JP7690102B2 - Toothed belt - Google Patents

Description

The present invention relates to a toothed belt.

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

JP 2004-138239 A

For example, toothed belts used in robots are required to have good positioning properties.
In addition, in the field of robotics, there is a demand for lighter and more compact parts to reduce inertia, and therefore there is a demand for toothed belts used in robots to meet the above-mentioned demands for lighter and more compact parts.
For example, when using a toothed belt to drive a robot arm, it has been proposed to use a toothed belt with a tooth pitch of 5 mm and a small diameter pulley with a diameter of about φ20 mm in a two-axis layout. In addition, toothed belts used in robots are also required to be capable of transmitting high loads.

The present invention was made in consideration of these circumstances, and aims to provide a toothed belt that has excellent positioning properties and can be used for high-load transmission.

(1) The toothed belt of the present invention is
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;
Equipped with
The core wire includes, as a constituent material, carbon fiber having a filament diameter of 4 to 6 μm, and is a twisted yarn of 5,000 to 7,000 filaments including the carbon fiber,
The twisted yarn has a number of single twists or second twists of 4 to 10 per 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, the specific core wires described above are embedded in the belt body at a predetermined pitch, so that the toothed belt has excellent positioning properties. Moreover, since the core wire of the toothed belt uses a core wire containing carbon fiber, the toothed belt can be suitably used for high-load transmission applications such as driving the arms of industrial robots.
In the present invention, positioning ability refers to the ability to stop a pulley rotated by a toothed belt at a commanded target position when a positioning operation is performed in which the pulley is rotated in one direction from a certain position and then stopped at a specified position, and the smaller the deviation between the target position and the actual stopping position, the better the positioning accuracy.

(2) The toothed belt preferably has a tooth pitch of 5 mm.
A toothed belt having the core wire described in (1) above is particularly suitable for improving the positioning ability of a toothed belt having such a tooth pitch.

(3) The toothed belt preferably has a bending stiffness of 7.33 ^Ncm2 or less.
In this case, the toothed belt can be bent with a small force when wound around the pulley, so there is no need to apply high tension to the belt and the rigidity of the device can be reduced. Furthermore, 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 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 that can suppress the elongation rate of the belt when a load is applied to the belt due to power transmission to about 1.0% at most. Therefore, a toothed belt having an elastic modulus in the above range when the elastic modulus M is 1.0% can suppress the elongation of the belt in response to a load when a load is applied, and the toothed belt has good positioning accuracy.

(5) In the toothed belt, the belt body is preferably 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 as well as good positioning ability.

The present invention provides a toothed belt with excellent positioning properties.

1 is a perspective view showing a toothed belt according to a first embodiment of the present invention; FIG. 2 is a front view taken along an arrow X in FIG. 1 . 2 is an end view of line AA in FIG. 1. FIG. 2 is a partial cross-sectional view of a belt forming die used for manufacturing a toothed belt. 3A to 3C are diagrams illustrating a manufacturing process of a toothed belt. 3A to 3C are diagrams illustrating a manufacturing process of a toothed belt. 3A to 3C are diagrams illustrating a manufacturing process of a toothed belt. FIG. 2 is a diagram showing the pulley layout of a belt testing machine used in evaluating positioning ability. 11 is a graph showing the relationship between the rotational torque and the amount of displacement on the pitch line of the toothed belt, obtained in an evaluation of positioning ability. FIG. 2 is a diagram showing a pulley layout of a belt tester used in evaluating responsiveness. 10 is a graph showing the evaluation results of the toothed belt of Example 2, and is a graph showing the change over time in the rotation speed of each of the drive pulley and the driven pulley. 10 is a graph showing the evaluation results of the toothed belt of Example 2, and is a graph showing the change over time of the difference in the rotation speed between the drive pulley and the driven pulley.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but 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 an arrow X in Fig. 1. Fig. 3 is an end view taken along line AA in Fig. 1.

The toothed belt 10 is used, for example, to drive a robot arm.
Although only a portion of the toothed belt 10 is shown in FIG. 1, the toothed belt 10 is an endless intermeshing power transmission belt.
As shown in FIG. 1 , the toothed belt 10 includes a belt body 11 , a core wire 13 , and a reinforcing fabric 14 .

The toothed belt 10 is a relatively small toothed belt, with a belt circumference (belt length at the belt pitch line BL) of, for example, 200 mm to 2000 mm, a belt width of, for example, 4 mm to 30 mm, and a maximum belt thickness of, for example, 3.0 mm to 4.0 mm. Even with these dimensions, the toothed belt 10 has excellent positioning properties. A toothed belt with these dimensions is also suitable for miniaturizing and reducing the weight of, for example, 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 at a predetermined pitch on the inner circumferential side.
The tooth profile of the belt teeth 12 is preferably a circular-arc tooth profile, and among the circular-arc tooth profiles, an S-tooth profile is more preferable. The S-tooth profile reduces backlash between the belt teeth and the pulley groove, and has a large belt tooth width and height. In addition, the tip of the belt tooth closely meshes with the bottom of the pulley groove, so the force on the pressure surface of the tooth portion that the toothed belt receives is distributed and uniform, and deformation of the tooth portion is small, making it suitable for a design with excellent positioning accuracy.

