JP2003001720A - Method for producing transmission belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a transmission belt such as a V-ribbed belt and a double ribbed belt which can be molded at a low cost with a production manday reduced, is excellent in side pressure resistance and reduces noise during traveling. SOLUTION: The method for producing the transmission belt includes the first process in which a cylindrical molding 13 having short fibers oriented in the circumferential direction by an annular expansion die 15 connected to an extruder is extrusion-molded and formed into a short fiber-oriented rubber sheet 18 while being cut linearly; the second process in which a rib groove 19 extending longitudinally is cut in the moving sheet 18 by a pair of cutters 31 having ultrasonic vibrators 32, and the third process in which the sheet 18 is wound onto a cylindrical molding mold to form a belt molding, and the belt molding is vulcanized to form a belt sleeve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a power transmission belt, and more specifically, a V-ribbed belt which can be manufactured at low cost by reducing the number of manufacturing steps, has excellent lateral pressure resistance, and reduces noise during running. Alternatively, it relates to a method for manufacturing a transmission belt such as a double ribbed belt.

[0002]

2. Description of the Related Art In a V-ribbed belt, a core wire is embedded in an adhesive rubber layer, and a cover canvas is laminated on the adhesive rubber layer.
A plurality of ribs are provided below the adhesive rubber layer. This V-ribbed belt is widely used instead of the V-belt as a power transmission for driving an auxiliary machine such as an air compressor or alternator of an automobile.

This belt is manufactured by laminating a belt sleeve in which a canvas, an adhesive rubber layer, a cord made of a cord, and a compression rubber layer are laminated and integrated by vulcanization, and the compression rubber layer is ground into a rib groove by a grinder wheel. It was something that was done. This belt has aramid short fibers exposed or protruding from the rib groove surface of the compression rubber layer, and when the aramid short fibers are suspended and run on a pulley for driving an auxiliary machine such as an air compressor or alternator of an automobile, the short aramid short fibers are projected. The fiber was interposed between the belt and the pulley to prevent noise and abnormal noise when the belt was running. However, in this belt manufacturing method, rubber scraps are generated when the rib groove is ground, and an early improvement is desired in view of environmental problems.

For this reason, recently, as a belt manufacturing method for reducing the amount of material waste as much as possible, Japanese Patent Laid-Open Publication No. HEI-1 has been proposed.
No. 0-86236 discloses that a belt sleeve having a buffer layer and a compression layer is produced, the belt sleeve is placed in a mold, the rib portion is marked, and then the resin is vulcanized to expose the fiber. A method of removing a thin surface layer is disclosed.

Further, Japanese Patent Laid-Open No. 8-74936 discloses that
A short rib is oriented by an extruder equipped with an expansion die at the outlet to extrude a cylindrical rib rubber tube having a V rib portion on the outer or inner circumference, which is incised to form a rib rubber sheet, which is wound around a mold. It is described that a belt molded body is obtained, which is vulcanized and the rib surface is ground to form a V-ribbed belt.

[0006]

However, in the method in which the belt sleeve is installed in a mold having an engraved inner surface and the ribs are engraved and then vulcanized, short fibers are contained in the rubber. In addition, under normal temperature and pressure conditions, the rib portion may not be sufficiently imprinted, so the level of these conditions was raised to give a large heat history to the rubber. Also,
Since the belt sleeve is installed inside the mold and the inner pressure is applied to press against the inner wall of the mold, it is difficult to remove the belt sleeve after molding. In addition, since the short fibers are oriented in a curved state in the rib portion of the obtained belt, the lateral pressure resistance of the belt was insufficient.

When a cylindrical rib rubber tube is extruded from an expansion die and cut into a rib rubber sheet to be used, the expansion die is used to form the V-rib portion. The short fibers were oriented in a curved state in the rib portion of the obtained belt, and similarly, the lateral pressure resistance of the belt was sometimes insufficient. In addition, it is necessary to increase the pressing force of the extruder, the internal heat generation is increased, and the rubber hardness is likely to be increased, which causes a problem of impairing the fluidity.

The present invention has been made in view of the above-mentioned actual situation and copes with the situation. A V which has a reduced number of manufacturing steps and can be molded at a low cost, has excellent lateral pressure resistance, and has reduced running noise.
An object of the present invention is to provide a method for manufacturing a transmission belt such as a ribbed belt or a double ribbed belt.

