JP2004188596A - Method for manufacturing transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a transmission belt which comprises extruding a rubber layer containing short fibers oriented in a definite direction and an adhesive rubber layer containing no short fibers while laminating them to prevent the roughening of a rubber surface and reduces the number of manufacturing processes to enable molding at a low cost. <P>SOLUTION: The transmission belt is manufactured by a method including a process (1) for molding the two-layer cylindrical molded object 17, wherein a short fiber-containing rubber 15 for inner peripheral side and an adhesive rubber 16 for outer peripheral side are laminated, extruded from an expansion die and the molded one is cut open to obtain a short fiber-oriented rubber sheet 20, a process (2) for interposing the sheet 20 between an inner mold 41 having a flexible jacket 42 on its outer surface and an outer mold 46 having a rib mold 45 carved in its inner surface, a process (3) for expanding the jacket 42 to form a preformed body 21 so as to bring the sheet 20 and the mold 45 to a close contact state, a process (4) for winding at least a core wire 48 around the surface of the jacket 42 of the mold 41 separated from the mold 46, a process (5) for arranging the mold 41 in the mold 46 and expanding the jacket 42 to integrally vulcanize the wire 48 and the body 21 and a process (6) for demolding the body 21 to manufacture a vulcanized belt sleeve 51 with rib parts. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a power transmission belt, and more particularly to a method for manufacturing a power transmission belt such as a V-ribbed belt which can be formed at low cost with a reduced number of manufacturing steps, has excellent lateral pressure resistance, and can reduce noise during traveling. It is.
[0002]
[Prior art]
Conventionally, as a method for orienting the short fibers in a certain direction in the unvulcanized rubber, as in a rolled sheet manufacturing process, the unvulcanized rubber containing the short fibers is put into a pair of calender rolls at different rotation speeds, and then rolled. The short fibers in the rubber sheet were oriented in the rolling direction of the sheet, and were cut in accordance with the belt width to be formed. Then, several cut rolled sheets are laminated and laminated to a predetermined thickness, and then a laminate in which short fibers are oriented in the width direction is wound around a forming drum to be used in the production of a power transmission belt as in a winding step. Was.
[0003]
That is, in a method of manufacturing a V-ribbed belt or a low-edge V-belt transmission belt, one or more sheets of cover canvas and an adhesive rubber layer are wound around the peripheral surface of a cylindrical forming drum, and a cord made of a cord is placed thereon. Was spirally spun, and a compressed rubber layer was sequentially wound thereon to obtain a laminate, which was then vulcanized to form a belt sleeve. The compressed rubber layer used here had a thickness of three to four rolled sheets stacked on each other, and was wound around a forming drum in which short fibers were oriented in the sheet width direction.
[0004]
However, if the thickness of the rolled sheet is not reduced, the short fibers cannot be sufficiently oriented in the sheet rolling direction. Was.
[0005]
As a method of improving this, an extruder equipped with an expansion die is used, and the short fibers are oriented in the circumferential direction of the extrusion cylindrical body. An enlarged space portion in which the flow passage width changes up to the flow passage width is formed, the cross-sectional area of the outlet space of the expansion die is formed to be larger than the cross-sectional area of the inlet space by a predetermined amount, and the flow passage width of the inlet portion is the flow of the intermediate portion. It has been proposed that the width of the outlet portion is smaller than the width of the intermediate portion and smaller than the width of the channel. (For example, see Patent Document 1)
[0006]
Furthermore, it has also been proposed to use a short-fiber-containing rubber composition formed into a sheet with an expansion die for a power transmission belt. For example, Patent Document 2 discloses that an expansion die having a V-rib portion forming groove is provided at an outlet portion. A cylindrical rib rubber tube is extruded by an extruder provided in the above, a V-ribbed belt molded body is molded on a mold using a sheet obtained by cutting the rib rubber tube, vulcanized, and the rib surface of the V-rib portion of the belt molded body is vulcanized. To produce a V-ribbed belt.
[0007]
[Patent Document 1]
Japanese Patent Publication No. 6-9847 [Patent Document 2]
JP-A-8-74936
[Problems to be solved by the invention]
However, even in the method using a conventional expansion die, for example, when using a material having a strong adhesiveness such as chloroprene and a high shear stress, the surface layer, particularly the outer peripheral layer, is large between the die inner peripheral surface and the die. The surface of the rubber surface became rough because frictional force was generated and it did not flow smoothly. For this reason, the adhesion between the matrix rubber and the fibers is poor, and the orientation is also poor. In practice, it has sometimes been difficult to use the matrix for the compressed rubber layer of the power transmission belt. Further, in order to extrude the short-fiber-containing rubber composition by molding with an accurate V-rib portion using an expansion die, it was necessary to improve the rubber compounding.
