JP7604153B2 - Toothed belt - Google Patents

Description

The present invention relates to 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.

The toothed belt can be configured as an endless belt with no end, or an open belt with both ends. Of these, the toothed belt with an open belt configuration is fixed to a cart, for example, so that its teeth can fit into a toothed pulley, and is used to move the cart up and down or left and right by rotating and driving the toothed pulley.

Some of the above-mentioned trolleys are equipped with stoppers to prevent the loaded cargo from slipping off the trolley. These stoppers may be electrically controlled so that they can be stored so as not to cause an obstacle when loading or unloading cargo onto the trolley. In this way, trolleys often have additional functions that are electrically controlled.

A toothed belt has been proposed in which the wiring for electrical signals and power sources (hereinafter simply referred to as "wiring") that control these additional functions is also used as a core cord (see JP 2019-60403 A). In this toothed belt, the core cord is made of a material that can conduct electricity, so it also doubles as a power supply cable, making it possible to embed the wiring within the toothed belt while preventing an increase in the thickness of the toothed belt.

JP 2019-60403 A

When the core cord of a toothed belt is also used as wiring, the number of core cords is determined by the greater of the number determined by the strength required for the toothed belt and the number of required wirings. For this reason, if the number of wirings is large, the number of core cords is determined by the number of wirings, and the width of the toothed belt tends to become unnecessarily large. If the width of the toothed belt becomes unnecessarily large, it may be difficult to reduce the size of the device incorporating this toothed belt, such as a cart.

The present invention was made in consideration of these inconveniences, and aims to provide a toothed belt that can prevent an increase in width while ensuring the number of core cords required for wiring electrical signals and power sources.

The toothed belt 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, and 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, the plurality of core cords including a conductive current-carrying core cord and a reinforcing core cord having a higher electrical resistance per unit length than the current-carrying core cord.

In this toothed belt, the electrical resistance per unit length of the current-carrying core cord is lower than that of the reinforcing core cord, so the number of parallel current-carrying core cords required to ensure the electrical resistance required for current flow can be reduced. Furthermore, the strength of this toothed belt can be maintained mainly by the reinforcing core cord. Therefore, the number of core cords required can be reduced, and an increase in width can be prevented while ensuring the number of core cords required for wiring electrical signals and power sources.

It is preferable that the material of the electric core cord is different from the material of the reinforcing core cord. By making the material of the electric core cord different from the material of the reinforcing core cord in this way, it is possible to use an electric core cord with a low electrical resistivity, which makes it easier to reduce the number of parallel electric core cords to ensure the required electrical resistance.

It is preferable that the average diameter of the electric core cord is larger than the average diameter of the reinforcing core cord. By making the average diameter of the electric core cord larger than the average diameter of the reinforcing core cord in this way, the electrical resistance per unit length of the electric core cord can be easily reduced.

The two core cords located on the outermost sides in the width direction are preferably reinforcing core cords. The electrical resistance of the two core cords located on the outermost sides in the width direction may increase over time due to wear caused by friction from the sides of the toothed belt. For this reason, the two core cords located on the outermost sides in the width direction are reinforcing core cords, and are not used for wiring for electrical signals or power, thereby improving the reliability of the wiring.

The plurality of core cords may include a plurality of the above-mentioned conductive core cords, and the above-mentioned reinforcing core cord may be disposed between adjacent conductive core cords. By disposing the above-mentioned reinforcing core cords between adjacent conductive core cords in this manner, it is possible to prevent a local decrease in the strength of the toothed belt.

As explained above, this toothed belt can prevent an increase in width while ensuring the number of core cords required for wiring electrical signals and power sources.

1 is a schematic perspective view showing a toothed belt according to an embodiment of the present invention; 2 is a schematic cross-sectional view of the toothed belt of FIG. 1 taken along line AA. 2 is a schematic cross-sectional view of the toothed belt of FIG. 1 taken along line BB. FIG. 4 is a schematic cross-sectional view showing a toothed belt different from that shown in FIG. 3 . FIG. 5 is a schematic cross-sectional view showing a toothed belt different from that shown in FIGS. 3 and 4.

