JP2008100365A - Manufacturing method of transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a transmission belt of high modulus by suppressing the damage of core wires. <P>SOLUTION: After an unvulcanized stretched rubber sheet is wound around an inner mold cylindrical drum 21 on which a flexible jacket 22 is mounted to arrange a stretched rubber layer 15, a twist yarn cord 13, which is obtained by mixing and twisting aramid fibers and fibers of which the raw yarn intermediate elongation is 4-15% at the time of a load of 4 cN/dtex so that the weight ratio of the aramid fibers becomes 50-90%, is spirally spun and the unvulacnized compression rubber sheet is wound to arrange a compression rubber layer 16 to form an unvulcanized belt sleeve 11. Subsequently, the cylindrical drum is placed and fixed inside an outer mold 26 and a flexible jacket 21 is expanded to uniformly expand the unvulcanized belt sleeve 11 mounted on the outer peripheral surface of the jacket in a radial direction. The unvulcanized belt sleeve is pressed to the V-shaped projections of the outer mold 26 to form a vulcanized belt sleeve having a plurality of V-shaped grooves on its surface. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a power transmission belt used for power transmission and the like.

  As power transmission belts used for power transmission, those having various shapes are known. One of them is a power transmission belt having an uneven portion on the inner peripheral surface of the belt. For example, a V-ribbed belt is a transmission belt in which the concavo-convex portion is a rib portion, and more specifically, a compressed rubber layer having a plurality of ribs extending in parallel to the belt longitudinal direction is disposed on the inner surface of the belt, and an upper portion thereof. An adhesive rubber layer in which cords made of cords are embedded is laminated, and an extension layer is disposed on the back side thereof. As a manufacturing method of such a V-ribbed belt, conventionally, ribs were formed by grinding a V-groove on a flat vulcanized sleeve. However, in recent years, the amount of discarded material has been reduced as much as possible and the manufacturing process has been simplified. There is a demand for construction methods that can

  In response to this requirement, there is a method in which an unvulcanized belt sleeve is wound around an inner drum provided with a rib marking on the peripheral surface, and then the rib portion is molded by pressing the belt sleeve against the inner drum by heat and pressure. Proposed. However, in the above-described method, the rib portion may not be sufficiently engraved under normal temperature and pressure conditions. If an attempt is made to accurately engrave these conditions at a high level, a large amount of heat is applied to the rubber or the core. There was a bad effect of giving a history. Further, in this method, as a method of forming an unvulcanized belt sleeve, since the core wire is spun after winding the compression rubber sheet and the adhesive rubber sheet, the core wire pitch is disturbed, and thus oscillation occurs when the belt molded body is driven, There was a problem of meandering. Further, since the belt sleeve is pressed against the inner drum, there is a problem that it is difficult to remove the belt sleeve after molding.

On the other hand, an unvulcanized stretched rubber sheet containing short fibers is spread on a flexible jacket mounted on a cylindrical drum, a core wire is spun on it, and then an unvulcanized compressed rubber sheet is rolled. A method has been proposed in which an endless unvulcanized belt sleeve is formed and then the jacket is expanded and the belt sleeve is pressed against an outer mold having a V-shaped projection to vulcanize and mold. (For example, see Patent Document 1)
JP 2005-125742 A

  In a drive device having a large engine load fluctuation, a transmission belt having a high modulus, specifically, a transmission belt having an aramid fiber cord as a core wire is applied. However, when this transmission belt was produced by the above-described manufacturing method, the aramid fiber cord could not cope with the expansion of the jacket, causing problems such as the core wire being cut or damaged. Even if cutting or damage does not occur, the core wire cannot be stretched uniformly and smoothly with respect to the expansion of the jacket, and as a result, the core wire pitch may be disturbed. In order to solve these problems, it has been considered to increase the number of twists of the aramid twisted yarn cord to lower the modulus of the cord, but there is a problem that although the arrangement of the cords is improved, the belt strength is lowered.

  In the present invention, there is provided a method for solving the above-described problems, suppressing the damage of the core wire and the disturbance of the core wire pitch, and having a high belt modulus, particularly suitable for a driving device having a large load fluctuation, and a method for easily manufacturing a transmission belt. The purpose is to provide.

  That is, the invention of claim 1 is a manufacturing method of a transmission belt having an uneven portion on the inner surface of the belt, and a rubber member that becomes the back surface of the transmission belt, a twisted cord, and a rubber member that becomes the inner surface of the transmission belt in the inner mold fitted with a jacket The step of forming the unvulcanized belt sleeve by sequentially arranging the sleeve, the jacket is expanded, and the unvulcanized belt sleeve is vulcanized by pressing the unvulcanized belt sleeve against the outer mold having a mark corresponding to the uneven portion. Forming a vulcanized belt sleeve engraved with an aramid fiber comprising aramid fiber and a fiber having an intermediate yarn elongation of 4 to 15% at 4 cN / dtex load as the twisted cord. A twisted yarn cord that is mixed and twisted so that the weight ratio is 50 to 90% is used.

  The invention of claim 2 of the present application is the method for manufacturing a transmission belt according to claim 1, wherein the twisted cord is a twisted structure, and the intermediate twisted yarn at the time of 4 cN / dtex load is obtained by twisting an aramid fiber. Is a twisted cord obtained by mixing and twisting a lower twisted cord obtained by twisting 4 to 15% of the fiber so that the upper twisting coefficient is 2.0 to 7.0.

  The invention of claim 3 of the present application is characterized in that, in the method of manufacturing a power transmission belt of claim 1 or 2, the 100 N elongation of the twisted cord is 1.3 to 5.0%.

  The invention of claim 4 of the present application is the method for manufacturing a transmission belt according to any one of claims 1 to 3, wherein the fiber having an intermediate yarn intermediate elongation of 4 to 15% at a load of 4 cN / dtex is a polyamide fiber. And / or polyethylene terephthalate fiber.

  The invention of claim 5 of the present application is characterized in that, in the method for manufacturing a transmission belt according to any one of claims 1 to 4, the uneven portion is a rib portion, and the transmission belt is a V-ribbed belt.

