JP7584260B2 - Manufacturing method of toothed belt - Google Patents

Description

The present invention relates to a toothed belt and a method for manufacturing a toothed belt.

Toothed belts are used for lifting and transporting objects in factories, warehouses, etc. This toothed belt has a belt body, teeth arranged at equal intervals in the length direction on one side of the belt body, and multiple core cords arranged at equal intervals in the width direction of the belt and embedded in the belt body along the length direction.

Such a toothed belt is manufactured by the following method (see JP 2019-35089 A). First, an inner mold is prepared that has grooves extending in the axial direction on the outer circumferential surface, the grooves are arranged at a predetermined pitch in the circumferential direction, and the protrusions between the grooves have protrusions at the tips for supporting multiple core cords, and the protrusions extend in the axial direction. Multiple core cords are wound around this inner diameter at equal intervals. Next, the inner mold with the core cords wound around it is set inside a cylindrical outer mold that has an inner diameter larger than the outer diameter of the inner mold by the thickness of the belt body. Then, a composition (e.g., a urethane composition) for forming the belt body and the teeth is prepared, poured between the inner mold and the outer mold, and molded. The toothed belt can be obtained by cutting to the desired width as necessary.

JP 2019-35089 A

In the conventional toothed belts described above, multiple core cords are embedded and arranged at equal intervals across the width of the belt, and are therefore manufactured with multiple core cords supported by ridges. As a result, in the manufactured toothed belt, the composition is not poured into the areas where the ridges contact the core cords, and recesses are formed on the tooth bottom surface between the teeth that reach down to the core cords. In other words, the multiple core cords are slightly exposed in these recesses.

When the core cord is exposed, there is a risk of dust emitting from the core cord if it is made of fiber, and there is a risk of sparks being generated when electricity is passed through the core cord if it is made of steel. For this reason, there is a demand for toothed belts in which the components embedded in the toothed belt, such as the core cord, are not exposed, for example for food applications and clean room applications.

The present invention was made in consideration of these inconveniences, and aims to provide a toothed belt and a method for manufacturing the toothed belt that is easy to manufacture and prevents the exposure of components embedded in the toothed belt, such as the core cord.

A toothed belt according to one embodiment of the present invention comprises a belt body, a plurality of teeth arranged at equal intervals in the longitudinal direction on one side of the belt body, a plurality of core cords spaced apart in the width direction of the belt body and embedded in the belt body along the longitudinal direction, and canvas embedded on the one side of the belt body relative to the plurality of core cords, and the main component of the belt body is a thermoplastic elastomer.

A method for manufacturing a toothed belt according to another embodiment of the present invention includes a step of unrolling a strip of canvas while placing multiple core cords on its upper surface at intervals in the width direction, and a step of covering the canvas with the multiple core cords from above and below by extrusion molding with a composition mainly composed of molten thermoplastic elastomer, and the canvas is in a mesh shape.

The toothed belt of the present invention is easy to manufacture and can prevent the exposure of components embedded in the toothed belt, such as the core cord. Furthermore, by using the manufacturing method of the toothed belt of the present invention, a toothed belt that prevents the exposure of components embedded in the toothed belt, such as the core cord, can be easily manufactured.

FIG. 1 is a schematic perspective view showing a toothed belt according to an embodiment of the present invention. FIG. 2 is a schematic oblique sectional view showing the vertical structure of the toothed belt of FIG. FIG. 3 is a schematic cross-sectional view of the toothed belt taken along line AA of FIG. FIG. 4 is a schematic cross-sectional view of the toothed belt taken along line BB of FIG. FIG. 5 is a flow diagram showing a method for producing a toothed belt according to another embodiment of the present invention.

[Description of the embodiments of the present invention]
First, the embodiments of the present invention will be listed and described.