[0009]
The present invention has been made in view of the above-described situation in view of the above-described circumstances, and a rubber layer corresponding to a compressed rubber layer in which short fibers are oriented in a certain direction and an adhesive rubber layer containing no short fibers are laminated, and smoothly. An object of the present invention is to provide a method for manufacturing a power transmission belt such as a V-ribbed belt which can be formed at a low cost by extruding to prevent rough surface of a rubber surface and to reduce the number of manufacturing steps.
[0010]
[Means for Solving the Problems]
That is, the invention according to claim 1 of the present application is directed to a method for manufacturing a power transmission belt having an adhesive rubber layer having a core wire buried along the belt longitudinal direction and a rib portion extending in the belt longitudinal direction adjacent to the adhesive rubber layer. ,
After extruding a two-layer cylindrical molded body with the short fiber-containing rubber laminated on the inner circumference and the adhesive rubber on the outer circumference, using an expansion die whose diameter is gradually expanded from the inlet to the discharge port, cut and bond Short fiber oriented rubber sheet laminated with rubber,
A short fiber oriented rubber sheet laminated with the above adhesive rubber is interposed between an inner mold having a flexible jacket attached to the outer peripheral surface and an outer mold having a rib mold stamped on the inner peripheral surface,
The flexible jacket is expanded to prepare an unvulcanized preform so that the short fiber oriented rubber sheet adheres to the imprinted rib mold of the outer mold,
At least a core wire is wound around the flexible jacket surface of the inner mold detached from the outer mold,
Again, placing the inner mold in the outer mold, inflating the flexible jacket and vulcanizing integrally with the preformed body with the core wire attached to the outer mold,
The present invention relates to a method for manufacturing a power transmission belt, in which a vulcanized belt sleeve having a rib portion is manufactured by demolding.
[0011]
In the present invention, after extruding a two-layer cylindrical molded body laminated so that the adhesive rubber is on the outer peripheral side of the short fiber-containing rubber, cut into a straight line to form a short fiber oriented rubber sheet laminated with the adhesive rubber By doing so, it is possible to smoothly extrude and prevent the roughening of the rubber surface from occurring, and to form the power transmission belt at low cost by reducing the number of manufacturing steps by laminating the adhesive rubber and the compressed rubber layer in advance. Further, in the belt forming step, in order to prepare an unvulcanized preformed body in advance, the amount of expansion of the core wire due to expansion of the flexible jacket can be set small, so that the core wire can be arranged flat. There is.
[0012]
The invention according to claim 2 of the present application is directed to a method of manufacturing a power transmission belt having an adhesive rubber layer having a core wire buried along the belt longitudinal direction and a rib portion extending in the longitudinal direction of the belt adjacent to the adhesive rubber layer,
A two-layer cylindrical molded body in which short fiber-containing rubber is laminated on the inner peripheral side and adhesive rubber is laminated on the outer peripheral side is extruded with an expansion die whose diameter is gradually increased from an inlet to an outlet, and the cylindrical molded body is extruded. Cut straight into a short fiber oriented rubber sheet laminated with adhesive rubber,
An unvulcanized rubber sleeve is formed by winding a short fiber oriented rubber sheet on which at least a core wire and an adhesive rubber are laminated on a stretchable flexible jacket surface attached to an inner mold,
Insert the inner mold into the outer mold with a rib mold stamped on the inner peripheral surface, enclose the pressure medium, expand the flexible jacket, press the unvulcanized rubber sleeve on the outer mold and vulcanize. In a method of manufacturing a power transmission belt.
[0013]
In the present invention, a two-layered cylindrical molded body in which the adhesive rubber is laminated so as to be on the outer peripheral side of the short fiber-containing rubber is extrusion-molded, and the cylindrical molded body is cut straight to form a short-circuit in which the adhesive rubber is laminated. By using a fiber oriented rubber sheet, smooth extrusion can be prevented and rough surface of the rubber surface can be prevented, and the transmission belt can be manufactured at low cost by reducing the number of manufacturing steps by laminating the adhesive rubber and the compressed rubber layer in advance. It has the effect that it can be molded.
[0014]
The invention according to claim 3 of the present application is characterized in that, in the step of forming a short fiber oriented rubber sheet in which adhesive rubber is laminated, the adhesive rubber is extruded on the outer peripheral surface of the previously extruded short fiber-containing rubber, and the diameter gradually increases from the inlet to the discharge port. The present invention relates to a method of manufacturing a power transmission belt for extruding a two-layered cylindrical molded product in which an adhesive rubber is surrounded by an expanded die composed of an expanded inner die and an outer die and is laminated on the outer peripheral surface of the short fiber-containing rubber.
[0015]
The invention according to claim 4 of the present application is that, in the step of forming a short fiber oriented rubber sheet in which the adhesive rubber is laminated, the outer peripheral surface of the previously extruded short fiber-containing rubber is coated with the adhesive rubber at the same time from the entrance of the expansion die. The present invention relates to a method for manufacturing a power transmission belt in which an adhesive rubber is extruded to surround an outer peripheral surface of a short fiber-containing rubber and formed into a laminated cylindrical molded body.