One embodiment of the present invention will be described in detail below with reference to the drawings as appropriate.

The toothed belt 1 shown in Figures 1, 2, and 3 comprises a belt body 10, a plurality of teeth 20 arranged at equal intervals in the longitudinal direction on one side of the belt body 10, and nine core cords 30 embedded in the belt body 10 along the longitudinal direction.

<Belt body>
The main component of the belt body 10 is rubber or resin. Examples of the rubber include ethylene-α-olefin elastomers such as ethylene-propylene rubber (EPR) and ethylene propylene diene monomer rubber (EPDM), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), and hydrogenated nitrile rubber (H-NBR). The rubber may be one of these, or may be a blend of two or more of these. Examples of the resin include thermoplastic polyester, polyamide, and polyurethane. The main component of the belt body 10 is preferably a resin from the viewpoint of low dust generation, and among these, thermoplastic urethane, which has excellent abrasion resistance, is preferable. Here, the term "main component" refers to the component with the highest content, and preferably refers to a component with a content of 50% by mass or more, and more preferably 90% by mass or more.

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 10 mm or less.

The length of the belt body 10 is determined appropriately depending on the application of the toothed belt 1. The toothed belt 1 is mainly used 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 of a trapezoid, a triangle, a semicircle, a mountain shape, a wave shape, a normal distribution curve shape, 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 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 nine core cords 30 are linear bodies having a circular cross section, and are arranged in the width direction of the belt body 10 as shown in FIG.

The nine core cords 30 include four conductive current-carrying core cords 31 and five reinforcing core cords 32 that have a higher electrical resistance per unit length than the current-carrying core cords 31.

(Material)
Examples of materials for the conductive core cord 31 include steel and copper. Among them, copper, which has a low electrical resistivity, is preferable.

The current-carrying core cord 31 can also be made of a conductor such as steel or copper, covered with an insulating layer. By covering it with an insulating layer in this way, even if it comes into contact with an adjacent core cord 30, the electrical signal or power supply function of the current-carrying core cord 31 is less likely to be affected. The main component of the insulating layer can be, for example, ethylene-tetrafluoroethylene copolymer (ETFE).

The reinforcing core cord 32 may be conductive as long as it has a higher electrical resistance per unit length than the current-carrying core cord 31, but it is preferable for the reinforcing core cord 32 to be insulating. By making the reinforcing core cord 32 insulating, even if it comes into contact with the current-carrying core cord 31, the electrical signal of the current-carrying core cord 31 or its function as a power source is unlikely to be affected. Therefore, it is possible to narrow the gap between the current-carrying core cord 31 and the reinforcing core cord 32, making it easier to prevent an increase in the width of the toothed belt 1.

Examples of the material for the conductive reinforcing core cord 32 include the same material as the conductive core cord 31. Examples of the material for the insulating reinforcing core cord 32 include aramid, glass, polyester, etc.

Although the material of the current-carrying core cord 31 and the material of the reinforcing core cord 32 can be the same, it is preferable that the material of the current-carrying core cord 31 is different from the material of the reinforcing core cord 32. By making the material of the current-carrying core cord 31 different from the material of the reinforcing core cord 32 in this way, it is possible to use a material with low electrical resistivity as the current-carrying core cord 31, making it easier to reduce the number of parallel current-carrying core cords 31 to ensure the required electrical resistance. In particular, it is preferable that the material of the current-carrying core cord 31 is copper, which has low electrical resistivity, and the material of the reinforcing core cord 32 is aramid, which has insulating properties.

In addition, when both the conductive core cord 31 and the reinforcing core cord 32 are conductive, it is preferable that the conductive core cord 31 is a copper cord that is a copper wire covered with an insulating layer, and the reinforcing core cord 32 is a steel cord that has a steel wire.

