V-ribbed belt and manufacturing method thereof

Abstract

The V-ribbed belt (B) has a plurality of V-wedges (14) provided so as to extend in parallel in the longitudinal direction of the belt. The plurality of V-wedges (14) are configured by covering a plurality of V-wedge bodies (11a) formed from a rubber composition with a covering cloth (15). The V-wedge (14)-side surface includes a non-cloth covering portion (16) that is provided so as to be sandwiched between the end edges of the covering cloth (15) and extend across the entire belt width.

Description

Technical Field

[0001] The invention relates to a multi-V belt and a manufacturing method thereof. Background Art

[0002] A V-ribbed belt in which the surface of the V-ribbed side is covered with a covering cloth is known. Patent Document 1 discloses that the two end edges of a cloth to be the covering cloth are joined by sewing to form a tube shape. Patent Document 2 discloses that the two end edges of a cloth to be the covering cloth are overlapped and joined by bonding to form a tube shape.

[0003] Prior art literature

[0004] Patent Document 1: Japanese Patent Publication No. 2019-132430

[0005] Patent Document 2: Japanese Patent No. 6690047 Summary of the invention

[0006] The present invention relates to a multi-V belt having a plurality of V-shaped ribs arranged in parallel to extend in the belt length direction, wherein the plurality of V-shaped ribs are formed by covering a plurality of V-shaped rib main bodies formed of a rubber composition with a covering cloth, and the surface of the V-shaped rib side includes a non-cloth covering portion, which is arranged to be sandwiched between the end edges of the covering cloth and extend across the entire belt width.

[0007] The present invention relates to a method for manufacturing a multi-V belt, comprising the steps of: using a sheet material for forming the non-cloth covering portion as a joining member, joining the end edges of a cloth material that will become the covering cloth, and laminating the cloth material with the end edges joined by the sheet material on an uncrosslinked rubber composition for forming a plurality of V-shaped rib bodies, thereby producing an uncrosslinked belt blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A is a perspective view of a piece of a V-ribbed belt according to an embodiment;

[0009] Figure 1B is a plan view of a piece of a V-ribbed belt according to an embodiment, as viewed from the V-ribbed side;

[0010] Figure 2A is a cross-sectional view of a cross-linking device;

[0011] Figure 2B is an enlarged cross-sectional view of a portion of a cross-linking device;

[0012] Figure 3A is a first explanatory diagram showing a method of joining fabrics to form a covering fabric;

[0013] Figure 3B is a second explanatory diagram showing a method of joining fabrics to form a covering fabric;

[0014] Figure 4A is a first explanatory diagram showing a method for manufacturing a V-ribbed belt according to an embodiment;

[0015] Figure 4B is a second explanatory diagram showing a method for manufacturing a V-ribbed belt according to an embodiment;

[0016] Figure 4C is a third explanatory diagram showing a method for manufacturing a V-ribbed belt according to the embodiment;

[0017] Figure 5 The diagram shows a pulley layout of a belt travel tester used for performing crack resistance test evaluation under room temperature environment. DETAILED DESCRIPTION

[0018] Hereinafter, the embodiments will be described in detail based on the drawings.

[0019] Figure 1A and Figure 1B A V-ribbed belt B according to an embodiment is shown. The V-ribbed belt B according to the embodiment is a rubber friction transmission belt used in, for example, an accessory drive belt transmission device installed in an engine room of an automobile.

[0020] The V-ribbed belt B according to the embodiment includes a belt body 10 composed of three layers: an inner compression rubber layer 11 , an intermediate adhesive rubber layer 12 , and an outer tension rubber layer 13 .

[0021] The compression rubber layer 11 is formed into a strip having a comb-tooth shape in cross section. In the compression rubber layer 11, a plurality of V-shaped wedge bodies 11a each consisting of a protrusion having a substantially inverted triangular cross section are provided to droop toward the inner peripheral side and extend in parallel along the strip length direction. The adhesive rubber layer 12 and the tensile rubber layer 13 are each formed into a strip having a horizontally long rectangular cross section. It should be noted that a back reinforcing cloth may be provided instead of the tensile rubber layer 13.

[0022] The compression rubber layer 11 including the plurality of V-shaped rib bodies 11a is formed of a rubber composition obtained by adding various rubber additives including a crosslinking agent to a rubber component and kneading the mixture to obtain an uncrosslinked rubber composition, and heating and pressurizing the uncrosslinked rubber composition to crosslink the rubber component, thereby obtaining the rubber composition.