[0016]
According to a fifth aspect of the present invention, in the step of forming a short fiber oriented rubber sheet on which an adhesive rubber is laminated, the short fiber-containing rubber is caused to enter from an inlet of the expansion die, and the adhesive rubber is formed between the inlet and the discharge port of the expansion die. There is a method of manufacturing a power transmission belt in which the adhesive rubber is intruded at a portion located therebetween and the adhesive rubber is surrounded on the outer peripheral surface of the short fiber-containing rubber and is extruded into a laminated cylindrical molded body, and the thickness of the adhesive rubber is extruded more uniformly. be able to.
[0017]
According to the invention of claim 6 of the present application, the position where the adhesive rubber enters is located between the entrance of the expansion die and the discharge port, and the gap of the rubber passage is laminated from the position where the adhesive rubber enters to the discharge port. It is in the method of manufacturing a power transmission belt that is increased in thickness by reducing the penetration resistance of the adhesive rubber into the rubber passage, making it easy to smoothly surround the adhesive rubber on the outer peripheral surface of the short fiber-containing rubber and stack it, and its thickness Can be made uniform.
[0018]
The invention according to claim 7 of the present application is a method for manufacturing a power transmission belt that exposes embedded short fibers by grinding the surface layer of a rib portion of a demolded vulcanized rubber sleeve.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic view of a process of forming a short fiber oriented rubber sheet in which an adhesive rubber is laminated while a cylindrical molded body formed by extrusion is linearly cut.
In the apparatus 1 used in this step, the first extruder 2a for kneading the short fiber-containing rubber by the rotation of the extrusion screw 4a in the cylinder 3a, and the rubber without the short fiber by the rotation of the extrusion screw 4b in the cylinder 3b. The second extruder 2b to be kneaded is connected to the back of the expanding die 5, and the rubber extruded by the first extruder 2a and the second extruder 2b is introduced into the rubber passage 8 formed by the shaft 6 and the cylinder 7. I do.
[0020]
In the expansion die 5, the rubber passage 8 is formed by a combination of the inner die 10 attached to the shaft portion 6 and the outer die 13 connected to the cylindrical portion 7. The inner die 10 is a conical body whose diameter is gradually expanded from the inlet 11 to the discharge port 12. In the vicinity of the entrance 11 of the outer die 13, the thickness of the extruded rubber can be made uniform by combining the alignment block 14.
[0021]
The second extruder 2b for kneading and extruding the adhesive rubber 16 containing no short fibers is disposed closer to the inlet 11 of the outer die 13 than the first extruder 2a, and the extruded short fiber-containing rubber is used. 15 is extruded into a two-layer cylindrical molded body 17 having an outer peripheral portion coated with an adhesive rubber 16. The adhesive rubber 16 has good fluidity of the rubber and completely surrounds the outer periphery of the short fiber-containing rubber 15. The extruded cylindrical molded body 17 is cut off by the cutting means 19 and then wound up.
[0022]
In the first extruder 2a and the second extruder 2b, the extruding screws 4a and 4b are rotatably accommodated in the cylinders 3a and 3b, and the rubber compound is introduced from the raw material inlet and the extruding screws 4a and 4b are rotated. Knead. At this time, the air and the gas generated from the rubber compound in the cylinders 3a and 3b are discharged from an exhaust port (not shown). The temperature of the cylinders 3a and 3b is changed according to the type of rubber, but is usually adjusted to 40 to 100 ° C., and the short fibers and rubber are heated to a temperature at which they can be easily mixed, thermoplasticized, and extruded. . The kneading time in this case is adjusted to such an extent that the vulcanization of the rubber does not proceed.
[0023]
The expansion die 5 accommodates a conical inner die 10 whose diameter is gradually expanded to the discharge port 12 in an outer die 13, and forms a rubber passage 8 having a gap of a predetermined thickness between the inner die 10 and the outer die 13. Provided. The short fiber-mixed rubber 15 orients the short fibers in the circumferential direction while being gradually extended from the inlet 11 to the discharge port 12 in the circumferential direction, and at the same time, surrounds the adhesive rubber 16 in the outer layer while forming the cylindrical molded body 17. Extrusion molding.
[0024]
The expansion die 5 is vertically arranged with respect to the first extruder 2a and the second extruder 2b which are horizontally arranged, and extrudes the cylindrical molded body 17 from the discharge port 12 so as to resist gravity. The deformation and the dimensional change of the shaped body 17 due to gravity are relatively small. Further, the expansion die 5 arranged in the vertical direction is hardly bent by the weight of the inner die 10, the gap between the inner die 10 and the outer die 13 is kept constant, and the cylindrical die 17 having a small thickness deformation can be finished. it can.