A toothed belt according to one embodiment of the present invention comprises a belt body, a plurality of teeth arranged at equal intervals in the longitudinal direction on one side of the belt body, a plurality of core cords spaced apart in the width direction of the belt body and embedded in the belt body along the longitudinal direction, and canvas embedded on the one side of the belt body relative to the plurality of core cords, and the main component of the belt body is a thermoplastic elastomer.

The toothed belt has canvas positioned between multiple core cords and one side of the belt body, preventing the exposure of the multiple core cords. In addition, the canvas itself is embedded in the belt body, preventing its exposure. Furthermore, the toothed belt has a thermoplastic elastomer as the main component of the belt body, so dust is less likely to be generated from the core cords and canvas, and the toothed belt can be easily manufactured by extrusion molding.

It is preferable that the belt body is constructed of a single layer. By constructing the belt body of the single layer in this way, the toothed belt can be manufactured more easily.

It is preferable that the canvas and the core cords are spaced apart. By spaced apart the canvas and the core cords in this way, wear caused by contact between the canvas and the core cords can be suppressed, thereby extending the life of the toothed belt.

It is preferable that the canvas is mesh-like. By making the canvas mesh-like in this way, it is possible to more reliably prevent the canvas itself from being exposed.

The porosity of the mesh of the canvas is preferably 35% or more and 95% or less. By setting the porosity of the mesh of the canvas within the above range, it is possible to easily control the embedding positions of the multiple core cords while preventing the canvas itself from being exposed.

The fibers of the canvas may include at least one of polyamide fibers and polyester fibers. By including at least one of polyamide fibers and polyester fibers in the fibers of the canvas, the rigidity of the teeth is increased and the skip torque is increased. In addition, the occurrence of chipped teeth can be suppressed.

The thermoplastic elastomer may include at least one of thermoplastic polyurethane, thermoplastic polyester, and thermoplastic polyamide. By including at least one of thermoplastic polyurethane, thermoplastic polyester, and thermoplastic polyamide in the thermoplastic elastomer, the toothed belt can be manufactured more easily.

It is preferable that the belt body does not have a recess on the tooth bottom surface between the teeth. If the tooth bottom surface between the teeth has a recess, the belt body is more likely to bend starting from the recess. As a result, when wound around a pulley, the belt body bends into a polygonal shape, and bending fatigue resistance is reduced. In contrast, by making the belt body not have a recess on the tooth bottom surface between the teeth, bending into a polygonal shape can be prevented and bending fatigue resistance can be improved.

A method for manufacturing a toothed belt according to another embodiment of the present invention includes a step of unrolling a strip of canvas while placing multiple core cords on its upper surface at intervals in the width direction, and a step of covering the canvas with the multiple core cords from above and below by extrusion molding with a composition mainly composed of molten thermoplastic elastomer, and the canvas is in a mesh shape.

In this method for manufacturing a toothed belt, the positions of the multiple core cords in the thickness direction of the belt body can be adjusted by supporting the multiple core cords with the canvas. In addition, in this method for manufacturing a toothed belt, since the canvas is mesh-like, when extrusion molding is performed, the composition mainly composed of molten thermoplastic elastomer passes through the mesh of the canvas, preventing the canvas itself from being extruded from the belt body and becoming exposed. Therefore, by using this method for manufacturing a toothed belt, it is possible to easily manufacture a toothed belt in which the exposure of the core cords and canvas is prevented by extrusion molding.

Here, the "main component" refers to the component that is contained in the greatest amount, for example, 50% by mass or more.

[Details of the embodiment of the present invention]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A toothed belt and a method for manufacturing a toothed belt according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[Toothed belt]
The toothed belt 1 shown in Figures 1 to 4 comprises a belt body 10, a plurality of tooth portions 20 arranged at equal intervals in the longitudinal direction on one side of the belt body 10, a plurality of core cords 30 spaced apart in the width direction of the belt body 10 and embedded in the belt body 10 along the longitudinal direction, and a canvas 40 embedded on the one side of the belt body 10 relative to the plurality of core cords 30.

