JP2004058545A - Mold device for driving belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold device for a driving belt, which enables the manufacture of the highly accurate driving belt by appropriately controlling the expansion of a flexible bladder, when the driving belt is manufactured by expanding the flexible bladder. <P>SOLUTION: The bladder 19 is formed in such a cylindrical shape as to be long enough to be elongated longer than a distance between both axial-length ends of a belt molding part 21; and both the sides, which are located outside both the axial-length ends of the molding part 21, of both the ends of the cylindrical shape are fixed to a cylindrical body 17 along an outer peripheral part 18 via rings 38 and 39. In the rings 38 and 39, an inside diameter, which is almost equal in dimension to an outside diameter of the bladder 19 mounted on the peripheral part 18, is possessed at least by the side of the molding part 21. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die apparatus for vulcanizing molding by pressing a ribbed transmission belt such as a V-ribbed belt or a double-ribbed belt provided with ribs extending in a belt longitudinal direction against an outer belt molding portion.
[0002]
[Prior art]
In order to manufacture this type of transmission belt, first, a canvas with rubber, an adhesive rubber sheet, a spiral-shaped tensile rope, and a rubber sheet having a certain thickness are sequentially wound around the outer peripheral surface of the drum in an endless manner to obtain a wide belt. The unvulcanized rubber sheet is reverse molded and vulcanized. A method of forming a plurality of ribs by cutting the surface of the vulcanized rubber sheet with a grinder having a triangular cross section has been adopted.
[0003]
However, in this method, since the cut rubber becomes scrap, in order to reduce the amount of rubber that becomes scrap as much as possible, a belt sleeve having a buffer layer and a compression layer is manufactured in JP-A-10-86236. A method is disclosed in which the belt sleeve is placed in a mold, a rib portion is stamped, and then vulcanization is performed.
[0004]
Japanese Patent Laying-Open No. 58-25948 discloses a cylindrical flexible jacket which is capable of expanding and contracting on the outer peripheral surface of a cylindrical drum provided with a fluid flow port for engraving a rib portion on the belt sleeve, An inner cylindrical drum in which a flexible jacket having upper and lower ends as flanges is arranged, and an outer cylindrical mold having a plurality of grooves extending in a circumferential direction on an inner peripheral surface and having a heating mechanism inside. Is disclosed.
[0005]
In addition, in Japanese Patent Application Laid-Open No. 53-40087, a connecting V-shaped ridge having a large number of air vent holes is provided on the inner peripheral surface for engraving a rib portion on the belt sleeve. Molding apparatus including a mold and a flexible cylindrical jacket which is mounted in the outer mold and whose upper and lower ends are sealably mounted, and which can be expanded in diameter by filling with high-pressure air. Is disclosed.
[0006]
[Problems to be solved by the invention]
When a flexible jacket having flanges formed at both ends of a cylindrical shape is used as in Japanese Patent Application Laid-Open No. 58-25948, there is a problem that the deformation of the flexible jacket during vulcanization is not uniform. .
Further, in the case of using an expandable cylindrical jacket whose upper and lower ends are sealably mounted as in JP-A-53-40087, it is not easy to expand and contract the cylindrical jacket while maintaining the sealing performance. There are points.
[0007]
The present invention has been made in view of the above problems, and when forming a tooth pattern of a transmission belt by expanding a flexible bladder, the expansion of the bladder is appropriately controlled to achieve a high-precision transmission belt. An object of the present invention is to provide a power transmission belt molding die apparatus that can be manufactured.
[0008]
[Means for Solving the Problems]
The invention according to claim 1, which solves the above-mentioned problem, has an outer mold in which a belt forming portion is formed on the inner periphery of a cylindrical body, and a flexible outer periphery of a cylindrical body inserted into the outer mold. A power transmission belt forming die device including an inner die equipped with a bladder,
The bladder has a cylindrical shape having a length extending beyond both ends of the axial length of the belt forming portion, and both ends of the cylindrical shape at both ends beyond the belt forming portion are formed on the outer periphery via a ring. It is fixed to the cylindrical body along the portion.
According to the above configuration, since the cylindrical bladder has a length extending beyond both ends of the axial length of the belt forming portion, the entire length of the belt sleeve pressed against the belt forming portion is reduced to the cylindrical bladder. Can be pressed to envelop. In addition, since both sides of the cylindrical bladder beyond the belt forming portion are fixed along the outer peripheral portion of the inner cylindrical body, the radial expansion of the bladder is substantially at least in the range of the belt forming portion. Performed uniformly.
