Belt

Abstract

A belt according to one embodiment of the present invention is provided with: a belt body in which the main component is an elastomer; and a plurality of core wires embedded in the belt body along the length direction such that there is an interval therebetween in the width direction of the belt body. Some or all of the core wires are hybrid core wires constituted of a plurality of wires having two or more different materials. Among the plurality of wires, the total cross-sectional area of low-resistance wires having an electrical resistivity less than the electrical resistivity of the core wires is 5 to 80% of the cross-sectional area of the hybrid core wires, and among the plurality of wires, high-resistance wires having an electrical resistivity equal to or greater than that of the electrical resistivity of the core wires and a breaking strength higher than the breaking strength of the low-resistance wires surround the low-resistance wires in a cross-sectional view.

Description

Belt

[0001] The present invention relates to a belt.

[0002] In factories, warehouses, etc., belts may be used for lifting and transporting articles. In this case, for example, a cart is fixed to the belt by a screw through a through hole opened in the belt, and the cart is moved up and down or left and right by rotating a pulley that drives the belt. The article is placed on the cart and lifted or transported.

[0003] Some carts are equipped with a stopper so that the loaded goods do not slip off the cart. This stopper may be electrically controlled so that it can be stored when loading or unloading the cart so as not to be an obstacle. Thus, it is not uncommon for carts to be equipped with additional functions controlled by electricity.

[0004] A belt that also serves as a core wire has been proposed for controlling electrical signals and power wiring (hereinafter simply referred to as "wiring") for such additional functions (see Japanese Patent Application Laid-Open No. 2019-60403). In this belt, by using a material that can conduct electricity through the core wire, it also serves as a power supply cable, so that the wiring can be embedded in the belt while suppressing an increase in the thickness of the belt.

[0005] Japanese Patent Application Laid-Open No. 2019-60403

[0006] When the belt is wound around a pulley, for example, it bends, and when unwound, it stretches. Thus, the belt repeats bending and stretching, and accordingly, the core wire that performs the energization function also repeats bending and stretching.

[0007] From the perspective of the energization function, a core wire with low resistance is preferable, and for example, a copper wire is suitable. However, if a copper wire is adopted, there is a risk that the low resistance cannot be maintained due to bending fatigue caused by repeated bending and stretching.

[0008] The present invention has been made in view of such inconveniences, and an object thereof is to provide a belt provided with a core wire having low resistance and excellent bending fatigue resistance.

[0009] A belt according to one embodiment of the present invention comprises a belt body whose main component is elastomer, and a plurality of core wires embedded in the belt body along its length at intervals in the width direction of the belt body, wherein part or all of the core wires are hybrid core wires composed of a plurality of wires of two or more different materials, the total cross-sectional area of ​​the low-resistance wires, whose electrical resistivity is less than the electrical resistivity of the core wire, is 5% to 80% of the cross-sectional area of ​​the hybrid core wire, and the high-resistance wires, whose electrical resistivity is equal to or greater than the electrical resistivity of the core wire and whose breaking strength is higher than the breaking strength of the low-resistance wires, surround the low-resistance wires in cross-section.

[0010] The belt of the present invention is equipped with a core wire that has low resistance and excellent bending fatigue resistance.

[0011] Figure 1 is a schematic perspective view showing a belt according to one embodiment of the present invention. Figure 2 is a schematic cross-sectional view of the belt in Figure 1 along line A-A. Figure 3 is a schematic cross-sectional view of the belt in Figure 1 along line B-B. Figure 4 is a schematic cross-sectional view showing an example of the configuration of the hybrid core wires of the belt in Figure 1. Figure 5 is a schematic cross-sectional view showing an example of the configuration of the hybrid core wires different from that in Figure 4. Figure 6 is a schematic perspective view showing a belt according to a different embodiment from that of the belt in Figure 1. Figure 7 is a schematic cross-sectional view showing the No. 1 core wire arrangement in the embodiment. Figure 8 is a schematic cross-sectional view showing the configuration of the No. 1 reinforcing core wire in the embodiment. Figure 9 is a schematic side view showing the configuration of the bending fatigue resistance measuring device in the embodiment. Figure 10 is a graph showing the results of the resistance change of the hybrid core wires in the embodiment. Figure 11 is a graph showing the results of the resistance change of the reinforcing core wires in the embodiment. Figure 12 is a schematic cross-sectional view showing an example in which high-resistance wires surround low-resistance wires. Figure 13 is a schematic cross-sectional view showing an example where high-resistance wires do not surround low-resistance wires.

[0012] [Description of Embodiments of the Invention] First, embodiments of the present invention will be listed and described.

[0013] (1) A belt according to one embodiment of the present invention comprises a belt body whose main component is elastomer, and a plurality of core wires embedded in the belt body along its length at intervals in the width direction of the belt body, wherein part or all of the core wires are hybrid core wires composed of a plurality of wires of two or more different materials, the total cross-sectional area of ​​the low-resistance wires, whose electrical resistivity is less than the electrical resistivity of the core wire, is 5% to 80% of the cross-sectional area of ​​the hybrid core wire, and the high-resistance wires, whose electrical resistivity is equal to or greater than the electrical resistivity of the core wire and whose breaking strength is higher than the breaking strength of the low-resistance wires, surround the low-resistance wires in cross-section.

[0014] The belt in question is a hybrid core wire in which part or all of the core wire is covered with a high-resistance wire that covers a low-resistance wire. In this hybrid core wire, the relatively high-strength high-resistance wire that covers the low-resistance wire protects the low-resistance wire, thereby improving the bending fatigue resistance of the low-resistance wire. Furthermore, by keeping the total cross-sectional area of ​​the low-resistance wire within the range specified above relative to the cross-sectional area of ​​the hybrid core wire, the electrical resistance of the hybrid core wire can be kept low, making the hybrid core wire low-resistance and highly resistant to bending fatigue. In addition, by making the main component of the belt body an elastomer, the wear resistance of the elastomer suppresses belt wear and prevents electrical short circuits caused by exposed core wires.

