Toothed belt

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

Technical Field

[0001] The present invention relates to a toothed belt.

Background Art

[0002] Toothed belts are suitable for applications that require synchronous rotation. For example, they are used as belts for synchronously transmitting the crankshaft and cam of an automobile engine (for example, Patent Document 1). In addition, for example, they are also used in belt drive systems that require synchronous transmission in precision machinery such as cameras, computers, and copiers, and general industrial machinery such as robots.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, toothed belts used in robots are required to have good positioning accuracy. In the field of robots, for inertia reduction, weight reduction and miniaturization of components are required. Therefore, toothed belts used in robots are also required to cope with the above-mentioned weight reduction and miniaturization. For example, when using a toothed belt for driving a robot arm, it has been proposed to use a toothed belt with a tooth pitch of 5 mm in a two-axis layout with a small-diameter pulley of about φ20 mm. In addition, toothed belts used in robots are also required to be capable of high-load transmission.

Means for Solving the Problems

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a toothed belt having excellent positioning performance and capable of being used for high-load transmission.

[0006] (1) The toothed belt of the present invention comprises a belt body having a plurality of tooth portions 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 helix having a pitch in the belt width direction along the belt length direction, and 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 number or a Z-twist number of 4 to 10 turns / 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.

[0007] According to the toothed belt of the present invention, since the above-described specific core wire is embedded in the belt body at a predetermined pitch, it has excellent positioning performance. Further, since the toothed belt uses a core wire containing carbon fibers as the core wire, it can be suitably used for high-load transmission applications such as driving the arm of an industrial robot. In the present invention, the positioning performance refers to the performance of stopping at a commanded target position when a positioning operation is performed in which a pulley rotated by a toothed belt is rotated in one direction from a certain position and then stopped at a predetermined position. The smaller the deviation between the target position and the actual stop position, the better the positioning accuracy.

[0008] (2) It is preferable that the toothed belt has a tooth pitch of 5 mm. The toothed belt provided with the core wire described in the above (1) is particularly suitable for making the positioning performance of the toothed belt having such a tooth pitch good.

[0009] (3) The toothed belt has a flexural rigidity of 7.33 Ncm2 The following are preferred. In this case, since the toothed belt can bend the belt with a small force when the belt is wound around the pulley, it is not necessary to apply a high tension to the belt, and the rigidity of the device can be reduced. Also, when the rigidity of the belt is lower, the power transmission energy loss becomes smaller, and the bending fatigue and responsiveness of the belt also improve.

[0010] (4) It is preferable that the toothed belt has an elastic modulus M1.0 (stress at an elongation rate of 1.0%) of 300 N / mm or more. In this case, the toothed belt has a belt strength capable of suppressing the elongation rate of the belt, even at most about 1.0%, when a load is applied to the belt due to power transmission. Therefore, a toothed belt with an elastic modulus at an elastic modulus of M1.0% within the above range can suppress the elongation of the belt with respect to the load when the load acts, and the positioning accuracy of the toothed belt becomes good.

[0011] (5) In the toothed belt, it is preferable that the belt body is composed of a rubber composition or an elastomer composition having a hardness (JIS-A) of 84 to 94. In this case, in addition to the positioning property, the responsiveness of the toothed belt also improves. [Advantages of the Invention]

[0012] According to the present invention, a toothed belt excellent in positioning property can be provided. [Brief Description of the Drawings]

[0013]

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BEST MODE FOR CARRYING OUT THE INVENTION

[0014] 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 taken along the arrow X in FIG. 1. FIG. 3 is an end view taken along the line A-A of FIG. 1.

[0015] The toothed belt 10 is used, for example, for driving a robot arm. Although only a part of the toothed belt 10 is shown in FIG. 1, the toothed belt 10 is an endless meshing transmission belt. As shown in FIG. 1, the toothed belt 10 includes a belt body 11, a core wire 13, and a reinforcing cloth 14.

[0016] The toothed belt 10 is a relatively small-sized toothed belt, and the belt circumference (the belt length at the belt pitch line BL) is, for example, 200 mm or more and 2000 mm or less, the belt width is, for example, 4 mm or more and 30 mm or less, and the maximum belt thickness is, for example, 3.0 mm or more and 4.0 mm or less. Even with such dimensions, the toothed belt 10 has excellent positioning accuracy. A toothed belt with such dimensions is also suitable for, for example, miniaturization and weight reduction of robots. Of course, the dimensions of the toothed belt according to the embodiment of the present invention are not limited to this range.

[0017] A plurality of belt teeth 12 are arranged on the inner peripheral side of the toothed belt 10 at a predetermined pitch. 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 the backlash between the belt tooth portion and the pulley groove, and the belt tooth width and the belt tooth height are large. In addition, since the tip of the belt tooth is in close contact with the bottom of the pulley groove and meshes therewith, the force on the pressure surface of the tooth portion received by the toothed belt is dispersed and becomes uniform, the deformation of the tooth portion is small, and it is suitable for a design with excellent positioning accuracy.

[0018] 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 other tooth profiles.

[0019] 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 teeth 12 may be skew teeth extending in a direction inclined with respect to the belt width direction.

[0020] In the toothed belt 10, the tooth pitch P of the belt teeth 12 (refer to P in FIG. 3) is, for example, 2 mm or more and 8 mm or less. The positioning accuracy is improved by subdividing the tooth pitch. A larger tooth size enables higher power transmission. Therefore, from the perspective 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.

[0021] The tooth height of the belt teeth 12 is defined as the dimension from the tooth bottom 15 between a pair of adjacent belt teeth 12 in the belt length direction to the tip of the belt teeth 12 (see H in FIG. 3), and is, for example, 1.7 mm or more and 2.2 mm or less. Also, the toothed belt 10 has, for example, 40 or more and 400 or less teeth, a tooth width (dimension in the belt length direction) of, for example, 200 mm or more and 2000 mm or less, and a PLD of, for example, 0.450 mm or more and 0.600 mm or less.