In an embodiment of the present invention, the tooth profile of the belt teeth 12 is not limited to an S-tooth profile, but may be a circular arc tooth profile other than an S-tooth profile, a trapezoidal tooth profile, or another tooth profile.

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 helical teeth 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, not less than 2 mm and not more than 8 mm.
Subdividing the tooth pitch improves the positioning accuracy. The larger the tooth size, the higher the power transmission capacity. 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 5 mm is particularly preferable.

The tooth height of the belt teeth 12 is defined by 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 tooth 12 (see H in Figure 3), and is, for example, 1.7 mm to 2.2 mm.
The toothed belt 10 has a number of teeth, for example, from 40 to 400, a tooth width (dimension in the belt length direction), for example, from 200 mm to 2000 mm, and a PLD, for example, from 0.450 mm to 0.600 mm.

The belt body 11 is made of rubber (including elastomer) and has an endless flat band-shaped back rubber part 11a and multiple tooth rubber parts 11b. The multiple tooth rubber parts 11b are integrally provided at intervals in the belt length direction on the inner peripheral side, which is one side of the back rubber part 11a. The belt body 11 is made of a rubber composition in which, for example, an unvulcanized rubber composition in which various rubber compounding agents are mixed with a rubber component is heated and pressurized 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 hydrogenated nitrile rubber (H-NBR), ethylene-α-olefin elastomer (e.g., EPDM, EPR, etc.), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), etc. The hydrogenated nitrile rubber (H-NBR) may contain an unsaturated carboxylate metal salt in H-NBR. These rubber components may be used alone or in combination of two or more kinds.
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 activity. 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 this viewpoint, it is preferable that the rubber component contains H-NBR.

When the rubber component of the rubber composition is H-NBR, the bound acrylonitrile content 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, and 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.

The above rubber compounding agents include, for example, vulcanization accelerators, antioxidants, reinforcing materials, plasticizers, co-crosslinking agents, crosslinking agents, etc.

Examples of the vulcanization accelerating aid include metal oxides such as zinc oxide (zinc white) and magnesium oxide, metal carbonates, fatty acids and derivatives thereof, etc. It is preferable to use one or more of these vulcanization accelerating aids, 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 based on 100 parts by mass of the rubber component.

Examples of the antiaging agent include benzimidazole-based agents, aromatic secondary amine-based agents, amine-ketone-based agents, etc. It is preferable to use one or more of these antiaging agents, and it is more preferable to use a combination of benzimidazole-based agents and aromatic secondary amine-based agents.
The amount of the antioxidant is, for example, 1.5 parts by mass or more and 3.5 parts by mass or less per 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, and acetylene black. These may be used alone or in combination of two or more kinds.
As the carbon black, it is preferable to use at least FEF or HAF.
The reinforcing material may be a combination of carbon black and silica.

When carbon black is used as the reinforcing material, the content thereof is, for example, 10 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the rubber component. The content of the carbon black is preferably 45 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the rubber component.
When silica is used as the reinforcing material, the content thereof is, for example, 10 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the rubber component.

Examples of the plasticizer include polyether esters, dialkyl sebacates such as dioctyl sebacate (DOS), dialkyl phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), dialkyl adipates such as dioctyl adipate (DOA), etc. These may be used alone or in combination of two or more kinds.
As the plasticizer, it is preferable to use at least a polyether ester.
The amount of the plasticizer is, for example, 5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the rubber component.

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

Examples of the crosslinking agent include sulfur, organic peroxides, etc. Either one of the two may be used alone, or they may be used in combination.
When only an organic peroxide is used as the crosslinking agent, the mixing amount of the organic peroxide is, for example, 2 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component.
In addition, when sulfur and an organic peroxide are used in combination as the crosslinking agent, the total compounding amount of the crosslinking agents is, for example, 0.1 part by mass or more and 0.7 parts by mass or less of sulfur and 1 part by mass or more and 5 parts by mass or less of the organic peroxide per 100 parts by mass of the rubber component.

In addition, the belt body 11 may be composed of a composition containing a thermosetting urethane elastomer in which an uncured thermosetting urethane composition in which a urethane prepolymer and a curing agent are mixed with various compounding agents is heated and pressurized during belt molding to crosslink the urethane prepolymer.
Furthermore, the belt body 11 may be formed of a thermoplastic elastomer composition obtained by blending various compounding ingredients with a thermoplastic elastomer and molding the thermoplastic elastomer composition in a mold.

The core wire 13 is embedded in the surface layer on the inner periphery of the back rubber portion 11a of the belt body 11 so that it extends in a spiral with a pitch in the belt width direction.

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 wires 13 (the 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 properties while reducing the flexural rigidity of the belt. Also, the responsiveness of the toothed belt 10 is easily ensured.