[0009]

That is, according to the first aspect of the present invention, the inner die connected to the extruder has a conical shape whose diameter is gradually expanded toward the discharge port, and is housed in the outer die. Then, the short fiber-containing rubber is stretched in the circumferential direction to extrude a cylindrical molded body in which the short fibers are oriented in the circumferential direction, and the cylindrical molded body is cut into straight lines while cutting. A first step of forming a fiber-oriented rubber sheet, and a second step of continuously cutting a rib groove extending in the longitudinal direction on a moving short fiber-oriented rubber sheet by a pair of cutter blades to which ultrasonic vibration is applied. , A belt component on the cylindrical mold,
And the short fiber oriented rubber sheet cut into a predetermined length is wound to form a belt molded body, the sheet-shaped rubber die is wound, and the rib groove of the short fiber oriented rubber sheet is fitted to the convex portion of the rubber die sheet. And a third step of vulcanizing and finishing into a belt sleeve. Particularly, in the second step of continuously cutting the rib groove extending in the longitudinal direction on the moving short fiber oriented rubber sheet by the cutter blade to which ultrasonic vibration is applied, the cutting blade reduces the resistance during processing. The cutting performance is also improved, and the ultrasonic vibration of the rib groove causes the short fibers to be loosened due to the friction between the cutter blade and the rubber, causing fluffing and easily protruding from the surface, and the ground unvulcanized short fiber mixed rubber can be reused. .
Also in the belt sleeve obtained by the vulcanization in the third step, the exposed short fibers remain on the surface of the rib groove, and therefore, it is not necessary to grind the rib groove surface layer, which reduces the number of steps and reduces the manufacturing cost. Can be reduced.

The invention according to claim 2 of the present application is the method of manufacturing a power transmission belt according to claim 1, which comprises a fourth step of grinding the surface layer of the rib groove of the belt sleeve. When the short fibers exposed on the surface of the rib groove of the obtained belt sleeve are small, only the surface layer of the rib groove can be ground as a post-process to reliably project the short fibers.

According to a third aspect of the present invention, at least the adhesive rubber sheet, the core wire, the belt constituent member of the adhesive rubber sheet, and the predetermined length are provided on the cylindrical molding die in the third step of the first aspect. The short fiber oriented rubber sheet cut into the above is wound to form a belt molded body for a V-ribbed belt. In the rib portion of the obtained V-ribbed belt, the short fibers are oriented in the belt width direction, so that the lateral pressure resistance is also improved.

According to a fourth aspect of the present invention, at least the short fiber orientation sheet, the adhesive rubber sheet, the core wire, and the belt component member of the adhesive rubber sheet are provided on the cylindrical molding die in the third step of the first aspect. , And the short fiber oriented rubber sheet cut into a predetermined length are wound to form a belt molded body for a double ribbed belt.

According to a fifth aspect of the present invention, in the fourth step of the third aspect, the rib groove surface layer formed on one surface of the belt sleeve is ground and the other surface is ground to form ribs. To form a part.

The invention according to claim 6 of the present application is to use a rubber composition for cross-linking an ethylene-α-olefin elastomer with an organic peroxide as a rubber for a short fiber oriented rubber sheet.

[0015]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. Hereinafter, FIG. 1 shows a first step of forming a short fiber oriented rubber sheet by linearly cutting an extruded cylindrical molded body, and a rib groove on the short fiber oriented rubber sheet by a cutter blade to which ultrasonic vibration is applied. It is a schematic diagram showing the 2nd process of cutting continuously.

In the first step and the second step, the manufacturing apparatus 1
To use. This apparatus 1 has a cylinder 2 for kneading rubber containing short fibers by rotation of an extrusion screw 3 and an extruder 6 composed of a connecting pipe 4 for moving a rubber 7 containing short fibers to the next step. The short fiber mixed rubber 7 extruded from 6 is passed through the gap between the inner die 9 and the outer die 10,
An annular expansion die 15 for extruding a cylindrical molded body 13 in which short fibers are oriented in the circumferential direction by imparting a gradually increasing circumferential direction toward the discharge port 11, and an annular expansion die 15 immediately after being extruded. Short fiber oriented rubber sheet 1 while incising a cylindrical molded body
8, a cutting means 20, and a cutting means 30 for continuously forming a rib groove 19 extending in the longitudinal direction on the short fiber oriented rubber sheet 18 by a cutter blade 31 to which ultrasonic vibration is applied,
A winding means 40 for the short fiber oriented rubber sheet 18 is provided.