[0022] The belt body 11 is made of rubber (including elastomers), and has an endless flat belt-shaped back rubber portion 11a and a plurality of tooth rubber portions 11b. The plurality of tooth rubber portions 11b are integrally provided at intervals in the belt length direction on the inner peripheral side, which is one side of the back rubber portion 11a. The belt body 11 is composed of, for example, an unvulcanized rubber composition in which various rubber compounding agents are compounded in a rubber component, and the rubber component is vulcanized when the belt is molded by heating and pressurization. The constituent materials of the back rubber portion 11a and the tooth rubber portion 11b may be the same or different.

[0023] Examples of the rubber component of the rubber composition forming the belt body 11 include hydrogenated nitrile rubber (H-NBR), ethylene-α-olefin elastomer (e.g., EPDM, EPR, etc.), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), etc. The above hydrogenated nitrile rubber (H-NBR) may contain an unsaturated carboxylic acid metal salt in the H-NBR. These rubber components may be used alone or in combination of two or more. The toothed belt 10 may be used as a toothed belt 10 for driving a robot arm in a robot used, for example, 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, it is preferable that the rubber component contains H-NBR.

[0024] When the rubber component of the rubber composition is H-NBR, the bound acrylonitrile amount is preferably 20% by mass or more and 50% by mass or less. Further, 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 40 ML 1+4 (100 °C) or more and 90 ML 1+4 (100 °C) or less is preferable.

[0025] Examples of the rubber compounding agent include vulcanization accelerator aids, anti-aging agents, reinforcing materials, plasticizers, co-crosslinking agents, crosslinking agents, and the like.

[0026] Examples of the vulcanization accelerator aid include metal oxides such as zinc oxide (zinc white) and magnesium oxide, metal carbonates, fatty acids and their derivatives, and the like. It is preferable to use one or more of these as the vulcanization accelerator aid, and it is more preferable to use zinc oxide. The content of the vulcanization accelerator 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.

[0027] Examples of the anti-aging agent include benzimidazole-based, aromatic secondary amine-based, amine-ketone-based ones, and the like. It is preferable to use one or more of these as the anti-aging agent, and it is more preferable to use a combination of benzimidazole-based and aromatic secondary amine-based ones. The content of the anti-aging 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.

[0028] Examples of the reinforcing material include carbon black, silica, and the like. 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. 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. The reinforcing agent may be used in combination with carbon black and silica.

[0029] When carbon black is used as the reinforcing agent, 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 agent, 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.

[0030] Examples of the plasticizer include polyether ester, dialkyl sebacate such as dioctyl sebacate (DOS), dialkyl phthalate such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), dialkyl adipate such as dioctyl adipate (DOA), and the like. These may be used alone or in combination of two or more. As the plasticizer, it is preferable to use at least 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.

[0031] Examples of the co-crosslinking agent include trimethylolpropane trimethacrylate, m-phenylene dimaleimide, zinc dimethacrylate, triallyl isocyanurate, and the like. These may be used alone or in combination of two or more. As the above-mentioned co-crosslinking agent, it is preferable to use trimethylolpropane trimethacrylate and m-phenylenedimaleimide in combination. The content of the above-mentioned 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.

[0032] Examples of the above-mentioned crosslinking agent include sulfur, organic peroxides, etc. Either one of them may be used alone, or they may be used in combination. When only an organic peroxide is used as the above-mentioned crosslinking agent, the compounding amount of the above-mentioned 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. Also, when sulfur and an organic peroxide are used in combination as the above-mentioned crosslinking agent, the total compounding amount of the above-mentioned crosslinking agent is, for example, sulfur is 0.1 part by mass or more and 0.7 part by mass or less, and the organic peroxide is 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the rubber component.

[0033] Further, the belt body 11 may be composed of a composition containing a thermosetting urethane elastomer in which an uncured thermosetting urethane composition in which various compounding agents are compounded in a urethane prepolymer and a curing agent is heated and pressurized during belt molding to crosslink the urethane prepolymer. Furthermore, the belt body 11 may be composed of a thermoplastic elastomer composition in which various compounding agents are compounded in a thermoplastic elastomer and which is molded in a mold.

[0034] The core wire 13 is embedded so as to form a helix having a pitch in the belt width direction on the surface layer on the inner peripheral side of the back rubber portion 11a of the belt body 11 and extend.

[0035] The core wire 13 has a core wire diameter of 0.50 mm or more and 0.60 mm or less. Also, 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 can reduce the bending rigidity of the belt while achieving good positioning accuracy. Also, it is easy to ensure the responsiveness of the toothed belt 10.

[0036] In particular, in the embodiment of the present invention, by adopting a core wire containing carbon fiber that can ensure sufficient tension even if it is thin as the core wire, while making the core wire diameter as thin as 0.50 mm or more and 0.60 mm or less, the arrangement pitch of the core wire is achieved to be as narrow as 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 accuracy even if it is a relatively small-sized toothed belt.

[0037] The core wire 13 contains carbon fiber as a constituent material. The core wire 13 may be composed of only carbon fiber, or may be composed of a composite of carbon fiber and other types of fiber. The carbon fiber may be of the PAN type, of the pitch type, or may contain both. A sizing agent such as an epoxy resin may be attached to the carbon fiber. Examples of the other types of fiber include inorganic fibers such as glass fiber and metal fiber, and organic fibers such as aramid fiber, polyester fiber, PBO fiber, nylon fiber, and polyketone fiber.

[0038] When the core wire 13 contains carbon fiber and other types of fiber as constituent materials, the proportion of carbon fiber in all the fibers is 50% by mass or more. The higher the proportion of the above carbon fiber (for example, 90% by mass or more), the better, and it may be 100%.