[0015] (2) In the belt described in (1) above, the total cross-sectional area of ​​the low-resistance wires is preferably 10% to 50% of the cross-sectional area of ​​the hybrid core wires. By keeping the total cross-sectional area of ​​the low-resistance wires within this range, it is possible to further reduce resistance while maintaining bending fatigue resistance.

[0016] (3) In the belt described in (1) or (2) above, the low-resistance wire is preferably a single-strand stranded wire, and the number of strands in the single-strand stranded wire is 1 x 3 strands or more and 1 x 50 strands or less. By using such a single-strand stranded wire, the bending fatigue resistance of the low-resistance wire can be improved.

[0017] (4) In the belt of (1) or (2) above, the low-resistance wire is a multi-stranded wire, and the number of strands of the multi-stranded wire is preferably 3 x 3 strands or more and 3 x 20 strands or less, 5 x 3 strands or more and 5 x 20 strands or less, or 7 x 3 strands or more and 7 x 20 strands or less. By using such a multi-stranded wire, it is possible to increase the cross-sectional area of ​​the low-resistance wire and lower the resistance value of the low-resistance wire while increasing the bending fatigue resistance.

[0018] (5) In any of the belts described in (1) to (4) above, it is preferable that some or all of the hybrid core wires have a connector at least on one end. By providing a connector at least on one end of some or all of the hybrid core wires in this way, they can be suitably used as core wires that perform the electrical function.

[0019] Here, "main component" refers to the component with the highest content, preferably with a content of 50% by mass or more, more preferably with a content of 90% by mass or more. The "electrical resistivity" ρ of the hybrid core wire is given by the resistance value of the hybrid core wire R (Ω) and the cross-sectional area S (cm²). ２ ), when the length is L (cm), it is a quantity expressed as ρ (Ω・cm) = R × S / L.

[0020] Furthermore, the statement "high-resistance wires surround low-resistance wires in cross-section" refers to the following state: In cross-sectional view, for all low-resistance wires, for every straight line passing through its centroid, there exists a pair of high-resistance wires on both sides of the centroid of the low-resistance wire, such that the line segment (including the centroid) connecting the centroids intersects the straight line. For example, in the hybrid core wire 20x shown in Figure 12, for every straight line L passing through the centroid G1 of the low-resistance wire 21, there exists a pair of high-resistance wires 22 on both sides of the centroid G1 of the low-resistance wire 21, such that the line segment M connecting the centroids G2 intersects the straight line L. Therefore, it can be said that the high-resistance wires 22 surround the low-resistance wire 21 in cross-section. On the other hand, in the hybrid core wire 20y shown in Figure 13, in the straight line L shown in Figure 13, there are no pairs of high-resistance wires 22 on the upper side of the drawing relative to the centroid G1 of the low-resistance wire 21, where the line segment M connecting the centroids G2 intersects the straight line L. In other words, in the hybrid core wire 20y shown in Figure 13, in the straight line L, there are high-resistance wires 22 on only one side of the drawing relative to the centroid G1 of the low-resistance wire 21, where the line segment M connecting the centroids G2 intersects the straight line L. Therefore, it can be said that in the hybrid core wire 20y, the high-resistance wires are not surrounded by the low-resistance wires in cross-sectional view.

[0021] "Breaking strength" refers to the breaking strength measured by a tensile test. Furthermore, if multiple types of low-resistance wires exist, "its breaking strength is higher than the breaking strength of the low-resistance wires" means that its breaking strength is higher than the breaking strength of the low-resistance wire with the highest breaking strength.

[0022] [Details of Embodiments of the Invention] A belt according to one embodiment of the present invention will be described with reference to the drawings.

[0023] [First Embodiment] The belt 1 shown in Figures 1, 2, and 3 comprises a belt body 10, a plurality of core wires 20, and a cover layer 30. The belt 1 is a flat belt. The belt 1 can be suitably used as a flat belt that requires an electrical conductivity function.

[0024] Furthermore, the belt body 10 has one or more (three in Figure 1) belt holes 11 that penetrate in the thickness direction, and the core wire 20 is embedded in the belt body 10 along the length direction with spacing in the width direction of the belt body 10.

[0025] <Belt Body> The main component of the belt body 10 is elastomer. By making the main component of the belt body 10 elastomer, the wear resistance of the elastomer suppresses belt wear and prevents electrical short circuits caused by exposed core wires.

[0026] The above-mentioned elastomer may be a thermoplastic elastomer, a thermosetting elastomer, or rubber, but a thermoplastic elastomer is preferred. By making the main component of the belt body 10 a thermoplastic elastomer, dust generation is reduced, which is advantageous as it can be used in applications where cleanliness is required, and it also has excellent recyclability. Examples of the above-mentioned thermoplastic elastomer include ethylene-α-olefin-based elastomers, thermoplastic polyurethanes, polyamide-based elastomers, and polyester-based elastomers. Among these, thermoplastic polyurethanes, polyamide-based elastomers, and polyester-based thermoplastic elastomers are preferred. Thermoplastic polyurethanes have low dust generation and excellent abrasion resistance. Polyamide-based elastomers have excellent oil resistance, chemical resistance, and abrasion resistance. Polyester-based elastomers have excellent water resistance, low-temperature flexibility, strength, and fatigue resistance.

[0027] Furthermore, the elastomer is preferably a flame-retardant material. The elastomer can be made flame-retardant by adding an appropriate amount of flame retardant. By making the elastomer a flame-retardant material in this way, ignition of the belt body 10 due to electrical leakage, etc., can be reliably suppressed.

[0028] The average thickness of the belt body 10 is determined appropriately based on the required strength of the belt 1, but can be, for example, 1 mm or more and 10 mm or less. Here, "average" refers to the average value of measurements taken at any 10 points. The same applies to all "averages" below.

[0029] The width and length of the belt body 10 are determined appropriately according to the intended use of the belt 1. The belt 1 is primarily used as an open belt with both ends.

[0030] The lower limit of the JIS-A hardness of the belt body 10 is preferably 60, and more preferably 70. On the other hand, the upper limit of the JIS-A hardness of the belt body 10 is preferably 98, and more preferably 90. If the JIS-A hardness of the belt body 10 is below the lower limit, the strength of the belt body 10, and consequently the strength of the belt 1, may be insufficient. Conversely, if the JIS-A hardness of the belt body 10 is above the upper limit, the transmission efficiency of the belt 1 may decrease. The range of the JIS-A hardness is preferably 60 to 98, and more preferably 70 to 95.