<Belt body>
The main component of the belt body 10 is a thermoplastic elastomer. The thermoplastic elastomer may include at least one of thermoplastic polyurethane, thermoplastic polyester, and thermoplastic polyamide. By including at least one of thermoplastic polyurethane, thermoplastic polyester, and thermoplastic polyamide in the thermoplastic elastomer, the toothed belt 1 can be manufactured more easily.

The belt body 10 may be constructed of a single layer. In other words, the belt body 10 does not have a layered structure and is formed as an integral unit. By constructing the belt body 10 in this manner as a single layer, the toothed belt 1 can be manufactured more easily.

In addition, the belt body 10 does not have a recess on the tooth bottom surface between the tooth portions 20. In other words, the belt body 10 is configured to have a uniform thickness. If there is a recess on the tooth bottom surface between the tooth portions 20, the belt body 10 is more likely to bend starting from the recess. As a result, when wound around a pulley, it bends into a polygonal shape, and bending fatigue resistance is reduced. In contrast, by making the belt body 10 not have a recess on the tooth bottom surface between the tooth portions 20, it is possible to prevent bending into a polygonal shape and improve bending fatigue resistance.

The average thickness of the belt body 10 is determined appropriately depending on the strength required for the toothed belt 1, and can be, for example, 1 mm or more and 15 mm or less. Note that throughout this specification, "average" refers to the average value of values measured at any 10 points.

The length of the belt body 10 is determined appropriately depending on the application of the toothed belt 1. The toothed belt 1 can be used as a closed belt that runs between a pair of pulleys, or as an open belt with both ends.

The belt body 10 may contain various additives. Examples of such additives include antioxidants, heat stabilizers, light stabilizers, anti-fogging agents, flame retardants, surface conditioners, pigments, fillers, waxes, etc.

<Tooth>
The tooth portion 20 is a convex portion having a cross section that is trapezoidal, triangular, semicircular, mountain-shaped, wavy, normal distribution curve-shaped, etc. The tooth portion 20 is arranged so that its ridge line (axial direction) coincides with the width direction of the belt body 10. The cross-sectional shape of the tooth portion 20 may be specified in accordance with standards such as JIS, ISO, and DIN.

The average height of the toothed portion 20 and the pitch between the toothed portions 20 are determined appropriately depending on the application of the toothed belt 1. The average height of the toothed portion 20 can be, for example, 1.0 mm or more and 10 mm or less. The pitch between the toothed portions 20 can be, for example, 2 mm or more and 25 mm or less.

The main components of the tooth portion 20 can be the same as those of the belt body 10. The tooth portion 20 may also contain the same additives as those of the belt body 10.

<Core cord>
The multiple core cords 30 are linear bodies having a circular cross section.

The multiple core cords 30 are embedded in the belt body 10 as described above. In other words, the multiple core cords 30 are not exposed. The multiple core cords 30 are arranged parallel to the length of the belt body 10 and at a constant distance from the other surface of the belt body 10 (the surface on which the tooth portion 20 is not arranged). In other words, the multiple core cords 30 are arranged in a plane, and the plane formed by the multiple core cords 30 is parallel to the other surface of the belt body 10. The multiple core cords 30 are also arranged at equal intervals. The multiple core cords 30 can improve the strength, durability, driving accuracy, etc. of the toothed belt 1.

Each core cord 30 may be composed of a single core wire, or may be composed of multiple core wires twisted together. The core wire constituting the core cord 30 may include at least one of an aramid core wire, a steel core wire, a carbon core wire, and a polyester core wire. In other words, a core cord 30 composed of multiple core wires may be composed of one type of core wire, or may be composed of two or more types of core wires. The multiple core cords 30 may be composed of different core wires or a combination of different core wires, but it is preferable that they have the same core wire configuration in order to ensure uniformity in the width direction of the belt body 10.

The cross-sectional diameter of each core cord 30 is not particularly limited, but is generally 0.2 mm or more and 2.5 mm or less.