[0039] The carbon fiber has a filament diameter of 4 μm or more and 6 μm or less. By using a core wire containing carbon fiber with the above filament diameter, the toothed belt 10 has good positioning accuracy.

[0040] The core wire 13 is a twisted yarn of 5,000 to 7,000 filaments containing the above carbon fiber. By using such a twisted yarn as the core wire, the toothed belt 10 has good positioning property.

[0041] The twisting method of the core wire 13 is single twist, complex twist, or lang lay. Among these twisting methods, single twist is preferable from the viewpoints of strength, elastic modulus, and adhesion treatment of the filaments constituting the core wire.

[0042] When the core wire 13 is a single-twist yarn, the number of single twists is 4 to 10 turns / 10 cm. If the number of single twists is less than 4 turns / 10 cm, the flexural fatigue property is poor and it is unsuitable as the core wire of the toothed belt. On the other hand, if the number of single twists exceeds 10 turns / 10 cm, the strength and elastic modulus decrease, and the positioning property of the toothed belt using this core wire deteriorates.

[0043] When the core wire 13 is a complex-twist yarn or a lang-lay yarn, the number of Z-twists is 4 to 8 turns / 10 cm. If the number of Z-twists is less than 4 turns / 10 cm, the flexural fatigue property is poor and it is unsuitable as the core wire of the toothed belt. On the other hand, if the number of Z-twists exceeds 10 turns / 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 complex twist or lang lay, the number of S-twists is not particularly limited, but for example, it is 6 to 12 turns / 10 cm.

[0044] In order to enhance the adhesive force with the belt body 11, the core wire 13 may be subjected to an adhesion treatment before the production of the toothed belt 10. As the above adhesion treatment, for example, one or both of an RFL treatment of immersing in an RFL aqueous solution and then heating, and a rubber paste treatment of immersing in a rubber paste and then drying, a treatment of immersing in an aqueous treatment agent containing a rubber latex and a crosslinking agent and then drying, etc. can be adopted. The above aqueous treatment agent contains rubber latex as the main component. Examples of the rubber latex include those containing at least one selected from the group consisting of nitrile rubber, hydrogenated nitrile rubber, carboxyl-modified nitrile rubber, and carboxyl-modified hydrogenated nitrile rubber as the rubber component. The above aqueous treatment agent may or may not contain an RFL condensate. The core wire 13 may be subjected to a base treatment in which it is immersed in an epoxy solution or an isocyanate solution and then heated before the above adhesion treatment.

[0045] When the core wire 13 is a single-twist yarn, the core wire can be obtained, for example, by twisting a fiber bundle composed of carbon fibers alone or a fiber bundle formed by bundling carbon fibers and other types of fibers in one direction (S direction or Z direction) at the above single-twist number.

[0046] When the core wire 13 is a multiple-twist yarn, the core wire can be obtained, for example, by collecting a plurality of single-twist yarns obtained by twisting each of a plurality of fiber bundles containing carbon fiber bundles in one direction (S direction or Z direction) in the lower-twist direction, and then twisting them in the upper-twist direction at the above upper-twist number in the direction opposite to the lower-twist direction.

[0047] When the core wire 13 is a lang lay yarn, the core wire can be obtained, for example, by collecting a plurality of single-twist yarns obtained by twisting each of a plurality of fiber bundles containing carbon fiber bundles in one direction (S direction or Z direction) in the lower-twist direction, and then twisting them in the upper-twist direction at the above upper-twist number in the same direction as the lower-twist direction.

[0048] In the toothed belt 10, the core wire 13 may be provided in a double helix such that two types, namely, an S-twist yarn (in the case of a multiple-twist yarn or a lang lay yarn, one with the upper-twist direction being the S direction) and a Z-twist yarn (in the case of a multiple-twist yarn or a lang lay yarn, one with the upper-twist direction being the Z direction), are used and arranged alternately in the belt width direction. In this case, it is suitable for suppressing the lateral displacement during the running of the toothed belt 10. The core wire 13 may be composed of a single S-twist yarn or Z-twist yarn.

[0049] The reinforcing fabric 14 is attached so as to cover the inner peripheral surface of the belt body 11 where a plurality of tooth rubber parts 11b are provided. Therefore, each belt tooth 12 has the tooth rubber part 11b covered with the reinforcing fabric 14. At the tooth bottom part 15, the reinforcing fabric 14 is disposed immediately inside of the core wire 13 embedded in the inner peripheral side part of the back rubber part 11a of the belt body 11. The thickness of the reinforcing fabric 14 is, for example, 0.1 mm or more and 0.6 mm or less.

[0050] The reinforcing fabric 14 is composed of, for example, a woven fabric, a knitted fabric, a non-woven fabric, etc. formed of yarns such as nylon fiber (polyamide fiber), polyester fiber, aramid fiber, polyparaphenylene benzobisoxazole (PBO) fiber, cotton, etc. Among these, a woven fabric of nylon fiber is preferable. The reinforcing fabric 14 preferably has elasticity, for example, like a woven fabric subjected to woolly processing or the like on the weft yarn.

[0051] One or more of an RFL treatment of heating after dipping in an RFL aqueous solution, a soaking treatment of drying after dipping in a low-viscosity rubber paste, and a coating treatment of applying and drying a high-viscosity rubber paste on the surface on the belt body side may be performed on the reinforcing fabric 14 as an adhesion treatment for enhancing the adhesion force with the belt body. The reinforcing fabric 14 may be subjected to a base treatment of heating after dipping in an epoxy solution or an isocyanate solution before the above adhesion treatment.

