Transmission belt

Abstract

To provide a transmission belt having excellent durability under high load transmission. The power transmission belt (B) comprises an elastomer belt body (11) and a carbon fiber core wire (12) embedded therein. The belt tension T per mm of belt width when the belt elongation rate is 0.2% is 0.2 The belt tension T per 1 mm of belt width when the belt elongation rate is 0.5% is 70 N / mm or more. 0.5 Belt tension T is 220N / mm or more. 0.2 Belt tension T 0.5 The ratio to is 0.33 or more.

Description

[Technical field]

[0001] The present invention relates to a power transmission belt. [Background technology]

[0002] 2. Description of the Related Art Power transmission belts using a core wire made of carbon fiber are known. For example, Patent Document 1 discloses a toothed belt in which a core wire made of carbon fiber is embedded in a rubber belt body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-24075 A Summary of the Invention

[0004] The present invention provides a power transmission belt comprising an elastomer belt body and a carbon fiber core wire embedded in the belt body and arranged to form a spiral having a pitch in the belt width direction, the total number of filaments of the carbon fibers constituting the core wire is 12,000, the core wire is a single-twisted yarn obtained by twisting a filament bundle of the carbon fibers in one direction, the number of twists of the single-twisted yarn per 10 cm of the length of the core wire is 4 turns / 10 cm or more and 10 turns / 10 cm or less, and the number of the core wires per 10 mm of the belt width is 7 turns / 10 mm or more and 9 turns / 10 mm or less, Belt tension T per mm of belt width when belt elongation rate is 0.2% 0.2 but 90N / mm End 140N / mm or less At the same time, the belt tension T per 1 mm of belt width when the belt elongation rate is 0.5% 0.5 is 220N / mm or more 300N / mm or less in be . [Brief description of the drawings]

[0005] [Figure 1A] FIG. 2 is a perspective view of one piece of a toothed belt according to an embodiment. [Figure 1B] FIG. 2 is a vertical cross-sectional view of a portion of a toothed belt according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing the configuration of a belt tensile tester. [Figure 3A] FIG. 2 is a first explanatory diagram of a method for producing a toothed belt according to the embodiment. [Figure 3B]FIG. 4 is a second explanatory diagram of the method for producing a toothed belt according to the embodiment. [Figure 3C] FIG. 6 is a third explanatory diagram of the method for producing a toothed belt according to the embodiment. [Figure 4] FIG. 2 is a layout diagram of pulleys in a belt running test machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] Hereinafter, the embodiments will be described in detail with reference to the drawings.

[0007] 1A and 1B show a toothed belt B according to an embodiment. The toothed belt B according to the embodiment is a meshing power transmission belt and is suitably used for high-load power transmission applications such as machine tools, printing machines, textile machines, and injection molding machines. The belt length of the toothed belt B according to the embodiment is, for example, 500 mm or more and 3000 mm or less. The belt width is, for example, 10 mm or more and 200 mm or less. The belt thickness (maximum) is, for example, 3 mm or more and 20 mm or less.

[0008] The toothed belt B according to the embodiment includes an endless toothed belt main body 11 made of an elastomer formed from polyurethane resin. The toothed belt main body 11 has a flat belt portion 111 having a horizontally elongated rectangular cross section and a plurality of tooth portions 112 integrally provided on the inner peripheral side thereof. The plurality of tooth portions 112 are provided at regular intervals in the belt length direction.

[0009] Examples of the tooth shape of the tooth portion 112 in a side view include an STS tooth shape with both sides bulging outward in an arc shape and a trapezoidal tooth shape. The number of teeth in the tooth portion 112 is, for example, 30 to 400. The tooth width (maximum dimension in the belt length direction) is, for example, 2 mm to 10 mm. The tooth height is, for example, 2 mm to 8 mm. The arrangement pitch is, for example, 8 mm to 14 mm.

[0010] The polyurethane resin forming the toothed belt body 11 is obtained by heating and pressurizing a urethane composition in which compounding agents such as a hardener and a plasticizer are mixed with a urethane prepolymer to harden it.

[0011] The urethane prepolymer is a relatively low molecular weight urethane compound having multiple NCO groups at the terminals, which is obtained by the reaction of an isocyanate component with a polyol component. Examples of the isocyanate component include tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). Examples of the polyol component include polytetramethylene ether glycol (PTMG). The urethane prepolymer may be composed of a single urethane compound or may be composed of a mixture of multiple urethane compounds.