  The invention of claim 6 of the present application is a method of manufacturing a transmission belt having an uneven portion on the inner surface of the belt, and forming a first unvulcanized sleeve in which a rubber member serving as the inner surface of the transmission belt is disposed on an inner mold fitted with a jacket. The step of inflating the jacket and pressing the first unvulcanized sleeve from the inner peripheral side to the outer mold having an indentation corresponding to the uneven portion to produce a preform with the uneven portion formed on the surface The step of forming the second unvulcanized sleeve by separating the inner mold from the outer mold in close contact with the preform, and sequentially arranging the rubber member and the twisted cord on the back of the transmission belt on the inner mold fitted with the jacket , And by inflating the jacket and pressing the second unvulcanized sleeve from the inner peripheral side to the outer mold to which the preformed body is in close contact, and vulcanizing integrally with the preformed body, Vulcanized belts with concave and convex parts A twisted cord, an aramid fiber and a fiber having an intermediate yarn elongation of 4 to 15% at a load of 4 cN / dtex and a weight ratio of the aramid fiber of 50 to 90 %, A transmission belt manufacturing method characterized in that a twisted cord that is mixed and twisted so as to be% is used.

  The invention of claim 7 of the present application is the method for producing a transmission belt according to claim 6, wherein the twisted cord is a twisted structure, and a lower twisted cord in which an aramid fiber is twisted, and a raw yarn intermediate elongation at 4 cN / dtex load. Is a twisted yarn cord in which a twisted cord obtained by twisting 4 to 15% of the fiber is mixed and twisted so that the upper twist coefficient is 2.0 to 7.0.

  The invention according to claim 8 of the present application is characterized in that, in the method for manufacturing a transmission belt according to claim 6 or 7, the elongation at 100 N of the twisted cord is 1.3 to 5.0%.

  The invention of claim 9 of the present application is the method for producing a transmission belt according to any one of claims 6 to 8, wherein the fiber having an intermediate yarn intermediate elongation of 4 to 15% at a load of 4 cN / dtex is a polyamide fiber. And / or polyethylene terephthalate fiber.

  The invention of claim 10 of the present application is characterized in that, in the method for manufacturing a transmission belt according to any one of claims 6 to 9, the uneven portion is a rib portion, and the transmission belt is a V-ribbed belt.

  By using a twisted cord in which an aramid fiber and a fiber having an intermediate yarn elongation of 4 to 15% at a load of 4 cN / dtex are mixed and twisted at a specific weight ratio as a core wire, the core wires can be aligned even in press molding. It is possible to manufacture a high-modulus transmission belt that can be used even in a drive device that suppresses the occurrence of defects and damage to the core wire and has a large engine load fluctuation. Moreover, by making the twisted yarn cord into a structure in which a lower twisted cord made of each fiber is twisted with a specific upper twisting coefficient, the modulus control of the twisted yarn cord is facilitated, and there is an effect that the composite can be sufficiently made. Further, by setting the elongation of the twisted cord to a specific value, it is possible to obtain a transmission belt in which irregularities in the core wire pitch and damage are further suppressed and irregularities are clearly marked. Moreover, there is an effect that the modulus design of the twisted cord becomes easy by using a specific fiber as a fiber having an intermediate elongation of 4 to 15% at a load of 4 cN / dtex. By applying it to a V-ribbed belt as a transmission belt, it is possible to easily manufacture a high-modulus V-ribbed belt that has a good core condition, a rib portion is clearly engraved, and a high modulus.

The transmission belt according to the present invention is a transmission belt having an uneven portion on the inner surface of the belt. As a specific example, a method for manufacturing a V-ribbed belt will be described with reference to FIGS.
FIG. 1 is a sectional view showing a state in which an unvulcanized belt sleeve of a belt vulcanizer used in the method for producing a V-ribbed belt according to the present invention is formed, and FIG. 2 shows a vulcanized belt sleeve of the belt vulcanizer. It is sectional drawing which shows the state after forming. In each of these drawings, an inner mold 20 is composed of an iron inner mold cylindrical drum 21 placed on a base and a cylindrical flexible jacket 22 that can be expanded and contracted comprising an elastic body mounted on the outer periphery of the drum 21. Become. The flexible jacket 22 is fixed to the inner cylindrical drum 21 at the upper and lower portions, and the main body is in close contact with the inner cylindrical drum 21. A medium flow port A for feeding and discharging a pressure medium, which will be described later, is provided at the center of the inner cylindrical drum 21.

  Further, a medium flow port A provided in the vicinity of the center of the inner cylindrical drum 21 passes a medium feed such as high-pressure steam or high-pressure air through a medium feed / discharge path B consisting of a joint J, a pipe or a flexible hose. It is connected to an incoming machine (not shown). The medium feed / discharge path B is also connected to a vacuum pump by a switching valve.

  The above is the configuration of the inner cylindrical drum 21, and the outer cylindrical mold 26 is fixed to the base so as to surround the outer cylindrical cylinder 26 with a certain distance from the outer periphery. The outer cylindrical mold 26 is provided with a plurality of horizontal V-shaped grooves extending in the circumferential direction on the inner peripheral surface thereof, and a heating mechanism (not shown) such as a heater and a steam vibe is installed therein. It becomes. The outer cylindrical mold 26 is normally a cylinder that cannot be divided, but can be divided into several pieces (for example, divided into two) in the axial direction.

  The belt vulcanizer used in the present invention is configured as described above. Next, a method for vulcanizing an unvulcanized belt sleeve that is carried out using this belt vulcanizer will be described.

  First, on the outer peripheral surface of the flexible jacket 22 attached to the inner drum 21, an unvulcanized stretched rubber sheet (rubber member serving as the back of the belt), a core wire (twisted cord), an unvulcanized compressed rubber sheet ( A flat wide unvulcanized belt sleeve 11 is formed by sequentially rubbing endless rubber members) on the belt inner surface. That is, an unvulcanized stretched rubber sheet is wound around an inner cylindrical drum 21 fitted with a flexible jacket 22, and the stretched rubber layer 15 is disposed. By wrapping the sheet, the unvulcanized belt sleeve 11 in which the compressed rubber layer 16 is disposed is formed.

  In addition, in order to improve the arrangement of the core wires 13 in the present production, the stretch rubber layer 15 can be composed of a rubber composition containing short fibers. In other words, since the stretched rubber layer having a high hardness is disposed adjacent to the inner peripheral surface of the core wire, the core wire is prevented from falling into the inner peripheral side during press molding to the outer mold, and the compressed rubber It becomes the structure which is hard to be influenced by the deformation of. As a result, the cord pitch is less disturbed, and since the canvas is not laminated on the back surface, the flexibility is high, the belt life is extended, and an inexpensive V-ribbed belt is obtained. In consideration of the flexibility of the belt, it is preferable that the short fibers contained in the unvulcanized stretched rubber layer 15 are arranged in the belt width direction. On the other hand, in order to ensure durability in multiple directions, it is preferable that the short fibers contained in the unvulcanized stretched rubber layer 15 are arranged in a random direction.