[0052] 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 is wound around a pulley, it is not necessary to apply a high tension to the belt, and the rigidity of the device can be reduced. Also, when the rigidity of the belt is lower, the power transmission energy loss becomes smaller, and the bending fatigue resistance and responsiveness of the belt also become better. On the other hand, a toothed belt with a large flexural rigidity is inferior in bending fatigue resistance and may not be suitable for use in combination with a small pulley. The lower limit of the bending rigidity is not particularly limited. For example, it is 6.50 Ncm 2 .

[0053] The bending rigidity is measured by the following method. For the toothed belt 10, in accordance with JIS K7106 (1995), the flexural strength E is obtained by a bending test using an Olsen bending tester, and the belt bending rigidity E·I is calculated by multiplying it by the second moment of area I of the toothed belt 10. Here, for the second moment of area I of the toothed belt 10, the belt width is taken as the width b of the test piece, the belt thickness at the tooth bottom 15 is taken as the thickness h of the test piece, and the cross-section of the toothed belt 10 is regarded as a rectangle, and the second moment of area is determined as I = bh 3 / 12. That is, in the present invention, when calculating the above second moment of area, the second moment of area is calculated ignoring the tooth rubber portion of the toothed belt 10.

[0054] The toothed belt 10 preferably has an elastic modulus M1.0 of 300 N / mm or more. In this case, it is more suitable for ensuring good positioning accuracy. The preferable upper limit of the elastic modulus M1.0 is 1000 N / mm. If the elastic modulus M1.0 is too large, there is a risk of plastic deformation and the strength of the belt may decrease.

[0055] In the embodiment of the present invention, the elastic modulus M1.0 of the toothed belt refers to the stress per unit width of the belt when the toothed belt is stretched by 1.0% in the belt length direction in a tensile test using the toothed belt as a measurement sample.

[0056] The elastic modulus M1.0 is measured by the following method using a tensile tester. First, the toothed belt 10 is cut out into a strip shape with a belt length of about 300 mm, and two marking lines about 100 mm apart are marked on the back surface of the toothed belt 10 to obtain a measurement sample. Next, both ends of the measurement sample in the belt length direction are gripped by the chuck part of the tensile tester, and the measurement sample is set on the tensile tester. Subsequently, the measurement sample is pulled in the belt length direction at a pulling speed of 50 mm / min, and the stress when the measurement sample is stretched by 1.0% based on the distance between the gauge marks is detected by a 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 is taken as the modulus of elasticity M1.0.

[0057] In the toothed belt 10, the hardness (JIS-A) of the rubber composition or 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 the bending fatigue resistance and responsiveness while ensuring excellent positioning accuracy. On the other hand, if the above hardness (JIS-A) is less than 84, the positioning accuracy of the toothed belt 10 may be inferior. Further, if the above hardness (JIS-A) exceeds 94, the toothed belt 10 may be inferior in bending fatigue resistance and responsiveness.

[0058] The hardness (JIS-A) of the above rubber composition or elastomer composition is the hardness measured using a Type A durometer in accordance with JIS K6253-3 (2012) and JIS K7312 (1996) with the rubber composition or elastomer composition constituting the belt body 11 formed into a predetermined shape and used as the measurement sample according to the measurement object.

[0059] The clearance ratio of the toothed belt 10 is preferably less than 30%. In this case, the positioning accuracy of the toothed belt 10 becomes better. The above clearance ratio is more preferably 28% or less. The above clearance ratio may be small from the viewpoint of positioning accuracy, but if it is too small, the occurrence rate of defective products in which the rubber composition is not filled in the tooth rubber portion during the manufacture of the toothed belt may increase. Therefore, the lower limit of the above clearance ratio is preferably 20% and more preferably 22% from the viewpoint of yield. The above clearance ratio refers to the ratio (%) of the total clearance dimension between the center lines in the width direction of the belt to the width dimension of the toothed belt. The smaller the above-mentioned void ratio, the larger the proportion of the core wire in the width direction of the belt.

[0060] The toothed belt 10 according to an embodiment of the present invention is wound around, for example, a pair of pulleys and transmits power from a drive source to a driven side. Here, the outer diameter of the pulley is, for example, 21.32 mm or more and 94.53 mm or less. Further, the belt running 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.

[0061] 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 fiber, and since this core wire 13 is embedded in the belt body 11 at a predetermined arrangement pitch, it has excellent positioning accuracy and good responsiveness.

[0062] Next, a method for manufacturing the toothed belt 10 according to the present embodiment will be described by taking the case where the belt body is made of the above rubber composition as an example, with reference to FIGS. 4 to 7. The method for manufacturing the toothed belt 10 includes a material preparation step, a molding step, a vulcanization step, and a finishing step.

[0063] <Material preparation step> A predetermined rubber component is kneaded, and various rubber compounding agents are added thereto and kneaded to obtain an unvulcanized rubber composition. Then, the obtained unvulcanized rubber composition is subjected to calender molding or the like to produce an unvulcanized rubber composition sheet 11'.

[0064] Adhesive treatment is performed on each of the core wire 13 and the reinforcing fabric 14. Further, the reinforcing fabric 14 is formed into a cylindrical shape.

[0065] <Molding step> FIG. 4 is a partial cross-sectional view showing a part of the belt molding die 30. The belt molding die 30 is cylindrical and has an outer peripheral surface on which a plurality of tooth portion forming grooves 31 formed to extend in the axial direction are arranged at intervals in the circumferential direction.

[0066] As shown in Fig. 5, a cylindrical reinforcing cloth 14 is put on the outer peripheral surface of the belt forming die 30, and the core wire 13 is spirally wound thereon from above. Then, an unvulcanized rubber composition sheet 11' is wound thereon to form an unvulcanized slab S' on the belt forming die 30. The unvulcanized rubber composition sheet 11' is preferably used so that the alignment direction corresponds to the belt length direction.