The lower limit of the average spacing between the multiple core cords 30 (the average distance between the central axes of the core cords 30) is preferably 0.3 mm, and more preferably 0.5 mm. On the other hand, the upper limit of the average spacing is preferably 4 mm, and more preferably 3 mm. If the average spacing is less than the lower limit, the flexibility of the toothed belt 1 may be insufficient. Conversely, if the average spacing exceeds the upper limit, the effect of improving the strength, durability, driving accuracy, etc. of the belt by the multiple core cords 30 may be insufficient.

The lower limit of the average distance between the central axis of the outermost core cord 30 and the side surface of the belt body 10 adjacent thereto is preferably 0.3 mm, more preferably 0.5 mm. On the other hand, the upper limit of the average distance is preferably 2 mm, more preferably 1.6 mm. If the average distance is less than the lower limit, the outermost core cord 30 may be exposed from the side surface of the belt body 10 during the manufacture of the toothed belt 1. Conversely, if the average distance exceeds the upper limit, the side edge of the belt body 10 may easily flutter when driven, and the effect of improving the accuracy of driving by the multiple core cords 30 may be insufficient. Note that there are two outermost core cords 30 on both sides of the belt body 10.

The number of core cords 30 is determined by the average width of the belt body 10, the average spacing between the core cords 30, and the average distance between the core cords 30 and the side of the belt body 10, but the number of core cords 30 is usually 10 or more and 100 or less.

<Canvas>
The canvas 40 is in a mesh shape as shown in Fig. 2. By forming the canvas 40 in a mesh shape in this manner, it is possible to more reliably prevent the canvas 40 itself from being exposed.

In FIG. 2, the canvas 40 is woven with multiple weft threads 41 arranged in the width direction of the belt body 10 and multiple warp threads 42 arranged in the conveying direction (longitudinal direction of the belt body 10), and has a rectangular gap 43 surrounded by two adjacent weft threads 41 and two adjacent warp threads 42. Note that the mesh configuration of the canvas 40 is not limited to the rectangular shape shown in FIG. 2, and the gap 43 may be hexagonal, for example.

The fibers of the canvas 40 (the fibers of the weft threads 41 and warp threads 42 in FIG. 2) may contain at least one of polyamide fibers and polyester fibers. By including at least one of polyamide fibers and polyester fibers in the fibers of the canvas 40 in this way, the rigidity of the tooth portion 20 is increased, and the skip torque is increased. In addition, the occurrence of chipped teeth can be suppressed.

The lower limit of the average fiber thickness of the canvas 40 is preferably 5 decitex, and more preferably 6 decitex. On the other hand, the upper limit of the average fiber thickness is preferably 200 decitex, and more preferably 150 decitex. If the average fiber thickness is less than the lower limit, the strength of the canvas 40 may be insufficient. Conversely, if the average fiber thickness exceeds the upper limit, the flexibility of the belt body 10 in the conveying direction may be insufficient, making it difficult to use, particularly in belt conveyors with small pulley diameters.

The lower limit of the porosity of the mesh of the canvas 40 is preferably 35%, more preferably 40%. On the other hand, the upper limit of the porosity is preferably 95%, more preferably 90%. If the porosity is less than the lower limit, when the toothed belt 1 is manufactured by extrusion molding, the canvas 40 may be easily moved due to the pressure when the composition mainly composed of the thermoplastic elastomer constituting the belt body 10 is injected, and the canvas 40 itself may be easily exposed to the surface of the belt body 10. On the other hand, by setting the porosity to be equal to or greater than the lower limit, when the composition is injected, the composition can pass through the voids 43 in the mesh of the canvas 40, so that the canvas 40 can be prevented from moving due to the pressure. Therefore, the exposure of the canvas 40 itself can be prevented. Conversely, if the void ratio exceeds the upper limit, the strength of the canvas 40 may be insufficient, and the canvas 40 may not be able to adequately support the multiple core cords 30 that are placed on and unwound from the canvas 40 when the toothed belt 1 is manufactured by extrusion molding. As a result, it may become difficult to control the embedding positions of the multiple core cords 30. The "porosity of the mesh" is a value calculated by dividing the total area of the geometric gaps (areas not occupied by threads in a plan view) observed from the surface of the canvas by the total area of the observed field of view.