The cylinder 2 of the extruder 6 has an extrusion screw 3 rotatably accommodated therein, a rubber compound containing short fibers is put in from a raw material charging port 17, and the short screw and the rubber are mixed by the rotation of the extrusion screw 3. Knead to mix short fiber rubber 7
To At this time, air generated in the cylinder 2 and the gas generated from the rubber compound are discharged from an exhaust port (not shown). The temperature of the cylinder 2 changes according to the rubber type,
Normally, the temperature is adjusted to 40 to 100 ° C., and the short fibers and the rubber are heated to a temperature at which they can be easily mixed to be thermoplasticized, so that they are easily extruded. Further, the kneading time in this case is adjusted so that the vulcanization of the rubber does not proceed. The connecting pipe 4 guides the short fiber mixed rubber 7 to the annular expansion die 15.

The annular expansion die 15 includes the inner die 9 and the discharge port 11
The diameter is gradually expanded toward the shape of a cone to be housed in the outer die 10, and a gap having a predetermined thickness is provided between the inner die 9 and the outer die 10. The short fiber-mixed rubber 7 is extruded into a cylindrical molded body 13 in which the short fibers are oriented in the circumferential direction while gradually expanding toward the discharge port 11 in the circumferential direction.

The annular expansion die 15 is vertically fixed to the extruder 6 arranged horizontally, and the cylindrical molded body 13 extruded from the discharge port 11 is placed so as to resist gravity, so that it has a cylindrical shape. The molded body 13 is not deformed by gravity and can be extruded in a state where the dimensional change is small. Further, the annular expansion die 15 arranged in the vertical direction is hard to bend due to the weight of the inner die 9, and the gap between the inner die 9 and the outer die 10 is kept constant,
As a result, the cylindrical molded body 13 with a small amount of thickness deformation can be finished.

The flow width of the inner die 9 and the outer die 10 is
The inner die 9 is connected to the extruder 6 through the root portion 23 to the discharge port 1
It becomes uniform up to 1 and smoothly flows in the longitudinal direction D without braking the extrusion of the cylindrical molded body 13, and the cylindrical molded body 13 having a uniform thickness without internal distortion is finished.

The shape of the inner die 9 becomes a factor that affects the magnitude of the shearing force. The taper angle θ at which the diameter gradually expands from the root portion 23 toward the discharge port 11 is 30 ° ≦ θ <
90 °, the rubber channel inlet is 20 to 60 mm, the rubber channel inlet / outlet is 100 to 440 mm, and the ratio of expansion (rubber channel inlet / outlet / rubber channel inlet) is 1.5 to 1
Set to 2.5. If it is less than this set range, the stretching in the circumferential direction in the vicinity of the discharge port 11 of the inner die 9 is small, and the short fibers are difficult to be oriented in the circumferential direction in the inner and outer layers of the thick cylindrical molded body 13. On the other hand, when the value exceeds this setting range, the circumferential expansion becomes too large, and when the extrusion pressure is poor, the cylindrical molded body 13 is likely to tear.

In order to suppress internal heat generation of the short fiber mixed rubber 7 between the inner die 9 and the outer die 10, a cooling device (not shown) for circulating cooling water may be provided inside the inner die 9. In the cooling device, cooling water is introduced from the outside of the inner die 9 and passed through a passage provided in the inner die 9 by a pump to be discharged from the inner die 9 and circulated.

In the cutting means 20, the cylindrical molded body 13 immediately after being extruded by the cutting member 21 is cut along the extrusion direction to form the short fiber oriented rubber sheet 18. The cutting member 21 includes a cutter such as a cutter or a knife, a laser knife, or ultrasonic vibration.

The short fiber oriented rubber sheet 18 is fed at a constant speed by the drive roll 25 via the guide rolls 24, 24, and the rib groove is continuously cut to form a take-up roll 41 on a liner such as canvas. 42 is laminated and wound up.