[0025]
In addition, the rubber passage 8 formed by the inner die 10 and the outer die 13 has a substantially uniform gap from the inlet 11 to the discharge port 12, so that the cylindrical molded body 17 can smoothly flow without applying a brake, and the internal distortion can be reduced. To a cylindrical molded body 17 having a uniform thickness without any irregularities.
[0026]
The shape of the inner die 10 affects the magnitude of the shearing force. The taper angle at which the diameter gradually expands from the inlet 11 to the outlet 12 is 30 ° or more and less than 90 °, the inlet has a diameter of 20 to 60 mm, the outlet has a diameter of 100 to 440 mm, and the expansion ratio (discharge ratio) Outlet / inlet) is set to 1.5-12.5. If it is less than the set range, the circumferential stretching around the discharge port 12 of the inner die 10 is small, and the short fibers are less likely to be circumferentially oriented in the inner and outer layers of the thick cylindrical molded body 17. On the other hand, if it exceeds this setting range, the stretching in the circumferential direction becomes too large, and when the extrusion pressure is inferior, the tubular molded body 17 is easily torn.
[0027]
In order to suppress internal heat generation of the rubber existing in the rubber passage 8 between the inner die 10 and the outer die 13, a cooling device (not shown) for circulating cooling water inside the inner die 10 may be provided. In the cooling device, the cooling water is circulated through a passage provided in each die by a pump.
[0028]
The cutting means 19 is formed by cutting the extruded cylindrical molded body 17 along the extruding direction into a rubber sheet 20 and using a cutting tool such as a cutter or a knife, a laser knife, or an ultrasonic vibration cutter. The rubber sheet 20 is fed at a constant speed by a driving roll via a guide roll, and is wound on a winding roll together with a liner such as canvas.
[0029]
In another apparatus 1 shown in FIG. 2, the first extruder 2a for kneading the short fiber-containing rubber 15 by the rotation of the extrusion screw 4a in the cylinder 3a, and the short fiber is not contained by the rotation of the extrusion screw 4b in the cylinder 3b. The second extruder 2 b for kneading the adhesive rubber 16 introduces the extruded rubber into the rubber passage 8.
[0030]
The first extruder 2a is directly connected to the expansion die 5 in the axial direction of the extrusion screw 4a, and the second extruder 2b is arranged at right angles to the first extruder 2a. When the adhesive rubber 16 extruded from the second extruder 2b collides with a rectifying projection provided at a position away from the tip end portion 25 of the extrusion screw 4a of the first extruder 2a, it is easy to surround the outer circumference of the short fiber-containing rubber 15. Become.
[0031]
The expansion die 5 accommodates an inner die 10 having a conical shape by gradually expanding the diameter to a discharge port 12 in an outer die 13, and a rubber passage 8 having a gap of a predetermined thickness between the inner die 10 and the outer die 13. Provided. The conical fluid splitting 27 attached and fixed to the inner die 10 divides the flow of the rubber uniformly to 360 degrees and pushes out the rubber passage 8 between the inner die 10 and the outer die 13.
[0032]
The short-fiber-mixed rubber 15 orients the short fibers in the circumferential direction while being gradually stretched in the circumferential direction toward the discharge port 12, and at the same time, as shown in FIG. Extruded into body 17. Then, as shown in FIG. 6, the cylindrical molded body 17 immediately after being extruded is cut by the cutting means 19 along the extrusion direction to form the rubber sheet 20. The thickness of the short fiber mixed rubber 15 is 1.5 to 10 mm, and the thickness of the adhesive rubber 16 is 0.1 to 1.0 mm.
[0033]
As described above, the apparatus 1 shown in FIG. 2 simultaneously extrudes the short fiber-containing rubber 15 extruded with the adhesive rubber 16 on the outer peripheral surface thereof from the inlet 11 of the expansion die 5 to remove the adhesive rubber 16. The device 1 shown in FIG. 3 has the short-fiber-containing rubber 15 penetrate from the inlet 11 of the expansion die 5 and is molded into a cylindrical molded body 17 that is surrounded and laminated on the outer peripheral surface of the short-fiber-containing rubber 15. The adhesive rubber 16 penetrates at a position P between the inlet 11 and the discharge port 12 of the expansion die 5 and is extruded into a cylindrical molded body 17 that is surrounded and laminated on the outer peripheral surface of the short fiber-containing rubber 15.
[0034]
That is, in the apparatus 1 shown in FIG. 3, the first extruder 2a that kneads the short fiber-containing rubber 15 by rotating the extrusion screw 4a extrudes the short fiber-containing rubber 15 from the inlet 11 of the expansion die 5 to the discharge port 12. On the other hand, a second extruder 2b for kneading the adhesive rubber 16 containing no short fibers is arranged in a state of intersecting with the first extruder 2a, and a rubber passage 36 is provided from a rubber reservoir 35 in which the adhesive rubber 16 is arranged in a circumferential direction. At the position P between the inlet 11 and the discharge port 12 of the expansion die 5 through the cylindrical shape.