[0031] As shown in Figures 1 and 2, the belt body 10 of the belt 1 has a plurality of recesses 10a on one side (the driving surface). In the belt 1, the belt body 10 can be manufactured, for example, by extrusion molding, while supporting the core wire 20 at the positions of the plurality of recesses 10a. In other words, these recesses 10a are remnants of when the support portion abutted the core wire 20 in order to control the embedded position of the core wire 20 during the manufacturing of the belt 1.

[0032] It is preferable that the recess 10a is covered. In the belt 1, it is covered by a second cover layer 32, which will be described later. By covering the recess 10a, it is possible to prevent the hybrid core wire 20a, which will be described later, from short-circuiting with other conductors when the belt 1 is used.

[0033] The belt body 10 may contain various additives. Examples of such additives include antioxidants, heat stabilizers, light stabilizers, anti-fogging agents, flame retardants, surface modifiers, pigments, fillers, waxes, and the like.

[0034] The belt holes 11 are used, for example, to secure an object to be connected, such as a trolley, to the belt 1. Specifically, screws are inserted into them to fasten them to the belt 1. The cross-sectional shape of the belt holes 11 is not particularly limited, but is generally circular. The following explanation assumes that the cross-section of the belt holes 11 is circular, but this does not exclude other shapes.

[0035] The belt holes 11 may be singular, but it is preferable to provide multiple holes to prevent the connected object from rotating. Furthermore, the number of belt holes 11 may be three or more depending on the weight of the connected object. Alternatively, the number of belt holes 11 may be greater than the number of fasteners to the connected object to allow for adjustment of the mounting position.

[0036] The belt hole 11 is preferably located in the center of the belt body 10 in the width direction. By providing the belt hole 11 in the center of the belt body 10 in the width direction, the objects to be connected can be stably connected.

[0037] Furthermore, the belt holes 11 are generally provided at one end or both ends of the belt body 10 in the longitudinal direction. This is because the object to be connected is often connected to the end of the belt body 10 in the longitudinal direction.

[0038] When multiple belt holes 11 are provided, the multiple belt holes 11 are arranged so that their centers are aligned along the length direction. The distance between adjacent belt holes 11 is appropriately determined so that the objects to be connected can be fastened. It is preferable that the multiple belt holes 11 are arranged at equal intervals. By arranging the multiple belt holes 11 at equal intervals in this way, the pressure applied to the belt body 10 when fastening the objects to be connected can be more evenly distributed, and it is possible to prevent localized pressure concentration that could damage the belt body 10.

[0039] The lower limit of the diameter of the belt hole 11 is preferably 2 mm, and more preferably 3 mm. On the other hand, the upper limit of the diameter of the belt hole 11 is preferably 7 mm, and more preferably 6 mm. If the diameter of the belt hole 11 is less than the lower limit, there is a risk that sufficient fastening strength with respect to the object to be connected cannot be ensured. Conversely, if the diameter of the belt hole 11 exceeds the upper limit, there is a risk that the strength of the belt body 10 near the belt hole 11 will be insufficient, or that a sufficient number of core bodies 20 cannot be ensured.

[0040] <Core Wires> In the belt 1, a portion of the core wire 20 is a hybrid core wire 20a composed of multiple wires of two different materials, while the other core wires 20 are reinforcing core wires 20b. In the belt 1, the core wire 20 is composed of a total of 10 core wires 20, consisting of 4 hybrid core wires 20a and 6 reinforcing core wires 20b, but the number of hybrid core wires 20a, reinforcing core wires 20b, and the total number are not limited to this combination. Furthermore, the arrangement of the hybrid core wires 20a and reinforcing core wires 20b is not limited to the configuration shown in Figure 1.

[0041] [Hybrid Core Wire] In the belt 1, the two types of wires are composed of a low-resistance wire 21 whose electrical resistivity is less than that of the hybrid core wire 20a, and a high-resistance wire 22 whose electrical resistivity is equal to or greater than that of the hybrid core wire 20a and whose breaking strength is higher than that of the low-resistance wire 21, as shown in Figure 4 or Figure 5. Note that the belt 1 does not include any wires whose electrical resistivity is equal to or greater than that of the hybrid core wire 20a and whose breaking strength is less than or equal to that of the low-resistance wire 21.

[0042] (Low-resistance wire) The material of the low-resistance wire 21 is preferably copper, and more preferably soft copper or copper alloy. Copper has a low electrical resistance per unit length and is suitable for electrical applications. Soft copper and copper alloys are moderately flexible, which helps prevent problems such as wire breakage due to bending of the belt. Soft copper wires with a breaking strength of 200 MPa to 250 MPa are generally known. The low-resistance wire 21 may also be made by plating a wire constructed using the above material with another material (for example, tin).

[0043] As the lower limit of the strand diameter of the low-resistance wire 21, 0.05 mm is preferable, and 0.08 mm is more preferable. On the other hand, as the upper limit of the strand diameter of the low-resistance wire 21, 0.32 mm is preferable, and 0.25 mm is more preferable. If the strand diameter of the low-resistance wire 21 is less than the above lower limit, there is a risk that problems such as wire breakage may easily occur. Conversely, if the strand diameter of the low-resistance wire 21 exceeds the above upper limit, there is a risk of insufficient flexibility. As the range of the strand diameter of the low-resistance wire 21, 0.08 mm or more and 0.25 mm or less is preferable.

[0044] The low-resistance wire 21 is preferably a stranded wire, and it may be a single stranded wire (single-wire stranded wire) or a plurality of stranded wires (multiple stranded wires).

[0045] When the low-resistance wire 21 is a single-wire stranded wire, the single-wire twist of the single-wire stranded wire may be 1×3 twists or more and 1×50 twists or less. By using such a single-wire stranded wire, the bending fatigue resistance of the low-resistance wire 21 can be enhanced. For example, in the hybrid core wire 20a shown in FIG. 4, the low-resistance wire 21 is a single-wire stranded wire with 1×7 twists, and in the hybrid core wire 20a shown in FIG. 5, the low-resistance wire 21 is a single-wire stranded wire with 1×3 twists.