In the second step, as shown in detail in FIGS. 2, 3 and 4, a pair of ultrasonic transducers 32 are provided on the short fiber oriented rubber sheet 18 and arranged at different angles. The cutter blade 31 grinds one rib groove 19. In order to simultaneously grind the multiple rib grooves 19, a pair of cutter blades 3
1 are arranged so as to be displaced in the longitudinal direction. Even if the cutter blade 31 has a large cutting resistance and is difficult to cut, it can be cut smoothly by applying ultrasonic vibration to reduce the cutting resistance. Therefore, as shown in FIG. 5, the short fibers 22 project from the surface of the rib groove 19.
The ultrasonic oscillator 32 is, for example, a PZT electrostrictive oscillator,
Speed 20,000-40,000 times / sec, Amplitude 20-1
It is 00 μm.

In the third step, as shown in FIG. 6, a synthetic fiber such as polyester, nylon, aramid, vinylon or a natural fiber such as cotton is used as a belt constituent member on a cylindrical molding die 50, or a mixture of these fibers. Plain weave canvas,
A cover cloth 51 formed by forming a knitted fabric into a tubular shape by a sewing machine joint, an adhesive rubber sheet 52, a core wire 53 made of a cord such as polyester fiber or aramid fiber, the adhesive rubber sheet 52, and the rib groove 19 cut into a predetermined length. The short fiber-oriented rubber sheet 18 with a mark is wound to form a belt molded body for a V-ribbed belt.

Further, FIG. 7 is a view showing a state in which a belt molded body for a double ribbed belt is finished in the third step. On the cylindrical molding die 50, a short fiber orientation sheet 54 as a belt constituent member and an adhesive are attached. Rubber sheet 52, core wire 5
3, the adhesive rubber sheet 52, and the short fiber oriented rubber sheet 18 with the rib groove 19 cut into a predetermined length are wound.

Then, the vulcanized sheet-shaped rubber die 55 is wound around the short fiber oriented rubber sheet 18 while the convex portion 56 of the rubber type sheet is fitted into the rib groove 19 of the short fiber oriented rubber sheet, and the adhesive tape is used. After joining the abutting portions of the rubber mold 55 and inserting the jacket, the belt sleeve is manufactured by vulcanizing by a usual method. In the case of the present embodiment, the sheet-shaped rubber die 55 becomes scrap when the number of times of use increases, so a split die may be used instead.

In the fourth step, the surface layer of the rib groove 19 of the belt sleeve is thinly polished to expose the short fibers, and is processed to improve the dimensional accuracy. This thickness is 20 ~
It is 1,000 μm. However, since the multiple rib grooves 19 are ground in the second step, the short fibers protrude from the surface of the rib groove 19, and even if vulcanized in this state, the short fibers remain partially exposed. Therefore, it is not necessary to grind.

When molding a double-ribbed belt,
The other surface is also ground to form rib grooves. This method
For example, it can be performed according to Patent Registration No. 2762238.

The rubber of the short fiber-containing rubber includes natural rubber, butyl rubber, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, alkylated chlorosulfanated polyethylene, hydrogenated nitrile rubber, hydrogenated nitrile rubber and unsaturated carboxylic rubber. Mixed polymers with acid metal salts, ethylene-propylene rubber (EPR) and ethylene-
A rubber material such as an ethylene-α-olefin elastomer composed of a propylene-diene monomer (EPDM) alone;
Or mixtures of these are used. Examples of the diene monomer include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene and the like.

The rubber is made of aramid fiber, polyamide fiber, polyester fiber, cotton or the like, and the length of the fiber varies depending on the kind of the fiber, but a short fiber of about 1 to 10 mm is used, for example, aramid fiber. And 3 to 7m
m, polyamide fiber, polyester fiber, and cotton, those having a diameter of about 5 to 10 mm are used. The addition amount is 10 to 40 parts by mass with respect to 100 parts by mass of rubber. Furthermore, a softening agent, a reinforcing agent made of carbon black, a filler, an antioxidant, a vulcanization accelerator, a vulcanizing agent and the like are added to the rubber of the present invention.

As the above-mentioned softening agent, a general plasticizer for rubber, for example, phthalate type such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP), adipate type such as dioctyl adipate (DOA), dioctyl sebacate (DOS). ) And the like, phosphates such as tricresyl phosphate, etc., and general petroleum-based softeners.

In the present invention, at least short fibers of rubber are preliminarily kneaded by an open roll, a kneader or the like to prepare a masterbatch. In this method, 10 to 40 parts by mass of short fibers are added to 100 parts by mass of a polymer by an open roll and kneaded, and then the kneaded master batch is once discharged and cooled to 20 to 50 ° C. This is to prevent rubber scorch.

