JP2006150612A - Manufacturing method of transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a transmission belt extended in its life by accurately molding cog ridge parts including the joint part in a compressed rubber layer and improving the bending fatigue resistance of the joint part. <P>SOLUTION: In the manufacturing method of the transmission belt wherein a compressed rubber layer 7 and a stretched rubber layer 6 are arranged so as to be adjacent to an adhesive rubber layer 6 in which core wires 3 are embedded and the compressed rubber layer 7 has cog parts 12 wherein cog ridge parts 9a and 9b and cog valley parts 8 are arranged alternately, the joint parts 14a and 35a of the compressed rubber layer 7 are allowed to exist in the region of the cog ridge parts 9a and one of the cog ridge parts 9a including at least the joint parts 14a is molded by a hard mold 20b while the other ridge parts 9b are molded by a mold 20a made of a rubber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a transmission belt, and is a high-load transmission belt used as a belt for snowmobiles, scooters and general industries, and the shape of a cog mountain portion where a joint portion of a compression rubber layer is located. The present invention relates to a method for manufacturing a transmission belt that is stabilized and has bending fatigue resistance of a joint portion.

  Conventionally, in a drive system of a scooter, a buggy, a snow vehicle, or a general industrial machinery field, a transmission belt is suspended between a drive pulley and a driven pulley and the effective diameter of the pulley is changed to change the speed. A type transmission is used. The power transmission belt used here has a cog that has cog crests and cog troughs alternately arranged on both the compressed rubber layer and the stretched rubber layer or on the rubber layer of the compressed rubber layer. It has a configuration embedded in a rubber layer and is known as a low-edge cogged belt such as a low-edge double cogged belt or a low-edge single cogged belt.

  In the above-mentioned low-edge cogged belt, the demand for extending the life is becoming stricter. In particular, when it is used for a continuously variable transmission belt that is hung on a variable groove width pulley and transmits power while changing the winding diameter of the pulley steplessly, because of excessive side pressure received from the pulley, side pressure resistance, Flexibility, abrasion resistance, heat resistance, etc. are required. For this reason, the shapes and dimensions of the upper and lower cog portions have been studied.

  In addition, as a manufacturing method of the low edge cogged belt, an unvulcanized rubber sheet is placed on a flat grooved mother die longer than a belt circumference prepared in advance, and is pressed into a cog shape by heating and pressing with a press. Make a cog pad. The cog pad is fitted into the concave and convex portions of the cylindrical master mold mounted on the forming drum, the cut surfaces of the cog pad are brought into contact with each other, the core wire is wound, and another rubber layer and reinforcing cloth are attached to the cog pad. After wrapping from above, the molding was completed and the process was shifted to the vulcanization process. (For example, Patent Document 1)

The cog pad is a laminate of one to several plies of reinforcing cloth and an unvulcanized rubber sheet, and has cog crests and cog troughs alternately at a constant pitch in the length direction.
JP 2001-317596 A

  However, when a thick sheet is fitted in a cylindrical matrix and joined together in a straight line, the difference in the inner and outer circumferences of the rubber sheet is large, resulting in poor joint molding workability. The joint mold is deformed during vulcanization, and the exact shape of the joint cannot be formed, and the cog including the joint is easily deformed and fatigued while the belt is running. May occur. In addition, the reinforcing cloth penetrates into the joint part and causes poor adhesion of the joint part, resulting in cracks from there, or a gap occurs in the butt part, resulting in volume cracking, resulting in defective joint joints. As a result, cracks may occur in the joint due to load fluctuations and heat generation during belt running.

  The present invention pays attention to such a problem, and as a result of earnest research, the cog mountain portion including the joint portion in the compressed rubber layer is accurately formed, and the bending fatigue resistance of the joint portion is improved to improve the belt life. It is an object of the present invention to provide a manufacturing method for an industrial belt.

  In order to achieve the above object, in the method for manufacturing a transmission belt according to the present invention, the compression rubber layer and the stretch rubber layer are disposed adjacent to the adhesive rubber layer in which the core wire is embedded, and the compression rubber layer is a cog mountain portion. And a cog trough having a cog portion alternately arranged, the joint portion of the compressed rubber layer being present in the region of the cog crest portion, and a cog including at least the joint portion. One of the ridges is molded with a hard mold, and the other cog ridge is molded with a rubber mold. If the rigid mold is a mold selected from metal, rubber, and resin, it is hard. Including the case where the number of the cog ridges including the joint part formed by the mold is 1 to 4, and the case of having the cog ridges in which the stretched rubber layer cog ridges and the cog valleys are alternately arranged. .