[0009]
According to a second aspect of the present invention, in the first aspect, the ring has an inner diameter substantially equal to an outer diameter of the bladder mounted on the outer peripheral portion at least on the belt forming portion side.
According to the above configuration, both sides of the cylindrical bladder beyond the belt forming portion are fixed along the outer diameter portion or the reduced diameter portion after being along the outer peripheral portion of the inner cylindrical body.
[0010]
The invention according to Claim 3 is the invention according to Claim 1 or 2, wherein the both ends in the axial direction of the belt forming portion have an extended inner peripheral portion having a diameter corresponding to the innermost diameter of the belt forming portion or a diameter smaller than this. The ring is disposed at both ends beyond the extended inner peripheral portion.
According to the above configuration, since the extended inner peripheral portion existing beyond both ends in the axial direction of the belt forming portion supports the bladder, the deformation of both ends of the bladder that presses the belt sleeve toward the belt forming portion is maintained so as not to be large. You.
[0011]
According to a fourth aspect of the present invention, in any one of the first to third aspects, among the rings, a ring on the distal end side in the insertion direction of the inner mold has a tapered surface that reduces the diameter of the bladder. The ring on the tip side in the direction opposite to the insertion direction has a tapered surface for expanding the diameter of the bladder.
According to the above configuration, the outer diameter of the ring having the tapered surface for reducing the diameter of the bladder, including the ring, is reduced, and the inner die is easily fitted into the outer die. On the other hand, on the side of the ring having a tapered surface for expanding the diameter of the bladder, the outer diameter including the ring is increased, and the bladder is securely held.
[0012]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the outer mold includes a jacket for temperature adjustment surrounding the belt forming section, and a plurality of jackets provided between the jacket and the belt forming section. And a hole communicating with an air vent hole opened on the outer periphery of the belt forming portion.
According to the above configuration, the belt sleeve pressed against the belt forming portion via the outer mold can be heated, and at the same time, air between the belt forming portion and the belt sleeve is exhausted from the air vent hole and the plurality of holes communicating with the air vent hole. can do.
[0013]
According to a sixth aspect of the present invention, in any one of the first to fourth aspects, the inner die has a pressure adjusting jacket surrounding the inner peripheral portion, and a plurality of through-holes communicating with the jacket and the inner peripheral portion. And pores.
According to the above configuration, the bladder can be uniformly inflated through the large number of ventilation holes communicating with the jacket.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a partial sectional view of a transmission belt obtained by the molding die apparatus of the present invention, and FIG. 1 is a sectional view of the molding die apparatus of the present invention.
[0015]
In FIG. 5, A is represented as a V-ribbed belt generally used as a power transmission belt. 1 is a compressed rubber layer, 2 is an adhesive rubber layer, 3 is a cord embedded in the adhesive rubber layer 2, and 4 is a canvas.
The compressed rubber layer has a rib 5 formed by flowing a rubber layer having short fibers 6 oriented in the belt width direction along the rib groove. For the compressed rubber layer 1, chloroprene having oriented short fibers 6, ethylene / propylene rubber, hydrogenated nitrile rubber, or the like is used. As the short fiber 6, a short fiber of about 1 to 10 mm made of polyester fiber, nylon fiber, aramid fiber or the like is used. The addition amount is 10 to 40 parts by weight based on 100 parts by weight of the rubber.
The adhesive rubber layer 2 is pressed between the first portion 2a on the side of the compressed rubber layer 1 and the second portion 2b on the side of the canvas 4 with the core wire 3 interposed therebetween, and the core wire 3 is embedded. is there. The core wire 3 is made of a cord such as polyester fiber, nylon fiber, and aramid fiber. In particular, cords of polyester fibers are preferably used because they do not stretch as much as nylon fibers and do not stretch as easily as aramid fibers.
[0016]
In FIG. 1, a molding die apparatus 10 used for manufacturing the transmission belt A includes an outer die 11 and an inner die 12. The inner mold 12 is freely inserted into the outer mold 11 by moving in the center axis direction.
[0017]
The outer die 11 is formed by forming a belt forming portion 21 corresponding to a rib on the inner peripheral portion 16 of the cylindrical main body 15. The belt forming section 21 has peaks and valleys corresponding to ribs arranged at a predetermined pitch. The inner peripheral portions 16 at both axial ends of the belt forming portion 21 have an upper extended inner peripheral portion 22 and a lower extended inner periphery having the same diameter as the innermost diameter of the belt forming portion 21 or a diameter smaller than the innermost diameter. A part 23 is provided. Further, the inner peripheral portion 16 has an enlarged diameter portion 24 at the upper end in the axial direction and a reduced diameter portion 25 at the lower end in the axial direction.