[0023] As rubber components, for example, ethylene-α-olefin elastomers such as ethylene-propylene-diene terpolymer (EPDM), ethylene-propylene copolymer (EPM), ethylene-butene copolymer (EDM), and ethylene-octene copolymer (EOM); chloroprene rubber (CR); chlorosulfonated polyethylene rubber (CSM); and synthetic rubbers such as hydrogenated nitrile rubber (H-NBR). The rubber component is preferably one of these or a mixed rubber in which two or more are mixed. From the viewpoint of obtaining excellent low-temperature properties, it is more preferable to include ethylene-α-olefin elastomers, and it is further preferable to include EPDM. As crosslinking agents, sulfur and organic peroxides can be listed. As rubber additives other than crosslinking agents, for example, reinforcing materials such as carbon black, fillers, anti-aging agents, softeners, vulcanization accelerators, and vulcanization accelerator aids can be listed.

[0024] The adhesive rubber layer 12 and the tensile rubber layer 13 are also formed of a rubber composition. It should be noted that the compression rubber layer 11, the adhesive rubber layer 12 and the tensile rubber layer 13 may be formed of the same rubber composition or different rubber compositions.

[0025] The V-ribbed belt B according to the embodiment has a plurality of V-ribbed belts 14 arranged to extend in parallel in the belt length direction. The number of the V-ribbed belts 14 is, for example, three to six (in Figure 1A and Figure 1B The plurality of V-shaped wedges 14 are formed by covering the plurality of V-shaped wedge bodies 11a of the compression rubber layer 11 with a covering cloth 15.

[0026] The covering cloth 15 is made of a fabric such as a woven cloth, a knitted cloth or a nonwoven cloth. Examples of fiber materials forming the covering cloth 15 include: cellulose fibers such as cotton, natural fibers such as wool and silk; synthetic fibers such as aliphatic polyamide fibers, aromatic polyamide fibers, polyester fibers, acrylic fibers, polyvinyl alcohol fibers, and polyurethane fibers. The covering cloth 15 may also be formed of a blended yarn or a twisted yarn using a plurality of fiber materials.

[0027] The cloth to be the covering cloth 15 may be subjected to an adhesive treatment for imparting adhesiveness to the cloth to be bonded to the V-shaped wedge body 11a. Examples of the adhesive treatment include the following: an adhesive treatment in which the cloth to be the covering cloth 15 is immersed in an epoxy resin solution or an isocyanate solution, the cloth is pulled up, and then heated; an adhesive treatment in which the cloth is immersed in an RFL aqueous solution, the cloth is pulled up, and then heated; an adhesive treatment in which the cloth is immersed in a low-viscosity rubber paste, the cloth is pulled up, and then dried; an adhesive treatment in which a high-viscosity rubber paste is applied to the surface of the cloth on the V-shaped wedge body 11a side, and then dried.

[0028] In the multi-V belt B involved in the embodiment, the end edges of the covering cloth 15 are not joined together, and the surface on the side of the V-wedge 14 serving as the power transmission surface includes a non-cloth covering portion 16, which is arranged to be sandwiched between the end edges of the covering cloth 15 and extends straight across the entire bandwidth in the bandwidth direction.

[0029] The non-cloth covering portion 16 is composed of a polymer layer covering the V-shaped wedge main body 11a. The polymer layer constituting the non-cloth covering portion 16 is formed of a polymer material.

[0030] The polymer material forming the non-cloth covering portion 16 may also be a cross-linked material. As a typical example of a polymer material that is a cross-linked material, the following rubber composition can be cited: a rubber composition obtained by adding various rubber additives including a cross-linking agent to a rubber component and kneading the mixture, and heating and pressurizing the uncross-linked rubber composition to cross-link the rubber component, thereby obtaining the above-mentioned rubber composition. In this case, from the viewpoint of obtaining the integrity with the V-shaped wedge body 11a, it is preferable that the rubber component of the rubber composition forming the non-cloth covering portion 16 is the same as the rubber component of the rubber composition forming the compression rubber layer 11 including the plurality of V-shaped wedge bodies 11a, and it is more preferable that the rubber composition forming the non-cloth covering portion 16 is the same as the rubber composition forming the compression rubber layer 11.