[0046] When the low-resistance wire 21 is a multiple stranded wire, the multiple twists of the multiple stranded wire may be 3×3 twists or more and 3×20 twists or less, 5×3 twists or more and 5×20 twists or less, or 7×3 twists or more and 7×20 twists or less. By using such a multiple stranded wire, while ensuring the bending fatigue resistance, the cross-sectional area of the low-resistance wire 21 can be increased and the resistance value of the low-resistance wire 21 can be decreased. In the case of "m×n twists" (m, n: integers), m is the number of stranded wires constituting the wire, which is 1 for a single-wire stranded wire and 2 or more for a multiple stranded wire, and n indicates the number of strands constituting one stranded wire. Note that making m an odd number has the advantage of easily making the cross-section of the stranded wire circular or nearly circular.

[0047] When the low-resistance wire 21 is a stranded wire, the lower limit of the twist pitch is preferably 2 mm, more preferably 4 mm. On the other hand, the upper limit of the twist pitch is preferably 50 mm, more preferably 45 mm. If the twist pitch is less than the above lower limit, there is a risk that problems such as wire breakage may easily occur. Conversely, if the twist pitch exceeds the above upper limit, there is a risk of insufficient flexibility. The range of the twist pitch when the low-resistance wire 21 is a stranded wire is preferably 2 mm or more and 45 mm or less.

[0048] Among the plurality of wires, the lower limit of the total cross-sectional area of the low-resistance wire 21 is 5% with respect to the cross-sectional area of the hybrid core wire 20a, and more preferably 10%. On the other hand, the upper limit of the total cross-sectional area of the low-resistance wire 21 is 80% with respect to the cross-sectional area of the hybrid core wire 20a, and more preferably 50%. If the total cross-sectional area of the low-resistance wire 21 is less than the above lower limit, the resistance of the entire hybrid core wire 20a may become too high, and there is a risk that the current-carrying performance cannot be sufficiently ensured. Conversely, if the total cross-sectional area of the low-resistance wire 21 exceeds the above upper limit, the proportion occupied by the high-resistance wire 22 decreases, so there is a risk that the flexural fatigue resistance cannot be sufficiently ensured. The range of the total cross-sectional area of the low-resistance wire 21 is preferably 10% or more and 50% or less with respect to the cross-sectional area of the hybrid core wire, and may be 10% or more and 30% or less.

[0049] (High-resistance wire) Among the plurality of wires, the high-resistance wire 22 surrounds the low-resistance wire 21 in a cross-sectional view. The high-resistance wire 22 has a breaking strength higher than that of the low-resistance wire 21. By surrounding the low-resistance wire 21 with the high-resistance wire 22 having a high breaking strength, the low-resistance wire 21 is protected and the flexural fatigue resistance can be ensured.

[0050] As the material for the high-resistance wire 22, a metal with relatively high breaking strength can be used. Since metals are conductive, they have the advantage of not significantly impairing the conductivity of the hybrid core wire 20a. Examples of such metal materials include steel, nickel alloy, and stainless steel. Among the above metals, steel is preferred. Steel wire has moderately high rigidity, can ensure strength even with a small diameter, and is also excellent in terms of processability and cost. High-strength steel wires with breaking strengths of 2000 MPa or more, and even 3000 MPa or more, are generally known for use in tire reinforcement and belt reinforcement. The high-resistance wire 22 may also be a wire formed using the above material and plated with another material (for example, zinc).

[0051] The lower limit of the strand diameter of the high-resistance wire 22 is preferably 0.06 mm, and more preferably 0.08 mm. On the other hand, the upper limit of the strand diameter of the high-resistance wire 22 is preferably 0.15 mm, and more preferably 0.12 mm. If the strand diameter of the high-resistance wire 22 is below the above lower limit, problems such as wire breakage may occur more easily. Conversely, if the strand diameter of the high-resistance wire 22 exceeds the above upper limit, the flexibility of the hybrid core wire 20a may be insufficient. The range of strand diameter for the high-resistance wire 22 is preferably 0.08 mm or more and 0.12 mm or less.

[0052] (Overall Hybrid Core Wire) The lower limit of the core diameter of the hybrid core wire 20a is preferably 0.3 mm, and more preferably 0.5 mm. On the other hand, the upper limit of the core diameter of the hybrid core wire 20a is preferably 1.35 mm, and more preferably 1 mm. If the core diameter of the hybrid core wire 20a is less than the lower limit, the resistance of the hybrid core wire 20a may become too high, making it difficult to use for electrical applications. Conversely, if the core diameter of the hybrid core wire 20a exceeds the upper limit, it may lack flexibility. The range of the core diameter of the hybrid core wire 20a is preferably 0.3 mm or more and 1.0 mm or less.

[0053] The hybrid core wire 20a is preferably a stranded wire overall. Its configuration may be 1 x 19 strands (see Figure 4) to 1 x 61 strands or 7 x 3 strands (see Figure 5).

[0054] When the hybrid core wire 20a is a stranded wire, the lower limit of the twist pitch is preferably 2 mm, and more preferably 4 mm. On the other hand, the upper limit of the twist pitch is preferably 14 mm, and more preferably 10 mm. If the twist pitch is below the lower limit, problems such as wire breakage may occur easily. Conversely, if the twist pitch exceeds the upper limit, flexibility may be insufficient. When the hybrid core wire 20a is a stranded wire, the range of the twist pitch is preferably 4 mm or more and 10 mm or less.

[0055] The lower limit of the breaking strength of the hybrid core wire 20a is preferably 20 N / wire, and more preferably 100 N / wire. On the other hand, the upper limit of the breaking strength of the hybrid core wire 20a is preferably 2000 N / wire, and more preferably 1000 N / wire. If the breaking strength of the hybrid core wire 20a is below the above lower limit, there is a risk that sufficient bending fatigue resistance cannot be ensured. Conversely, if the breaking strength of the hybrid core wire 20a exceeds the above upper limit, there is a risk that flexibility will be insufficient. The range of the breaking strength of the hybrid core wire 20a is preferably 20 N / wire or more and 1000 N / wire or less, and more preferably 100 N / wire or more and 800 N / wire or less.