It is possible to add 1 to 10 parts by mass of the softening agent together with the short fibers. This not only improves the familiarity between the short fibers and the rubber and improves the dispersion in the rubber, but also has the effect of preventing the short fibers themselves from becoming entangled and forming a cotton shape. That is, the softening agent penetrates into the short fibers and plays a role as a lubricant for loosening the entanglement between the elementary fibers,
Prevents short fibers from becoming cotton-like, and improves the familiarity between short fibers and rubber to improve short fiber dispersion.

[0036]

EXAMPLES Next, specific examples of the method for producing a rubber molding containing short fibers will be shown below. Example 1 Using EPDM rubber compounds shown in Table 1, short fibers were previously added to rubber by an open roll and kneaded, and then the kneaded master batch was once discharged and cooled to room temperature. This masterbatch and other compounding agents were put into the cylinder of the apparatus for producing a rubber molding containing short fibers shown in FIG. 1, and short fibers were mixed by rotating an extrusion screw.

[0037]

[Table 1]

Then, depending on the dimensional conditions of the annular expansion die shown in Table 2 and the temperature conditions of the extruder, the short fiber mixed rubber is gradually expanded toward the discharge port in the circumferential direction, and a shearing force is applied to the cylinder to form a cylinder. The shaped body was extruded and cut into a short fiber oriented rubber sheet.

[0039]

[Table 2]

Subsequently, an ultrasonic vibrator (ultrasonic vibration speed 2
2,000 times / sec, amplitude 70 μm, vibrator: PZT electrostrictive vibrator) A pair of cutter blades (arrow type, material SKH, thickness 0.6 mm) were used to cut a single rib groove at the same time. After forming a rib groove using three sets of cutter blades, a short fiber oriented rubber sheet with a rib groove was finished.

In the V-ribbed belt manufactured in this embodiment,
Two plies of cotton canvas with rubber are laminated on a cylindrical mold, and an adhesive rubber sheet, a core wire made of polyester fiber rope,
An adhesive rubber sheet and a short fiber oriented rubber sheet with rib grooves were wound to form a belt molded body. The adhesive rubber layer is shown in Table 1.
A rubber composition obtained by removing the cut yarn from the rubber composition shown in FIG.

Then, while fitting the convex portion of the rubber mold sheet into the rib groove of the short fiber oriented rubber sheet, the sheet rubber mold is wrapped around the short fiber oriented rubber sheet, and the abutting portions of the rubber mold are joined by an adhesive tape. After the jacket was inserted, it was vulcanized by a usual method. After vulcanization, the jacket was pulled out, the belt sleeve was released from the mold, the adhesive tape was removed, and the rubber mold sheet was peeled off to produce a belt sleeve. Since the short fibers were partially projected in the rib groove of the sleeve, grinding by a grinder was not performed. Then, the belt sleeve was cut into individual belts to manufacture V-ribbed belts.

The obtained V-ribbed belt is a K-shaped 3-ribbed belt having a length of 975 mm according to the RMA standard, and has a rib pitch of 3.56 mm, a rib height of 2.0 mm, a belt thickness of 4.30 mm and a rib angle of 40 °.

Comparative Example 1 In the same manner as in Example 1, a cylindrical molded body was extruded using an annular expansion die and cut into a short fiber oriented rubber sheet. Subsequently, a rib groove is formed by using three sets of cutter blades with a cutter blade (arrow shape, material SKH, thickness 0.6 mm) without operating the ultrasonic vibrator, and then a short fiber oriented rubber sheet with a rib groove is formed. Finished. No short fibers protruded into the rib groove of the sleeve. Using this, a belt sleeve was produced in the same manner as in Example 1. Since the short fibers were not exposed at all in the rib groove of the sleeve,
The surface layer of the rib groove is ground by a grinder and V
A ribbed belt was produced.