Copper has low electrical resistance per unit length and is suitable for electrical current applications. On the other hand, copper wire is easily bent, so by using a copper cord coated with an insulating layer, it is possible to prevent defects such as wire breakage. In addition, steel cords have high rigidity and can maintain their strength even if they have a small diameter. This steel cord can be configured without a coating layer. Since the copper cord that is the electrical current core cord 31 has an insulating layer that covers the periphery, even if a steel cord without a coating layer comes into contact with the electrical current core cord 31, the electrical signal or power supply function of the electrical current core cord 31 is unlikely to be affected. In this way, the steel cord does not need to be provided with an insulating layer and can be made small in diameter, so it does not require any space in the width direction. Therefore, by using a steel cord as the reinforcing core cord 32, it is possible to maintain the strength of the toothed belt while ensuring a wide area for the electrical current core cord 31. From the above, by making the current-carrying core cord 31 a copper cord coated with an insulating layer and the reinforcing core cord 32 a steel cord, it is possible to further suppress an increase in the width of the toothed bell while ensuring the number of core cords required for wiring electrical signals and power sources.

The main component of the insulating layer of the copper cord is preferably ethylene-tetrafluoroethylene copolymer (ETFE).

In addition, one or both of the copper wires of the copper cord and the steel wires of the steel cord may be twisted wires.

(Average diameter)
The lower limit of the average diameter of the electric core cord 31 is preferably 0.2 mm, more preferably 0.5 mm, and even more preferably 1 mm. On the other hand, the upper limit of the average diameter of the electric core cord 31 is preferably 2.5 mm, and more preferably 1.5 mm. If the average diameter of the electric core cord 31 is less than the lower limit, the electric resistance of the electric core cord 31 is not sufficiently reduced, and the electric core cord 31 may not fully function as an electric signal or power source. On the other hand, if the average diameter of the electric core cord 31 exceeds the upper limit, the width of the toothed belt 1 may become too large.

The lower limit of the average diameter of the reinforcing core cord 32 is preferably 0.1 mm, more preferably 0.2 mm, and even more preferably 0.5 mm. On the other hand, the upper limit of the average diameter of the reinforcing core cord 32 is preferably 2 mm, and more preferably 1 mm. If the average diameter of the reinforcing core cord 32 is less than the above lower limit, the strength of the reinforcing core cord 32 may be insufficient. Conversely, if the average diameter of the reinforcing core cord 32 exceeds the above upper limit, the width of the toothed belt 1 may become too large.

The average diameter of the conductive core cord 31 is preferably larger than the average diameter of the reinforcing core cord 32. By making the average diameter of the conductive core cord 31 larger than the average diameter of the reinforcing core cord 32 in this way, the electrical resistance per unit length of the conductive core cord 31 can be easily reduced. In particular, when the material of the conductive core cord 31 and the material of the reinforcing core cord 32 are the same, it is possible to reduce the electrical resistance per unit length by making the average diameter of the conductive core cord 31 larger than the average diameter of the reinforcing core cord 32.

(array)
As shown in Fig. 3, the nine core cords 30 (four conductive core cords 31 and five reinforcing core cords 32) are arranged so that the shortest distance from one surface of the belt body 10 (the surface on which the teeth 20 are arranged) to the outer periphery of the core cords 30 is constant. By arranging them in this manner, the belt body 10 can be easily manufactured by extrusion molding while supporting the nine core cords 30 from below.

It is preferable that the two core cords 30 positioned on the outermost side in the width direction of the toothed belt 1 are reinforcing core cords 32. The electrical resistance of the two core cords 30 positioned on the outermost side in the width direction may increase over time due to wear caused by friction from the side of the toothed belt 1. For this reason, the two core cords 30 positioned on the outermost side in the width direction are reinforcing core cords 32, and are not used for wiring for electrical signals or power, thereby improving the reliability of the wiring.