[0035]
At the intrusion position P, a clear step is provided in the rubber passage 8 as shown in FIG. 4, and the gap of the rubber passage 8 from the intrusion position P to the discharge port 12 is equal to the thickness of the adhesive rubber 16 to be laminated. It is large and reduces the resistance of the adhesive rubber 16 from entering the rubber passage 8, smoothly surrounds the short fiber-containing rubber 15 on the outer peripheral surface, and makes the thickness of the adhesive rubber 16 uniform. There is no problem if the intrusion position P is between the inlet 11 and the discharge port 12, but it is preferable that the intrusion position P is near the middle between the inlet 11 and the discharge port 12.
[0036]
Next, a method of manufacturing a V-ribbed belt using the rubber sheet 20 with the adhesive rubber 16 obtained by the above method will be described with reference to FIGS.
[0037]
First, the short fiber oriented rubber sheet 20 with the adhesive rubber 16 is wound around the outer peripheral surface of the flexible jacket 42 attached to the inner die 41 so that the adhesive rubber 16 faces the flexible jacket 42.
[0038]
Next, as shown in FIG. 7, the inner mold 41 of the belt vulcanizer 40 on which the short fiber oriented rubber sheet 20 with the adhesive rubber 16 is wound is mounted on a base so as to form a constant gap inside the outer mold 46. Place on top. Since the inner mold 41 is moved from another molding step, the medium circulation port A and the medium feeding / discharging path B are separated from each other. After the inner mold 41 is placed on the base, the medium circulation port A is Connect to the pipe at joint J.
[0039]
The medium feeder is operated to feed high-pressure air or high-pressure steam into the flexible jacket 42 through the medium feed / discharge path B and the medium flow port A. Since the upper and lower portions of the flexible jacket 42 are hermetically sealed on the inner mold 41, the space between the inner surface of the flexible jacket 42 and the outer surface of the inner mold 41 is filled with air. It expands gradually. Then, the rubber sheet 20 mounted on the outer peripheral surface is uniformly expanded in the radial direction, and is brought into contact with the rib mold 45 of the outer mold 46 heated to 100 to 160 ° C. with a heater or high-temperature steam for 30 to 120 seconds.
[0040]
At this time, the short fiber oriented rubber sheet 20 with the adhesive rubber 16 is pressed by the rib mold 45 of the outer mold 46 by the expansion pressing force of the flexible jacket 42, and a plurality of V-shaped protrusions are formed on the surface as shown in FIG. To form an unvulcanized preformed body 21 having
[0041]
Thereafter, the valve is switched to the vacuum pump to exhaust the air filled in the flexible jacket 42, and then the flexible jacket 42 is contracted and returned to the original position shown in FIG. 7 by suction. .
[0042]
Then, the inner die 41 is removed from the outer die 46, and a reinforcing cloth 47 and a cord 48 made of a cord are sequentially wound around the outer peripheral surface of the flexible jacket 42 of the inner die 41. Thereafter, as shown in FIG. 9, the inner mold 41 is placed in the outer mold 46, and then the flexible jacket 42 is expanded as shown in FIG. 10, and the reinforcing cloth 47 and the core wire 48 are uniformly distributed in the radial direction. The belt sleeve 51 is produced by expanding and intimately and integrally vulcanizing the preform 21 attached to the rib mold 45 of the outer mold 46 heated to 100 to 180 ° C. by a heater or high-temperature steam. By molding the unvulcanized preformed body 21 as in the above-described manufacturing method, the amount of expansion of the core wire 48 due to expansion of the flexible jacket 42 during molding can be suppressed, and the core wire 48 can be arranged flat. A V-ribbed belt having excellent stability can be manufactured.
[0043]
In the method of the present invention, a tubular laminate of the short fiber oriented rubber sheet 20 with the adhesive rubber 16 is interposed between the inner mold 41 equipped with the flexible jacket 42 and the outer mold 46 engraved with the rib mold 45. You can also. That is, the cylindrical laminated body of the short fiber oriented rubber sheet 20 with the adhesive rubber 16 is arranged in contact with the rib mold 45 of the outer mold 46, and a gap is provided between the inner mold 41 and the outer mold 46. It can also be arranged to form an unvulcanized preform 21.
[0044]
After vulcanization, as shown in FIG. 11, the flexible jacket 42 is contracted, the inner die 41 is pulled out from the outer die 46, and then the vulcanized belt sleeve 51 attached to the outer die 46 is taken out. Then, the vulcanized belt sleeve 51 is cut into a predetermined width in the circumferential direction while being inserted into another drum and rotated, and is taken out from the drum and inverted so that the V-shaped rib is accurately formed. A plurality of attached V-ribbed belts 1 are obtained. When the outer mold 46 is a split mold, the insertion of the unvulcanized sleeve and the removal of the vulcanized sleeve become easy, and the split surface functions as a kind of air vent, thereby further increasing the V-shaped rib. It can be formed accurately.