In particular, in an embodiment of the present invention, a core wire containing carbon fiber that can ensure sufficient tension even though it is thin is used as the core wire, thereby achieving a thin core wire diameter of 0.50 mm or more and 0.60 mm or less while narrowing the core wire arrangement pitch to 0.70 mm or more and 0.85 mm or less.
Therefore, the toothed belt according to the embodiment of the present invention has excellent positioning properties even though it is a relatively small toothed belt.

The core wire 13 includes 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 PAN-based, may be pitch-based, or may include both. A sizing agent such as 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, and organic fibers such as aramid fibers, polyester fibers, PBO fibers, nylon fibers, and polyketone fibers.

When the core wire 13 contains carbon fiber and other types of fiber as its constituent materials, the proportion of carbon fiber to all fibers is 50 mass % or more.
The proportion of the carbon fibers is preferably as high as possible (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 a core wire containing carbon fibers having the above filament diameter, the toothed belt 10 has good positioning properties.

The core wire 13 is a twisted yarn containing the above-mentioned carbon fiber and having 5,000 to 7,000 filaments.
By using such twisted yarn as the core wire, the toothed belt 10 can be well positioned.

The twisting method of the core wire 13 is single twist, double twist, or Lang twist. Among these twisting methods, single twist is preferred from the viewpoints of strength, elasticity, and adhesive treatment of the filaments that make up the core wire.

When the core wire 13 is a single-twisted yarn, the number of single twists is 4 to 10 times per 10 cm. If the number of single twists is less than 4 times per 10 cm, the bending fatigue resistance is poor and it is unsuitable as a core wire for a toothed belt. On the other hand, if the number of single twists exceeds 10 times per 10 cm, the strength and elasticity are reduced, and the positioning of the toothed belt using this core wire is deteriorated.

When the core wire 13 is a ply yarn or a lange twist yarn, the number of final twists is 4 to 8 times per 10 cm. If the number of final twists is less than 4 times per 10 cm, the bending fatigue is poor and the core wire is not suitable for a toothed belt. On the other hand, if the number of final twists exceeds 10 times per 10 cm, the strength and elastic modulus decrease, and the positioning of the toothed belt using this core wire becomes poor.
When the core wire 13 is a ply or rung twist, the number of times of first twist is not particularly limited, but is, for example, 6 to 12 times per 10 cm.

The core wires 13 may be subjected to an adhesive treatment before the toothed belt 10 is produced in order to increase the adhesive strength between the core wires 13 and the belt body 11 .
As the above-mentioned adhesive treatment, for example, one or both of an RFL treatment in which the substrate is immersed in an RFL aqueous solution and then heated, and a rubber paste treatment in which the substrate is immersed in rubber paste and then dried, a treatment in which the substrate is immersed in an aqueous treatment agent containing rubber latex and a crosslinking agent and then dried, etc. can be used.
The aqueous treatment agent is mainly composed of rubber latex. The rubber latex may contain at least one rubber component selected from the group consisting of nitrile rubber, hydrogenated nitrile rubber, carboxyl-modified nitrile rubber, and carboxyl-modified hydrogenated nitrile rubber. The aqueous treatment agent may or may not contain an RFL condensate.
Prior to the above-mentioned adhesion treatment, the core wires 13 may be subjected to a surface preparation treatment in which the core wires 13 are immersed in an epoxy solution or an isocyanate solution and then heated.

When the core wire 13 is a single-twist yarn, the core wire can be obtained, for example, by twisting a fiber bundle of carbon fiber alone, or a fiber bundle of carbon fiber and another type of fiber, in one direction (S direction or Z direction) with the above number of single twists.

When the core wire 13 is a ply yarn, the core wire can be obtained by, for example, collecting a number of strands of fiber bundles, each of which is first twisted in one direction (S direction or Z direction), including fiber bundles of carbon fiber, and then top twisting the strands in the direction opposite to the first twist direction with the number of top twists described above.

When the core wire 13 is a Lang twisted yarn, the core wire can be obtained by, for example, collecting a number of strands of fiber bundles, each of which is first twisted in one direction (S direction or Z direction), including fiber bundles of carbon fiber, and then top twisting the strands in the same direction as the first twist with the number of top twists described above.

In the toothed belt 10, the core wires 13 may be of two types, S-twisted yarn (in the case of ply-twisted yarn or Lang-twisted yarn, the upper twist direction is S direction) and Z-twisted yarn (in the case of ply-twisted yarn or Lang-twisted yarn, the upper twist direction is Z direction), and may be arranged in a double helix so that they are alternately arranged in the belt width direction. In this case, it is suitable to suppress deviation of the toothed belt 10 during running.
The core wire 13 may be constructed from a single S-stranded or Z-stranded yarn.

The reinforcing cloth 14 is applied so as to cover the surface of the inner circumferential side on which the plurality of toothed rubber portions 11b of the belt body 11 are provided. Therefore, the toothed rubber portion 11b of each belt tooth 12 is covered with the reinforcing cloth 14.
At the tooth bottom portion 15, the reinforcing cloth 14 is disposed immediately inside the core wire 13 embedded in the inner peripheral portion of the back rubber portion 11a of the belt 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 fabric 14 is made of, for example, a woven fabric, knitted fabric, nonwoven fabric, etc., formed from yarns such as nylon fibers (polyamide fibers), polyester fibers, aramid fibers, polyparaphenylenebenzobisoxazole (PBO) fibers, cotton, etc. Of these, a woven fabric made of nylon fibers is preferable.
The reinforcing fabric 14 is preferably elastic, for example, a woven fabric having weft yarns that have been subjected to a wooly finish.