[0067] <Vulcanization step> As shown in Fig. 6, a rubber sleeve 32 is put on the unvulcanized slab S' on the belt forming die 30, and it is placed in a vulcanizing can and sealed. At the same time, the vulcanizing can is filled with high-temperature and high-pressure steam and held for a predetermined molding time. In this way, while pressing and heating the unvulcanized slab S' toward the belt forming die 30, the unvulcanized rubber composition sheet 11' is passed between the core wires 13 to press the reinforcing cloth 14 and at the same time, the unvulcanized rubber composition sheet 11' is caused to flow into each of the plurality of tooth portion forming grooves 31 of the belt forming die 30 and vulcanized. At the same time, the core wire 13 and the reinforcing cloth 14 are integrally combined, and finally, as shown in Fig. 7, a cylindrical belt slab S is formed.

[0068] <Finishing step> The inside of the vulcanizing can is depressurized to release the seal, and the belt slab S formed between the belt forming die 30 and the rubber sleeve 32 is taken out and demolded, and is cut into a predetermined width to obtain a toothed belt 10. By going through such steps, a toothed belt 10 whose belt body is composed of a rubber composition can be manufactured.

[0069] In addition, a toothed belt 10 whose belt body 11 is composed of a thermosetting urethane elastomer composition or a thermosetting elastomer composition can be manufactured, for example, by the following method. That is, (1) The core wire 13 is spirally wound on the outer peripheral surface of the cylindrical belt forming die 30 used in the manufacture of the toothed belt whose belt body is composed of a rubber composition. (2) Next, the cylindrical belt forming die 31 is accommodated in a cylindrical outer die 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.

[0070] (3-1) Next, an uncured thermosetting urethane composition containing a urethane prepolymer and a curing agent is injected into and filled in the cavity and heated. At this time, the uncured thermosetting urethane composition cures in a state of also entering 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, a thermoplastic elastomer composition imparted with fluidity by heating is injected into and filled in the cavity and then cooled. At this time, the thermoplastic elastomer solidifies in a state of also entering the tooth portion forming groove 31, and a cylindrical slab in which the thermoplastic elastomer and the core wire 13 are integrated is formed.

[0071] (4) Thereafter, the cylindrical slab is demolded from the belt forming die 31 and the outer die, a reinforcing cloth is attached to the inner peripheral surface (tooth rubber portion side) thereof, and then the toothed belt 10 is obtained by cutting the slab provided with the reinforcing cloth into rings. By performing such steps, a toothed belt 10 in which the belt body is composed of a thermosetting urethane elastomer composition or a thermosetting elastomer composition can be manufactured.

Example

[0072] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the following examples.

[0073] Examples 1 to 3 and Comparative Examples 1 to 4 Here, a toothed belt having a tooth type of S5M (JIS B1857) was manufactured and its performance was evaluated. Each toothed belt was manufactured by the method described above. An unvulcanized rubber composition, a core wire, and a reinforcing cloth for forming the belt body (back rubber portion and tooth rubber portion) were prepared as follows.

[0074] (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 compounding amounts are shown in parts by mass. · Rubber Composition A: Based on a rubber obtained by mixing 45 parts by mass of hydrogenated nitrile rubber (H-NBR) (manufactured by Nippon Zeon Co., Ltd., trade name: Zetpol 2020) and 55 parts by mass of hydrogenated nitrile rubber containing an unsaturated carboxylic acid metal salt obtained by mixing an unsaturated carboxylic acid metal salt (manufactured by Nippon Zeon Co., Ltd., trade name: ZSC2195), 5 parts by mass of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., trade name: Zinc Oxide No. 3), 1 part by mass of stearic acid (manufactured by Shin Nippon Rika Co., Ltd., trade name: Stearic Acid), 10 parts by mass of dioctyl sebacate (DOS) (manufactured by Dainippon Ink and Chemicals, Inc., trade name: Monosizer W280), 60 parts by mass of carbon black FEF (manufactured by Tokai Carbon Co., Ltd., trade name: Seast SO), 3 parts by mass of an antioxidant (manufactured by Ouchi Shinko Chemical Industrial Co., Ltd., trade name: No Crack MB), 3 parts by mass of trimethylolpropane triacrylate (TMPT) (manufactured by Sanshin Chemical Industry Co., Ltd., trade name: Sun Ester TMP), and 7 parts by mass of Peroximon F40 (manufactured by NOF Corporation) were compounded and kneaded to obtain an unvulcanized rubber composition as Rubber Composition A.

[0075] Regarding Rubber Composition A, when the hardness (JIS-A) of the vulcanizate vulcanized under the same conditions as the vulcanization conditions during the production of the toothed belt was measured, it was 89. The hardness of the above vulcanizate was measured using a Type A durometer in accordance with JIS K6253-3 (2012). The same method was used to measure the hardness of the vulcanizates of the following rubber compositions B to D.

[0076] · Rubber Composition B: Prepared in the same manner as Rubber Composition A except that the ratio of carbon black FEF was changed. Regarding Rubber Composition B, when the hardness (JIS-A) of the vulcanizate vulcanized under the same conditions as the vulcanization conditions during the production of the toothed belt was measured, it was 86.

[0077] · Rubber composition C: Prepared in the same manner as rubber composition A, except that the proportion of carbon black FEF was changed. For rubber composition C, when the hardness (JIS-A) of the vulcanizate vulcanized under the same conditions as the vulcanization conditions during the production of the toothed belt was measured, it was 95.

[0078] · Rubber composition D: Prepared in the same manner as rubber composition A, except that the proportion of carbon black FEF was changed. For rubber composition D, when the hardness (JIS-A) of the vulcanizate vulcanized under the same conditions as the vulcanization conditions during the production of the toothed belt was measured, it was 80.