[0018]
The cylindrical body 15 includes an outer portion 26 having a bottom, and an inner portion 27 having the belt forming portion 21 and fitted into the outer portion 26. A sealed portion surrounded by the outer portion 26 and the inner portion 27 forms a jacket 28 for temperature adjustment surrounding the belt forming portion 21. As described above, when the cylindrical main body 15 of the outer mold 11 is divided into the outer portion 26 and the inner portion 27, when the shape or diameter of the belt forming portion 21 is different, the outer portion 26 is shared and the inner portion 27 is replaced. Can be used for various types.
[0019]
The jacket 28 is provided with an upper port 28a and a lower port 28b. A steam supply device or a cooling water supply device (not shown) is connected to the ports 28a and 28b via a switching valve. When connected to a steam supply device, the upper port 28a serves as a supply port, and the lower port 28b serves as a drain outlet. When connected to the cooling water supply device, the lower port 28b serves as a supply port, and the upper port 28a serves as a discharge port. During preheating and vulcanization of the unvulcanized belt sleeve attached to the outer mold 11, steam is introduced into the jacket 28, and the entire outer mold 11 is heated. When the vulcanized belt sleeve mounted on the outer mold 11 is cooled, cooling water is introduced into the jacket 28 to cool the entire outer mold 11.
[0020]
A plurality of (for example, four every 90 degrees) holes 29 extending in the axial direction are provided at equal circumferentially distributed positions of the solid portion between the jacket 28 and the belt forming portion 21 of the inner portion 27 of the outer mold 11. The small-diameter air vent holes 30 for communicating between the holes 29 and the bottom of the belt forming portion 21 are arranged in a row in the axial direction. The hole 29 communicates with the supply / discharge port 31. The supply / discharge port 31 is connected to a suction device or a pressure feeding device (not shown) via a switching valve. When forming the belt sleeve, the supply / discharge port 31 is connected to a suction device, and excess air between the belt forming portion 21 and the belt sleeve is discharged. When the vulcanized belt sleeve is released from the mold, the supply / discharge port 31 is connected to a pressure feeding device to feed air between the belt forming section 21 and the vulcanized belt sleeve.
[0021]
The inner die 12 is obtained by attaching a flexible bladder 19 to an outer peripheral portion 18 of a cylindrical main body 17. The outer peripheral portion 18 has a straight portion 35, an outward tapered surface 36 from the upper end of the straight portion 35, and an inward tapered surface 37 from the lower end of the straight portion 35. The straight portion 35 has a length equal to or longer than the length obtained by combining the belt forming portion 21 of the corresponding outer die 11 and the extended inner diameter portions 22 and 23 at the upper and lower ends thereof. The outward tapered surface 36 is located at the corresponding enlarged diameter portion 24 of the outer mold 11. The inward tapered surface 37 is located at the corresponding reduced diameter portion 23 of the outer mold 11.
[0022]
The entire length of the bladder 19 is cylindrical with the same inner diameter. The upper end of the bladder 19 is fixed along the outer peripheral portion 18 by an upper ring 38. As clearly shown in FIG. 2, the upper ring 38 has a tapered surface 38a corresponding to the outward tapered surface 36. The end of the tapered surface 38a on the side of the belt forming portion 21 has an inner diameter substantially equal to the outer diameter of the bladder 19 on the straight outer peripheral portion 18. The end of the bladder 19 is fixed without being extremely bent. The fixed upper end of the bladder 19 is enlarged in diameter by an outward tapered surface 36, and is hooked on a reduced diameter stepped portion 36 b via an enlarged diameter portion 36 a following the outward tapered surface 36. The upper ring 38 is pulled up by a bolt 17b toward a detachable flange 17a at the upper end of the cylindrical body 17. The upper ring 38 has a size that fits inside the enlarged diameter portion 24 of the outer die. The upper portion of the bladder 19 is sandwiched and fixed between the outward tapered surface 36 and the tapered surface 38a. The corner of the upper ring 38 on the side of the bladder 19 and the corner of the upper extended inner diameter portion 22 of the outer die are chamfered or rounded because the bladder 19 hits the corner.