[0012] Examples of the curing agent include amine compounds such as 1,4-phenylenediamine, 2,6-diaminotoluene, 1,5-naphthalenediamine, 4,4'-diaminodiphenylmethane, and 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA). The curing agent preferably contains one or more of these. The amine compound curing agent is a NH 2 The α value (NH 2 It is preferable that the ratio of NCO groups / NCO groups be 0.70 or more and 1.10 or less.

[0013] Examples of the plasticizer include dialkyl phthalates such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP); dialkyl adipates such as dioctyl adipate (DOA); and dialkyl sebacates such as dioctyl sebacate (DOS). The plasticizer preferably contains one or more of these. The amount of the plasticizer is, for example, 3 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the urethane prepolymer.

[0014] Examples of other compounding agents include colorants, antifoaming agents, and stabilizers.

[0015] The hardness of the polyurethane resin forming the toothed belt main body 11 is, for example, not less than 70° and not more than 100°. The hardness of this polyurethane resin is measured based on JIS K7312:1996.

[0016] The toothed belt B according to the embodiment includes a core wire 12 made of carbon fiber embedded in the flat belt portion 111 of the toothed belt main body 11. From the viewpoint of obtaining excellent durability in high load transmission, the outer diameter of the core wire 12 is preferably 0.6 mm or more and 2.2 mm or less, and more preferably 0.8 mm or more and 1.2 mm or less.

[0017] From the viewpoint of obtaining excellent durability in high load transmission, the carbon fiber constituting the core wire 12 is preferably a PAN-based carbon fiber. From the same viewpoint, the filament diameter of the carbon fiber is preferably 4 μm or more and 9 μm or less, more preferably 6 μm or more and 8 μm or less.

[0018] From the viewpoint of obtaining excellent durability in high load transmission, the total number of filaments of the carbon fiber constituting the core wire 12 is preferably 6000 (6K) or more and 48000 (48K) or less, more preferably 9000 (9K) or more and 18000 (18K), and even more preferably 12000 (12K). From the same viewpoint, the fineness of the carbon fiber constituting the core wire 12 is preferably 400 tex or more and 3200 tex or less, more preferably 600 tex or more and 1200 tex or less, and even more preferably 800 tex.

[0019] From the viewpoint of obtaining excellent durability in high load transmission, the core wire 12 is preferably a twisted yarn. Examples of the twisted yarn constituting the core wire 12 include single twisted yarn, multiple twisted yarn, and Lang twisted yarn. From the same viewpoint, the twisted yarn core wire 12 is preferably a single twisted yarn obtained by twisting a filament bundle of carbon fiber in one direction. From the same viewpoint, the number of twists of the single twisted yarn core wire 12 is preferably 4 turns / 10 cm or more and 12 turns / 10 cm or less, more preferably 6 turns / 10 cm or more and 10 turns / 10 cm or less. For the single twisted yarn core wire 12, either an S twisted yarn, a Z twisted yarn, or both may be used.

[0020] The core wires 12 are arranged to form a spiral having a pitch in the belt width direction. The core wires 12 may be composed of two threads, an S twisted thread and a Z twisted thread, which are arranged to form a double spiral. The core wires 12 are arranged to extend in parallel at intervals in the belt width direction. In this case, the number of core wires 12 per 10 mm of belt width is preferably 6 threads / 10 mm or more and 10 threads / 10 mm or less, more preferably 7 threads / 10 mm or more and 9 threads / 10 mm or less, from the viewpoint of obtaining excellent durability in high load transmission.

[0021] It is preferable that the core wires 12 are subjected to an adhesive treatment such as immersing them in a liquid adhesive and then drying them before molding.

[0022] The toothed belt B according to the embodiment includes a nonwoven fabric 13 embedded along the belt length direction on the inner circumferential side of the position in the belt thickness direction of the toothed belt main body 11 where the core wire 12 is embedded. The nonwoven fabric 13 may be composed of either one sheet or multiple sheets.

[0023] The nonwoven fabric 13 contains the polyurethane resin that forms the toothed belt main body 11, and is provided so as to form a layer in a side view. The portions of the nonwoven fabric 13 that correspond to the tooth portions 112 penetrate into the tooth portions 112 so as to bulge outward in a side view and spread thickly in the belt thickness direction. The portions of the nonwoven fabric 13 that correspond to the spaces between the tooth portions 112 come into contact with the core wire 12 and are compressed thin in the belt thickness direction.