[0079]

Table 1

[0080] (Preparation of core wire) · Core wire A: Carbon fiber (trade name: Torayca T800HB-6000, filament diameter 5.0 μm, number of filaments 6000) was used, and the single-twist yarn twisted at a single-twist rate of 6 turns / 10 cm was used as core wire A. The core wire diameter of core wire A is 0.55 mm. As core wire A, two types of S-twist yarn and Z-twist yarn were prepared.

[0081] · Core wire B: Carbon fiber (trade name: Torayca T800HB-6000, filament diameter 5.0 μm, number of filaments 6000) was used, and the single-twist yarn twisted at a single-twist rate of 8 turns / 10 cm was used as core wire B. The core wire diameter of core wire B is 0.58 mm. As core wire B, two types of S-twist yarn and Z-twist yarn were prepared.

[0082] · Core wire C: Carbon fiber (trade name: Torayca T300B-6000, filament diameter 7.0 μm, number of filaments 6000) was used, and the single-twist yarn twisted at a single-twist rate of 7.5 turns / 10 cm was used as core wire C. The core wire diameter of core wire C is 0.70 mm. As core wire C, two types of S-twist yarn and Z-twist yarn were prepared.

[0083] · Core wire D: Carbon fiber (product name: Torayca T300B-3000, filament diameter 7.0 μm, number of filaments 3000) manufactured by Toray Industries, Inc. was used. A single-twist yarn twisted at a single-twist rate of 6 turns / 10 cm was used as core wire D. The core wire diameter of core wire D is 0.48 mm. As core wire D, two types of S-twist yarn and Z-twist yarn were prepared.

[0084] · Core wire E: Carbon fiber (product name: Torayca T300B-3000, filament diameter 7.0 μm, number of filaments 3000) manufactured by Toray Industries, Inc. was used. A single-twist yarn twisted at a single-twist rate of 12 turns / 10 cm was used as core wire E. The core wire diameter of core wire E is 0.53 mm. As core wire E, two types of S-twist yarn and Z-twist yarn were prepared.

[0085] · Core wire F: High-hardness glass fiber (high-strength glass cord, filament diameter 7.0 μm) manufactured by Nippon Sheet Glass Co., Ltd. was used. Three filaments of 200 filaments each were collected and twisted in one direction at a lower-twist rate of 8 turns / 10 cm to obtain 8 lower-twist yarns. These 8 lower-twist yarns were then twisted in the opposite direction of the lower-twist direction at an upper-twist rate of 8 turns / 10 cm to obtain a complex-twist yarn as core wire F. The core wire diameter of core wire F is 0.72 mm. As core wire F, two types of S-twist yarn and Z-twist yarn were prepared. The total number of filaments of core wire F is 4800.

[0086] (Preparation of reinforcing fabric) The following nylon canvas was prepared as the reinforcing fabric. Resorcinol (product name: Resorcinol, manufactured by Sumitomo Chemical Co., Ltd.) and formalin (product name: Formalin, manufactured by Mitsui Chemicals, Inc.) were added to a sodium hydroxide solution at a molar ratio of R / F = 1 / 2 and stirred and mixed to obtain an initial condensate solution. To the obtained solution, hydrogenated acrylonitrile-butadiene-methacrylic acid terpolymer (X-NBR) latex (product name: ZLX-B, manufactured by Nippon Zeon Co., Ltd.) and water were added and stirred and mixed to prepare an RFL solution with a mass ratio of RF / L = 1 / 8 of resorcinol·formalin to latex.

[0087] Next, to this RFL liquid, 80 parts by mass of polytetrafluoroethylene (manufactured by Asahi Glass Co., Ltd., trade name: Fluon AD911, average particle diameter: 0.25 μm) and 30 parts by mass of blocked isocyanate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27, dissociation temperature of the bond: 180 °C) were added per 100 parts by mass of the latex solid content of the RFL liquid, and they were stirred and mixed. Further, carbon black (manufactured by Fuji Pigment Industry Co., Ltd., trade name: Fuji SP Black 203) was added so as to be 5% by mass of the whole and dispersed to prepare a treatment liquid having a solid content concentration of 15% by mass.

[0088] A 2 / 2 twill woven fabric using woolen processed yarns (breaking elongation of 150% or more) of 6,6-nylon fibers with a warp of 235 dtex and a weft of 155 dtex was immersed in this treatment liquid, then pulled up and passed between a pair of pressure rolls to squeeze and attach the treatment liquid to the twill woven fabric. At this time, the liquid temperature of the treatment liquid was 20 °C, the immersion time was 2 seconds, and the number of treatment times was 2 times. Also, the clearance of the pressure rolls was adjusted so that the basis weight of the RFL film would be about 30% by mass.

[0089] The twill woven fabric with the treatment liquid attached was passed through a heat drying furnace to be heat dried to prepare a nylon canvas. At this time, the furnace temperature (heat drying temperature) of the heat drying furnace was 150 °C, and the heat treatment time was 2 minutes. This nylon canvas was used as the reinforcing fabric to be used in the examples and comparative examples.

[0090] <Example 1> Using rubber composition A as the unvulcanized rubber composition for forming the belt body, core wire A as the core wire, and the above nylon canvas as the reinforcing fabric, a toothed belt with a tooth type of S5M was manufactured by the above-described manufacturing method (see FIGS. 4 to 7). The belt width was 10 mm and the belt length was 800 mm. At this time, as the core wire A, a rubber latex mainly composed of hydrogenated nitrile rubber and not containing an RFL condensate and a crosslinking agent were used, and it was immersed in an aqueous treatment agent A and then dried by an adhesion treatment. Further, the core wire A was provided in a double spiral shape such that S-twisted yarns and Z-twisted yarns were alternately arranged in the belt width direction and the adjacent core wire pitch was 0.75 mm. In addition, the gap ratio of the manufactured toothed belt is 26.7%.