  In the method of manufacturing the transmission belt according to the present invention, the shape of the cog mountain portion including the joint portion is accurately formed, and the repeated deformation of the cog mountain portion including the joint portion is prevented during belt running, and fatigue caused thereby is prevented. By avoiding this, there is an effect that the cracks from the joint portion can be reduced and the belt life can be improved.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a partial front view of a transmission belt according to the present invention, and FIG. 2 is a partial front view of another transmission belt according to the present invention.

  The power transmission belt 1 of the present invention has a cord 3 made of polyester fiber, aramid fiber, glass fiber or the like embedded in an adhesive rubber layer 2, and a reinforcing cloth 4 and an upper portion of the adhesive rubber layer 2, respectively. There is a stretched rubber layer 6 in which the rubber layer 5 is laminated, and a compressed rubber layer 7 in which the reinforcing cloth 4 and the rubber layer 5 are laminated in the same manner. The compressed rubber layer 7 is provided with lower cog portions 12 in which cog valley portions 8 and cog mountain portions 9 are alternately arranged at a constant pitch along the belt longitudinal direction.

  In this embodiment, the stretched rubber layer 6 does not have a cog, and both side surfaces may be cut surfaces that are cut in an inverted V shape from the top of the cog crest 9 to the bottom of the cog valley 8. . Thereby, the side pressure in the pulley can be borne from the core wire 3 to the compressed rubber layer 7, and the peeling or loss of the stretched rubber layer 6 above the core wire 3 can be delayed.

  Further, in this embodiment, when the belt thickness is H and the distance from the pitch line of the core wire 3 to the deepest portion of the cog valley portion 9 of the compressed rubber layer 7 is D, 0.2 ≦ D / H ≦ 0. .26 is satisfied. This value indicates the ratio of the distance D from the pitch line of the core wire 3 to the deepest part of the cog valley portion 9 of the compressed rubber layer 7 with respect to the belt thickness H, and the distance D is less than 0.20. Becomes too small, and the side pressure resistance of the belt decreases, leading to an early life. On the other hand, if it exceeds 0.26, the flexibility of the belt is lowered and the bending resistance is poor, and cracks are likely to occur from the deepest part of the cog valley at an early stage.

  Further, in the compressed rubber layer 7 shown in FIG. 1, the joint portion 14a exists in the region of the cog mountain portion 9, and the region of the cog mountain portion 9a including the joint portion 14a (in this embodiment, the diagonal line intersecting at two mountain peaks). The area that has) is molded with a hard mold, so that the cog shape is accurately molded without deformation, preventing repeated deformation of the cog crest including the joint during belt running, and fatigue due to it By avoiding this, cracks from the joint can be reduced. The number of cog ridges in the region molded with the hard mold is 1 to 4, and when it exceeds 4, the cost of the mold increases.

  In the other power transmission belt 1 shown in FIG. 2, the stretched rubber layer 6 has upper cog portions 11 in which cog mountain portions 9 and cog valley portions 8 are alternately arranged. The joint portion 14b provided in the stretched rubber layer 6 is present in the region of the cog crest portion 9 of the upper cog portion 11 (in this embodiment, a region having diagonal lines intersecting with two or more crests) and is perpendicular to the core wire 3. It is preferable to make it. This is because even if the rubber of the adhesive rubber layer 6 enters the joint portion 14b, it does not enter the surface. The position of the joint part 14b is preferably different from the joint part 14a in order to prevent stress concentration and prevent cracks.

  The rubber to be the compression rubber layer 6 and the stretch rubber layer 7 is natural rubber, butyl rubber, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, alkylated chlorosulfanated polyethylene, hydrogenated nitrile rubber, hydrogenated nitrile rubber. A rubber material such as a mixed polymer of an unsaturated carboxylic acid metal salt or a mixture thereof is used.

  The compressed rubber layer 6 and the stretched rubber layer 7 are made of fibers such as aramid fiber, polyamide fiber, polyester fiber, and cotton, and the length of the fiber varies depending on the type of fiber, but short fibers of about 1 to 10 mm are used. For example, about 3 to 5 mm for aramid fibers, about 5 to 10 mm for polyamide fibers, polyester fibers, and cotton are used. And the direction of the short fiber in the rubber layer is oriented within the range of 70 to 110 ° when the direction perpendicular to the longitudinal direction of the belt is 90 °. Is desirable. The adhesive rubber layer 2 may include the short fibers, but preferably does not include them.