[0045]
The vulcanized belt sleeve 51 extracted from the inner die 41 is thereafter inserted into another drum, and the rib surface layer of the vulcanized belt sleeve 51 is ground using a known grinder wheel to project short fibers. You may let it.
[0046]
Further, in this embodiment, the vulcanized belt sleeve 51 can be manufactured by a method as shown in FIG.
That is, the short fiber-containing rubber sheet 20 having the reinforcing cloth 47, the core wire 48, and the rib portion 29 with the adhesive rubber 16 is sequentially wound around the outer peripheral surface of the flexible jacket 42 attached to the inner die 41, and the wide width is not applied. A vulcanized belt sleeve 51 is arranged. In this case, in the rubber sheet 20, the adhesive rubber 16 is arranged on the core wire 48 side, and the short fiber-containing rubber sheet 20 having the rib portion 29 is arranged on the outermost side.
[0047]
Next, with the unvulcanized belt sleeve 51 wound around the inner mold 41, the belt sleeve 51 is placed and fixed on a base so as to form a constant gap inside the outer mold 46. Next, as shown in FIG. 10, high-pressure air or high-pressure steam is fed into the flexible jacket 42 in the same manner as described above. Since the upper and lower portions of the flexible jacket 42 are hermetically sealed on the inner mold 41, the space between the inner surface of the flexible jacket 42 and the outer surface of the inner mold 41 is filled with air. It expands gradually. Then, the unvulcanized belt sleeve 51 mounted on the outer peripheral surface is uniformly expanded in the radial direction, and is brought into contact with the rib mold 45 of the outer mold 46 heated with a heater or high-temperature steam.
[0048]
At this time, the rib portion 29 of the short fiber-containing rubber sheet 20 on the surface of the unvulcanized belt sleeve 51 is fitted to the rib mold 45 of the outer mold 46 by the expansion pressing force of the flexible jacket 42, and FIG. A vulcanized belt sleeve 51 having a plurality of V-shaped protrusions on the surface is formed.
[0049]
Then, as shown in FIG. 11, after vulcanization, the valve is switched to the vacuum pump, and the vacuum pump is operated to exhaust the air filled in the flexible jacket 42. The elastic jacket 42 is contracted and returned to the original position. After releasing the inner die 41, the vulcanized belt sleeve 51 attached to the outer die 46 is released.
[0050]
FIG. 13 is a sectional view of the obtained V-ribbed belt. The V-ribbed belt 100 has a cord 102 made of a cord of high strength and low elongation embedded in an adhesive rubber layer 103, and has a compression rubber layer 104 as an elastic layer below the core. The compressed rubber layer 104 is provided with a plurality of ribs 106 having a substantially triangular cross section and extending in the longitudinal direction of the belt.
[0051]
The short fibers 110 contained in the rib portion 106 are aligned in a wave shape at the rib portion 106 when the unvulcanized belt sleeve is vulcanized in close contact with the engraved rib mold as shown below. As a result, the belt maintains the lateral pressure resistance and eliminates the generation of scraps that would otherwise become scrap.
[0052]
The short fibers 110 contained in the rib portion 106 improve the lateral pressure resistance of the rib portion 106 by mixing short fibers made of nylon 6, nylon 66, polyester, cotton, and aramid. Aramid short fibers are preferred.
[0053]
In order for the aramid short fiber to sufficiently exhibit the above-described effects, the fiber length of the aramid fiber is 1 to 20 mm, and the amount of the aramid fiber is 1 to 30 parts by mass with respect to 100 parts by mass of rubber. The aramid fiber is an aramid having an aromatic ring in its molecular structure, such as Conex, Nomex, Kevlar, Technora, Twaron, and the like.
[0054]
When the amount of the aramid short fiber is less than 1 part by mass, the lateral pressure resistance of the rib portion 106 may be lacking. On the other hand, when the amount exceeds 30 parts by mass, the short fiber is not uniformly dispersed in the rubber. . However, the addition of the aramid short fibers is not essential, and the short fibers made of other materials may be added.
[0055]
As the rubber used for the adhesive rubber layer 103 and the compressed rubber layer 104, hydrogenated nitrile rubber, chloroprene rubber, natural rubber, CSM, ACSM, SBR, and ethylene-α-olefin elastomer are used. The addition ratio is 80% or more, and preferably 90% or more in order to exhibit heat resistance and ozone resistance characteristics. A 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%. Among them, an ethylene-α-olefin elastomer having oil resistance and cold resistance is preferable.
[0056]
A typical example of the ethylene-α-olefin elastomer is EPDM, which is an ethylene-propylene-diene monomer. Examples of diene monomers include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene and the like. Ethylene-propylene rubber (EPR) can also be used.