[0023]
The lower end of the bladder 19 is fixed along the outer peripheral portion 18 by a lower ring 39. As clearly shown in FIG. 3, the lower ring 39 has a tapered surface 39 a corresponding to the inward tapered surface 37. The end on the side of the belt forming portion 21 of the tapered surface 39a has an inner diameter substantially equal to the outer diameter of the bladder 19 on the straight outer peripheral portion 18. The lower end of the bladder 19 is fixed without being extremely bent. The fixed lower end of the bladder 19 is reduced in diameter along the inward tapered surface 37, and is hooked on the reduced diameter stepped portion 37a. The lower ring 39 is pushed up by the bolt 17c. The lower ring 39 has a size that fits in the reduced diameter portion 25 of the outer die. Therefore, the lower part of the bladder 19 is sandwiched and fixed between the inward tapered surface 37 and the tapered surface 39a. Further, the corner of the lower ring 39 on the bladder 19 side and the corner of the outer extended lower inner diameter portion 23 are chamfered or rounded because the bladder 19 hits the corner.
[0024]
Returning to FIG. 1, a jacket 41 is formed inside the cylindrical main body 17 at a position facing the straight portion 35. The jacket 41 and the outer peripheral portion 35 of the columnar body 17 communicate with each other through a number of ventilation holes 42. The jacket 41 communicates with the supply / discharge port 40. The supply / discharge port 40 is connected to a suction device or a pressure feeding device (not shown) via a switching valve. When the bladder 19 is inflated, it is connected to a pressure feeding device that feeds pressurized air of a predetermined pressure, and when the bladder 19 is contracted, the supply / discharge port 40 is connected to a suction device.
[0025]
An example of a method for manufacturing the power transmission belt A using the above-described mold device 10 will be described with reference to FIG.
A first sleeve 7 in which a compressed rubber layer 1 in which short fibers are oriented in the width direction is laminated on the outer periphery of the first portion 2a of the adhesive rubber layer is formed, and the first sleeve 7 is pressed from the inner peripheral side. A rib is formed on the surface of the compressed rubber layer 1 (first step). Next, the second sleeve 8 is put on the first sleeve 7 and pressed (second step). A case where the sleeve is formed in two stages will be described.
[0026]
As shown in FIG. 4A, the first sleeve 7 reduced in diameter due to wrinkles on the inner circumference is inserted into the outer mold 11 so as to ride on the belt forming portion 21. The inner peripheral side of the first sleeve 7 is pressed, and the compressed rubber layer 1 of the sleeve 7 is pushed toward the belt forming portion 21 so that the inner mold 12 can be inserted. Next, the inner mold 12 is inserted into the outer mold 11.
[0027]
Next, as shown in FIG. 4B, the bladder 19 is expanded radially outward by introducing compressed air into the jacket 38 of the inner mold 12. The compressed rubber layer 1 is pressed into the belt forming portion 21 via the first portion 2a of the adhesive rubber layer. At this time, since the outer mold 11 is in the preheated state and the belt forming section 21 is in the suction state, the compressed rubber layer 1 is preformed into a highly accurate shape along the belt forming section 21. This preliminary molding by heating is performed to improve the moldability to the extent that the compressed rubber layer 1 is not vulcanized.
[0028]
As shown in FIG. 4C, the bladder 19 of the inner mold 12 is reduced in diameter by suction, and then the canvas 4 and the second portion 2b of the adhesive rubber layer 2 are wound on the bladder 19 in this order. The second sleeve 8 is formed by spirally winding the wire 3 at a predetermined pitch. The formation of the second sleeve 8 is performed in a state where the inner mold 12 is removed from the outer mold 11.
[0029]
As shown in FIG. 4C, the inner mold 12 on which the second sleeve 8 is formed is inserted into the outer mold 11. At this time, by reducing the difference ε between the outer diameter of the core wire 3 in the second sleeve 8 and the inner diameter of the first portion 2a of the adhesive rubber layer 2, the extent to which the second sleeve 8 expands is reduced. can do.
[0030]
As shown in FIG. 4D, the bladder 19 is expanded by introducing compressed air into the jacket 41 of the inner mold 12, and the second portion 2b of the adhesive rubber layer 2 in the second sleeve 8 and the compressed rubber The first portion 2a of the adhesive rubber layer 2 with respect to the inner periphery of the layer 1 is united so that the core wire 3 is embedded in the adhesive rubber layer 2. At this time, pressurized steam is introduced into the jacket 28, and the compressed rubber layer 1 and the adhesive rubber layer 2 are vulcanized while being pressed in the molds 11 and 12.