[0091] <Example 2> A toothed belt was manufactured in the same manner as in Example 1, except that rubber composition B was used instead of rubber composition A as the unvulcanized rubber composition.

[0092] <Example 3> A toothed belt was manufactured in the same manner as in Example 1, except that rubber composition C was used instead of rubber composition A as the unvulcanized rubber composition.

[0093] <Example 4> A toothed belt was manufactured in the same manner as in Example 2, except that core wire B was used instead of core wire A as the core wire. At this time, as the core wire B, a product obtained by immersing it in the above aqueous treatment agent A and then drying it by an adhesion treatment was used. Further, the core wire B was provided in a double spiral shape such that S-twisted yarns and Z-twisted yarns were alternately arranged in the belt width direction and the adjacent core wire pitch was 0.75 mm. In addition, the gap ratio of the manufactured toothed belt is 22.7%.

[0094] <Comparative Example 1> Using rubber composition D as the unvulcanized rubber composition forming the belt body, core wire C as the core wire, and the above nylon canvas as the reinforcing cloth, a toothed belt of tooth type S5M was manufactured by the above-described manufacturing method (see FIGS. 4 to 7). The belt width was 10 mm and the belt length was 800 mm. At this time, as the core wire C, one that was immersed in the aqueous treatment agent A and then subjected to an adhesion treatment of drying was used. Further, the core wire C was provided in a double helix shape such that S-twisted yarns and Z-twisted yarns were alternately arranged in the belt width direction and the adjacent core wire pitch was 1.0 mm. The clearance ratio of the toothed belt is 30.0%.

[0095] <Comparative Example 2> A toothed belt was manufactured in the same manner as in Example 1, except that core wire D was used instead of core wire A as the core wire and the following core wire pitch was adopted. At this time, as the core wire D, one that was immersed in the aqueous treatment agent A and then subjected to an adhesion treatment of drying was used. Further, the core wire D was provided in a double helix shape such that S-twisted yarns and Z-twisted yarns were alternately arranged in the belt width direction and the adjacent core wire pitch was 0.80 mm. Also, the clearance ratio of the manufactured toothed belt is 40.0%.

[0096] <Comparative Example 3> A toothed belt was manufactured in the same manner as in Example 1, except that core wire E was used instead of core wire A as the core wire and the following core wire pitch was adopted. At this time, as the core wire E, one that was immersed in the aqueous treatment agent A and then subjected to an adhesion treatment of drying was used. Further, the core wire E was provided in a double helix shape such that S-twisted yarns and Z-twisted yarns were alternately arranged in the belt width direction and the adjacent core wire pitch was 0.80 mm. Also, the clearance ratio of the manufactured toothed belt is 33.8%.

[0097] <Comparative Example 4> A toothed belt was manufactured in the same manner as in Example 3, except that core wire F was used instead of core wire A as the core wire and the following core wire pitch was adopted. At this time, as the core wire F, one that was immersed in the aqueous treatment agent A and then subjected to an adhesion treatment of drying was used. Further, the core wire F was provided in a double helix shape such that S-twisted yarns and Z-twisted yarns were alternately arranged in the belt width direction and the adjacent core wire pitch was 1.2 mm. In addition, the clearance ratio of the manufactured toothed belt is 40.0%.

[0098] (Evaluation method) For the toothed belts manufactured in the examples and comparative examples, the flexural rigidity and elastic modulus M1.0 were measured. Furthermore, the positioning property and responsiveness of the toothed belts manufactured in the examples and comparative examples were evaluated. These results are shown in Table 3.

[0099] <Flexural rigidity> The above 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, for the measurement sample of the toothed belt, in accordance with JIS K7106 (1995), the flexural strength E was obtained by a bending test using an Olsen bending tester, and it was multiplied by the second moment of area I of the toothed belt cross-section to calculate the belt flexural rigidity E·I (Ncm 2 ).

[0100] The measurement sample of the toothed belt had a tooth profile: S5M, width: 10 mm, thickness: 3.61 mm, and length: 70 mm. The second moment of area I of the measurement sample of the toothed belt was regarded as a rectangle ignoring the tooth part of the toothed belt cross-section. The width b of the test piece was taken as the belt width of 10 mm, the thickness h of the test piece was taken as the belt thickness of 1.70 mm at the tooth root part, and the second moment of area was obtained from the calculation of I = bh 3 / 12.

[0101] Also, for the measurement sample of the toothed belt, the parameters of Equation (6) for obtaining the flexural strength E described in 8.3 of JIS K7106 (1995) were: support distance S: 1.27 cm, width b of the test piece: 10 mm, thickness of the test piece: 3.61 mm, moment M of the pendulum at 100% of the load scale 0 : 0.0846 N·m, bending angle φ: 0.1745 rad. The test was conducted under the conditions of normal temperature 25 ± 5°C and humidity 50 ± 5%.

[0102] <Elastic modulus M1.0> The elastic modulus M1.0 was measured using a tensile testing machine by the method described above. Here, the tensile speed was set to 50 mm / min. The measurement was performed three times, and the average value was taken as the elastic modulus M1.0.

[0103] <Positioning accuracy> Figure 8 shows the pulley layout of the belt testing machine 100. The belt testing machine 100 is configured such that a driving pulley 120 fixed to a rotating shaft and a driven pulley 130 fixed to a fixed shaft so as not to rotate are arranged at a lateral interval, and a torque meter is connected to the rotating shaft of the driving pulley 120 so that the driving pulley 120 can be rotated by applying torque to this rotating shaft. Also, at the position M above the driving pulley 120, it is configured to be able to measure the movement amount (rotation angle deg) on the pitch line of the toothed belt 110.