[0057]
For crosslinking of the rubber, sulfur or an organic peroxide is used. Examples of the organic peroxide include dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, benzoyl peroxide, and 1,1. 3-bis (t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5- (benzoylperoxy) Hexane, 2,5-dimethyl-2,5-mono (t-butylperoxy) hexane and the like can be mentioned.
[0058]
Further, by blending a crosslinking assistant (co-agent), the degree of crosslinking can be increased and problems such as adhesive wear can be prevented. Examples of the crosslinking aid include TIAC, TAC, 1,2 polybutadiene, metal salts of unsaturated carboxylic acids, oximes, guanidine, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, NN′-m- It is usually used for peroxide crosslinking such as phenylene bismaleimide and sulfur.
[0059]
In addition, if necessary, carbon black, reinforcing agents such as silica, fillers such as calcium carbonate and talc, plasticizers, stabilizers, processing aids, normal rubber compounds such as coloring agents. What is used is used.
[0060]
The rubber composition used for the adhesive rubber 103 is similar to the rubber compound of the compressed rubber layer 104 except for short fibers. Of course, short fibers may be included.
[0061]
As the core wire 102, polyester fiber, aramid fiber, and glass fiber are used, and among them, a total denier of 4,000 to 8, which is obtained by twisting a polyester fiber filament group having ethylene-2,6-naphthalate as a main constituent unit, is used. 000 bonded cords are preferred because the belt slip rate can be kept low and the belt life is extended. The core wire 102 is subjected to an adhesive treatment for the purpose of improving the adhesiveness with rubber. As such an adhesive treatment, the fiber is generally immersed in a resorcinol-formalin-latex (RFL) solution and then dried by heating to form an adhesive layer uniformly on the surface. However, without being limited to this, there is a method of performing a pretreatment with an epoxy or isocyanate compound and then treating with an RFL solution.
[0062]
The core wire 102 can be finished into a belt having a high modulus by setting the spinning pitch, that is, the winding pitch of the core wire to 0.9 to 1.3 mm. If it is less than 0.9 mm, the cord runs over the adjacent cord and cannot be wound, while if it exceeds 1.3 mm, the modulus of the belt gradually decreases.
[0063]
The back reinforcing member 105 is selected from a woven fabric, a knitted fabric, and a nonwoven fabric, and a more preferable one is a nonwoven fabric. Examples of the fiber material include natural fibers such as cotton, hemp and rayon, and organic fibers such as polyamide, polyester, polyethylene, polyurethane, polystyrene, polyfluoroethylene, polyacryl, polyvinyl alcohol, wholly aromatic polyester, and aramid. No. The canvas is immersed in a resorcinol-formalin-latex solution (RFL solution) according to a known technique and then frictionally rubbed with an unvulcanized rubber against the back reinforcing material 105, or soaked in a solvent after immersion in the RFL solution. Immerse in liquid.
[0064]
The V-ribbed belt thus obtained can form a power transmission belt at low cost by reducing the number of manufacturing steps by laminating the adhesive rubber and the compressed rubber layer in advance. In order to produce the preformed body of (1), the cords can be arranged flat, and the running life of the belt is also improved.
[0065]
【The invention's effect】
As described above, in the inventions described in the claims of the present application, after extruding a two-layer cylindrical molded body in which the adhesive rubber is laminated on the outer peripheral side of the short fiber-containing rubber, the adhesive rubber is cut in a straight line to form an adhesive rubber. The rubber sheet is a short fiber oriented rubber sheet laminated with a rubber layer, which enables smooth extrusion and prevents the occurrence of rough surface on the rubber surface, and reduces the manufacturing man-hours by laminating the adhesive rubber and the compressed rubber layer in advance, resulting in low cost. In addition, in the belt forming process, an uncured preformed body can be formed in advance, so that the amount of expansion of the core wire due to expansion of the flexible jacket can be set small, and the core wire can be formed. There is an effect that it can be arranged flat.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a step of forming a short fiber oriented rubber sheet while linearly cutting an extruded cylindrical molded body.
FIG. 2 is a schematic diagram showing another process of forming a short fiber oriented rubber sheet while cutting an extruded cylindrical molded body linearly.
FIG. 3 is a schematic view showing still another process of forming a short fiber oriented rubber sheet while linearly cutting an extruded cylindrical molded body.
FIG. 4 is an enlarged view of a portion C in FIG. 3;
FIG. 5 is a sectional view taken along the line AA in FIG.
FIG. 6 is a perspective view of a sheet cut into a short fiber oriented rubber sheet with an adhesive rubber.
FIG. 7 is a longitudinal sectional view showing a state where a preform is being formed.
FIG. 8 is a cross-sectional view showing a state after a preformed body is manufactured.
FIG. 9 is a sectional view of a state before an unvulcanized belt sleeve is manufactured.
FIG. 10 is a cross-sectional view of a state where the belt sleeve is vulcanized.