  Here, if the rubber layer surrounding the core wire 13 is a mixture containing all short fibers, the adhesion between the core wire 13 and the belt main body is difficult. For example, the stretch rubber layer 15 and the compression rubber layer 16 contain short fibers. When contained, it is preferable that the stretched rubber layer 15 and the compressed rubber layer 16 are not adjacent to each other and the adhesive rubber layer 12 is interposed. That is, after winding an unvulcanized stretched rubber sheet and spinning the core wire 13, before unwrapping the unvulcanized compressed rubber sheet, the unvulcanized adhesive rubber sheet is wound and the adhesive rubber layer 12 is disposed. By wrapping a rubber sheet in which the adhesive rubber layer 12 is laminated on the inner peripheral surface of the compressed rubber layer 16 as a vulcanized compressed rubber sheet, the adhesive rubber layer 12 that does not contain short fibers is disposed around the core wire 13, Improvements can be made. At this time, since the adhesive rubber layer 12 is disposed after spinning the core wire 13, the entire core wire is not embedded in the adhesive rubber layer in the vulcanized belt molded body, and part of the core wire is not molded. It will be in the state embed | buried under the extending | stretching rubber layer adjacent to a back side by the pressure of.

  Here, the core wire 13 is characterized by using a twisted yarn cord in which aramid fibers and fibers having an intermediate elongation of 4 to 15% are mixed and twisted so that the weight ratio of the aramid fibers is 50 to 90%. With this configuration, the initial modulus of the twisted yarn cord is lowered, that is, the initial elongation is increased, and the yarn can be smoothly stretched in response to the expansion of the jacket. Thus, it is possible to easily manufacture a high-modulus power transmission belt that is suitably used for a drive device having a large load fluctuation. When the weight ratio is less than 50%, the belt strength is lowered, and therefore cannot be applied to belt transmission with high load fluctuation. On the other hand, if the weight ratio exceeds 90%, the initial modulus does not decrease and the arrangement of the cores becomes poor. Here, the raw yarn intermediate elongation is a value of elongation at a load of 4 cN / dtex. If it is less than 4%, the initial elongation required at the time of jacket expansion cannot be secured, while if it exceeds 15%, the modulus of the twisted cord is too low.

  Furthermore, it is desirable to give the twisted yarn cord the characteristic that the elongation at 100 N is 1.3 to 5.0%. With this configuration, the cord can be smoothly extended with respect to the expansion of the jacket, so that the arrangement of the cores can be improved and the damage to the cores can be suppressed, and ribs (unevenness) are clearly formed on the belt sleeve surface. There is an effect that can be engraved. Here, the elongation at 100 N is a value of elongation at a load of 100 N (JIS L1017). If it is less than 1.3%, the initial elongation required at the time of expansion of the jacket cannot be ensured. On the other hand, if it exceeds 5.0%, the modulus of the belt is too low.

  As the fiber having a raw yarn intermediate elongation of 4 to 15%, a synthetic fiber having a lower modulus than that of aramid is preferably used. Specifically, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene Examples thereof include polyester fibers such as terephthalate (PET) fibers, polyamide fibers such as nylon 66 and nylon 46, and the like. Of these, polyamide and / or polyethylene terephthalate are preferably used. The twisted yarn cord preferably has a twisted structure, and a lower twisted cord obtained by twisting an aramid fiber and a lower twisted cord obtained by twisting a fiber having an intermediate elongation of 4 to 15% at a load of 4 cN / dtex is described below. When the upper twist coefficient defined by [Equation 1] is 2.0 to 7.0, the compounding is sufficient. If the upper twist coefficient is less than 2.0, the bending fatigue property of the cord is deteriorated. On the other hand, if it exceeds 7.0, the cord modulus is excessively lowered. More preferably, the lower twist cord made of aramid fiber has a lower twist coefficient of 2.0 to 7.0, and a lower twist cord made of fiber having an intermediate elongation of 4 to 15% at a load of 4 cN / dtex. It is desirable that the coefficient is 2.0 to 7.0. It is also possible to provide a medium twist between the upper twist and the lower twist. In addition, examples of compounding other than mixed twist include compounding by a core-sheath structure. Which fiber is used as the core or sheath can be determined as desired.

  The total fineness of the twisted cord is preferably 3,000 to 12,000 dtex. When the total fineness is less than 3,000 dtex, the modulus and strength of the cord are too low. On the other hand, when the total fineness exceeds 12,000 dtex, the belt becomes thick and the bending fatigue property is deteriorated. Moreover, as a structure of the lower twisted cord, the fineness of the lower twisted cord made of aramid fiber is 400 to 2,000 dtex, and the fineness of the lower twisted cord made of fiber having a raw yarn intermediate elongation of 4 to 15% is 400 to 2,000 dtex. It is preferable that

  As the core wire 13, a twisted cord subjected to an adhesion treatment can be used. As such an adhesion treatment, it is common to immerse the fiber in resorcin-formaldehyde-latex (RFL solution) and then heat-dry to form a uniform adhesion layer on the surface. However, the present invention is not limited to this, and there is also a method of performing a pretreatment with an epoxy or isocyanate compound and then treating with an RFL solution.

  The core wire 13 is desirably arranged so that the fineness in the belt width direction is 2,000 to 5,000 dtex / mm, more preferably 2,000 to 4,000 dtex / mm. If it is less than 2,000 dtex / mm, there is a risk that the belt strength becomes too low and the belt modulus gradually decreases. On the other hand, if it exceeds 5,000 dtex / mm, the belt modulus may be too high. Even if the fineness per belt width is the same, the heat generated by bending is less when using a thin cord, and the uniformity of the belt is better when the thin cord is wound more densely than when the thick cord is wound roughly. Lead to life. Further, when the cord is wound roughly, the cord pitch may be disturbed.

  Next, the unvulcanized belt sleeve 11 is placed and fixed on the base so as to form a certain gap inside the outer mold 26 while the unvulcanized belt sleeve 11 is being rubbed against the inner cylindrical drum 21. In this case, because the inner drum 21 is moved from another molding step, the medium flow port A and the medium feeding / discharging path B are separated, and after the inner cylindrical drum 21 is placed on the base The medium distribution port A is connected to the pipe by a joint J.