[0031]
When the vulcanization molding is completed, cooling water flows through the jacket 28 of the outer mold 11 to cool the outer mold 11 and the inner mold 12. Next, the jacket 41 of the inner mold 12 is sucked, the diameter is reduced by peeling off the bladder 19, compressed air is fed into the hole 29 of the outer mold 11, and the compressed rubber layer 1 is extruded from the belt forming section 21. . The inner mold 12 is removed from the outer mold 11, and the vulcanized power transmission belt A is pulled out from the outer mold 11. Then, it is cut into an appropriate width, and when turned upside down, a predetermined V-ribbed belt is obtained.
[0032]
The advantages of the molding apparatus for molding the vulcanized power transmission belt A in this manner will be described below.
[0033]
Since the bladder 19 has a cylindrical shape over its entire length in the axial direction and is fixed along the outer peripheral portion 18 of the cylindrical main body 17 of the inner mold 12, the degree of loosening and wrinkling accompanying expansion and contraction is reduced. Excellent in durability. Further, since the bladder 19 has a straight cylindrical shape, the bladder 19 can be manufactured uniformly and at low cost.
[0034]
A cylindrical bladder 19 is put on the straight portion 35 of the inner mold 12 and the cylindrical portion of the bladder 19 is pressed and fixed by the rings 38 and 39 located at both ends of the straight portion 35. It is performed based on a cylindrical shape. Therefore, a local load is not applied with the expansion and contraction of the bladder 19.
[0035]
Since there are extended inner peripheral portions 22 and 23 having the same diameter as the innermost diameter of the belt forming portion 21 or smaller than the innermost diameter at both sides of the both ends of the belt forming portion 21, the bladders 19 located at both ends of the belt forming portion 21 are provided. The amount of deformation is suppressed by the extended inner peripheral portions 22 and 23. For this reason, it is possible to prevent the vicinity of both ends of the bladder 19 from being greatly deformed and locally applying a load.
[0036]
Since the ring 39 on the distal end side in the insertion direction for fixing the bladder 19 has an inward tapered surface 37 for reducing the diameter of the bladder 19, the outer diameter of the ring 39 is substantially equal to the outer diameter of the bladder 19. can do. Therefore, the protrusion on the insertion side of the inner die 12 inserted into the outer die 11 can be reduced as much as possible, and the interval between the bladder 19 and the belt forming portion 21 can be reduced so that the bladder 19 is not excessively expanded. Further, since the ring 38 on the distal end side in the direction opposite to the insertion side for fixing the bladder 19 has an outward tapered surface 36 for expanding the diameter of the bladder 20, the bladder 19 can be firmly fixed.
[0037]
Since the portion that the bladder 19 contacts when inflated is chamfered or rounded, the bladder 19 is less likely to be scratched when inflated.
[0038]
The outer die 11 has a jacket 28 surrounding the belt forming section 21 and a plurality of holes 29 communicating with the air vent holes 30 between the belt forming section 21 and the jacket 28. For this reason, it is possible to discharge the air accumulated in the belt forming section 21 during the molding without hindering the heating and cooling effect of the belt forming section 21 by the jacket 28. Therefore, a power transmission belt having excellent surface accuracy can be manufactured.
[0039]
The inner mold 12 has a large number of ventilation holes 42 reaching the outer peripheral portion 18 surrounded by the bladder 19, and a jacket 41 communicating with the ventilation holes 42. Therefore, the bladder 19 can be expanded and contracted substantially uniformly in the axial direction and the circumferential direction. Therefore, the degree of pressing on the belt forming portion 21 becomes uniform, and a high-precision transmission belt can be manufactured.
[0040]
The embodiment described above can be modified and implemented as follows.
[0041]
The entire length of the bladder 19 is not limited to a cylindrical shape. If the length extending beyond both ends of the axial length of the belt forming portion 21 is a cylindrical shape, the other portions have a reduced diameter or The diameter may be enlarged.
[0042]
As a method of manufacturing a power transmission belt to which the molding die apparatus 10 is applied, the case of two-stage molding of a compressed rubber layer and an adhesive rubber layer has been described. Also, the present invention can be applied to the case of single-stage molding in which the bladder 19 is mounted on the airbag 11 and molded once.
[0043]
【The invention's effect】
According to the molding apparatus of the first to sixth aspects, the durability of the flexible bladder is excellent, and the transmission belt can be molded with high accuracy by appropriately deforming the bladder. To play.