It is preferable that the canvas 40 and the core cords 30 are spaced apart as shown in FIG. 4. By spaced apart the canvas 40 and the core cords 30 in this manner, wear caused by contact between the canvas 40 and the core cords 30 can be suppressed, thereby extending the life of the toothed belt 1.

The canvas 40 is not exposed. Therefore, the width of the canvas 40 is narrower than the width of the belt body 10. On the other hand, since the canvas 40 also supports the multiple core cords 30 that are placed on the canvas 40 and unwound when the toothed belt 1 is manufactured by extrusion molding, the width of the canvas 40 is wider than the width of the plane formed by the multiple core cords 30. In addition, both ends of the canvas 40 in the width direction are located outside both ends of the plane formed by the multiple core cords 30.

<Advantages>
In the toothed belt 1, the canvas 40 is located between the multiple core cords 30 and one surface of the belt body 10, so that the exposure of the multiple core cords 30 can be prevented. In addition, in the toothed belt 1, the canvas 40 itself is embedded in the belt body 10, so that the exposure of the canvas 40 can also be prevented. Furthermore, in the toothed belt 1, the main component of the belt body 10 is a thermoplastic elastomer, so that dust is unlikely to be generated from the core cords and the canvas, and the toothed belt 1 can be easily manufactured by extrusion molding.

[Method of manufacturing toothed belt]
A method for producing a toothed belt according to another embodiment of the present invention includes a feeding step S1, a covering step S2, and a tooth portion forming step S3, as shown in Fig. 5. By the method for producing a toothed belt, the toothed belt 1 shown in Figs. 1 to 4 can be produced.

<Maneuvering process>
In the unwinding step S1, a strip-shaped canvas 40 is unwound while a plurality of core cords 30 are placed on the upper surface of the strip-shaped canvas 40 at intervals in the width direction. The canvas 40 is in a mesh shape.

Specifically, while the canvas 40 is being unwound from a roll of canvas 40 prepared in advance, multiple core cords 30 are placed on the unwound canvas 40 while being passed through a crosshead attached to the tip of the cylinder of the extruder. This allows the multiple core cords 30 to be arranged at equal intervals in a flat plane.

<Coating process>
In the covering step S2, the canvas 40 on which the multiple core cords 30 are placed is covered from above and below by extrusion molding with a composition mainly composed of molten thermoplastic elastomer. In the covering step S2, the canvas 40 on which the multiple core cords 30 are placed is arranged so that the canvas 40 is on the lower side and the multiple core cords 30 are on the upper side. In the manufacturing method of the toothed belt, extrusion molding with a composition mainly composed of thermoplastic elastomer is used, so that the toothed belt can be easily made long.

This covering step S2 produces an extrusion molded body in which multiple core cords 30 and canvas 40 are embedded. This extrusion molded body, or a part of it, constitutes the belt body 10.

Since the canvas 40 is in a mesh shape, the composition passes through the mesh gaps 43 of the canvas 40 even when pressure is applied due to extrusion molding, preventing the canvas 40 from moving in the vertical direction. This prevents the canvas 40 from being exposed on the surface of the belt body 10.

In addition, the pressure of the extrusion molding from below causes the composition to pass through the gaps 43 in the mesh of the canvas 40 from below and push up the multiple core cords 30. This pushing up pressure lifts the multiple core cords 30, separating the canvas 40 from the multiple core cords 30. In addition, when the multiple core cords 30 are lifted, they are pushed up so that the pushing up pressure and the weight of the core cords 30 are balanced, so that the multiple core cords 30 are arranged in a plane and can be positioned so that the plane formed by the multiple core cords 30 is parallel to the other surface of the belt body 10. In other words, by using the manufacturing method for toothed belts, the multiple core cords 30 can be embedded in a suitable position in the belt body 10.