The reinforcing cloth 14 may be subjected to one or more of the following adhesive treatments to increase the adhesive strength with the belt body: an RFL treatment in which the reinforcing cloth 14 is immersed in an RFL aqueous solution and then heated; a soaking treatment in which the reinforcing cloth 14 is immersed in low-viscosity rubber paste and then dried; and a coating treatment in which high-viscosity rubber paste is applied to the surface of the belt body side and then dried.
Prior to the above-mentioned adhesion treatment, the reinforcing fabric 14 may be subjected to a preliminary treatment in which the fabric is immersed in an epoxy solution or an isocyanate solution and then heated.

The toothed belt 10 preferably has a bending stiffness of 7.33 Ncm ² or less.
In this case, the toothed belt 10 can be bent with a small force when it is wound around the pulley, so there is no need to apply high tension to the belt and the rigidity of the device can be reduced. Also, the lower the rigidity of the belt, the smaller the power transmission energy loss and the better the bending fatigue resistance and responsiveness of the belt. On the other hand, a toothed belt with a high bending rigidity has poor 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, but is, for example, 6.50 ^Ncm2 .

The bending stiffness is measured by the following method.
The bending stiffness E of the toothed belt 10 is determined by a bending test using an Olsen bending tester in accordance with JIS K7106 (1995), and is multiplied by the second moment of area I of the toothed belt 10 to calculate the belt bending stiffness E·I.
Here, the second moment of area I of the toothed belt 10 is calculated as I=bh3/12, assuming that the belt width is the width b of the test specimen, the belt thickness at the tooth bottom portion 15 is the thickness h of the test specimen, and the cross section of the toothed belt 10 is rectangular ^. That is, in the present invention, the second moment is calculated by ignoring the tooth rubber portion of the toothed belt 10.

The toothed belt 10 preferably has an elastic modulus M1.0 of 300 N/mm or more.
In this case, it is more suitable to ensure good positioning.
A preferred 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 an embodiment of the present invention, the elastic modulus M1.0 of a toothed belt refers to the stress per unit width of the belt when 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 elastic modulus M1.0 is measured by the following method using a tensile tester.
First, the toothed belt 10 is cut into a strip having a belt length of about 300 mm, and two benchmark lines spaced apart 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 chucks of a tension tester, and the measurement sample is set in the tensile tester.
Thereafter, 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 elongated by 1.0% based on the gauge length 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 carried out three times, and the average value is regarded as the elastic modulus M1.0.

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 bending fatigue resistance and responsiveness while ensuring excellent positioning properties.
On the other hand, if the hardness (JIS-A) is less than 84, the positioning ability of the toothed belt 10 may be poor. If the hardness (JIS-A) is more than 94, the toothed belt 10 may be poor in bending fatigue resistance and responsiveness.

The hardness (JIS-A) of the rubber composition or elastomer composition is measured by molding the rubber composition or elastomer composition constituting the belt body 11 into a predetermined shape, using this as a measurement sample, and measuring the hardness using a Type A durometer in accordance with JIS K6253-3 (2012) or JIS K7312 (1996) depending on the object to be measured.

The gap ratio of the toothed belt 10 is preferably less than 30%, which improves the positioning ability of the toothed belt 10. The gap ratio is more preferably 28% or less.
The above gap ratio may be small from the viewpoint of positioning, 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, from the viewpoint of yield, the lower limit of the above gap ratio is preferably 20%, and more preferably 22%.
The above-mentioned gap ratio refers to the ratio (%) of the total gap dimensions between the core wires in the width direction of the belt to the width dimension of the toothed belt.
The smaller the gap ratio, the greater the proportion of the cord in the width direction of the belt.

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. 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.

According to the toothed belt 10 of this embodiment, which has the above-mentioned configuration, the core wire 13 has a specific configuration that includes carbon fiber, and this core wire 13 is embedded in the belt body 11 at a predetermined arrangement pitch, so that it has excellent positioning properties and good responsiveness.

Next, a method for producing the toothed belt 10 according to the present embodiment will be described with reference to FIGS. 4 to 7, taking as an example a case in which the belt body is made of the above-mentioned rubber composition.
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>
A predetermined rubber component is masticated, and various rubber compounding agents are added thereto and kneaded to obtain an unvulcanized rubber composition. The unvulcanized rubber composition thus obtained is then calendered or otherwise molded to produce an unvulcanized rubber composition sheet 11'.

The core wire 13 and the reinforcing cloth 14 are each subjected to an adhesive treatment. The reinforcing cloth 14 is then formed into a cylindrical shape.

<Molding process>
FIG. 4 is a partial cross-sectional view showing a part of the belt forming die 30. As shown in FIG.
The belt forming mold 30 is cylindrical and has an outer circumferential surface on which a plurality of teeth forming grooves 31 are formed and spaced apart in the circumferential direction so as to extend in the axial direction.