[0056] As for specific combinations of low-resistance wires 21 and high-resistance wires 22 that constitute the hybrid core wire 20a, as previously mentioned, a low-resistance wire 21 made of copper (preferably soft copper or copper alloy) and a high-resistance wire 22 made of one or more of steel, nickel alloy, or stainless steel can be used. Among these, a combination in which the low-resistance wire 21 is copper wire and the high-resistance wire 22 is steel wire is preferred because it offers a good balance in terms of performance and cost. In this case, the copper wire may be plated with tin or the like, and the steel wire may be plated with zinc or the like.

[0057] [Reinforcement core wire] The reinforcement core wire 20b is a linear body and, for example, has a circular cross-section. It is preferable that the reinforcement core wire 20b has a greater cutting strength than the hybrid core wire 20a.

[0058] The reinforcing core wire 20b can be made of steel, aramid, or the like. Steel wire has high rigidity and can maintain its cutting strength even with a small diameter. Aramid has insulating properties, so when the hybrid core wire 20a is used as the core wire responsible for the current-carrying function, it can prevent short-circuit failures with adjacent hybrid core wires 20a.

[0059] The lower limit of the core diameter of the reinforcing core wire 20b is preferably 0.1 mm, and more preferably 0.2 mm. On the other hand, the upper limit of the core diameter of the reinforcing core wire 20b is preferably 2 mm, and more preferably 1 mm. If the core diameter of the reinforcing core wire 20b is less than the lower limit, the cutting strength of the reinforcing core wire 20b may be insufficient. Conversely, if the core diameter of the reinforcing core wire 20b exceeds the upper limit, the weight of the belt 1 may become too heavy, the bending rigidity of the belt 1 may become too high, making it difficult to wrap around small diameter pulleys in particular, and the belt body 10 for covering the reinforcing core wire 20b may become too thick. The range of the core diameter of the reinforcing core wire 20b is preferably 0.3 mm or more and 1 mm or less.

[0060] The core diameter of the reinforcing core wire 20b is preferably equal to the core diameter of the hybrid core wire 20a. By making the core diameter of the reinforcing core wire 20b equal to that of the hybrid core wire 20a, the flatness of the belt body 10 can be improved.

[0061] It is preferable that the outermost core wires 20 in the width direction of the belt body 10 are reinforcing core wires 20b. The outermost core wires 20 in the width direction may experience increased electrical resistance over time due to wear caused by friction from the sides of the belt 1. Therefore, by making the outermost core wires 20 in the width direction reinforcing core wires 20b and not using them for electrical signal or power supply wiring, the reliability of the wiring can be improved.

[0062] The average distance between the central axis of the outermost reinforcing core wire 20b and the adjacent side surface of the belt body 10 must be at least half the core wire diameter of the core wire 20b. The lower limit of the gap between the reinforcing core wire 20b and the adjacent side surface of the belt body 10 (the average distance between the central axis of the reinforcing core wire 20b and the adjacent side surface of the belt body, minus half the core wire diameter of the core wire 20b) is preferably 0.3 mm, and more preferably 0.5 mm. On the other hand, the upper limit of the above gap is preferably 2.5 mm, and more preferably 2 mm. If the above gap is less than the lower limit, the outermost reinforcing core wire 20b may be exposed from the side surface of the belt body 10 during the manufacturing of the belt 1. Conversely, if the above gap exceeds the upper limit, the side edge of the belt body 10 may flap more easily during driving, and the effect of improving the accuracy of driving by the reinforcing core wire 20b may be insufficient. The above interval range is preferably 0.3 mm to 2.5 mm, and more preferably 0.5 mm to 2 mm.

[0063] If a belt hole 11 is provided, it is preferable that the core wires 20 adjacent to each other on both sides of the belt hole 11 are reinforcing core wires 20b. A screw is inserted into the belt hole 11 to fasten the object to be connected to the belt 1. Structurally, the upper surface of the screw has a larger diameter than the belt hole 11. Therefore, when the screw is tightened to fix the belt 1 to the object to be connected, the upper surface of the screw is pressed against the belt 1. At this time, the core wires 20 located in the area close to the upper surface of the screw may have their resistance changed by this pressing pressure, potentially resulting in undesirable electrical characteristics. Consequently, hybrid core wires 20a that can be used for electrical conductivity should not be core wires adjacent to the belt hole 11.

[0064] As shown in Figure 3, the belt holes 11 may be provided on the reinforcing core wire 20b. In other words, the reinforcing core wire 20b may be cut by the belt holes 11. In this case, the reinforcing core wire 20b will reinforce the area where the belt holes 11 are not provided. On the other hand, the belt holes 11 cannot be provided on the hybrid core wire 20a because it would result in a loss of electrical connection. Conversely, the hybrid core wire 20a is arranged to avoid the belt holes 11.

[0065] It is preferable that the reinforcing core wires 20b are arranged one on each side of the hybrid core wire 20a. More preferably, the hybrid core wires 20a and reinforcing core wires 20b are arranged alternately on each side of the belt hole 11. By arranging them in this way, it is possible to prevent a localized decrease in the strength of the belt 1.

[0066] The reinforcing core wires 20b are arranged one on each side of the hybrid core wire 20a, and when the hybrid core wire 20a is a stranded wire, it is preferable that the reinforcing core wires 20b are also stranded wires. The preferred method of stranding is that the core wires 20 (hybrid core wire 20a and reinforcing core wire 20b) alternate between S-twist and Z-twist. By combining S-twist and Z-twist core wires 20 in this way, the meandering of the belt 1 can be suppressed.

[0067] The arrangement of the hybrid core wire 20a and the reinforcing core wire 20b is preferably symmetrical with respect to the longitudinal center of the belt body 10. The belt 1 is used under tension when driven, and by arranging the hybrid core wire 20a and the reinforcing core wire 20b symmetrically in this way, tension is applied uniformly in the width direction of the belt body 10, preventing the belt 1 from shifting during travel.