[0031] The polymer material forming the non-cloth covering portion 16 may also be an uncrosslinked thermoplastic material. Examples of the polymer material that is an uncrosslinked thermoplastic material include uncrosslinked EPDM, uncrosslinked 1,2-polybutadiene, polyethylene, ethylene vinyl acetate copolymer (EVA), and a composition using these as a base polymer. When the non-cloth covering portion 16 is formed of only an EPDM polymer, since no additive is contained, the processability is excellent and the deterioration during storage can be slowed down.

[0032] The dimension L of the non-cloth covering portion 16 in the belt length direction may be 0.5 μm or more, 1 mm or more, or 3 mm or more. From the viewpoint of suppressing the noise and wear when the belt is running, the dimension L of the non-cloth covering portion 16 in the belt length direction is preferably 60 mm or less, more preferably 50 mm or less, further preferably 10 mm or less, and further preferably 5 mm or less. The dimension L of the non-cloth covering portion 16 in the belt length direction is preferably uniform in the belt width direction.

[0033] Such a non-cloth covering portion 16 may be provided at one location in the tape length direction, or may be provided at a plurality of locations in the tape length direction.

[0034] When the two end edges of the cloth to be the covering cloth are joined by sewing or bonding, the deformation of the joint portion of the covering cloth on the surface of the V-shaped ribs is limited when the multi-V belt made of the cloth is running, so stress sometimes concentrates there and cracks are generated. However, according to the multi-V belt B involved in the above-mentioned embodiment, since the end edges of the covering cloth 15 are not joined in this way and the non-cloth covering portion 16 is provided between the end edges, stress does not concentrate on this portion when the belt is running, and excellent crack resistance can be obtained.

[0035] A core wire 17 is buried in the middle portion of the adhesive rubber layer 12 in the belt thickness direction, and the core wire 17 is configured to form a spiral having a pitch in the belt width direction. The core wire 17 is composed of, for example, a twisted wire. Examples of fiber materials forming the core wire 17 include polyamide fibers, polyester fibers, and aramid fibers. It is preferred that the twisted wire that becomes the core wire 17 is subjected to an adhesive treatment for imparting adhesiveness to the adhesive rubber layer 12 to the twisted wire. Examples of the adhesive treatment include: an adhesive treatment in which the twisted wire that becomes the core wire 17 is immersed in an epoxy resin solution or an isocyanate resin solution and heated; an adhesive treatment in which the twisted wire is immersed in an RFL aqueous solution and then heated; and an adhesive treatment in which the twisted wire is immersed in a rubber paste and then dried.

[0036] Next, a method for manufacturing the V-ribbed belt B according to the embodiment will be described.

[0037] Figure 2A and Figure 2B A cross-linking device 20 for manufacturing a V-ribbed belt B according to the embodiment is shown.

[0038] The cross-linking device 20 includes a base 21 , a cylindrical expansion drum 22 vertically disposed on the base 21 , and a cylindrical mold 23 disposed outside the expansion drum 22 .

[0039] The expansion drum 22 has a drum body 22a formed in a hollow cylindrical shape and a cylindrical rubber expansion sleeve 22b embedded in the outer periphery of the drum body 22a. A plurality of vent holes 22c are formed on the outer periphery of the drum body 22a and are connected to the interior. The two ends of the expansion sleeve 22b are sealed with the drum body 22a by fixing rings 24 and 25, respectively. A pressurizing mechanism (not shown) for introducing high-pressure air into the interior of the drum body 22a and pressurizing it is provided on the cross-linking device 20. When the high-pressure air is introduced into the interior of the drum body 22a by the pressurizing mechanism, the high-pressure air enters between the drum body 22a and the expansion sleeve 22b through the vent holes 22c, causing the expansion sleeve 22b to expand radially outward.

[0040] The cylindrical mold 23 can be removed and installed relative to the base 21. The cylindrical mold 23 installed on the base 21 is arranged concentrically with the expansion drum 22 with a gap between them. On the inner peripheral surface of the cylindrical mold 23, a plurality of V-shaped wedge-forming grooves 23a extending in the circumferential direction are continuously arranged in the axial direction (groove width direction). The cross-linking device 20 is provided with a heating mechanism and a cooling mechanism (both not shown) of the cylindrical mold 23, and the temperature of the cylindrical mold 23 can be controlled by these heating mechanisms and cooling mechanisms.

[0041] When manufacturing the V-ribbed belt B according to the embodiment, first, various materials are prepared.