[0024] Examples of fiber materials constituting the nonwoven fabric 13 include nylon fibers, polyester fibers, aramid fibers, polyketone fibers, carbon fibers, etc. The nonwoven fabric 13 may be formed of either a single type of fiber or multiple types of fibers.

[0025] It is preferable that the nonwoven fabric 13 is subjected to an adhesive treatment such as immersing it in a liquid adhesive and then drying it before molding.

[0026] The toothed belt B according to the embodiment has a belt tension T per mm of belt width when the belt elongation rate is 0.2%. 0.2 The belt tension T is 70N / mm or more. 0.2 From the viewpoint of obtaining excellent durability in high load transmission, the belt tension T is preferably 80 N / mm or more, and more preferably 90 N / mm or more. 0.2 From the viewpoint of avoiding a decrease in resistance to bending fatigue due to an increase in bending rigidity, the bending strength is preferably 140 N / mm or less, and more preferably 120 N / mm or less.

[0027] The toothed belt B according to the embodiment has a belt tension T per mm of belt width when the belt elongation rate is 0.5%. 0.5 The belt tension T is 220N / mm or more. 0.5 From the viewpoint of obtaining excellent durability in high load transmission, the belt tension T is preferably 230 N / mm or more, and more preferably 240 N / mm or more. 0.5 From the viewpoint of avoiding a decrease in bending fatigue resistance due to an increase in bending rigidity, the bending strength is preferably 440 N / mm or less, and more preferably 300 N / mm or less.

[0028] Here, these belt tensions T 0.2 and belt tension T 0.5 It is calculated as follows:

[0029] First, in an atmosphere of 25° C., as shown in FIG. 2, the toothed belt B according to the embodiment is wound around a pair of flat pulleys 21, each of which has a pulley diameter of 95.4 mm, of a belt tensile tester 20 so that the back surface of the belt is in contact with the pulley.

[0030] Next, one flat pulley 21 is moved away from the other flat pulley 21 at a speed of 50 mm / min. At this time, the relationship between the displacement between the pair of flat pulleys 21 and the tension detected through either of the pair of flat pulleys 21 is recorded.

[0031] Next, the displacement between the pair of flat pulleys 21 is doubled to calculate the belt elongation amount, and this is divided by the belt length of the toothed belt B according to the embodiment in an unloaded state to convert the displacement between the pair of flat pulleys 21 into a belt elongation rate. Also, the detected tension is divided by 2 to calculate the belt tension, and this is divided by the belt width of the toothed belt B according to the embodiment to convert the detected tension into belt tension per mm of belt width.

[0032] Then, based on the relationship between these belt elongation rates and belt tension, zero correction is performed so that the point where the belt tension per 1 mm of belt width is 50 N is the starting point, and the belt tension T 0.2 and belt tension T 0.5 Request.

[0033] In the toothed belt B according to the embodiment, the belt tension T 0.2 Belt tension T 0.5 Ratio to belt tension T 0.2 / Belt tension T 0.5 ) is 0.33 or more. 0.2 / Belt tension T 0.5 From the viewpoint of obtaining excellent durability in high load transmission, the belt tension T is preferably 0.35 or more, and more preferably 0.38 or more. 0.2 / Belt tension T 0.5 From a practical viewpoint, it is preferably 0.55 or less, more preferably 0.50 or less, and further preferably 0.45 or less.

[0034] According to the toothed belt B according to the embodiment of the above configuration, the belt tension T 0.2 is 70N / mm or more, and the belt tension T 0.5 is 220N / mm or more, and the belt tension T 0.2 Belt tension T 0.5 By making the ratio to 0.33 or more, excellent durability can be obtained under high load transmission. 0.2 is 70N / mm or more, and the belt tension T 0.5The belt tension T is 220N / mm or more, which provides excellent dimensional stability in a wide range of high load applications. 0.2 / Belt tension T 0.5 It is presumed that because the ratio is 0.33 or more, even if the belt elongation rate increases due to thermal expansion of the pulley, the generation of excessive tension is suppressed, thereby making it possible to suppress the progress of wear.