[0068] The lower limit of the average pitch P of adjacent core wires 20 (see Figure 3; average distance in the width direction between the central axes of adjacent core wires of the belt 1) is preferably 0.3 mm, and more preferably 0.5 mm. On the other hand, the upper limit of the average pitch P is preferably 4 mm, and more preferably 2 mm. If the average pitch P is less than the lower limit, there is a risk that sufficient insulation between multiple hybrid core wires 20a cannot be ensured, or that the flexibility of the belt 1 will be insufficient. Conversely, if the average pitch P exceeds the upper limit, there is a risk that the belt 1 will become unnecessarily large in the width direction, or that the effect of the reinforcing core wires 20b on improving the strength, durability, and driving accuracy of the belt 1 will be insufficient. However, if a core wire 20 is not placed in a position that overlaps with the belt hole 11, this does not apply to the average pitch P between two core wires 20 that are placed on either side of the belt hole 11.

[0069] Preferably, the average pitch P is constant regardless of the combination of adjacent core wire types 20 (hybrid core wire 20a and reinforcing core wire 20b). In other words, it is preferable that the average pitch P is equal between adjacent hybrid core wires 20a, between adjacent reinforcing core wires 20b, and between adjacent hybrid core wires 20a and reinforcing core wires 20b, regardless of the combination of adjacent core wires 20. By arranging the core wires 20 at equal pitches regardless of the type of core wire 20 in this way, flapping during the driving of the belt body 10 can be suppressed. Furthermore, by making the average pitch P equal, the load is applied uniformly to each core wire 20, thus preventing premature breakage due to localized load on a specific core wire 20 and preventing an increase in the electrical resistance of the hybrid core wire 20a. Note that "equal average pitch P" includes not only cases where they are perfectly equal, but also cases where each average pitch P falls within a practical range of error (for example, an error range of 5% or less from the median).

[0070] (Connectors) In the belt 1, all of the hybrid core wires 20a have connectors 23 at least at one end, preferably at both ends.

[0071] The connector 23 is a component for connecting the hybrid core wire 20a to a signal wire outside the belt 1. By providing the connector 23 to the hybrid core wire 20a in this way, it can be suitably used as the core wire 20 that performs the electrical function.

[0072] In this belt 1, all of the hybrid core wires 20a have connectors 23, but some of the hybrid core wires 20a may have connectors 23, meaning that some hybrid core wires 20a may not have connectors 23. Connectors 23 do not need to be provided for hybrid core wires 20a that are not used for energization. Also, connectors 23 do not need to be provided when electrically connecting directly to other equipment without using connectors 23.

[0073] <Cover Layer> In the belt 1, the cover layer 30 consists of a first cover layer 31 that covers the conveying surface of the belt body 10 and a second cover layer 32 that covers the driving surface. In other words, in the belt 1, the cover layer 30 covers both sides of the belt body 10.

[0074] It is preferable that the coefficient of friction of the cover layer 30 is lower than that of the belt body 10. By providing a cover layer 30 with a low coefficient of friction in this way, the belt 1 can be made to have excellent wear resistance during use. Specifically, it is preferable that the coefficient of friction of the cover layer 30 be 0.15 or more and 0.25 or less.

[0075] In this case, the main component of the cover layer 30 is preferably a polyamide resin or a fluororesin. By making the main component of the cover layer 30 a polyamide resin or a fluororesin in this way, the coefficient of friction of the cover layer 30 can be reduced. Examples of the polyamide resin include nylon 6,6 and nylon 6. Examples of the fluororesin include polytetrafluoroethylene (PTFE) and perfluoroalkoxyalkane (PFA).

[0076] Furthermore, it is preferable that the hardness of the cover layer 30 is higher than that of the belt body 10. By providing such a high-hardness cover layer 30, the strength and wear resistance of the belt 1 can be increased. From the viewpoint of effectiveness, the JIS-A hardness of the cover layer 30 is preferably 85 to 95.

[0077] The main component of the cover layer 30 is preferably a thermoplastic elastomer. By making the main component of the cover layer 30 a thermoplastic elastomer in this way, it is possible to make it difficult for the belt body 10 and the cover layer 30 to separate. Examples of the above-mentioned thermoplastic elastomer include thermoplastic polyurethane (TPU) elastomer.

[0078] The first cover layer 31 and the second cover layer 32 can be made of different materials. For example, the first cover layer 31 can be made of a nylon polyamide resin or a fluororesin whose coefficient of friction is lower than that of the belt body 10, and the second cover layer 32 can be made of a thermoplastic elastomer whose hardness is higher than that of the belt body 10.

[0079] The lower limit of the average thickness of the cover layer 30 is preferably 15 μm, and more preferably 25 μm. On the other hand, the upper limit of the average thickness of the cover layer 30 is preferably 3000 μm, and more preferably 2000 μm. If the average thickness of the cover layer 30 is less than the lower limit, the cover layer 30 may become prone to tearing. Conversely, if the average thickness of the cover layer 30 exceeds the upper limit, the rigidity of the belt 1 may become too high. The average thickness of the first cover layer 31 and the average thickness of the second cover layer 32 may be different, but it is preferable that they be equal from the viewpoint of preventing warping of the belt 1. The range of the average thickness of the cover layer 30 is preferably 50 μm or more and 500 μm or less.

[0080] <Method for manufacturing the belt> The belt 1 can be manufactured, for example, by a manufacturing method comprising an extrusion molding process and a cover layer lamination process.

[0081] (Extrusion molding process) In the extrusion molding process, an extruded molded body is formed by extrusion molding, the main component of which is an elastomer composition in which a hybrid core wire 20a and a reinforcing core wire 20b are embedded.

[0082] Specifically, multiple core wires 20 (hybrid core wires 20a and reinforcing core wires 20b) are inserted into a crosshead attached to the cylinder tip of an extruder, and while being supported by a core support located in a recess 10a, they are extruded so as to cover both sides with a molten elastomer composition. Alternatively, the multiple core wires 20 may be embedded in the elastomer composition by sandwiching the molten extruded elastomer composition and the multiple core wires 20 between a pair of rolls and applying pressure. This elastomer composition constitutes the belt body 10.