The lower limit of the average distance between the central axis of the outermost reinforcing core cord 32 and the side of the belt body 10 adjacent thereto (also referred to as the "average distance between the reinforcing core cord 32 and the side of the belt body 10") is preferably 0.3 mm, more preferably 0.5 mm. On the other hand, the upper limit of the average distance between the reinforcing core cord 32 and the side of the belt body 10 is preferably 1 mm, more preferably 0.7 mm. If the average distance between the reinforcing core cord 32 and the side of the belt body 10 is less than the lower limit, there is a risk that the outermost reinforcing core cord 32 will be exposed from the side of the belt body 10 during the manufacture of the toothed belt 1. Conversely, if the average distance between the reinforcing core cord 32 and the side of the belt body 10 exceeds the upper limit, the side edge of the belt body 10 will be prone to flapping when driven, and the effect of improving the accuracy of driving by the core cord 30 may be insufficient.

It is also preferable that a reinforcing core cord 32 is arranged between adjacent conductive core cords 31. By arranging the reinforcing core cord 32 between adjacent conductive core cords 31 in this manner, it is possible to prevent the strength of the toothed belt 1 from being reduced locally.

In other words, as shown in FIG. 3, the four conductive core cords 31 and the five reinforcing core cords 32 are arranged alternately from the outside in the width direction in the order of reinforcing core cords 32, conductive core cords 31. By arranging them in this way, it becomes easier to narrow the spacing between the core cords 30, especially when the five reinforcing core cords 32 are insulating.

The lower limit of the average spacing between adjacent core cords 30 (the distance in the width direction of the toothed belt 1 between the central axes of the core cords 30) is preferably 0.3 mm, more preferably 0.5 mm. On the other hand, the upper limit of the average spacing is preferably 4 mm, more preferably 1 mm. If the average spacing is less than the lower limit, there is a risk that the insulation between the multiple current-carrying core cords 31 may not be sufficiently ensured, or the flexibility of the toothed belt 1 may be insufficient. Conversely, if the average spacing exceeds the upper limit, there is a risk that the toothed belt 1 may become unnecessarily large in the width direction, or the effect of the core cords 30 in improving the strength, durability, driving accuracy, etc. of the toothed belt 1 may be insufficient.

<Method of Manufacturing Toothed Belt>
The toothed belt 1 can be manufactured by a manufacturing method including, for example, an extrusion molding step and a tooth portion forming step.

(Extrusion molding process)
In the extrusion molding step, an extrusion molded body containing a rubber or resin composition as a main component and having the core cord 30 embedded therein is formed by extrusion molding.

Specifically, the multiple core cords 30 are inserted through a crosshead attached to the tip of the cylinder of the extruder, and extruded so that both sides are covered with molten rubber or resin composition. Alternatively, the multiple core cords 30 may be embedded in the rubber or resin composition by sandwiching the molten extruded rubber or resin composition and the multiple core cords 30 between a pair of rolls and applying pressure.

The heating temperature for melting the rubber or resin composition in extrusion molding depends on the type of rubber or resin, whether a curing agent is used, etc., but the lower limit of the heating temperature is preferably 150°C. On the other hand, the upper limit of the heating temperature is preferably 250°C. If the heating temperature is below the lower limit, the rubber or resin composition may not melt sufficiently, making extrusion molding difficult. Conversely, if the heating temperature exceeds the upper limit, the extrusion molded body becomes unnecessarily hot, which may result in an unnecessarily long cooling time and a decrease in the manufacturing efficiency of the toothed belt 1.

(Tooth forming process)
In the toothed portion forming step, the toothed portion 20 is formed on the extrusion molded body after the extrusion molding step, 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.

The heating temperature in the tooth portion forming process is appropriately determined according to the temperature at which the extrusion molded body can melt and form the tooth portion 20 on one side, but the lower limit of the heating temperature is preferably 150°C. On the other hand, the upper limit of the heating temperature is preferably 250°C. If the heating temperature is below the lower limit, the extrusion molded body may not be softened sufficiently, making it difficult to form the tooth portion 20. Conversely, if the heating temperature exceeds the upper limit, the entire toothed belt 1 may be easily deformed by heat.