[0035] Next, a method for producing the toothed belt B according to the embodiment will be described.

[0036] 3A, nonwoven fabric 13 is placed over cylindrical inner die 31, and core wire 12 is spirally wound thereon. At this time, grooves 32 extending in the axial direction and having a cross section shaped to correspond to teeth 112 are provided at regular intervals in the circumferential direction on the outer periphery of inner die 31, and ridges 33 extending in the axial direction are formed between each groove 32. Therefore, nonwoven fabric 13 and core wire 12 are provided so as to be supported by ridges 33.

[0037] 3B, the inner die 31 is housed in a cylindrical outer die 34. At this time, a cavity C for molding the toothed belt main body is formed between the inner die 31 and the outer die 34.

[0038] Next, as shown in FIG. 3C, a liquid urethane composition made by mixing a compounding agent with a urethane prepolymer is injected into the sealed cavity C to fill it and is heated. At this time, the urethane composition flows and hardens to form a toothed belt main body 11 of polyurethane resin. Also, teeth 112 are formed in the recessed grooves 32. The core wire 12 is adhered to and embedded in the toothed belt main body 11. Furthermore, the nonwoven fabric 13 is impregnated with the urethane composition and hardens, and is adhered to and embedded in the toothed belt main body 11. In this manner, the toothed belt main body 11, the core wire 12, and the nonwoven fabric 13 are integrated to form a cylindrical belt slab S.

[0039] Finally, the belt slab S is removed from the inner die 31 and the outer die 34 and cut into rings to obtain the toothed belt B according to the embodiment.

[0040] In the above embodiment, the toothed belt B is composed of the toothed belt main body 11, the core wire 12, and the nonwoven fabric 13, but this is not particularly limited, and a reinforcing cloth may be provided on the toothed portion side surface on the inner circumference side of the toothed belt main body and / or on the back surface on the outer circumference side of the toothed belt main body.

[0041] In the above embodiment, the toothed belt B has a toothed belt body formed of a polyurethane resin, but this is not particularly limited, and the belt body may be formed of a cross-linked rubber composition.

[0042] In the above embodiment, the toothed belt B is used as the power transmission belt, but the present invention is not limited to this, and may be a flat belt, a V-belt, a V-ribbed belt, or the like. EXAMPLES

[0043] (Toothed belt) Toothed belts were produced for Example and Comparative Examples 1 to 3. The configurations of each are also shown in Table 1.

[0044] <Example> A toothed belt with an STS tooth profile having the same configuration as the above embodiment was used as the example.

[0045] The toothed belt of the example had a belt length of 800 mm, a belt width of 8 mm, and a belt thickness (maximum) of 4.8 mm. The tooth portion was S8M as specified in ISO13050:2014(E).

[0046] The urethane composition for forming the toothed belt body was prepared by blending 13 parts by mass of 3,3'-dichloro-4,4'-diaminodiphenylmethane as a hardener and 10 parts by mass of dioctyl phthalate as a plasticizer with 100 parts by mass of urethane prepolymer. The hardness of the polyurethane resin forming the toothed belt body was 92° as measured according to JIS K7312.

[0047] For the core, a single-twist yarn was used, which was a filament bundle of carbon fiber (Tenax-J UTS50 F22, Teijin, 12K, 800tex, filament diameter: 7.0μm) with 12,000 filaments twisted in one direction at 6 twists per 10cm length. For the single-twist yarn core, S-twist yarn and Z-twist yarn were prepared, and they were subjected to an adhesive treatment by immersing in an adhesive and then drying. The single-twist yarn core of S-twist yarn and Z-twist yarn was arranged so that they were alternately arranged in the belt width direction to form a double helix. The number of core wires per 10mm of belt width was 8. The outer diameter of the core wire was 0.9mm.

[0048] The nonwoven fabric used was made of nylon fibers produced without pressure by the needle punch method. No adhesive treatment was applied to the nonwoven fabric.

[0049] Belt tension T of the toothed belt in the embodiment 0.2 is 100N / mm, and belt tension T 0.5 The belt tension was 250N / mm. Therefore, the belt tension T 0.2 / Belt tension T 0.5 is 0.40.

[0050] <Comparative Example 1> Comparative Example 1 was a toothed belt having the same configuration as the embodiment except that the number of core wires per 10 mm of belt width was six.