[0104] This evaluation was performed on the toothed belts 110 manufactured in the examples and comparative examples by winding them around the driving pulley 120 and the driven pulley 130 of the belt testing machine 100 according to the following procedure. In this evaluation, the rotational torque for rotating the driving pulley 120 clockwise is defined as +torque, and the rotational torque for rotating the driving pulley 120 counterclockwise is defined as -torque. The setting conditions during the evaluation are as shown in Table 2.

[0105]

Table 2

[0106] (1) The state before rotating the driving pulley 120 is defined as the initial state. (2) Apply a torque of -15 Nm to rotate the driving pulley 120 counterclockwise, and measure the movement amount on the pitch line of the toothed belt 110 at that time. (3) Release the torque applied to the driving pulley 120, and measure the movement amount on the pitch line of the toothed belt 110 at that time. (4) Apply a torque of +15 Nm to rotate the driving pulley 120 clockwise, and measure the movement amount on the pitch line of the toothed belt 110 at that time. Release the torque applied to the drive pulley 120 and measure the amount of movement (displacement angle deg) on the pitch line of the toothed belt 110 at that time. (6) Consider one set of such measurements (1) to (5). Repeat this set three times.

[0107] 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) on the pitch line of the toothed belt 110 can be shown as in the graph of Fig. 9. Fig. 9 is a graph of the data obtained in the first set in the evaluation of the positioning accuracy of Example 1. In the graph of Fig. 9, the states after each of the procedures (1) to (5) correspond to A to E. In this evaluation, based on the difference between C and E in Fig. 9, it was determined that the smaller this difference, the better the positioning accuracy. This is because the smaller the difference between C and E, the closer it returns to the initial state each time the torque is released. Note that in Table 3, the rotation angle of the drive pulley corresponding to the difference between C and E is described as the evaluation value. Also, the average value of three sets is described as the evaluation value. In this case, the smaller the rotation angle, the shorter the distance between C and E, and the better the positioning accuracy.

[0108] <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 can be moved in the lateral direction and the set weight SW can be fixed. Also, the belt tester 200 is equipped with an encoder (not shown) for acquiring the rotational speed of each of the drive pulley 220 and the driven pulley 230. Both the drive pulley 220 and the driven pulley 230 have 24 teeth and are of type S5M.

[0109] In this evaluation, the toothed belt 210 manufactured in the examples and comparative examples was wound around the drive pulley 220 and the driven pulley 230 of the belt tester 200, and the set weight of the driven pulley 230 was fixed so that a belt tension of 45 N was applied to the toothed belt 210. Also, the flywheel effect (GD 2 ) of the driven pulley 230 is 0.040 kgf·m 2 . Next, at room temperature, the drive pulley 220 was driven under the conditions that the rotational speed was accelerated from 0 to 100 rpm in an acceleration time of 0.02 seconds and then traveled at a constant speed of 100 rpm, and the rotational speeds of the drive pulley 220 and the driven pulley 230 were measured respectively.

[0110] Summarizing the test conditions of this evaluation, they are as follows. · Acceleration time: 0.02 sec · Rotational speed: 0 → 100 rpm · Flywheel effect (GD 2 ): 0.040 kgf·m 2

[0111] After measurement, along the time axis, the difference between the rotational speed of the drive pulley 220 and the rotational speed of the driven pulley 230 was obtained, and the maximum value of the absolute value of this difference was taken as the evaluation value in this evaluation. In this evaluation, the smaller the above evaluation value, the more it means that the toothed belt has good responsiveness.

[0112] Figures 11 and 12 are graphs showing an example of the data obtained in this evaluation. Figure 11 is a graph showing the evaluation result of the toothed belt of Example 2, and shows the time change of the rotational speeds of the drive pulley 220 and the driven pulley 230 respectively. Figure 12 is a graph showing the evaluation result of the toothed belt of Example 2, and shows the time change of the difference in rotational speed between the drive pulley 220 and the driven pulley 230. As can be understood from these graphs, the rotational speed of the driven pulley starts rising with a delay relative to the driving pulley. After greatly exceeding the rotational speed of the driving pulley, it gradually synchronizes with the rotational speed of the driving pulley. Therefore, when the difference in rotational speed between the two is small when the rotational speed of the driving pulley is first greatly exceeded, the toothed belt has good responsiveness.

[0113]

Table 3

Explanation of Signs

[0114] Toothed belts with 10, 110, and 120 teeth 11 Belt body 11a Back rubber part 11b Tooth rubber part 12 Belt teeth 13 Core wire 14 Reinforcing cloth 15 Tooth bottom 30 Belt forming die 31 Tooth part forming groove 32 Rubber sleeve 100, 200 Belt testing machines 120, 220 Driving pulleys 130, 230 Driven pulleys

Claims

1. A belt body having a plurality of teeth provided at a constant pitch on an 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 along the belt length direction; A toothed belt comprising: The core wire includes carbon fiber having a filament diameter of 5 μm as a constituent material, and is a twisted yarn of 6.0×10 3 filaments including the carbon fiber; The belt body is made of a rubber composition or an elastomer composition having a hardness (JIS-A) of 84 to 95, A toothed belt having an elastic modulus M1.0 of 350 N / mm or more.

2. The toothed belt according to claim 1, wherein the belt body is composed of a rubber composition or an elastomer composition having a hardness (JIS-A) of 86 to 89.

3. The diameter of the core wire is 0.55 to 0.58 mm, 3. The toothed belt according to claim 1, wherein the cord has a gap ratio of less than 30%.

4. A toothed belt as described in any one of claims 1 to 3, wherein the twisted yarn is a single-twisted yarn and the number of single-twist turns is 4 to 10 times per 10 cm.

5. 5. The toothed belt according to claim 1, wherein the tooth pitch is 5 mm.

6. The bending stiffness is 6.96 Ncm 2 or more and 7.33 Ncm 2 or less, 6. The toothed belt according to claim 1, which is used for a pulley having an outside diameter of 21.32 mm or more and 94.53 mm or less.

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