The lower limit of the melting temperature of the composition is preferably 170°C, more preferably 180°C. On the other hand, the upper limit of the melting temperature of the composition is preferably 210°C, more preferably 200°C. If the melting temperature of the composition is below the lower limit, the viscosity of the molten composition is high, and it may be difficult to embed the core cord 30 in a suitable position in the belt body 10. Conversely, if the melting temperature of the composition exceeds the upper limit, the viscosity of the molten composition is low, and extrusion molding may be difficult.

<Tooth forming process>
In the toothed portion forming step S3, the toothed portion 20 is formed on the extrusion molded body after the covering step S2, whereby the toothed belt 1 can be obtained.

Specifically, for example, a cylindrical mold roll having recesses on its outer circumferential surface corresponding to the teeth 20 is prepared, and the extrusion molded body is wrapped around the mold roll while one side of the body is heated, thereby forming the teeth 20.

Alternatively, the teeth portion 20 may be formed by melt-bonding the teeth portion 20 to the extrusion molded body.

<Advantages>
In this manufacturing method for a toothed belt, the positions of the multiple core cords 30 in the thickness direction of the belt body 10 can be adjusted by supporting the multiple core cords 30 with the canvas 40. Furthermore, in this manufacturing method for a toothed belt, since the canvas 40 is mesh-shaped, a composition mainly composed of a molten thermoplastic elastomer passes through the mesh of the canvas 40 during extrusion molding, preventing the canvas 40 itself from being extruded and exposed from the belt body 10. Therefore, by using this manufacturing method for a toothed belt, a toothed belt in which the exposure of the core cords 30 and the canvas 40 is prevented by extrusion molding can be easily manufactured.

[Other embodiments]
The present invention is not limited to the above-described embodiment, and can be embodied in various other forms in addition to the above-described forms with various modifications and improvements.

In the above embodiment, the belt body is configured not to have a recess on the bottom surface between the teeth, but the belt body may have a recess on the bottom surface between the teeth depending on the meshing with the pulley, etc. In this case, the recess is provided so that the canvas and the multiple core cords are not exposed.

In the above embodiment, the canvas is described as being mesh-like, but it is also possible to use canvas that is not mesh-like, i.e., canvas that is tightly woven and has no voids.

In the above embodiment, a method for manufacturing the toothed belt of the present invention by extrusion molding has been described, but the toothed belt can also be manufactured by other methods. The toothed belt can also be manufactured by, for example, the following manufacturing method. An inner mold having a recess corresponding to the tooth portion and an outer mold arranged outside the inner mold and spaced apart from the outer diameter of the inner mold by the thickness of the belt body are prepared. A canvas 40 on which multiple core cords 30 are placed is sandwiched between the inner mold and the outer side so that the canvas 40 faces the inner mold, and a composition mainly composed of molten thermoplastic elastomer is poured between the inner mold and the outer side and pressurized to obtain the toothed belt.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]
Using steel cords as core cords, mesh-like canvas with a void ratio of 80%, and a composition mainly composed of a thermoplastic elastomer, the toothed belt of Example 1 was produced by extrusion molding according to the above-mentioned method for producing a toothed belt of the present invention. Note that, in the method for producing the toothed belt of Example 1, no protrusions (hereinafter simply referred to as "protrusion supports") for supporting the core cords were used.

[Example 2]
A toothed belt of Example 2 was produced in the same manner as in Example 1, except that an aramid cord was used as the core cord.

[Comparative Example 1 and Comparative Example 2]
The toothed belts of Comparative Example 1 and Comparative Example 2 were manufactured in the same manner as in Example 1 and Example 2, respectively, except that the toothed belts were manufactured without using canvas and with the core cord supported by protruding supports. Since the toothed belts of Comparative Example 1 and Comparative Example 2 use protruding supports, exposure of the core cord was observed in the recesses of the belt body formed by these protruding supports. In other words, in these toothed belts, the core cord is not embedded in the belt body.