  The reinforcing cloth 4 is made of cotton, polyester fiber, nylon or the like, and is a cloth woven into a plain weave, twill weave, satin weave, or the like, and may be a wide angle canvas with a warp and weft crossing angle of about 90 to 120 °. The reinforcing cloth 4 is subjected to RFL treatment, and then the rubber composition is subjected to fiction and coaching to obtain a canvas with rubber. The RFL liquid is obtained by mixing an initial condensate of resorcin and formalin into a latex. Examples of the latex used here include chloroprene, styrene / butadiene / vinylpyridine terpolymer, hydrogenated nitrile, NBR, and the like.

  FIG. 3 is an example of a method for manufacturing the transmission belt 1 (cogged belt) shown in FIG. 1 and shows a state of producing a molded body comprising a compression rubber layer, a core wire, and an extension rubber layer on the mold. First, the mold 20 having the teeth 21 and the grooves 22 alternately is mounted on the perfect circle 19. The molding die 20 is formed by joining a rubber die 20a made of vulcanized rubber and a hard die 20b selected from metal, a hard rubber, and a thermosetting resin such as phenol and polyacetal. It is a thing. The rubber mold 20a and the hard mold 20b are joined by applying a cross-linking adhesive to the interface and heating. Further, a reinforcing cloth can be pasted across the inner surfaces of the rubber mold 20a and the hard mold 20b.

  As shown in FIG. 4, one to several sheets of reinforcing cloth and an unvulcanized rubber sheet to be a compressed rubber layer are laminated, and this is prepared on a flat mold in which teeth and grooves prepared alternately are arranged. The cog pad portion 30 and the cog valley portion 28 are finished into a cog pad 30 by installing and pressurizing.

  One cutting portion 32 of the cog pad 30 is cut at an angle α of 0 to 10 ° at the top portion 31 of the cog crest portion 28 as shown in FIG. 4, and the other cutting portion 33 is similarly turned by inverting the cog pad 30. It is cut so as to incline in the reverse direction at the cog mountain portion 29. When making the cog pad 30 endless, the cut surface adheres well.

  The molding die 20 is mounted on a molding machine (not shown), and the cog pad 30 of the cog pad is fitted around the groove 22 of the mold while the cog pad 30 of a predetermined length is wound around the mold 20 to face the cut end. The joint part 35a is formed by contact. The joint portion 35 a is positioned in the groove portion 22 of the metal hard die 20 b of the forming die 20. And after winding the unvulcanized rubber sheet 40 used as an adhesive rubber layer, the core wire 41 is wound around the spiral, and 1 to several sheets of reinforcing cloth 42 and the unvulcanized rubber sheet 43 of the stretched rubber layer are laminated thereon. An object is wound and the cut end portion is brought into surface contact to form the joint portion 35b.

  In the present embodiment, the grooved mold 20 taken out from the molding machine is placed on a support base, and a cylindrical mother die made of vulcanized rubber and a jacket (not shown) are fitted therein.

  As a final step, the molded body is transferred to a vulcanizing can and vulcanized by a normal method. After vulcanization, the jacket, the mother die, and then the cylindrical sleeve are removed from the forming die 20, and the sleeve is cut to a predetermined width to finish the cogged belt 1 as shown in FIG. In this way, the cog mountain portion including the joint portion 35a formed by the metal hard mold 20b is accurately formed in the cog shape, and the cog mountain portion including the joint portion 35a is accurately formed. Bending fatigue resistance is improved.

Hereinafter, the effects of the present invention will be confirmed by more specific experimental examples.
Example 1 and Comparative Example 1
Twisted configuration of 1,500 denier aramid fiber (trade name: Twaron) as a core wire, twisted in the upside down direction with an upper twist number of 19.7 times / 10 cm and a lower twist number of 15.8 times / 10 cm And an unprocessed code with a total denier of 9,000 was prepared. Next, this untreated cord was pre-dipped with an isocyanate-based adhesive, dried at about 170 to 180 ° C., immersed in an RFL solution, and then stretched and fixed at 200 to 240 ° C. to obtain a treated cord. .