[0045]

As described above, in the invention described in each of the claims of the present application, a cylindrical molded body is extruded by using an annular expansion die so as to orient the short fibers in the circumferential direction, and this is cut linearly. While doing the first step of making a short fiber oriented rubber sheet,
A second step of continuously cutting a rib groove extending in the longitudinal direction on a moving short fiber oriented rubber sheet by a pair of cutter blades to which ultrasonic vibration is applied, and forming a belt molded body on a cylindrical molding die Then, the sheet-shaped rubber die is wound, the rib groove of the short fiber oriented rubber sheet is fitted into the convex portion of the rubber-shaped sheet, and then the third step of vulcanizing and finishing into a belt sleeve is performed. In the manufacturing method, the second
In the process of, the cutter blade reduces the resistance at the time of processing and improves the cutting performance.In addition, the ultrasonic vibration causes the rib grooves to loosen the short fibers due to the friction between the cutter blade and the rubber, causing fluffing and protruding from the surface. The unvulcanized short fiber mixed rubber that has been ground can be reused. Also, in the belt sleeve obtained by the vulcanization in the third step, the exposed short fibers remain on the surface of the rib groove, and therefore the rib groove surface layer does not need to be ground, and the number of steps is reduced. This has the effect of reducing manufacturing costs.

[Brief description of drawings]

FIG. 1 is a first step of cutting an extruded cylindrical molded body into a short fiber oriented rubber sheet while linearly cutting it, and continuously cutting a rib groove in the short fiber oriented rubber sheet. It is a schematic diagram showing the 2nd process.

FIG. 2 is a plan view of FIG. 1 viewed from the AA direction.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a front view of a cutter blade to which ultrasonic vibration is applied.

FIG. 5 is a cross-sectional view of a short fiber oriented rubber sheet with rib grooves.

FIG. 6 is a cross-sectional view of a state where a belt molded body for a V-ribbed belt is manufactured on a cylindrical molding die.

FIG. 7 is a cross-sectional view of a state where a belt molded body for a double ribbed belt is manufactured on a cylindrical molding die.

[Explanation of symbols]

6 extruder 13 Cylindrical compact 15 Ring expansion die 18 Short fiber oriented rubber sheet 19 rib groove 22 Short fiber 31 cutter blade 32 ultrasonic transducer

Claims (6)

[Claims] 1. A method for producing a power transmission belt having an adhesive rubber layer in which a cord is embedded along the longitudinal direction of the belt, and a rib portion adjacent to the adhesive rubber layer and extending in the longitudinal direction of the belt, wherein the transmission belt is connected to an extruder. The inner die was made into a conical shape in which the diameter was gradually expanded toward the discharge port, and this was housed in the outer die, and the short fiber-containing rubber was stretched in the circumferential direction, so that the short fibers were circumferentially expanded. The first step of extruding an oriented cylindrical molded body and cutting the cylindrical molded body linearly into a short fiber oriented rubber sheet and moving by a pair of cutter blades to which ultrasonic vibration is applied A second step in which a rib groove extending in the longitudinal direction is continuously cut on a short fiber oriented rubber sheet, and a belt forming member and the short fiber oriented rubber sheet cut into a predetermined length are wound on a cylindrical mold. To form a belt, Wound the door-shaped rubber mold, after which the rib groove of the short fiber orientation rubber sheet fitted to the convex portion of the rubber mold sheet,
And a third step of vulcanizing and finishing into a belt sleeve. 2. The method for manufacturing a power transmission belt according to claim 1, further comprising a fourth step of grinding the surface layer of the rib groove of the belt sleeve. 3. The cylindrical molding die in the third step is wrapped with at least an adhesive rubber sheet, a core wire, a belt constituent member of the adhesive rubber sheet, and the short fiber oriented rubber sheet cut into a predetermined length. The method for producing a power transmission belt according to claim 1 or 2, wherein the belt molded body is used as a V-ribbed belt. 4. The cylindrical molding die in the third step has at least a short fiber orientation sheet, an adhesive rubber sheet, a core wire, a belt constituent member of the adhesive rubber sheet, and the short fibers cut into a predetermined length. The method for producing a power transmission belt according to claim 1 or 2, wherein an oriented rubber sheet is wound to form a belt molded body for a double ribbed belt. 5. The method according to claim 2, wherein in the fourth step, the rib groove surface layer formed on one surface of the belt sleeve is ground and the rib portion is ground on the other surface. Manufacturing method of power transmission belt. 6. The method for producing a power transmission belt according to claim 1, wherein a short fiber oriented rubber sheet and a rubber composition in which an ethylene-α-olefin elastomer is crosslinked with an organic peroxide are used as the rubber.