  Next, the medium feeder is operated to feed high-pressure air or high-pressure steam into the flexible jacket 22 through the medium inlet / outlet passage B and the medium circulation port A. Since the upper and lower portions of the flexible jacket 22 are hermetically fixed on the inner cylindrical drum 21, air is filled between the inner surface of the flexible jacket 22 and the outer surface of the inner cylindrical drum 21. The flexible jacket 22 gradually expands. Then, the unvulcanized belt sleeve 11 mounted on the outer peripheral surface thereof is uniformly expanded in the radial direction and brought into contact with the V-shaped protrusions of the outer mold 26 heated by a heater or high temperature steam.

  At this time, the unvulcanized compressed rubber of the unvulcanized belt sleeve 11 is vulcanized while gradually flowing with the heat of the outer mold 26 due to the expansion pressing force of the flexible jacket 22, and the outer mold The vulcanized belt sleeve 11 ′ having a plurality of V-shaped grooves on the surface as shown in FIG. In the present invention, a twisted cord that has a large elongation and maintains strength is used as the core wire, so that it is possible to press vulcanize the belt sleeve with a high expansion pressing force without damaging the core wire. It can be engraved clearly and accurately. At this time, if the rubber composition constituting the stretched rubber layer 15 ′ contains short fibers, the rubber composition is hardly affected by the flow of the compressed rubber, and deformation in the radial direction is reduced. As a result, the rubber composition is adjacent to the stretched rubber layer 15 ′. There is an effect that the alignment state of the core wires 13 'is maintained. When the compressed rubber layer 16 'contains short fibers, the short fibers are in a flow state along the rib shape in the compressed rubber layer after vulcanization molding.

  Then, after vulcanization, the valve is switched to the vacuum pump, the vacuum pump is operated, the air filled in the flexible jacket 22 is exhausted, and then the flexible jacket 22 is moved to the first by suction action. The contraction is restored to the original position shown in the figure.

  Next, the vulcanized belt sleeve 11 ′ is taken out from the inner cylindrical drum 21, and the taken out vulcanized belt sleeve 11 ′ is inserted into another drum thereafter, and the vulcanized belt sleeve 11 ′ is set to a predetermined width in the circumferential direction. By cutting it into two pieces, taking it out from the drum and inverting it, a plurality of V-ribbed belts having a constant peripheral length and accurately shaped V-shaped ribs are obtained. When the outer cylindrical mold 26 is a split mold as described above, the unvulcanized belt sleeve 11 can be easily inserted and the vulcanized sleeve can be removed, and this split surface is a kind of air vent function. As a result, the V-shaped rib can be formed more accurately.

  According to the manufacturing method described above, a V-ribbed belt in which ribs are accurately engraved in a simple process, damage to the core wire and disturbance of the core wire pitch can be suppressed, and high strength can be maintained. There are advantages such as.

  Next, another method for manufacturing the V-ribbed belt according to the present invention will be described with reference to FIGS. FIG. 3 is a sectional view showing a state in which a first unvulcanized sleeve of a belt vulcanizer used in another method for producing a V-ribbed belt according to the present invention is formed, and FIG. 4 is a preformed belt vulcanizer. FIG. 5 is a sectional view showing a state in which the second unvulcanized sleeve of the belt vulcanizer is formed, and FIG. 6 is a sectional view showing the vulcanized belt sleeve of the belt vulcanizer. It is sectional drawing which shows the formed state. The belt vulcanizer used here can be the same as described above.

  First, as shown in FIG. 3, a flat shape in which an unvulcanized adhesive rubber sheet and an unvulcanized compressed rubber sheet are sequentially wound around an outer peripheral surface of a flexible jacket 22 attached to an inner cylindrical drum 21 in an endless manner. Wide unvulcanized sleeve (first unvulcanized sleeve 30) is formed. That is, after the unvulcanized adhesive rubber sheet is wound around the inner cylindrical drum 21 to which the flexible jacket 22 is attached and the adhesive rubber layer 12 is disposed, the unvulcanized compressed rubber sheet is wound around to form the compressed rubber layer 16. The arranged first unvulcanized sleeve 30 is formed. Note that the first unvulcanized sleeve 30 may be formed by winding an unvulcanized rubber sheet in which the adhesive rubber layer 12 and the compressed rubber layer 16 are laminated in advance.

  Here, although the structure which has the adhesive rubber layer 12 was mentioned as the 1st unvulcanized sleeve 30, it is also possible to set it as the structure only of the compression rubber layer 16 without arrange | positioning the adhesive rubber layer 12. FIG. However, if the rubber layer surrounding the core wire 13 contains all short fibers, the adhesion between the core wire 13 and the belt body is difficult, so if the compressed rubber layer 16 contains short fibers, the stretch rubber It is preferable that the adhesive rubber layer 12 be interposed without the layer 15 and the compressed rubber layer 16 being adjacent to each other.

  Next, a certain gap is formed inside the outer cylindrical mold 26 while the compressed rubber layer 16 with the adhesive rubber layer 12 (first unvulcanized sleeve 30) is being rubbed against the inner cylindrical drum 21. Place and fix on the base. Since the inner cylindrical drum 21 is moved from another molding step, the medium circulation port A and the medium feeding / discharging path B are separated, and after the inner cylindrical drum 21 is placed on the base, the medium The distribution port A is connected to the pipe by a joint J.

  Next, the medium feeder is operated to feed high-pressure air or high-pressure steam into the flexible jacket 22 through the medium inlet / outlet passage B and the medium circulation port A. Since the upper and lower portions of the flexible jacket 22 are hermetically fixed on the inner cylindrical drum 21, air is filled between the inner surface of the flexible jacket 22 and the outer surface of the inner cylindrical drum 21, and the flexible jacket 22 is flexible. The sex jacket 22 expands gradually. The first unvulcanized sleeve 30 mounted on the outer peripheral surface is uniformly expanded in the radial direction, and the outer cylindrical mold 26 having V-shaped protrusions heated to 130 to 160 ° C. with a heater or high-temperature steam. For 10 to 30 seconds.

  At this time, the compression rubber layer 16 is pressed against the V-shape of the outer cylindrical mold 26 by the expansion pressing force of the flexible jacket 22, and the preformed body 31 having a plurality of V-shaped grooves on the surface as shown in FIG. To form.

  After that, the valve is switched to the vacuum pump, the vacuum pump is operated, the air filled in the flexible jacket 22 is exhausted, and then the flexible jacket 22 is shown in FIG. Restore contraction to the position. At this time, the preformed body 31 is in close contact with the outer cylindrical mold 26.