<Advantages>
In the toothed belt 1, the electrical resistance per unit length of the current-carrying core cord 31 is lower than that of the reinforcing core cord 32, so that the number of parallel current-carrying core cords 31 required to ensure the electrical resistance required for current flow can be reduced. Furthermore, the toothed belt 1 can maintain its strength mainly through the reinforcing core cord 32. Therefore, the toothed belt 1 can reduce the number of necessary core cords, and therefore can suppress an increase in width while ensuring the number of core cords 30 required for wiring electrical signals and power.

[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 reinforcing core cords 32 and the conductive core cords 31 are alternately arranged in this order from the outside in the width direction, but the arrangement of the conductive core cords 31 and the reinforcing core cords 32 is not limited to this. Several modified examples are described below. Note that components in each modified example that are similar to those in the toothed belt 1 shown in Figure 3 are given the same reference numerals and detailed description is omitted.

<Modification 1>
The toothed belt 2 shown in Figure 4 has 10 core cords 30, each of which has four conductive conductive core cords 31 and six reinforcing core cords 32 having a higher electrical resistance per unit length than the conductive core cords 31.

In this toothed belt 2, the same number (three on each side) of reinforcing core cords 32 are arranged on both sides in the width direction, and all (four) of the conductive core cords 31 are gathered in the center.

When the average diameter of the conductive core cords 31 is made larger than the average diameter of the reinforcing core cords 32, arranging these two types of core cords 30 alternately may cause unevenness to easily occur on the surface of the belt body 10 due to the difference in average diameter. By arranging the conductive core cords 31 together in the center in this way, it is possible to make it less likely that the above-mentioned unevenness will occur.

In addition, when the current-carrying core cords 31 are arranged continuously as in the toothed belt 2, it is preferable that the current-carrying core cords 31 have an insulating layer covering the periphery of the conductor.

<Modification 2>
The toothed belt 3 shown in Figure 5 has 11 core cords 30, each of which has four conductive conductive core cords 31 and seven reinforcing core cords 32 having a higher electrical resistance per unit length than the conductive core cords 31.

In the toothed belt 3, two conductive core cords 31 run parallel to each other, three reinforcing core cords 32 are arranged between them, and two reinforcing core cords 32 are arranged on each side in the width direction.

This type of configuration is useful, for example, when two parallel current-carrying core cords 31 are used as the same electrical signal or power source. In addition, by distributing multiple reinforcing core cords 32, it is easier to ensure the strength of the toothed belt 3.

＜Other＞
In the above embodiments, a specific number of core cords are provided, but the number of core cords is not limited to the number in each embodiment as long as it is three or more.

In addition, the arrangement pattern of the conductive core cord and the reinforcing core cord is not limited to the above-mentioned embodiment, but can be selected appropriately according to the wiring of the required electrical signal or power supply.

In the above embodiment, the case where the current-carrying core cord is used as wiring for electrical signals or power and the reinforcing core cord is used for reinforcement is described, but there may be current-carrying core cords that are not used as wiring, and conversely, there may be reinforcing core cords that are used as wiring.

The toothed belt of the present invention can prevent an increase in width while ensuring the number of core cords required for wiring electrical signals and power sources.

1, 2, 3: toothed belt 10: belt body 20: tooth portion 30: core cord 31: current-carrying core cord 32: reinforcing core cord

Claims (4)

The belt body,
A plurality of teeth are disposed on one surface of the belt body at equal intervals in the longitudinal direction;
a plurality of core cords spaced apart in a width direction of the belt body and embedded in the belt body along the length direction,
The plurality of core cords are
A conductive core cord;
and a reinforcing core cord having a higher electrical resistance per unit length than the conductive core cord,
A toothed belt in which the average diameter of the current-carrying core cords is larger than the average diameter of the reinforcing core cords. 2. The toothed belt according to claim 1, wherein the same number of said reinforcing core cords are arranged on both sides in the width direction, and all of said conductive core cords are gathered in the center . 2. The toothed belt according to claim 1 , wherein the two core cords positioned on the outermost sides in the width direction are reinforcing core cords. The plurality of core cords include a plurality of the conductive core cords,
4. The toothed belt according to claim 1, wherein the reinforcing core cord is disposed between adjacent conductive core cords.

Images