  A wide-angle plain woven canvas using a 50:50 blended yarn of aramid fiber (trade name: Twaron) and polyethylene terephthalate fiber in a weight ratio was used as the reinforcing fabric. These canvases were immersed in an RFL solution and then heat treated at 150 ° C. for 2 minutes to obtain treated canvases. Thereafter, a rubber composition was friction coated with these treated canvases to obtain rubberized canvases.

  A rubber composition made of chloroprene rubber containing short aramid fibers was used for the compression rubber layer and the stretch rubber layer, and a rubber composition made of chloroprene rubber containing no short fibers was used for the adhesive rubber layer.

  As a cog pad, a laminate of a single reinforcing cloth and a sheet for a compressed rubber layer having a predetermined thickness is placed on a flat cog mold in which teeth and grooves are alternately arranged, and is pressed by pressing at 75 ° C. The part was formed on a cog pad with a mold. Both ends of the cog pad were cut vertically from the top of the cog crest.

  A soft mold made of vulcanized rubber and two hard molds made of stainless steel at the cog mountain portion were joined to form a cylindrical mold.

  After preparing these materials and molds, wrap a cog pad around the above mold and place the joint part in the groove of the hard mold, and then wrap the adhesive rubber sheet, core wire, flat stretch rubber layer, and reinforcing cloth in order. Thus, a molded body was produced. Subsequently, after the mold was installed at a predetermined position on the support base, a vulcanized rubber cylindrical matrix having grooves and protrusions was inserted into the inner peripheral surface at regular intervals. Then, the jacket was put on and the mold was placed in a vulcanizing can and vulcanized to obtain a belt sleeve. This sleeve was cut into a V shape by a cutter to finish a transmission belt (size: upper width 29.8 mm, thickness 16.4 mm, outer peripheral length 866 mm) which is a double cogged belt.

  A cut sample (length 100 mm × width 5 mm × thickness 2 mm) of the compressed rubber layer including the joint portion of the obtained belt and positioned at a right angle and parallel to the core wire was taken, and this sample was collected at 100 ° C. After leaving in a high temperature chamber for 30 minutes, a tensile test was performed with a strograph to measure the tensile strength (N = 4), and the breakage position was confirmed. As a result, the tensile strength was 4.9 MPa and the cut part of the joint part was 25%.

Comparative Example 1
A soft mold made of vulcanized rubber was used as a mold, and a cog pad joint portion wound around the mold was disposed. Other than that was carried out similarly to Example 1, and produced the double cogged belt.
The tensile strength (N = 4) of the sample including the joint portion of the obtained belt was 3.5 MPa, and the cut portion of the joint portion was 100%.
As a result, it was found that the strength of the joint portion of the example was definitely improved as compared with the comparative example.

  The power transmission belt of the present invention is suitable for snowmobiles, scooters and general industrial transmission belts.

FIG. 1 is a partial front view of a transmission belt according to the present invention. FIG. 2 is a partial front view of another transmission belt according to the present invention. It is a figure which shows the state which produces the molded object on the mold for the transmission belt which concerns on this invention. It is a perspective view of the cog pad which the transmission belt concerning the present invention uses.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission belt 2 Adhesive rubber layer 3 Core wire 4 Reinforcement cloth 5 Rubber layer 6 Stretch rubber layer 7 Compression rubber layer 8 Cog valley part 9a Cog mountain part 9b Cog mountain part 11 Upper cog part 12 Lower cog part 14a Joint part 35a Joint Part 20a Rubber mold 20b Hard mold

Claims (4)

  A transmission belt having a compression rubber layer and a stretch rubber layer adjacent to an adhesive rubber layer in which a core wire is embedded, and the compression rubber layer having a cog portion in which a cog peak portion and a cog valley portion are alternately arranged. A method of manufacturing, wherein the joint portion of the compressed rubber layer is present in the region of the cog crest, and at least one of the cog crests including the joint is molded with a hard mold, and the other cog crest is made of rubber. A method of manufacturing a transmission belt, characterized by being molded with a mold.   2. The method of manufacturing a transmission belt according to claim 1, wherein the hard mold is a mold selected from metal, rubber, and resin.   The method for manufacturing a transmission belt according to claim 1 or 2, wherein the number of cog ridges including a joint portion formed by a hard mold is 1 to 4. The method of manufacturing a transmission belt according to any one of claims 1 to 3, wherein the stretched rubber layer has a cog portion in which a cog mountain portion and a cog valley portion are alternately arranged.

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