  Then, after taking out the inner cylindrical drum 21 from the outer cylindrical mold 26 and winding the unvulcanized stretched rubber sheet around the outer peripheral surface of the flexible jacket 22 of the inner cylindrical drum 21, the stretched rubber layer 15 is disposed. The second unvulcanized sleeve 32 is formed by spinning the core wire 13 in a spiral shape. Here, considering the flexibility of the belt, the unvulcanized stretched rubber layer 15 is preferably arranged so that the short fibers are oriented in the belt width direction. Then, after the inner cylindrical drum 21 is installed in the outer cylindrical mold 26 as shown in FIG. 5, the flexible jacket 22 is expanded as shown in FIG. 6, and the stretched rubber layer 15 and the core wire 13 ( The second unvulcanized sleeve 32) is uniformly expanded in the radial direction and pressed against the preform 31 that is in close contact with the outer cylindrical mold 26 having a V-shaped projection heated to 150 to 180 ° C. with a heater or high-temperature steam. Are integrally vulcanized to produce a vulcanized belt sleeve 11 '.

  Here, the core wire 13 uses the same twisted yarn cord as described above. In the present invention, a twisted cord that has a large initial elongation and maintains strength as a core wire is used. Therefore, it is possible to press vulcanize the belt sleeve with a high expansion pressing force without damaging the core wire, and consequently The rib can be engraved precisely and accurately. The obtained V-ribbed belt has a high modulus and is suitably used for a drive device having a large engine load fluctuation.

  At this time, since the adhesive rubber layer 12 exists on the outer periphery of the core wire 13 as a preformed body 31, the entire core wire is not embedded in the adhesive rubber layer in the belt molded body after vulcanization. The portion is embedded in the stretched rubber layer adjacent to the back side due to the pressure during molding. Since the preform is prepared in advance, the core wire is not easily affected by the flow of the compressed rubber and the radial deformation is reduced. As a result, the core wire 13 'adjacent to the stretched rubber layer 15' is aligned. Is maintained. Further, when a rubber composition containing short fibers is used as the rubber composition constituting the stretched rubber layer 15 ′, it is possible to further suppress the radial deformation of the core wire.

  Next, the vulcanized belt sleeve 11 ′ is taken out from the inner cylindrical drum 21, and the taken out vulcanized belt sleeve 11 ′ is inserted into another drum thereafter, and the vulcanized belt sleeve 11 ′ is set to a predetermined width in the circumferential direction. By cutting it into two pieces, taking it out from the drum and inverting it, a plurality of V-ribbed belts having a constant peripheral length and accurately shaped V-shaped ribs are obtained. When the split mold as described above is used as the outer cylindrical mold 26, the unvulcanized sleeve can be easily inserted and the vulcanized sleeve can be removed, and this split surface can function as a kind of air vent. In addition, the V-shaped rib can be formed more accurately.

  According to the manufacturing method described above, there is an advantage that a rib can be accurately engraved, a damage to the core wire and a disturbance in the core wire pitch can be suppressed, and a V-ribbed belt that maintains strength can be manufactured. Further, by forming the unvulcanized preform 31, it is possible to manufacture a V-ribbed belt excellent in dimensional stability because the amount of elongation of the core wire 13 is suppressed and the shrinkage after demolding is small.

  In addition, the manufacturing method of this invention can also spin a twisted cord, after arrange | positioning an extending | stretching layer and an contact bonding layer one by one. Further, after the extension layer and the adhesive layer are sequentially arranged, the twisted yarn cord is spun, and further, the adhesive layer and the compressed rubber layer can be sequentially arranged. However, considering the arrangement of the core wires, it is desirable not to dispose the adhesive layer before spinning the twisted cord, that is, to dispose the adhesive layer on the inner peripheral side of the twisted cord in forming the unvulcanized belt sleeve.

  The stretch layer may be a stretch rubber layer containing short fibers in a random orientation state. As a result, since it is resistant to forces acting from multiple directions without showing directionality in a certain direction, it is possible to suppress the occurrence of cracks and cracks from multiple directions, thereby improving the belt life. Can play. At this time, the short fiber is preferably a short fiber having a bend, for example, a nylon milled fiber. Alternatively, the concavo-convex pattern may be formed on the surface of the stretched rubber layer by performing vulcanization with the concavo-convex pattern transfer material interposed between the stretched rubber layer and the inner mold, and then peeling off the concavo-convex pattern transfer material.

  Moreover, the said manufacturing method may include the process of flocking the surface of compressed rubber. As a manufacturing method including this process, there exist the following, for example.

  (A) A non-vulcanized compressed rubber sheet is subjected to flocking, and the unvulcanized compressed rubber sheet is rubbed against an inner mold, thereby placing a compressed rubber layer subjected to flocking. That is, a compressed rubber layer in which flocking is performed in advance on the inner mold is disposed. The unvulcanized compressed rubber sheet can be produced by forming an adhesive layer on the sheet surface and attaching short fibers on the adhesive layer.

  (B) After placing the compression rubber layer on the inner mold, flocking is performed. Specifically, an unvulcanized compressed rubber sheet is spread on an inner mold and a compressed rubber layer is disposed, and then an adhesive layer is formed on the surface, and short fibers are adhered onto the adhesive layer.

  (C) The hair is planted by pressing an unvulcanized sleeve having a compressed rubber layer disposed on the outer periphery thereof onto an outer mold having rib markings with short fibers attached to the inner peripheral surface. Specifically, an outer mold having rib imprints with short fibers attached to the inner peripheral surface via an adhesive layer is prepared, and an unvulcanized sleeve having a compressed rubber layer disposed on the outer periphery is pressed against the outer mold. Short fibers are attached to the sleeve surface.

  (D) Planting the vulcanized belt sleeve with ribs. Specifically, an adhesive layer is formed on the surface of the compressed rubber layer of the vulcanized belt sleeve in which the ribs are engraved, and the short fibers are adhered onto the adhesive layer. At this time, the adhesive layer may be formed or the short fibers may be attached while the vulcanized belt sleeve is installed on one shaft or is stretched on two shafts and rotated.

  Examples of a method for forming an adhesive layer in flocking include a method in which an adhesive is applied by a spray method, a dip method, or the like. Before forming the adhesive layer, the surface may be subjected to a pretreatment such as a cleaning treatment such as alcohol wiping or a primer treatment.

  Examples of the adhesive include RFL (resorcin-formaldedo-latex) liquid, urethane emulsion, acrylic emulsion, vinyl acetate emulsion, styrene emulsion, rubber adhesive, and organic solvent adhesive. The RFL liquid is obtained by mixing an initial condensate of resorcin and formaldehyde in a latex. Examples of the latex used here include chloroprene, styrene-butadiene-vinylpyridine terpolymer, hydrogenated nitrile, NBR, ethylene. This is an α-olefin / diene copolymer rubber latex. An isocyanate compound can also be added to the RFL solution.