[0083] The heating temperature for melting the elastomer composition in extrusion molding depends on the type of elastomer and whether or not a curing agent is used, but a lower limit of 150°C is preferred. On the other hand, a higher limit of 250°C is preferred. If the heating temperature is below the lower limit, the elastomer composition may not melt sufficiently, making extrusion molding difficult. Conversely, if the heating temperature exceeds the upper limit, the extruded product will become unnecessarily hot, resulting in an unnecessarily long cooling time, which may reduce the manufacturing efficiency of the belt 1.

[0084] The belt body 10 can be obtained by cooling the extruded body described above.

[0085] <Cover Layer Lamination Process> In the cover layer lamination process, a cover layer 30 is laminated on both sides of the belt body 10 obtained in the extrusion molding process.

[0086] The lamination of the cover layer 30 can be performed by, during the extrusion molding process described above, unwinding a thin film-shaped cover layer 30 from the top, bottom, or both sides of the belt body 10 and inserting it, for example, between the belt body 10 and the roll, and sandwiching it in place.

[0087] Next, the laminate, in which the cover layer 30 is laminated onto the belt body 10, is cooled. Examples of cooling methods include air cooling and water cooling. There are no particular limitations on the temperature and time conditions for cooling, but examples of setting conditions include conditions that can cool the internal temperature of the formed laminate to between 10°C and 40°C.

[0088] The belt 1 can be manufactured in the manner described above.

[0089] <Advantages> The belt 1 is a hybrid core wire 20a in which a portion of the core wire 20 is covered with a high-resistance wire 22 over a low-resistance wire 21. In this hybrid core wire 20a, the relatively high-strength high-resistance wire 22 that covers the low-resistance wire 21 protects it, thereby increasing the bending fatigue resistance of the low-resistance wire 21. In addition, since the total cross-sectional area of ​​the low-resistance wire 21 is set to 5% or more and 80% or less of the cross-sectional area of ​​the hybrid core wire 20a, the electrical resistance of the hybrid core wire 20a can be kept low, making the hybrid core wire 20a low-resistance and with excellent bending fatigue resistance.

[0090] [Second Embodiment] The belt 2 shown in Figure 6 comprises a belt body 10 whose main component is elastomer, a plurality of core wires 20 embedded in the belt body 10 along the length direction with spacing in the width direction of the belt body 10, and a plurality of teeth 40 arranged at equal intervals along the length direction on one surface of the belt body 10. A portion of the core wires 20 is a hybrid core wire 20a composed of a plurality of wires of two different materials, the total cross-sectional area of ​​the low-resistance wires 21 among the plurality of wires being 5% to 80% of the cross-sectional area of ​​the hybrid core wire 20a, and the high-resistance wires 22 among the plurality of wires surrounding the low-resistance wires 21 in cross-sectional view. The high-resistance wires 22 have a breaking strength higher than the breaking strength of the low-resistance wires 21.

[0091] The belt 2 can be constructed in the same manner as the belt 1 shown in Figure 1, except that it has teeth 40 and does not have a cover layer 30, so the same reference numerals are used and detailed explanations are omitted. In the belt 2, the belt holes 11 may be provided between the teeth 40 as shown in Figure 6, but they may also be provided so as to penetrate the teeth 40. Also, when there are multiple belt holes 11, the spacing of the belt holes 11 may match the spacing of the teeth 40 as shown in Figure 6, but they do not have to match.

[0092] <Tooth Section> The tooth section 40 has a cross-section that is a convex shape such as a trapezoid, triangle, semicircle, mountain shape, wave shape, or normal distribution curve. The tooth section 40 is also arranged so that its ridge line (axial direction) coincides with the width direction of the belt body 10.

[0093] The average height of the teeth 40 and the pitch between the teeth 40 are determined appropriately according to the intended use of the belt 2. The average height of the teeth 40 can be, for example, 1.0 mm or more and 10 mm or less. The pitch between the teeth 40 can be, for example, 2 mm or more and 25 mm or less.

[0094] The main components of the teeth 40 can be the same as those of the belt body 10. The teeth 40 may also contain the same additives as those in the belt body 10.

[0095] <Advantages> The belt 2 can be suitably used in toothed belts that require an electrical conductivity function.

[0096] [Other Embodiments] The present invention is not limited to the embodiments described above, and can be implemented in various modified and improved forms in addition to those described above.

[0097] In the above embodiment, a case was described in which the core wire is composed of a hybrid core wire and another core wire, but it is also possible for all core wires to be hybrid core wires.

[0098] In the above embodiment, a case was described in which the hybrid core wire is composed of multiple wires of two different materials, but the wires constituting the hybrid core wire may be three or more types. In this case, there may be two or more types of low-resistance wires, two or more types of high-resistance wires, or two or more types of both.

[0099] In the above embodiment, a case where the belt body has belt holes was described, but belt holes are not an essential component, and belts without belt holes are also covered by the present invention. In this case, it is preferable that the hybrid core wire and reinforcing core wire are arranged alternately across the entire width direction of the belt body.

[0100] In the above embodiment, a case was described in which the hybrid core wire has a connector on at least one end, but belts in which the hybrid core wire does not have a connector are also intended to be used in the present invention.

[0101] Conversely, in the above embodiment, only the hybrid core wire has a connector, but if the reinforcing core wire is not made of an insulator, it is not prevented to provide a connector to it and use it as a core wire with an electrical conductivity function.

[0102] In the above embodiment, a case was described in which the belt body has a recess on one side, but the belt body may also be configured to have recesses on both sides, or conversely, to have no recesses.

[0103] In the first embodiment described above, the case in which the cover layer covers both sides of the belt body was explained, but it is also possible to configure the cover layer to cover only one of the conveying surface or the driving surface. Furthermore, a belt without a cover layer is also an intention of the present invention.

[0104] In the second embodiment described above, a toothed belt without a cover layer was explained, but the belt may have a cover layer that covers one or both sides of the belt body. In this case, the cover layer can be configured in the same way as the cover layer in the first embodiment.

[0105] The present invention will be described in more detail below with reference to examples, but the invention is not limited to the following examples.