[0042] Various rubber additives including a cross-linking agent are added to the rubber component, kneaded with a kneader, internal mixer or the like, and then processed into a sheet having the same cross-sectional shape as the compression rubber layer 11. Thus, a rubber sheet of an uncross-linked rubber composition for forming the compression rubber layer 11 including a plurality of V-shaped rib bodies is prepared.

[0043] The rubber components are mixed with various rubber additives including a crosslinking agent, kneaded with a mixer such as a kneader or an internal mixer, and then processed into a thin sheet. Thus, a rubber sheet of an uncrosslinked rubber composition for forming the adhesive rubber layer 12 and the stretch rubber layer 13 is prepared.

[0044] After the cloth to be the covering cloth 15 is subjected to a predetermined bonding process, the end edges of the cloth are joined together using the elongated sheet material for forming the non-cloth covering portion 16 as a joining member to form a tubular shape. Figure 3A As shown, one long side of the sheet 16' overlaps with the inner side of one end side of the cloth 15' on the belt body 10 side, and the other long side of the sheet 16' overlaps with the inner side of the other end side of the cloth 15', and as shown Figure 3B As shown, the cloth 15' and the sheet 16' are pressed and bonded at these overlapping portions, thereby processing into a cylindrical shape.

[0045] When the polymer material forming the non-cloth covering portion 16 is an uncrosslinked thermoplastic material, the sheet 16' is a sheet of the thermoplastic material; when the polymer material forming the non-cloth covering portion 16 is a rubber composition, the sheet 16' is a sheet of an uncrosslinked rubber composition. It should be noted that at this stage, the two end edges of the cloth 15' may be butted with or without a gap. In addition, the twisted yarn that becomes the core yarn 17 is subjected to a prescribed bonding treatment.

[0046] Next, if Figure 4AAs shown, after the rubber sleeve 27 is put on the cylindrical drum 26 with a smooth surface, the rubber sheet 13' for forming the tensile rubber layer and the rubber sheet 12' for forming the adhesive rubber layer are firstly wound and stacked in sequence on the rubber sleeve 27, and then the twisted wire 17' which becomes the core wire 17 is spirally wound on the rubber sheet 12', and then the rubber sheet 12' for forming the adhesive rubber layer is wound and stacked on the twisted wire 17', and then the rubber sheet 11' for forming the compression rubber layer is wound and stacked from the rubber sheet 12' with the rib side located on the outside, and finally the tubular cloth 15' which becomes the covering cloth 15 with the end edges joined by the sheet 16' is covered and stacked on the rubber sheet 11', thereby producing the uncrosslinked strip S'.

[0047] Next, the rubber sleeve 27 provided with the uncrosslinked strip S' is removed from the cylindrical drum 26 and Figure 4B As shown in the figure, the rubber sleeve 27 is embedded in the inner circumferential surface side of the cylindrical mold 23 in a manner that the ribs of the rubber sheet 11' for forming the compressed rubber layer are accommodated in the corresponding V-shaped wedge forming grooves 23a while being covered by the cloth 15', and then the cylindrical mold 23 provided with the uncrosslinked strip S' is installed on the base 21 in a manner that covers the expansion drum 22.

[0048] Then, the cylindrical mold 23 is heated, and as Figure 4C As shown in the figure, high-pressure air is injected between the drum body 22a of the expansion drum 22 and the expansion sleeve 22b through the vent hole 22c to expand the expansion sleeve 22b. At this time, the uncrosslinked strip S' is abutted against the cylindrical mold 23, and the rubber sheet 11' for forming the compression rubber layer, the rubber sheet 12' for forming the adhesive rubber layer, and the rubber sheet 13' for forming the tensile rubber layer are integrated, the rubber components are crosslinked, and the fabric 15' and the sheet 16' for joining the end edges of the fabric 15' and the twisted yarn 17' are compounded thereon, and finally formed into a cylindrical strip S. It should be noted that in the case where the sheet 16' is an uncrosslinked rubber composition sheet, its rubber components will be crosslinked.

[0049] Then, after the high-pressure air is discharged from between the drum body 22a of the expansion drum 22 and the expansion sleeve 22b, the strip blank S formed on the inner circumferential surface of the cylindrical mold 23 is taken out, and the strip blank S is cut into rings, each ring having a specified number of V-shaped wedges 14, and then the strip blank S is turned inside out to obtain a multi-V belt B.