  The thickness of the adhesive layer is not particularly limited, but is 0.05 to 1 mm, preferably 0.05 mm to 0.5 mm.

  The method for attaching the short fiber is not limited to a mechanical or electrostatic method. For example, the short fibers are adhered to the rubber surface by dropping or spraying the compressed fibers on the compressed rubber on which the adhesive layer is formed, and then natural or heat drying is performed. Also, for example, a short fiber in which an electric field is formed by applying a voltage to an electrode of an electrostatic flocking machine, and a surface in which the surface is electrodeposited is formed by applying a voltage to an electrode of an electrostatic flocking machine. , Fly and stick to the rubber surface to attach the short fibers, and then perform natural or heat drying.

  As a method of attaching short fibers to the inner peripheral surface of the outer mold through an adhesive layer, for example, after applying a release agent such as silicone oil to the inner peripheral surface, the adhesive layer is formed by the method described above. Then, the short fiber can be attached by dropping or spraying, or the outer mold can be charged and the short fiber can be blown by the lines of electric force and attached.

The material of the short fiber is selected from polyester, nylon, aramid, vinylon, carbon fiber, polytetrafluoroethylene, cotton and the like as desired. The length of the short fiber is preferably 0.1 to 5.0 mm, and the aspect ratio (length Lmm / thickness diameter Dmm) is preferably 30 to 300. Further, the density of the short fibers contributes to the friction coefficient and the sound during running, and is specifically 10,000 to 500,000 pieces / cm ² but is not limited.

  Instead of forming an adhesive layer on the surface of the compressed rubber and attaching the short fibers, an adhesive containing short fibers may be attached to the surface of the compressed rubber.

  One embodiment of the V-ribbed belt obtained by such a manufacturing method is shown in FIG. In the V-ribbed belt 1, the back surface 8 is formed of an extended rubber layer 5 containing short fibers 4, and a core wire 3 is disposed adjacent to the extended rubber layer 5 in the belt longitudinal direction. The portion is embedded in the stretched rubber layer 5. In addition, an adhesive rubber layer 2 and a compressed rubber layer 6 containing short fibers 4 are arranged below the stretched rubber layer 5. The compressed rubber layer 6 is provided with a plurality of rib portions 7 having a substantially triangular cross section extending in the belt longitudinal direction.

  FIG. 8 shows another embodiment of the V-ribbed belt. In the V-ribbed belt 1, the back surface 8 is formed of an extended rubber layer 5 containing short fibers 4, and a core wire 3 is disposed adjacent to the extended rubber layer 5 in the belt longitudinal direction. The portion is embedded in the stretched rubber layer 5. The lower layer of the stretched rubber layer 5 has a configuration in which a compressed rubber layer 6 not containing short fibers is disposed. The compressed rubber layer 6 is provided with a plurality of rib portions 7 having a substantially triangular cross section extending in the longitudinal direction of the belt, and short fibers 9 are planted on the surface.

  The rubber used for the compressed rubber layer 6 includes ethylene-α-olefin elastomer, nitrile rubber, hydrogenated nitrile rubber, hydrogenated nitrile rubber added with unsaturated carboxylic acid metal salt, chlorosulfonated polyethylene, chloroprene. , Urethane rubber, epichlorohydrin rubber, natural rubber, CSM, ACSM, SBR and the like.

  Hydrogenated nitrile rubber has a hydrogenation rate of 80% or more, and preferably 90% or more in order to exhibit heat resistance and ozone resistance characteristics. Hydrogenated nitrile rubber having a hydrogenation rate of less than 80% has extremely low heat resistance and ozone resistance. In consideration of oil resistance and cold resistance, the amount of bound acrylonitrile is preferably in the range of 20 to 45%.

  Chlorosulfonated polyethylene has a chlorine content of 15 to 35% by weight, preferably 25 to 32% by weight, and a chlorosulfonated linear chain having a sulfur content in the range of 0.5 to 2.5% by weight. Low density polyethylene.

  Examples of the ethylene-α-olefin elastomer include ethylene-propylene rubber (EPR) and ethylene-propylene-diene monomer (EPDM). Examples of diene monomers include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene, and the like.

  A peroxide can be added as a vulcanizing agent for the ethylene-α-olefin elastomer. In addition, as a co-agent, TIAC, TAC, 1,2 polybutadiene, metal salt of unsaturated carboxylic acid, oximes, guanidine, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, NN′-m -Phenylene bismaleimide, sulfur and the like are usually used for peroxide crosslinking.

  Among these, N, N'-m-phenylene dimaleimide is preferable, and by adding this, the degree of crosslinking can be increased to prevent adhesive wear and the like. The addition amount of N, N′-m-phenylene dimaleimide is 0.2 to 10 parts by weight with respect to 100 parts by weight of the ethylene-α-olefin elastomer. The effect of improving wear resistance and adhesive wear resistance is small, and when the amount exceeds 10 parts by weight, the elongation of the vulcanized rubber is remarkably lowered, resulting in a problem in bending resistance.

  For the above rubber, publicly known rubber compounding agents such as reinforcing materials such as short fibers, carbon black and silica, fillers such as clay and calcium carbonate, plasticizers, softeners, processing aids, anti-aging agents, vulcanizing agents A co-crosslinking agent and the like can be blended as desired.

  Further, as shown in FIG. 8, it is also possible to plant short fibers 9 on the surface of the compressed rubber layer of the V-ribbed belt 1 to reduce noise during belt running.

  The stretch rubber layer 5 can use the same matrix rubber and compounding agent as the compression rubber layer described above. As the short fiber 4 to be blended, nylon 6, nylon 66, polyester, cotton, aramid and the like can be used, and those having a fiber length of 1 to 20 mm are preferably used. The amount added is 1 to 30 parts by weight per 100 parts by weight of rubber.

  Moreover, the short fiber 4 can also be a short fiber having a bend. The short fiber having bending may be any fiber having one or more bent portions per one short fiber. Specifically, milled fiber can be used. The milled fiber is a short fiber obtained by, for example, pulverizing chopped strands with a mill or the like, and can form a short fiber having an appropriate bent portion by a load during the pulverizing process. The stretch rubber layer 5 may also contain short fibers that do not have a bent portion in addition to short fibers that have a bent portion. For example, polyamide (such as nylon short fiber) can be used as the material, and the fiber length is preferably in the range of 0.1 to 3.0 mm.