[0106] [No. 1] As belt No. 1, a belt 3 was prepared comprising a belt body 10 as shown in Figure 7, and 16 core wires 20 embedded in the belt body 10 along its length with spacing in the width direction of the belt body 10, where four of the core wires 20 are hybrid core wires 20 composed of multiple wires of two different materials, and the other core wires 20 are reinforcing core wires 20b. The average pitch P of adjacent core wires 20 is 1.7 mm.

[0107] Belt 3 is a flat belt (belt width 30 mm, thickness 1.2 mm). The main component of the belt body 10 is thermoplastic polyurethane elastomer (TPU), and its JIS-A hardness is 70. In addition, as shown in Figure 7, of the 16 core wires 20 of belt 3, the third and fourth core wires 20 from both ends are hybrid core wires 20a having the cross-section shown in Figure 5.

[0108] The low-resistance wire 21 of the hybrid core wire 20a is made of tin-plated copper wire with a strand diameter of 0.12 mm (breaking strength of 200 MPa), and the high-resistance wire 22 is made of zinc-plated steel wire with a strand diameter of 0.1 mm (breaking strength of 2400 MPa). Both the low-resistance wire 21 and the high-resistance wire 22 are 1x3 stranded wires with a twist pitch of 5 mm. The entire hybrid core wire 20a is also a stranded wire with a twist pitch of 5 mm. The core diameter of this hybrid core wire 20a is 0.6 mm, the breaking strength is 400 N / strand, and the cross-sectional area ratio of the low-resistance wire 20a was 19%.

[0109] As shown in Figure 8, the reinforcing core wire 20b is a stranded wire (twist pitch 8 mm) made by further twisting together three strands of high-resistance wire 22, which consists of galvanized steel wire (1 x 3 strands, twist pitch 9 mm) with a strand diameter of 0.15 mm. The core wire diameter of this reinforcing core wire 20b is 0.6 mm, and its breaking strength was 400 N / strand.

[0110] The 16 core wires 20 (hybrid core wires 20a and reinforcing core wires 20b) are arranged in alternating S-twist and Z-twist configurations.

[0111] [No. 2] Belt No. 2 was prepared with the same configuration as No. 1, except that the JIS-A hardness of the belt body 10 was 90 and all of the core wires 20 were replaced with reinforcing core wires 20b.

[0112] [No. 3] Belt No. 3 was prepared with the same configuration as No. 1, except that the following conductive core wires were used instead of the hybrid core wire 20a.

[0113] The conductive core wire of No. 3 is a stranded wire (with a twist pitch of 5 mm) made by twisting together three strands of low-resistance wire 21, which consists of tin-plated copper wire (1 x 13 strands) with a strand diameter of 0.08 mm. The core diameter of this conductive core wire was 0.7 mm, and its breaking strength was 40 N / strand.

[0114] [Evaluation] The flexural fatigue resistance of belts No. 1 to No. 3 was evaluated using the measuring device 100 shown in Figure 9. Specifically, the total length of belt 3 was set to 3 m, and as shown in Figure 9, a 40 kgf dead weight 101 was attached to one end to apply a constant tensile load. As shown in Figure 9, belt 3 was stretched over three flat pulleys 102 (diameters of 60 mm, 100 mm, and 60 mm from the side closest to the dead weight 101), and the other end was connected to a control device (not shown) so that the head portion of belt 3 could reciprocate along the flat pulleys 102. Using this measuring device 101, belt 3 was moved back and forth at 14 reciprocations / minute. The number of flexions was set to 6 per reciprocation, as flexion occurs at the three flat pulleys 102.

[0115] The belts No. 1 to No. 3 were repeatedly bent a predetermined number of times, and the electrical resistance per unit length (Ω / m) of the hybrid core wire 20a (conductive core wire in No. 3) and the reinforcing core wire 20b was measured. The results are shown in Figures 10 and 11.

[0116] From the results shown in Figures 10 and 11, the belt using the hybrid core wire of the present invention (No. 1) exhibits excellent electrical conductivity and bending fatigue resistance. On the other hand, the belt composed only of reinforcing core wire (No. 2) has inferior electrical conductivity, and the belt composed only of low-resistance wire (No. 3) has inferior bending fatigue resistance.

[0117] The belt of the present invention has a core wire that is low-resistance and has excellent bending fatigue resistance. Therefore, the belt of the present invention can be suitably used as a conveying or power transmission belt that also performs an electrical conductivity function.

[0118] 1, 2, 3 Belt 10 Belt body 10a Recess 11 Belt hole 20 Core wire 20a, 20x, 20y Hybrid core wire 21 Low resistance wire 22 High resistance wire 23 Connector 20b Reinforcement core wire 30 Cover layer 31 First cover layer 32 Second cover layer 40 Teeth 100 Measuring device 101 Dead weight 102 Flat pulley G1, G2 Center of gravity L Straight line M Line segment P Average pitch

Claims

1. A belt comprising a belt body whose main component is elastomer, and a plurality of core wires embedded in the belt body along its length at intervals in the width direction, wherein part or all of the core wires are hybrid core wires composed of two or more different wire materials, the total cross-sectional area of ​​the low-resistance wires, whose electrical resistivity is less than that of the core wire, is 5% or more and 80% or less of the cross-sectional area of ​​the hybrid core wire, and the high-resistance wires, whose electrical resistivity is equal to or greater than that of the core wire and whose breaking strength is higher than that of the low-resistance wires, surround the low-resistance wires in cross-section.

2. The belt according to claim 1, wherein the total cross-sectional area of ​​the low-resistance wires is 10% or more and 50% or less of the cross-sectional area of ​​the hybrid core wire.

3. The belt according to claim 1 or claim 2, wherein the low-resistance wire is a single-stranded wire, and the number of single strands in the single-stranded wire is 1 x 3 strands or more and 1 x 50 strands or less.

4. The belt according to claim 1 or claim 2, wherein the low-resistance wire is a multi-stranded wire, and the number of strands in the multi-stranded wire is 3x3 or more and 3x20 or less, 5x3 or more and 5x20 or less, or 7x3 or more and 7x20 or less.

5. The belt according to claim 1 or claim 2, wherein some or all of the hybrid core wires have a connector at at least one end.

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