[0050] It should be noted that, in the above-mentioned embodiment, the non-cloth covering portion 16 is arranged in a manner extending straight along the bandwidth direction, but is not limited to this. The non-cloth covering portion can also be arranged in a manner having an angle relative to the bandwidth direction. Furthermore, the non-cloth covering portion can also be arranged in a manner forming a curve or a serrated line.

[0051] [Example]

[0052] (Multi-V belt)

[0053] <Example 1>

[0054] The following multi-V belt was produced as Example 1: wherein the structure of the compression rubber layer is the same as that in the above-mentioned embodiment, the compression rubber layer is formed of an EPDM rubber composition whose rubber component is EPDM, the number of V-shaped ribs is three, the non-cloth covering portion is formed of the same EPDM rubber composition as the compression rubber layer which is a cross-linked material, and the dimension L of the non-cloth covering portion in the belt length direction is 1 μm.

[0055] It should be noted that the adhesive rubber layer and the tensile rubber layer are formed of EPDM rubber compositions having different compositions from those of the compression rubber layer. The cover cloth is made of knitted cloth, which is formed by interweaving cotton and polyurethane yarns that have been subjected to adhesive treatment. The core wire is made of twisted wire made of aramid fiber that has been subjected to adhesive treatment.

[0056] <Example 2>

[0057] The following V-ribbed belt was produced as Example 2. The belt had the same structure as Example 1 except that the dimension L of the non-cloth covered portion in the belt length direction was 5 mm.

[0058] <Example 3>

[0059] The following V-ribbed belt was produced as Example 3. The structure was the same as that of Example 1 except that the dimension L of the non-cloth covered portion in the belt length direction was 50 mm.

[0060] <Example 4>

[0061] The following V-ribbed belt was produced as Example 2. The belt had the same structure as Example 1 except that the dimension L of the non-cloth covered portion in the belt length direction was 60 mm.

[0062] <Example 5>

[0063] As Example 5, a V-ribbed belt was produced, which had the same structure as that of Example 1 except that the non-cloth covering portion was formed only of a polymer of uncrosslinked EPDM, which is a thermoplastic material.

[0064] <Example 6>

[0065] As Example 6, a V-ribbed belt was produced, which had the same structure as that of Example 3 except that the non-cloth covering portion was formed only of a polymer of uncrosslinked EPDM, which is a thermoplastic material.

[0066] <Example 7>

[0067] As Example 7, a V-ribbed belt was produced, which had the same structure as that of Example 4 except that the non-cloth covering portion was formed only of a polymer of uncrosslinked EPDM, which is a thermoplastic material.

[0068] <Example 8>

[0069] As Example 8, a V-ribbed belt was produced, which had the same structure as that of Example 4 except that the non-cloth covering portion was formed only of a polymer of uncrosslinked 1,2-polybutadiene, which was a thermoplastic material.

[0070] <Comparative Example 1>

[0071] As Comparative Example 1, the following V-ribbed belt was produced. The structure was the same as that of Example 1 except that a cloth obtained by butting both end edges and joining them by sewing was used as a covering cloth.

[0072] <Comparative Example 2>

[0073] As Comparative Example 2, the following V-ribbed belt was produced. The structure was the same as that of Example 1 except that a cloth obtained by overlapping both end edges and bonding them together was used as a covering cloth.

[0074] (Test evaluation method)

[0075] Figure 5 The pulley layout of the belt travel tester 30 used for performing crack resistance test evaluation under room temperature environment is shown.

[0076] In the belt running test machine 30, a driving pulley 31 on the lower side and a first driven pulley 32 on the upper side are arranged at intervals in the vertical direction, and the driving pulley 31 and the first driven pulley 32 are each a multi-V pulley with a pulley diameter of 45 mm. On the right side of the middle of the driving pulley 31 and the first driven pulley 32, a pair of idler pulleys 33 are arranged at intervals in the vertical direction, and the pair of idler pulleys 33 are each a flat pulley with a pulley diameter of 40 mm. On the right side of the pair of idler pulleys 33, a second driven pulley 34 is arranged, and the second driven pulley 34 is a multi-V pulley with a pulley diameter of 45 mm. In the belt running test machine 30, the multi-V belt B is wound such that the V-ribbed side of the multi-V belt B contacts the driving pulley 31 and the first driven pulley 32 and the second driven pulley 34, and the back side of the multi-V belt B contacts the pair of idler pulleys 33.