  The surface layer of the belt back surface 8 can be provided with a concavo-convex pattern so as to suppress abnormal noise during back surface driving. For example, in the above-described step, vulcanization is performed in a state where the uneven pattern transfer material is interposed between the flexible jacket 22 and the stretched rubber layer 15, and then the uneven pattern transfer material is peeled off to give the uneven pattern. Further, for example, a flexible jacket 22 having an uneven pattern can be used. Examples of the concavo-convex pattern include a knitted fabric pattern, a woven fabric pattern, a suede woven fabric pattern, and the like, and most preferably a woven fabric pattern. Due to the unique pattern of the fabric pattern, it is possible to prevent the friction coefficient from being lowered and to effectively prevent the generation of abnormal noise when driving the back surface.

  To illustrate a specific process for forming the concave / convex pattern, a cylindrical canvas having an ultrasonic welding joint is inserted into an inner cylindrical drum 21 to which a flexible jacket 22 is attached. As this tubular canvas, a fabric woven into plain weave, twill weave, satin weave, etc. using yarns composed of organic fibers such as polyamide, polyester, polyethylene, polyurethane, polystyrene, polyfluoroethylene, polyacryl, polyvinyl alcohol, etc. It is also a knitted fabric. Then, an unvulcanized stretched rubber sheet is wound on the tubular canvas and molded in the same manner as described above to form a vulcanized belt sleeve. The obtained vulcanized sleeve is extracted from the mold, and the concave-convex pattern can be imparted by forcibly peeling the cylindrical fabric.

  Although it is the depth of an uneven | corrugated pattern, it is preferable to set it as the pattern of the range of 0.1-0.6 mm in average depth. If this average depth is less than 0.1 mm, the convex portion of the pattern becomes small, and the friction coefficient does not decrease, so that abnormal noise is easily generated when driving the back surface. Conversely, the depth exceeds 0.6 mm. If it is, the convex part on the surface of the transport surface may be scraped or torn off due to friction with the transported object, so that the rubber powder may be scattered around and the belt may be damaged in some cases. It is not preferable.

  When the adhesive rubber layer 2 is disposed, the same rubber composition as that of the compressed rubber layer 6 is used. However, ethylene-α-olefins by sulfur vulcanization that do not contain peroxide in order to bond well with aramid fibers, which are core wires, and fibers with an intermediate elongation of 4-15% at 4 cN / dtex load. Elastomer compositions, chlorosulfonated polyethylene compositions or hydrogenated nitrile rubber compositions can also be used. It is desirable not to mix short fibers.

  In addition, as an embodiment of the V-ribbed belt, the adhesive rubber layer 2 is disposed, and the V-ribbed belt (FIG. 7) configured of a rubber composition containing short fibers as the compressed rubber layer 6 and the adhesive rubber layer 2 are not disposed. Although the V-ribbed belt (FIG. 8) which comprised the rubber composition which does not contain a short fiber as the compression rubber layer 6 and planted the short fiber 9 on the surface was illustrated, for example, the adhesive rubber layer 2 is arrange | positioned and the compression rubber layer 6 is used. The V-ribbed belt composed of a rubber composition not containing short fibers, the V-ribbed belt composed of a rubber composition containing short fibers as the compressed rubber layer 6 and having the short fibers 9 planted on the surface thereof, etc. Belongs to a range.

Further, although the V-ribbed belt having the rib portion is exemplified as the transmission belt, the present invention is not limited to this, and the present manufacturing method can be applied to any transmission belt having an uneven portion on the inner surface of the belt.

Hereinafter, the present invention will be described in more detail with reference to specific examples.
Examples 1-7, Comparative Examples 1-3
First, as shown in Table 1, 1,100 dtex para-aramid fiber, 940 dtex nylon 66 fiber, 1,100 dtex polyethylene terephthalate fiber (PET fiber) are twisted with the lower twist coefficient shown in Table 1, respectively, A lower twisted cord made of fiber was produced. In Examples 1 to 5, three aramid under twisted cords and one nylon under twisted cord, in Example 6, two aramid under twisted cords and two nylon under twisted cords, and in Example 7, an aramid under twisted cord. Table 1 shows three cords and one PET twisted cord. In Comparative Examples 1 and 2, three aramid twisted cords, and in Comparative Example 3, one aramid twisted cord and three nylon twisted cords are shown in Table 1. Various twists were made with the upper twist coefficient shown to prepare a twisted cord that becomes a core wire.

  Next, each twisted yarn cord was pre-dipped with 90 g of toluene and an adhesive composed of 10 g of PAPI (polyisocyanate compound manufactured by Kasei Upjohn), and then passed through a drying oven set at 200 ° C. for 2 minutes and dried. Subsequently, the adhesive composed of the RFL liquid shown in Table 2 was impregnated and heat-treated at 230 ° C. for 2 minutes, and heat-stretched and fixed at a heat-set stretch rate of 0 to 3% during this heat treatment. Furthermore, each cord was immersed in rubber paste diluted with the compounded rubber shown in Table 3 so that the solid content concentration became 10%, and then heat treated at 160 ° C. for 4 minutes to bond the twisted cord.

  As the physical properties of this adhesion-treated cord, the following elongation at 100 N (%) and cord tensile strength (N) were measured.

(1) 100N elongation (%)
Each twisted cord was pulled at a speed of 300 mm / min, and the elongation (%) at 100 N was measured.

(2) Cord tensile strength (N)
Each twisted cord was pulled at a speed of 300 mm / min, and the tensile strength (N) when the cord was cut was measured.

The manufacturing method of the V-ribbed belt in the present embodiment is as follows.
First, a stretched rubber sheet is wound around a flexible jacket mounted on a cylindrical molding drum, a twisted cord that has been subjected to the above-described adhesion treatment is spun, and further, a compressed rubber sheet is wound around and an unvulcanized belt Form a sleeve. Then, the flexible jacket is expanded, the unvulcanized sleeve is pressed against an outer mold having a stamp corresponding to the rib portion, vulcanized, and the obtained vulcanized belt sleeve is cut into individual belts by a cutter. Thus, a V-ribbed belt was obtained.

  Here, the compressed rubber sheet was prepared by preparing a rubber composition according to the composition shown in Table 3, kneading with a Banbury mixer, and rolling with a calender roll. In addition, a rubber composition in which nylon milled fiber (fiber length: 2 mm) is blended with 10 parts by weight with respect to 100 parts by weight of the rubber component in the composition shown in Table 2 is prepared, kneaded with a Banbury mixer, rolled with a calendar roll, and stretched. A rubber sheet was prepared.

