, the core wire F is provided in a double spiral so that the S twisted yarn and the Z twisted yarn are alternately arranged in the belt width direction and the adjacent core wire pitch is 1.2 mm.
The clearance ratio of the manufactured toothed belt is 40.0%.

(Evaluation method)
The flexural rigidity and elastic modulus M1.0 were measured for the toothed belts produced in Examples and Comparative Examples. Further, the toothed belts produced in Examples and Comparative Examples were evaluated for positioning and responsiveness. These results are shown in Table 3.

<Flexural rigidity>
The flexural rigidity was measured by the method described above using a toothed belt cut to a length of 70 mm as a sample.
That is, the flexural rigidity E of the measurement sample of the toothed belt is obtained by a bending test using an Orzen bending tester according to JIS K7106 (1995), and is multiplied by the moment of inertia of area I of the toothed belt. -I (Ncm ² ) was calculated.

The measurement sample of the toothed belt had a tooth profile: S5M, a width of 10 mm, a thickness of 3.61 mm, and a length of 70 mm.
The moment of inertia of area I of the measurement sample of the toothed belt is regarded as a rectangle ignoring the tooth portion of the toothed belt cross section, the width b of the test piece is the belt width 10 mm, and the thickness h of the test piece is the belt of the tooth bottom portion. The thickness was 1.70 mm, and the moment of inertia of area was obtained from the calculation of I = bh ^3/12 .

Further, in the measurement sample of the toothed belt, the parameters of the equation (6) for obtaining the bending stiffness E described in 8.3 of JIS K7106 (1995) are the distance between columns S: 1.27 cm, and the test piece. The width b: 10 mm, the thickness of the test piece: 3.61 mm, the moment of the pendulum at 100% load scale M ₀ : 0.0846 N · m, and the bending angle φ: 0.1745 rad.
The test was conducted under the conditions of room temperature of 25 ± 5 ° C. and humidity of 50 ± 5%.

<Elastic modulus M1.0>
The elastic modulus M1.0 was measured by the method described above using a tensile tester.
Here, the tensile speed was set to 50 mm / min. The measurement was performed three times, and the average value was defined as an elastic modulus of M1.0.

<Positioning>
FIG. 8 shows the pulley layout of the belt tester 100.
In the belt tester 100, the drive pulley 120 fixed to the rotating shaft and the driven pulley 130 fixed to the fixed shaft so as not to rotate are arranged at lateral intervals, and the rotation of the drive pulley 120 is performed. A torque meter is connected to the shaft, and it is configured so that torque can be applied to the rotating shaft to rotate the drive pulley 120.
Further, the position M on the upper side of the drive pulley 120 is configured so that the amount of movement (rotation angle deg) on the pitch line of the toothed belt 110 can be measured.

This evaluation was carried out by winding the toothed belt 110 manufactured in Examples and Comparative Examples around the drive pulley 120 and the driven pulley 130 of the belt tester 100 and following the procedure below. In this evaluation, the rotational torque for rotating the drive pulley 120 to the right is defined as + torque, and the rotational torque for rotating the drive pulley 120 to the left is defined as-torque.
The setting conditions at the time of evaluation are as shown in Table 2.

(1) The initial state is the state before the drive pulley 120 is rotated.
(2) A torque of -15 Nm is applied to rotate the drive pulley 120 counterclockwise, and the amount of movement of the toothed belt 110 on the pitch line at that time is measured.
(3) The torque applied to the drive pulley 120 is released, and the amount of movement of the toothed belt 110 on the pitch line at that time is measured.
(4) A torque of +15 Nm is applied to rotate the drive pulley 120 clockwise, and the amount of movement of the toothed belt 110 on the pitch line at that time is measured.
(5) The torque applied to the drive pulley 120 is released, and the amount of movement (displacement angle deg) on the pitch line of the toothed belt 110 at that time is measured.
(6) Such measurements (1) to (5) are regarded as one set. Repeat this set 3 times.

When one set of this measurement is performed, the relationship between the rotational torque and the amount of movement (displacement amount from the initial state) of the toothed belt 110 on the pitch line can be shown as shown in the graph of FIG.
FIG. 9 is a graph of the data acquired in the first set in the evaluation of the positioning property of the first embodiment.
In the graph of FIG. 9, the states in which each of the procedures (1) to (5) are completed correspond to A to E.
Then, in this evaluation, the difference between CEs in FIG. 9 was used as a reference, and it was judged that the smaller the difference, the better the positioning property. This is because the smaller the difference between CEs, the closer to the initial state each time the torque is released.
In Table 3, the rotation angle of the drive pulley corresponding to the difference between CEs is shown as an evaluation value. Moreover, as the evaluation value, the average value of three sets was described.
In this case, the smaller the rotation angle, the shorter the distance between CEs, and the better the positioning.