[0077] The poly-V belt B of each of Examples 1 to 8 and Comparative Examples 1 to 2 was wound on a belt running test machine 30. A static load (DW) of 588N was applied upward to the first driven pulley 32 to give the belt tension. In this state, the driving pulley 31 was rotated at a speed of 5100 rpm to run the belt under room temperature (23±5°C). In addition, the belt was stopped periodically and the V-shaped wedge side surface of the poly-V belt B was visually observed. The belt running was terminated at the time when the crack reaching the bottom of the V-shaped wedge was confirmed, and the belt running time up to this point was taken as the crack resistance life at room temperature.

[0078] In addition, the evaluation was A when the sound was small during the belt running, and B when the sound was loud during the belt running.

[0079] (Test results)

[0080]

Table 1

[0081]

[0082]

Table 2

[0083]

[0084] The test results are shown in Tables 1 and 2. As can be seen from Tables 1 and 2, Examples 1 to 8, in which the surface of the V-shaped wedge side includes a non-cloth covering portion, have better crack resistance than Comparative Example 1 in which the covering cloth is made of a cloth having both end edges joined by bonding, and Comparative Example 2 in which the covering cloth is made of a cloth having both end edges joined by sewing.

[0085] - Industrial Applicability -

[0086] The present invention is useful in the technical field of multi-V belts and methods for manufacturing the same.

[0087] - Explanation of symbols -

[0088] B Multi-V belt

[0089] S Strip

[0090] S' uncrosslinked strip

[0091] 10 with main body

[0092] 11Compression rubber layer

[0093] 11', 12', 13' rubber sheet

[0094] 12 Bonding rubber layer

[0095] 13 tensile rubber layer

[0096] 14V-shaped wedge

[0097] 15 Covering cloth

[0098] 15' fabric

[0099] 16 Non-cloth covered part

[0100] 16' sheet

[0101] 17 core wire

[0102] 17' twist line

[0103] 20 Cross-linking device

[0104] 21 Base

[0105] 22 Expansion Drum

[0106] 22a Drum body

[0107] 22b expansion sleeve

[0108] 22c vents

[0109] 23 Cylinder Mould

[0110] 23a V-shaped wedge forming groove

[0111] 24, 25 fixed ring

[0112] 26 cylindrical drum

[0113] 27 Rubber sleeve

[0114] 30 belt running test machine

[0115] 31 driving pulley

[0116] 32 First driven pulley

[0117] 33 Idler

[0118] 34 Second driven pulley.

Claims

1. A V-ribbed belt having a plurality of V-ribs arranged in parallel and extending in a belt length direction, characterized in that: The plurality of V-shaped wedges are formed by covering a plurality of V-shaped wedge bodies formed of a rubber composition with a covering cloth, The surface of the V-shaped wedge side includes a non-cloth covering portion, which is arranged to be sandwiched between the end edges of the covering cloth and extends across the entire belt width.

2. The multi-V belt according to claim 1, characterized in that: The non-cloth covering portion is formed of a rubber composition.

3. The multi-V belt according to claim 2, characterized in that: The rubber component of the rubber composition forming the non-cloth covered portion is the same as the rubber component of the rubber composition forming the plurality of V-shaped cleat bodies.

4. The multi-V belt according to claim 3, characterized in that: The rubber composition forming the non-cloth covering portion is the same as the rubber composition forming the plurality of V-shaped cleat main bodies.

5. The multi-V belt according to claim 1, characterized in that: The non-cloth covering portion is formed of a thermoplastic material.

6. The multi-V belt according to claim 1, characterized in that: The dimension of the non-cloth-covered portion in the tape length direction is not less than 0.5 μm and not more than 60 mm.

7. The multi-V belt according to claim 1, characterized in that: The non-cloth-covered portion is provided so as to extend straightly in the belt width direction.

8. A method for manufacturing a multi-V belt, wherein the multi-V belt is the multi-V belt according to claim 1, characterized in that: The method for manufacturing the multi-V belt includes the following steps: using a sheet material for forming the non-cloth covering portion as a joining member, joining the end edges of the cloth that will become the covering cloth, and laminating the cloth formed by joining the end edges using the sheet material on an uncrosslinked rubber composition for forming a plurality of the V-shaped rib bodies, thereby producing an uncrosslinked belt blank.

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