As shown in FIG. 5, a cylindrical reinforcing cloth 14 is placed on the outer circumferential surface of a belt forming mold 30, and a core wire 13 is wound around the reinforcing cloth 14 in a spiral shape.
Then, an unvulcanized rubber composition sheet 11' is wrapped around it, and an unvulcanized slab S' is molded on the belt molding die 30. The unvulcanized rubber composition sheet 11' is preferably used so that the grain direction corresponds to the belt length direction.

<Vulcanization process>
As shown in Fig. 6, the unvulcanized slab S' on the belt mold 30 is covered with a rubber sleeve 32, which is then placed in a vulcanizer can and sealed, and the vulcanizer can is filled with high-temperature, high-pressure steam and held for a specified molding time. In this way, the unvulcanized slab S' is pressed against the belt mold 30 and heated, whereby the unvulcanized rubber composition sheet 11' is passed between the cords 13 and flows into each of the multiple tooth-forming grooves 31 of the belt mold 30 while pressing the reinforcing cloth 14, and vulcanized. At the same time, the cords 13 and the reinforcing cloth 14 are integrated into a composite, and finally, a cylindrical belt slab S is molded as shown in Fig. 7.

<Finishing process>
The pressure inside the vulcanizer is reduced to release the seal, and the belt slab S molded between the belt mold 30 and the rubber sleeve 32 is taken out and demolded, and then cut into rings of a predetermined width to obtain the toothed belt 10.
Through these steps, the toothed belt 10 having the belt body made of the rubber composition can be manufactured.

The toothed belt 10 in which the belt body 11 is made 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 wound spirally around the outer circumferential surface of a cylindrical belt forming die 30 that has been used in the manufacture of a toothed belt having a belt body made of a rubber composition.
(2) Next, the cylindrical belt forming die 31 is placed 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 main 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, filling it and heating it. At this time, the uncured thermosetting urethane composition hardens while also entering the teeth forming grooves 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 that has been made fluid by heating is injected into the cavity, which is then cooled. At this time, the thermoplastic elastomer solidifies while also entering the tooth-forming grooves 31, and a cylindrical slab in which the thermoplastic elastomer and the core wires 13 are integrated is formed.

(4) After that, the cylindrical slab is demolded from the belt molding die 31 and the outer die, and a reinforcing cloth is attached to its inner surface (the toothed rubber portion side). Then, the slab with the reinforcing cloth is cut into rings to obtain the toothed belt 10.
By carrying out these steps, it is possible to manufacture the toothed belt 10 whose belt body is made of a thermosetting urethane elastomer composition or a thermosetting elastomer composition.

The present invention will be described in more detail below 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 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, core wire, and reinforcing fabric for forming the belt body (back rubber portion and tooth rubber portion) were prepared as follows.

(Preparation of Unvulcanized Rubber Composition)
The following rubber compositions A to D were prepared, each having the composition shown in Table 1. In Table 1, the compounding amounts are shown in parts by mass.
Rubber composition A: A rubber obtained by mixing 45 parts by mass of hydrogenated nitrile rubber (H-NBR) (manufactured by Nippon Zeon Co., Ltd., product name: Zettpol 2020) and 55 parts by mass of hydrogenated nitrile rubber (manufactured by Nippon Zeon Co., Ltd., product name: ZSC2195) containing an unsaturated carboxylic acid metal salt mixed with an unsaturated carboxylic acid metal salt, was used as a base rubber, and 5 parts by mass of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., product name: Zinc Oxide 3), stearic acid (Nippon Zeon Co., Ltd., product name: Zinc Oxide 3), and 100 parts by mass of this base rubber were mixed. An unvulcanized rubber composition was prepared by blending and kneading 1 part by mass of stearic acid (manufactured by Honrika Co., Ltd., trade name: stearic acid), 10 parts by mass of dioctyl sebacate (DOS) (manufactured by Dainippon Ink and Chemicals Incorporated Co., Ltd., trade name: Monosizer W280), 60 parts by mass of carbon black FEF (manufactured by Tokai Carbon Co., Ltd., trade name: Seest SO), 3 parts by mass of an antioxidant (manufactured by Ouchi Shinko Chemical Co., Ltd., trade name: Nocrac MB), 3 parts by mass of trimethylolpropane triacrylate (TMPT) (manufactured by Sanshin Chemical Industry Co., Ltd., trade name: Sunester TMP), and 7 parts by mass of Peroximon F40 (manufactured by NOF Corporation), to obtain a rubber composition A.

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

Rubber composition B: prepared in the same manner as rubber composition A, except that the proportion of carbon black FEF was changed.
The hardness (JIS-A) of the vulcanizate of rubber composition B vulcanized under the same vulcanization conditions as those used in producing the toothed belt was measured and found to be 86.

Rubber composition C: prepared in the same manner as rubber composition A, except that the proportion of carbon black FEF was changed.
The hardness (JIS-A) of the vulcanizate of rubber composition C vulcanized under the same vulcanization conditions as those used in producing the toothed belt was measured and found to be 95.