<Responsiveness>
FIG. 10 shows the pulley layout of the belt tester 200.
In the belt tester 200, the drive pulley 220 and the driven pulley 230 are arranged at intervals in the lateral direction, and the driven pulley is moved in the lateral direction so that the set weight SW can be fixed. Further, the belt tester 200 includes an encoder (not shown) for acquiring the rotation speeds of the drive pulley 220 and the driven pulley 230, respectively.
The drive pulley 220 and the driven pulley 230 both have 24 teeth and a type: S5M.

In this evaluation, the toothed belt 210 manufactured in Examples and Comparative Examples is wound around the drive pulley 220 and the driven pulley 230 of the belt testing machine 200, and driven so that the toothed belt 210 is loaded with a belt tension of 45N. The set weight of the pulley 230 was fixed. The flywheel effect (GD ² ) of the driven pulley 230 is 0.040 kgf · m ² .
Next, at room temperature, the drive pulley 220 is driven under the condition that the rotation speed is accelerated from 0 to 100 rpm at an acceleration time of 0.02 seconds and then the drive pulley 220 is driven at a constant speed at 100 rpm, and the drive pulley 220 and the driven pulley 230 are each driven. The number of revolutions of was measured.

The test conditions for this evaluation are summarized below.
・ Acceleration time: 0.02 sec
・ Rotation speed: 0 → 100 rpm
・ Flywheel effect (GD ² ): 0.040kgf ・ m ²

After the measurement, the difference between the rotation speed of the drive pulley 220 and the rotation speed of the driven pulley 230 was acquired along the time axis, and the maximum value of the absolute value of this difference was used as the evaluation value in this evaluation.
In this evaluation, the smaller the above evaluation value, the better the responsiveness of the toothed belt.

11 and 12 are graphs showing an example of the data acquired in this evaluation.
FIG. 11 is a graph showing the evaluation results of the toothed belt of the second embodiment, and shows the time change of the rotation speed of each of the drive pulley 220 and the driven pulley 230.
FIG. 12 is a graph showing the evaluation results of the toothed belt of the second embodiment, and shows the time change of the difference in the number of rotations between the drive pulley 220 and the driven pulley 230.
As can be seen from these graphs, the rotation speed of the driven pulley rises behind the drive pulley, greatly exceeds the rotation speed of the drive pulley, and then gradually synchronizes with the rotation speed of the drive pulley. Therefore, if the difference between the two rotation speeds is small when the rotation speed of the drive pulley is greatly exceeded for the first time, the responsiveness of the toothed belt becomes good.

10, 110, 120 Toothed belt 11 Belt body 11a Back rubber part 11b Tooth rubber part 12 Belt tooth 13 Core wire 14 Reinforcing cloth 15 Tooth bottom 30 Belt forming type 31 Tooth forming groove 32 Rubber sleeve 100, 200 Belt testing machine 120 , 220 Drive pulley 130, 230 Driven pulley

Claims (5)

A belt body having multiple teeth provided at a constant pitch on the inner circumference of the belt,
A core wire embedded in the belt body so as to form a spiral having a pitch in the belt width direction as well as in the belt length direction.
Equipped with
The core wire contains carbon fibers having a filament diameter of 4 to 6 μm as a constituent material, and is a twisted yarn of 5000 to 7000 filaments containing the carbon fibers.
The twisted yarn has a single twist count or an upper twist count of 4 to 10 times / 10 cm.
The diameter of the core wire is 0.50 to 0.60 mm, and the diameter of the core wire is 0.50 to 0.60 mm.
The pitch of the core wire is 0.70 to 0.85 mm.
Toothed belt. The toothed belt according to claim 1, wherein the tooth pitch is 5 mm. The toothed belt according to claim 1 or 2, wherein the flexural rigidity is 7.33 Ncm ² or less. The toothed belt according to any one of claims 1 to 3, wherein the elastic modulus M1.0 is 300 N / mm or more. The toothed belt according to any one of claims 1 to 4, wherein the belt body is made of a rubber composition or an elastomer composition having a hardness (JIS-A) of 84 to 94.

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