[0051] Belt tension T of the toothed belt of Comparative Example 1 0.2 is 65N / mm, and belt tension T 0.5 The belt tension was 200N / mm. Therefore, the belt tension T 0.2 / Belt tension T0.5 is 0.33.

[0052] <Comparative Example 2> A toothed belt having the same configuration as that of the embodiment except that the number of twists per 10 cm of the core wire length was 12 / 10 cm and the number of core wires per 10 mm of the belt width was 10 was used as Comparative Example 2. The outer diameter of the core wire was 1.0 mm.

[0053] Belt tension T of the toothed belt of Comparative Example 2 0.2 is 80N / mm, and belt tension T 0.5 The belt tension was 260N / mm. Therefore, the belt tension T 0.2 / Belt tension T 0.5 is 0.31.

[0054] <Comparative Example 3> A toothed belt having the same configuration as that of the embodiment except that the number of twists per 10 cm of the core wire length was 9 times / 10 cm was used as Comparative Example 3. The outer diameter of the core wire was 1.0 mm.

[0055] Belt tension T of the toothed belt of Comparative Example 3 0.2 is 80N / mm, and belt tension T 0.5 The belt tension was 210N / mm. Therefore, the belt tension T 0.2 / Belt tension T 0.5 is 0.38.

[0056] [Table 1]

[0057] (High load durability test) 4 shows the pulley layout of a belt running tester 40 used in the high-load durability test. This belt running tester 40 has a drive pulley 41 with 22 teeth and a driven pulley 42 with 33 teeth provided to the right of the drive pulley 41. The driven pulley 42 is configured to be movable left and right so that it can bear an axial load and also a load torque.

[0058] For each of the toothed belts B of the example and comparative examples 1 to 3, they were wound around a driving pulley 41 and a driven pulley 42 in an atmosphere of 60°C, and a fixed shaft load (SW) of 608 N was applied to the driven pulley 42 to apply tension to the toothed belt B, and a load torque of 34.24 N m was applied, and in this state, the driving pulley 41 was rotated at a rotation speed of 4212 rpm. Then, the time until the toothed belt B broke was measured, and this time was defined as the high load durability life.

[0059] (Test Results) The test results are shown in Table 1. From this, it can be seen that the embodiment example has much better durability in high load transmission than the comparative examples 1 to 3. [Industrial Applicability]

[0060] The present invention is useful in the technical field of power transmission belts. [Explanation of symbols]

[0061] B Toothed belt (power transmission belt) C Cavity S Belt Slab 11 Toothed belt body 111 Flat belt 112 Teeth 12 Core Wire 13 Nonwoven fabrics 20 Belt tensile testing machine 21 Flat pulley 31 Inner mold 32 Groove 33 protrusion 34 Outer mold 40 Belt running test machine 41 Drive pulley 42 Driven pulley

Claims

1. A power transmission belt comprising: a belt body made of an elastomer; and a carbon fiber core wire embedded in the belt body and arranged to form a spiral having a pitch in the belt width direction, The total number of filaments of the carbon fiber constituting the core wire is 12,000, The core wire is a single-twist yarn obtained by twisting the filament bundle of the carbon fiber in one direction, The number of twists per 10 cm of the core wire of the single twisted yarn is 4 times / 10 cm or more and 10 times / 10 cm or less, The number of the core wires per 10 mm of belt width is 7 wires / 10 mm or more and 9 wires / 10 mm or less, Belt tension T per 1 mm of belt width when belt elongation rate is 0.2% ０．２ is 90 N / mm or more and 140 N / mm or less, and the belt tension T per 1 mm of belt width when the belt elongation rate is 0.5% ０．５ The power transmission belt has a strength of 220 N / mm or more and 300 N / mm or less.

2. The power transmission belt according to claim 1, The belt body is made of a polyurethane resin.

3. The power transmission belt according to claim 1 or 2, The power transmission belt, wherein the carbon fiber constituting the core wire is a PAN-based carbon fiber.

4. The power transmission belt according to any one of claims 1 to 3, The carbon fiber filament diameter is 4 μm or more and 9 μm or less.

5. The power transmission belt according to any one of claims 1 to 4, The belt tension T ０．２ / Belt tension T ０．５ A power transmission belt having a coefficient of friction (Ri) of 0.55 or less.

6. The power transmission belt according to any one of claims 1 to 5, The belt body is a toothed belt body.

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