Rubber composition D: prepared in the same manner as rubber composition A, except that the proportion of carbon black FEF was changed.
Regarding rubber composition D, the hardness (JIS-A) of the vulcanizate vulcanized under the same vulcanization conditions as those used in producing the toothed belt was measured and found to be 80.

(Preparing the core wire)
Core Wire A: Carbon fiber (manufactured by Toray Industries, Inc., product name: Torayca T800HB-6000, filament diameter 5.0 μm, number of filaments 6000) was used, and this was twisted 6 times per 10 cm to form a single twist yarn, which was used as core wire A. The core wire diameter of core wire A was 0.55 mm. Two types of core wire A were prepared: an S twist yarn and a Z twist yarn.

Core wire B: Carbon fiber (manufactured by Toray Industries, product name: Torayca T800HB-6000, filament diameter 5.0 μm, number of filaments 6,000) was used, and this was twisted 8 times per 10 cm to form a single-twisted yarn, which was used as core wire B. The diameter of core wire B was 0.58 mm. Two types of core wire B were prepared: S-twisted yarn and Z-twisted yarn.

Core wire C: Carbon fiber (manufactured by Toray Industries, product name: Torayca T300B-6000, filament diameter 7.0 μm, number of filaments 6,000) was used, and this was twisted 7.5 times per 10 cm to form a single-twisted yarn, which was used as core wire C. The core wire diameter of core wire C was 0.70 mm. Two types of core wire C were prepared: S-twisted yarn and Z-twisted yarn.

Core wire D: Carbon fiber (manufactured by Toray Industries, product name: Torayca T300B-3000, filament diameter 7.0 μm, number of filaments 3000) was used, and this was twisted 6 times per 10 cm to form a single-twisted yarn, which was used as core wire D. The core wire diameter of core wire D was 0.48 mm. Two types of core wire D were prepared: S-twisted yarn and Z-twisted yarn.

Core Wire E: Carbon fiber (manufactured by Toray Industries, product name: Torayca T300B-3000, filament diameter 7.0 μm, number of filaments 3000) was used, and this was twisted 12 times per 10 cm to form a single-twisted yarn, which was used as core wire E. The core wire diameter of core wire E was 0.53 mm. Two types of core wire E were prepared: S-twisted yarn and Z-twisted yarn.

Core wire F: High-hardness glass fiber (high-strength glass cord manufactured by Nippon Sheet Glass, filament diameter 7.0 μm) was used. Three strands of 200 filaments were collected together and twisted in one direction with 8 twists/10 cm to create a first twist yarn. Eight strands were collected together and twisted in the opposite direction to the first twist with 8 twists/10 cm to create a multi-twist yarn, which was used as core wire F. The core wire diameter of core wire F was 0.72 mm. Two types of core wire F were prepared: S-twisted yarn and Z-twisted yarn. The total number of filaments in core wire F was 4,800.

(Preparation of reinforcing fabric)
The following nylon canvas was prepared as the reinforcing fabric.
Resorcin (manufactured by Sumitomo Chemical Co., Ltd., product name: Resorcinol) and formalin (manufactured by Mitsui Chemicals, Inc., product name: Formalin) were added to a sodium hydroxide solution in a molar ratio of R/F = 1/2 and mixed with stirring to obtain an initial condensation product solution. Hydrogenated acrylonitrile butadiene methacrylic acid terpolymer (X-NBR) latex (manufactured by Nippon Zeon Co., Ltd., product name: ZLX-B) and water were added to the obtained solution and mixed with stirring to prepare an RFL liquid in which the mass ratio of resorcin-formalin to latex is RF/L = 1/8.

Next, 80 parts by mass of polytetrafluoroethylene (manufactured by Asahi Glass Co., Ltd., product name: Fluon AD911, average particle size: 0.25 μm) and 30 parts by mass of blocked isocyanate (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., product name: Elastron BN-27, bond dissociation temperature 180°C) were added to this RFL liquid per 100 parts by mass of the latex solids of the RFL liquid, and mixed by stirring. Furthermore, carbon black (manufactured by Fuji Pigment Industries Co., Ltd., product name: Fuji SP Black 203) was added and dispersed to make 5% by mass of the total, preparing a treatment liquid with a solids concentration of 15% by mass.

A 2/2 twill fabric made of woolly processed 6,6-nylon fiber with a warp of 235 dtex and a weft of 155 dtex (breaking elongation of 150% or more) was immersed in this treatment solution, then pulled out and passed between a pair of pressure rolls and squeezed to apply the treatment solution to the twill fabric. The temperature of the treatment solution was 20°C, the immersion time was 2 seconds, and the treatment was repeated twice. The clearance of the pressure rolls was also adjusted so that the basis weight of the RFL coating was approximately 30% by mass.

The twill fabric with the treatment solution was passed through a heating and drying oven and dried to prepare a nylon canvas. The oven temperature (heating and drying temperature) was 150° C. and the heat treatment time was 2 minutes.
This nylon canvas was used as the reinforcing fabric in the examples and comparative examples.