  In the manufactured V-ribbed belt, a cord made of a twisted cord is embedded in the belt body, the back surface (extension portion) is formed of a rubber layer, and three rib portions are attached to the compression portion provided on the other surface side of the belt. It is arranged in the longitudinal direction. The stretched portion contains short fibers, and the short fibers are oriented in a random direction. This V-ribbed belt was a K-type 3-ribbed belt having a length of 1,100 mm according to the RMA standard, and had a rib pitch of 3.56 mm, a rib height of 2.9 mm, and a rib angle of 40 °.

  Next, the V-ribbed belt was evaluated. The results are shown in Table 4. The test method is as follows.

(1) Belt tensile strength (kN / rib)
By pulling the belt at a speed of 50 mm / min, the tensile strength required to cut the belt was measured and converted to the tensile strength per rib (3.56 mm).

(2) Arrangement of core wires The cross-section in the width direction of the belt was confirmed by an enlarged surface photograph, and it was confirmed whether there was any pitch disturbance.

  As a result, it was found that the V-ribbed belt of the present invention is a V-ribbed belt having favorable core alignment and high modulus.

  The transmission belt obtained by the manufacturing method according to the present invention is attached to a drive device for automobiles or general industries. Especially, it is used suitably in the drive device with a large load fluctuation.

It is sectional drawing which shows the state which formed the unvulcanized belt sleeve of the belt vulcanizer used in the manufacturing method of the V-ribbed belt which concerns on this invention. It is sectional drawing which shows the state which formed the vulcanization belt sleeve of the belt vulcanizer used in the manufacturing method of the V-ribbed belt which concerns on this invention. It is sectional drawing which shows the state which formed the 1st unvulcanized sleeve of the belt vulcanizer used in another manufacturing method of the V-ribbed belt which concerns on this invention. It is sectional drawing which shows the state which produced the preformed body of the belt vulcanizer used in another manufacturing method of the V-ribbed belt which concerns on this invention. It is sectional drawing which shows the state which formed the 2nd unvulcanized sleeve of the belt vulcanizer used in another manufacturing method of the V-ribbed belt which concerns on this invention. It is sectional drawing which shows the state which produced the vulcanization belt sleeve of the belt vulcanizer used in another manufacturing method of the V-ribbed belt which concerns on this invention. It is sectional drawing of the V-ribbed belt obtained by the manufacturing method which concerns on this invention. It is sectional drawing of another V-ribbed belt obtained by the manufacturing method which concerns on this invention.

Explanation of symbols

1 V-ribbed belt 2 Adhesive rubber layer 3 Core wire 4 Short fiber 5 Stretch rubber layer 6 Compressed rubber layer 7 Rib part 8 Back

Claims (10)

In the method of manufacturing a transmission belt having an uneven portion on the inner surface of the belt,
A step of forming an unvulcanized belt sleeve by sequentially arranging a rubber member on the back surface of the transmission belt, a twisted cord, and a rubber member on the inner surface of the transmission belt on the inner mold fitted with the jacket, and expanding the jacket Including pressing the unvulcanized belt sleeve against an outer mold having a mark corresponding to the part to vulcanize, and forming a vulcanized belt sleeve having a concavo-convex portion engraved on the surface,
As the twisted yarn cord, a twisted yarn cord in which aramid fiber and a fiber having an intermediate elongation of 4 to 15% at a load of 4 cN / dtex are mixed and twisted so that a weight ratio of the aramid fiber is 50 to 90% is used. A method for manufacturing a transmission belt.   The twisted yarn cord has a multi-twisted structure, and the upper twisting factor is 2 when the lower twisted cord obtained by twisting aramid fibers and the lower twisted cord obtained by twisting fibers having an intermediate elongation of 4 to 15% at 4 cN / dtex load. The method for manufacturing a transmission belt according to claim 1, wherein the twisted cord is mixed and twisted so as to be 0.0 to 7.0.   The process for producing a transmission belt according to claim 1 or 2, wherein the twisted cord has an elongation at 100 N of 1.3 to 5.0%.   The method for producing a transmission belt according to any one of claims 1 to 3, wherein the fiber having an intermediate yarn intermediate elongation of 4 to 15% at a load of 4 cN / dtex is a polyamide fiber and / or a polyethylene terephthalate fiber.   The method for manufacturing a transmission belt according to any one of claims 1 to 4, wherein the uneven portion is a rib portion, and the transmission belt is a V-ribbed belt. In the method of manufacturing a transmission belt having an uneven portion on the inner surface of the belt,
A step of forming a first unvulcanized sleeve in which a rubber member serving as an inner surface of a transmission belt is disposed on an inner mold fitted with a jacket, the jacket is expanded, and the outer mold having an indentation corresponding to the uneven portion is A process for producing a preform by pressing an unvulcanized sleeve from the inner peripheral side and engraving irregularities on the surface, an inner mold is separated from an outer mold in close contact with the preform, and a jacket is attached In the mold, a rubber member serving as the back surface of the transmission belt, a twisted cord is sequentially disposed to form a second unvulcanized sleeve, and an outer mold is inflated to closely contact the preformed body. (2) A step of forming a vulcanized belt sleeve having a concavo-convex portion engraved on the surface by pressing the unvulcanized sleeve from the inner peripheral side and vulcanizing integrally with the preform,
As the twisted yarn cord, a twisted yarn cord obtained by mixing aramid fiber and low modulus fiber having a raw yarn intermediate elongation of 4 to 15% at 4 cN / dtex load so that the weight ratio of the aramid fiber is 50 to 90% is used. A manufacturing method of a transmission belt characterized by the above.   The twisted yarn cord has a multi-twisted structure, and the upper twisting factor is 2. The lower twisted cord obtained by twisting aramid fiber and the twisted cord obtained by twisting a fiber having an intermediate elongation of 4 to 15% at a load of 4 cN / dtex. The method for manufacturing a transmission belt according to claim 6, wherein the twisted cord is mixed and twisted so as to be 0 to 7.0.   The method for manufacturing a transmission belt according to claim 6 or 7, wherein the elongation at 100 N of the twisted cord is 1.3 to 5.0%.   The method for manufacturing a transmission belt according to any one of claims 6 to 8, wherein the fiber having an intermediate elongation of 4 to 15% at a load of 4 cN / dtex is a polyamide fiber and / or a polyethylene terephthalate fiber.   The method for manufacturing a transmission belt according to any one of claims 6 to 9, wherein the uneven portion is a rib portion, and the transmission belt is a V-ribbed belt.

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