[Comparative Example 3]
The toothed belt of Comparative Example 3 was manufactured in the same manner as Example 1, except that a non-mesh canvas (void ratio 0%) was used and the canvas was supported by protruding supports to manufacture the toothed belt. Since the toothed belt of Comparative Example 3 uses protruding supports, exposure of the canvas was observed in the recesses of the belt body formed by these protruding supports. In other words, in this toothed belt, the canvas is not embedded in the belt body.

[Comparative Example 4]
The toothed belt of Comparative Example 4 was manufactured by seamless molding using a steel cord as the core cord and a composition mainly composed of a thermosetting elastomer. The toothed belt of Comparative Example 4 did not use canvas. In addition, because a protruding support was used, the core cord was exposed in the recessed portion of the belt body formed by the protruding support. In other words, in this toothed belt, the core cord was not embedded in the belt body.

[evaluation]
The following evaluations were carried out on the toothed belts of Examples 1 and 2 and Comparative Examples 1 to 4. The results are shown in Table 1.

(Dust generation)
All of the toothed belts were actually used and the presence or absence of dust generation from the core cord and canvas, which is particularly important for food applications, was judged by visual inspection.

(spark)
The occurrence of sparks was judged for Example 1, Comparative Example 1, Comparative Example 3, and Comparative Example 4, which used steel cords. Specifically, a current of 0.2 A or more and 0.3 A or less was passed through the steel cord, and the occurrence of sparks was visually confirmed.

(Flexural fatigue resistance)
All toothed belts were judged for flex fatigue. Specifically, when the core wire constituting the core cord was arc-shaped (no bends) based on the state of winding the toothed belt around the pulley in use, it was judged that the flex fatigue was high ("high" in Table 1), and when it was polygonal (bends were present), it was judged that the flex fatigue was low ("low" in Table 1). The judgment was made by observing the shape of the core cord of the toothed belt from the outside, either visually or using a microscope.

In Table 1, "-" in the porosity and canvas exposure columns means that canvas is not present. "-" in the spark column means that it is not subject to evaluation. Additionally, the "Long Specification" column in Table 1 indicates whether or not a long belt can be manufactured using the belt specifications and manufacturing method of each example and comparative example, with "Yes" meaning that a long belt can be manufactured and "No" meaning that a long belt cannot be manufactured.

The results in Table 1 show that in the toothed belts of Examples 1 and 2, in which the main component of the belt body is a thermoplastic elastomer and the core cord and canvas are embedded in the belt body, exposure of the embedded components is suppressed, and dust generation and spark generation in the conductive cord can be reduced.

On the other hand, the toothed belts of Comparative Examples 1 to 4 use protruding supports, which result in exposure of the core cord or canvas, and dust generation in these toothed belts. In addition, sparks are observed in Comparative Examples 1, 2, and 4, which use conductive steel cords. Furthermore, the toothed belt of Comparative Example 4 is made of a thermosetting material as the main component of the belt body, and is manufactured by seamless molding, making it impossible to manufacture a long toothed belt.

The toothed belt of the present invention is easy to manufacture and can prevent the exposure of components embedded in the toothed belt, such as the core cord. Furthermore, by using the manufacturing method of the toothed belt of the present invention, a toothed belt that prevents the exposure of components embedded in the toothed belt, such as the core cord, can be easily manufactured.

REFERENCE SIGNS LIST 1 toothed belt 10 belt body 20 tooth portion 30 core cord 40 canvas 41 weft thread 42 warp thread 43 gap

Claims (1)

A step of unwinding a strip of canvas while placing a plurality of core cords on an upper surface of the strip at intervals in the width direction;
and a step of covering the canvas on which the plurality of core cords are placed from above and below by extrusion molding with a composition mainly composed of a molten thermoplastic elastomer so that the canvas is not exposed.
A method for manufacturing a toothed belt, wherein the canvas is in a mesh form.

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