Example 1
Using rubber composition A as the unvulcanized rubber composition forming the belt body, core wire A as the core wire, and the nylon canvas as the reinforcing cloth, a toothed belt with a tooth type of S5M was manufactured by the above-mentioned manufacturing method (see Figs. 4 to 7). The belt width was 10 mm, and the belt length was 800 mm.
At this time, the core wire A used was one that had been immersed in an aqueous treatment agent A containing a crosslinking agent and a rubber latex containing hydrogenated nitrile rubber as a main component and not containing an RFL condensate, and then dried for adhesion treatment. The core wire A was arranged in a double helix such that the S twisted yarn and the Z twisted yarn were alternately arranged in the belt width direction and the pitch of adjacent core wires was 0.75 mm.
The gap ratio of the manufactured toothed belt was 26.7%.

Example 2
A toothed belt was produced 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.

Example 3
A toothed belt was produced 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.

Example 4
A toothed belt was produced in the same manner as in Example 2, except that the core wire B was used instead of the core wire A.
At this time, the core wire B used was one that had been subjected to an adhesive treatment by immersing in the above-mentioned aqueous treatment agent A and then drying. The core wire B was arranged in a double helix such that the S twisted yarn and the Z twisted yarn were alternately arranged in the belt width direction and the pitch between adjacent core wires was 0.75 mm.
The gap ratio of the manufactured toothed belt was 22.7%.

<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 nylon canvas as the reinforcing cloth, a toothed belt with a tooth type of S5M was manufactured by the above-mentioned manufacturing method (see Figs. 4 to 7). The belt width was 10 mm, and the belt length was 800 mm.
At this time, the core wire C used was one that had been subjected to an adhesive treatment by immersing in the above-mentioned aqueous treatment agent A and then drying. The core wire C was arranged in a double helix such that the S twisted yarn and the Z twisted yarn were alternately arranged in the belt width direction and the pitch between adjacent core wires was 1.0 mm.
The gap ratio of the toothed belt is 30.0%.

<Comparative Example 2>
A toothed belt was produced in the same manner as in Example 1, except that core wire D was used instead of core wire A and the following core wire pitch was adopted.
At this time, the core wire D used was one that had been subjected to an adhesive treatment by immersing in the above-mentioned aqueous treatment agent A and then drying. The core wire D was arranged in a double helix such that the S twisted yarn and the Z twisted yarn were alternately arranged in the belt width direction and the pitch between adjacent core wires was 0.80 mm.
The gap ratio of the manufactured toothed belt was 40.0%.

<Comparative Example 3>
A toothed belt was produced 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, the core wire E used was one that had been subjected to an adhesive treatment by immersing in the above-mentioned aqueous treatment agent A and then drying. The core wire E was arranged in a double helix such that the S twisted yarn and the Z twisted yarn were alternately arranged in the belt width direction and the pitch between adjacent core wires was 0.80 mm.
The gap ratio of the manufactured toothed belt was 33.8%.

<Comparative Example 4>
A toothed belt was produced 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, the core wire F used was one that had been subjected to an adhesive treatment by immersing in the above-mentioned aqueous treatment agent A and then drying. The core wire F was arranged in a double helix such that the S twisted yarn and the Z twisted yarn were alternately arranged in the belt width direction and the pitch between adjacent core wires was 1.2 mm.
The gap ratio of the manufactured toothed belt was 40.0%.

(Evaluation Method)
The toothed belts manufactured in the examples and the comparative examples were measured for bending stiffness and elastic modulus M1.0. Furthermore, the toothed belts manufactured in the examples and the comparative examples were evaluated for positioning ability and responsiveness. These results are shown in Table 3.

<Bending rigidity>
The bending stiffness was measured by the above-mentioned method using a toothed belt cut to a length of 70 mm as a sample.
That is, for a measurement sample of a toothed belt, bending stiffness E was obtained by a bending test using an Olsen bending tester in accordance with JIS K7106 (1995), and this was multiplied by the second moment of area I of the toothed belt to calculate belt bending stiffness E·I (Ncm ² ).

The measurement sample of the toothed belt had a tooth shape of S5M, a width of 10 mm, a thickness of 3.61 mm and a length of 70 mm.
The second moment of area I of the measurement sample of the toothed belt was determined by assuming the toothed belt cross section to be rectangular, ignoring the teeth, setting the width b of the test piece to the belt width of 10 mm, and the thickness h of the test piece to the belt thickness at the tooth bottom portion of 1.70 mm, and calculating I = ^bh3 /12.

The parameters of the formula (6) for calculating the bending stiffness E of the measurement sample of the toothed belt as described in 8.3 of JIS K7106 (1995) were: distance between supports S: 1.27 cm, width b of the test piece: 10 mm, thickness of the test piece: 3.61 mm, pendulum moment M0 at 100% load scale _: 0.0846 N·m, and bending angle φ: 0.1745 rad.
The test was carried out under conditions of room temperature of 25±5° C. and humidity of 50±5%.

<Elastic modulus M1.0>
The elastic modulus M1.0 was measured using a tensile tester by the method described above.
The tensile speed was 50 mm/min. The measurement was carried out three times, and the average value was taken as the elastic modulus M1.0.