[0044]
In particular, according to the molding die apparatus of the first aspect, since the cylindrical bladder has a length extending beyond both ends of the axial length of the belt forming section, it is pressed against the belt forming section. The entire length of the belt sleeve can be pressed so as to surround the cylindrical bladder. Since both sides of the cylindrical bladder beyond the belt forming portion are fixed along the outer peripheral portion of the inner cylindrical body, the radial expansion of the bladder is substantially uniform at least in the range of the belt forming portion. This has the effect of being performed. According to the molding die apparatus of the second aspect, both sides of the cylindrical bladder beyond the belt molding portion are fixed along the outer peripheral portion of the inner cylindrical body and then through the enlarged diameter portion or the reduced diameter portion. This has the effect of being performed.
According to the molding die apparatus of the third aspect, since the extended inner peripheral portion existing beyond both ends in the axial direction of the belt forming portion supports the bladder, the both ends of the bladder pressing the belt sleeve toward the belt forming portion are deformed. Is maintained so as not to increase.
According to the molding die apparatus of the fourth aspect, the outer diameter of the ring having the tapered surface for reducing the diameter of the bladder including the ring is reduced, and the inner die is easily fitted into the outer die. On the other hand, on the side of the ring having the tapered surface for expanding the diameter of the bladder, the outer diameter including the ring is increased, and the effect of securely holding the bladder is achieved.
According to the molding die apparatus of the fifth aspect, the belt sleeve pressed against the belt forming portion via the outer mold can be heated, and at the same time, the air between the belt forming portion and the belt sleeve is released into the air vent hole and the air vent hole. There is an effect that exhaust can be performed from a plurality of communicating holes.
According to the molding die apparatus of the sixth aspect, there is an effect that the bladder can be inflated uniformly through a large number of ventilation holes communicating with the jacket.
[Brief description of the drawings]
FIG. 1 is a sectional view of a molding die apparatus of the present invention.
FIG. 2 is an enlarged view of an upper section in the axial direction of a belt forming section.
FIG. 3 is an enlarged view of a lower cross section in the axial direction of a belt forming portion.
FIG. 4 is a view showing a process of manufacturing a power transmission belt using the molding die apparatus of the present invention.
FIG. 5 is a sectional view of a power transmission belt manufactured by the molding die apparatus of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Molding apparatus 11 Outer mold 12 Inner mold 15 Cylindrical body 16 Inner peripheral part 17 Cylindrical body 18 Outer peripheral part 19 Bladder 21 Belt forming part 22 Extended inner diameter part 23 Extended inner diameter part 28 Jacket 29 Hole 30 Air vent hole 38 Upper ring 38a Tapered surface 39 Lower ring 39a Tapered surface 41 Jacket 42 Vent hole

Claims (6)

A transmission belt comprising: an outer die having a belt forming portion formed on an inner peripheral portion of a cylindrical main body; and an inner die having a flexible bladder mounted on an outer peripheral portion of a cylindrical main body inserted into the outer die. A molding die apparatus,
The bladder has a cylindrical shape having a length extending beyond both ends of the axial length of the belt forming portion, and both ends of the cylindrical shape at both ends beyond the belt forming portion are formed on the outer periphery via a ring. A molding device for a power transmission belt fixed along the portion to the cylindrical body. 2. The apparatus according to claim 1, wherein the ring has an inner diameter substantially equal to an outer diameter of a bladder mounted on the outer peripheral portion at least on the side of the belt forming section. 3. At both ends in the axial direction of the belt forming portion, there is an extended inner peripheral portion having a diameter corresponding to or smaller than the innermost diameter of the belt forming portion, and the ring is disposed at both end positions exceeding this extended inner peripheral portion. 3. The molding apparatus for a power transmission belt according to claim 1, wherein Among the rings, the ring on the distal end side in the insertion direction of the inner mold has a tapered surface that reduces the diameter of the bladder, and the ring on the distal end side in the insertion direction of the inner mold increases the diameter of the bladder. The mold device for forming a power transmission belt according to any one of claims 1 to 3, which has a tapered surface. The outer mold has a jacket for temperature adjustment surrounding the belt forming section, and a plurality of holes provided between the jacket and the belt forming section, and an air vent hole opened on the outer periphery of the belt forming section. The mold device for forming a power transmission belt according to any one of claims 1 to 4, further comprising a communicating hole. The power transmission belt according to any one of claims 1 to 4, wherein the inner mold includes a pressure adjustment jacket surrounding the inner peripheral portion, and a number of ventilation holes communicating with the jacket and the inner peripheral portion. Molding equipment for molding.

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