FIG. 11 is a sectional view showing a state after vulcanizing the belt sleeve.
FIG. 12 is a longitudinal sectional view showing a state after an unvulcanized belt sleeve is formed by another method.
FIG. 13 is a sectional view of a V-ribbed belt according to the present invention.
[Explanation of symbols]
2a First extruder 2b Second extruder 5 Expansion die 8 Rubber passage 10 Inner die 11 Inlet 12 Discharge port 13 Outer die 15 Short fiber-containing rubber 16 Adhesive rubber 17 Cylindrical molded body 19 Cutting means 20 Short fiber oriented rubber sheet 21 Preformed body 41 Inner mold 42 Flexible jacket 45 Rib mold 46 Outer mold 48 Core 51 Belt sleeve

Claims (7)

In a method for manufacturing a power transmission belt having a bonding rubber layer in which a cord is embedded along the belt longitudinal direction and a rib portion extending in the belt longitudinal direction adjacent to the bonding rubber layer,
After extruding a two-layer cylindrical molded body with the short fiber-containing rubber laminated on the inner circumference and the adhesive rubber on the outer circumference, using an expansion die whose diameter is gradually expanded from the inlet to the discharge port, cut and bond Short fiber oriented rubber sheet laminated with rubber,
A short fiber oriented rubber sheet laminated with the adhesive rubber is interposed between an inner mold having a flexible jacket attached to the outer peripheral surface and an outer mold having a rib mold stamped on the inner peripheral surface,
The flexible jacket is expanded to prepare an unvulcanized preform so that the short fiber oriented rubber sheet is in close contact with the engraved rib mold of the outer mold,
At least a core wire is wound around the flexible jacket surface of the inner mold detached from the outer mold,
Again, placing the inner mold in the outer mold, inflating the flexible jacket and vulcanizing integrally with the preformed body with the core wire attached to the outer mold,
Demold to produce a vulcanized belt sleeve with ribs,
A method for manufacturing a power transmission belt, comprising: In a method for manufacturing a power transmission belt having a bonding rubber layer in which a cord is embedded along the belt longitudinal direction and a rib portion extending in the belt longitudinal direction adjacent to the bonding rubber layer,
A two-layer cylindrical molded body in which short fiber-containing rubber is laminated on the inner peripheral side and adhesive rubber is laminated on the outer peripheral side is extruded with an expansion die whose diameter is gradually increased from the inlet to the discharge port, and the cylindrical molded body is extruded. Cut straight into a short fiber oriented rubber sheet laminated with adhesive rubber,
An unvulcanized rubber sleeve is formed by winding a short fiber oriented rubber sheet on which at least a core wire and an adhesive rubber are laminated on a stretchable flexible jacket surface attached to an inner mold,
Insert the inner mold into the outer mold with a rib mold stamped on the inner peripheral surface, seal the pressure medium, expand the flexible jacket, press the unvulcanized rubber sleeve on the outer mold and vulcanize. Do
A method for manufacturing a power transmission belt, comprising: In the process of forming a short fiber oriented rubber sheet in which the adhesive rubber is laminated, the adhesive rubber is extruded so as to cover the outer peripheral surface of the previously extruded short fiber-containing rubber, and the diameter of the inner die is gradually increased from the inlet to the discharge port. 3. The method for manufacturing a power transmission belt according to claim 1, wherein an adhesive rubber is surrounded on the outer peripheral surface of the short fiber-containing rubber and a laminated two-layer cylindrical molded body is extruded from an expansion die comprising an outer die and an outer die. In the process of forming a short fiber oriented rubber sheet in which the adhesive rubber is laminated, the rubber extruded from the short fiber-containing rubber that has been previously extruded and coated with the adhesive rubber is simultaneously extruded from the entrance of the expansion die to contain the adhesive rubber containing the short fibers. 4. The method of manufacturing a power transmission belt according to claim 3, wherein the power transmission belt is formed into a cylindrical molded body that is surrounded and laminated on an outer peripheral surface of rubber. In the step of forming a short fiber oriented rubber sheet in which the adhesive rubber is laminated, the short fiber-containing rubber is caused to enter from the entrance of the extension die, while the adhesive rubber is caused to enter at a portion located between the entrance and the discharge port of the extension die. 4. The method for manufacturing a power transmission belt according to claim 3, wherein the adhesive rubber is extruded into a cylindrical molded body that is surrounded and laminated on the outer peripheral surface of the short fiber-containing rubber. 6. The adhesive rubber intruding position is between the entrance of the expansion die and the discharge port, and the gap of the rubber passage from the adhesive rubber intrusion position to the discharge port is increased by the thickness of the laminated adhesive rubber. A method for manufacturing the transmission belt according to the above. The method for manufacturing a power transmission belt according to any one of claims 1 to 6, wherein the rib surface layer of the demolded vulcanized rubber sleeve is ground.

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