<Positioning ability>
FIG. 8 shows the pulley layout of the belt testing machine 100.
The belt testing machine 100 comprises a drive pulley 120 fixed to a rotating shaft and a driven pulley 130 fixed to a fixed shaft so as not to rotate, which are arranged at a laterally spaced interval, and a torque meter is connected to the rotating shaft of the drive pulley 120 so that the drive pulley 120 can be rotated by applying a torque to this rotating shaft.
At a position M above the drive pulley 120, the amount of movement (rotation angle deg) on the pitch line of the toothed belt 110 can be measured.

This evaluation was performed according to the following procedure by wrapping the toothed belts 110 manufactured in the examples and comparative examples around the drive pulley 120 and driven pulley 130 of the belt testing machine 100. In this evaluation, the rotational torque that rotates the drive pulley 120 to the right is defined as +torque, and the rotational torque that rotates the drive pulley 120 to the left is defined as -torque.
The conditions set during the evaluation are as shown in Table 2.

(1) The state before the drive pulley 120 is rotated is defined as the initial state.
(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) of the toothed belt 110 on the pitch line at that time is measured.
(6) Such measurements from (1) to (5) constitute one set. This set is repeated three times.

When one set of such measurements is performed, the relationship between the rotational torque and the amount of movement on the pitch line of the toothed belt 110 (amount of displacement from the initial state) can be shown as in the graph of FIG.
FIG. 9 is a graph of the first set of data obtained in the evaluation of the positioning ability of Example 1.
In the graph of FIG. 9, the states at the end of steps (1) to (5) respectively correspond to A to E.
In this evaluation, the difference between C and E in Fig. 9 was used as the standard, and it was determined that the smaller this difference was, the better the positioning performance was. This is because the smaller the difference between C and E is, the closer the state returns to the initial state each time the torque is released.
In addition, the rotation angle of the drive pulley corresponding to the difference between C and E is shown as the evaluation value in Table 3. In addition, the average value of three sets is shown as the evaluation value.
In this case, the smaller the rotation angle, the shorter the distance between CE and the sensor, resulting in superior positioning performance.

<Responsiveness>
FIG. 10 shows the pulley layout of the belt testing machine 200 .
The belt testing machine 200 has a driving pulley 220 and a driven pulley 230 arranged at a distance in the lateral direction, and is configured so that the driven pulley can be moved in the lateral direction to fix the set weight SW. The belt testing machine 200 also includes an encoder (not shown) for acquiring the number of rotations of the driving pulley 220 and the driven pulley 230.
The driving pulley 220 and the driven pulley 230 each have 24 teeth and are of the S5M type.

In this evaluation, the toothed belt 210 manufactured in the examples and comparative examples was wound around the driving pulley 220 and driven pulley 230 of the belt testing machine 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. In addition, the flywheel effect ( ^GD2 ) of the driven pulley 230 was 0.040 kgf· ^m2 .
Next, at room temperature, the drive pulley 220 was accelerated from 0 to 100 rpm in an acceleration time of 0.02 seconds, and then driven at a constant speed of 100 rpm, and the rotation speeds of the drive pulley 220 and driven pulley 230 were measured.

The test conditions for this evaluation are summarized as follows:
・Acceleration time: 0.02sec
・Rotation speed: 0→100 rpm
Flywheel effect ( ^GD2 ): 0.040 kgf· ^m2

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

11 and 12 are graphs showing examples of data obtained in this evaluation.
FIG. 11 is a graph showing the evaluation results of the toothed belt of Example 2, illustrating the change over time in the rotation speed of each of the driving pulley 220 and the driven pulley 230.
FIG. 12 is a graph showing the evaluation results of the toothed belt of Example 2, and shows the change over time of the difference in the rotation speed between the driving pulley 220 and the driven pulley 230.
As can be seen from these graphs, the rotation speed of the driven pulley rises later than that of the driving pulley, and after it greatly exceeds the rotation speed of the driving pulley, it gradually synchronizes with the rotation speed of the driving pulley. Therefore, if the difference in rotation speed between the two is small when the rotation speed of the driven pulley greatly exceeds the rotation speed of the driving pulley at first, the toothed belt has good responsiveness.

REFERENCE SIGNS LIST 10, 110, 120 toothed belt 11 belt body 11a back rubber portion 11b toothed rubber portion 12 belt teeth 13 core wire 14 reinforcing cloth 15 tooth bottom portion 30 belt forming mold 31 tooth portion forming groove 32 rubber sleeve 100, 200 belt testing machine 120, 220 driving pulley 130, 230 driven pulley

Claims (6)

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 made of a rubber composition or an elastomer composition having a hardness (JIS-A) of 86 to 89. 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. The toothed belt according to claim 1, wherein the twisted yarn is a single twisted yarn, and the number of single twists is 4 to 10 times per 10 cm. 5. The toothed belt according to claim 1 , wherein the tooth pitch is 5 mm. Bending stiffness: 6.96 Ncm ² 7.33Ncm or more ² is as follows:
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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