JP4772518B2 - Manufacturing method of power transmission belt - Google Patents

Description

The present invention is a low-edge single cogged belt or a low-edge double cogged belt used as a transmission belt for snowmobiles, scooters and general industries, and cracks are generated near the interface between the cogging portion of the compressed rubber layer and the adhesive rubber layer. The present invention relates to a manufacturing method of a difficult power transmission belt.

  2. Description of the Related Art Conventionally, in a drive system in the mechanical field for scooters or general industries, a belt-type transmission that suspends a transmission belt between a driving pulley and a driven pulley and changes the effective diameter of the pulley to change the speed is used. The power transmission belt used here has a cog portion in which a cog crest portion and a cog trough portion are alternately arranged on at least one of the compression rubber layer and the stretch rubber layer, and the core wire is placed in the adhesive rubber layer. Low-edge cogged belts such as a low-edge single cogged belt or a low-edge double cogged belt are known.

  The low edge cogged belt is manufactured by sequentially winding the outer reinforcing cloth mounted on the molding die, the rubber sheet of the stretched rubber layer, the core wire, the rubber sheet of the compressed rubber layer, and the inner reinforcing cloth. In general, a cylindrical base mold having alternating shaped parts is inserted and then vulcanized, and the inner reinforcing cloth is shrunk by pressure during vulcanization, and a method of molding the rubber sheet of the compressed rubber layer is generally used. It was.

  However, since the belt produced by this method tends to stretch easily, the following method has been proposed. That is, an unvulcanized rubber sheet is placed on a planar grooved mold longer than the belt circumference prepared in advance, and a cog pad molded in a cog shape by heating and pressing with a press is produced. This cog pad is fitted into the projecting part and groove part of a cylindrical master mold mounted on a molding drum, the cut surfaces of the cog pad are brought into contact with each other, a core wire is wound, and another rubber layer and reinforcing cloth are attached to this cog pad. It was wound from above and finished forming and vulcanized. (For example, disclosed in Patent Document 1)

Further, as another method, a reinforcing cloth or a rubber sheet, which is a constituent material of the compressed rubber layer, is wound around a mold having alternating protruding portions and groove-shaped portions, covered with a jacket, and heated and pressed to form a mold. An unvulcanized sleeve was formed by cogging the protrusions and the grooves. On the back surface of the unvulcanized sleeve, dents may occur at the respective cog peaks because rubber flows into the groove-like part. If the belt was molded with the dent remaining, pinholes were generated in the belt, causing cracks. To remove this, the back side of the sleeve is cut, ground, or polished to finish it flat, and then a rubber sheet that forms the core wire and the stretched rubber layer is wound in order to produce a belt molded body, which is then vulcanized. It was. (For example, it is disclosed in Patent Document 2.)
JP 2002-1691 A JP 2005-54851 A

  However, in order to remove the indentation that occurred on the back of the sleeve, cutting, grinding, or polishing the back to make it flat will generate a lot of scrap, such as cutting, grinding, or polishing. I was letting. For this reason, a countermeasure for reducing the generation of scrap has been strongly desired.

The present invention has been made in view of the above points, and suppresses generation of scraps such as cutting scraps, grinding scraps, or polishing scraps, and is generated near the interface between the cogging portion of the compressed rubber layer and the adhesive rubber layer. An object of the present invention is to provide a method of manufacturing a power transmission belt that eliminates pinholes that occur and prevents early cracking during belt travel.

According to a first aspect of the present invention, there is provided a method for producing a power transmission belt in which a core wire is interposed between a compressed rubber layer and an extended rubber layer, and at least a cogg portion is provided in the compressed rubber layer.
A sheet for compressed rubber having ridges at predetermined intervals on the back as a material to become a compressed rubber layer is wound around a mold having alternating protrusions and grooves, and the ridges above the groove Placed in
Pressurizing the compressed rubber sheet under heating to form an unvulcanized sleeve having a flat back surface with a cog,
After producing a belt molded body by winding at least a material to be a core wire and a stretched rubber layer around the back surface of the sleeve,
This is a method for producing a power transmission belt, in which the belt molded body is heated and pressurized to be vulcanized.
In this method, the raised portion provided on the compressed rubber sheet is placed on the groove-shaped portion of the mold, and the compressed rubber sheet is heated and pressed in this state, so that the raised portion having a volume is the groove-shaped portion. A flat back unvulcanized sleeve that is fully press-fitted and has no dents. Thereby, generation | occurrence | production of the pinhole in the interface of a compression rubber layer and an adhesive rubber layer is suppressed, and the running life of a belt also becomes long.

According to the second aspect of the present invention, a sheet for compressed rubber having raised portions on the back surface at predetermined intervals is a laminate of a layer provided with raised portions and a flat layer. This is a method for manufacturing power transmission belts whose hardness is larger than that of a flat layer. By hardening the layer provided with the raised portions, the press fit into the groove-shaped portion is ensured, and the compressed rubber layer Generation of pinholes at the interface between the adhesive rubber layer and the adhesive rubber layer is suppressed.

In the power transmission belt of the present invention, the compressed rubber layer is divided into a first layer located away from the lower adhesive rubber layer and a second layer closely contacting the lower adhesive rubber layer, and the first layer and the second layer are separated from each other. The interface is an uneven pattern, and a flat surface is maintained at the interface between the second layer of the compressed rubber layer and the lower adhesive rubber layer. As a result, there is no occurrence of pinholes, and the occurrence of cracks during belt running can be reduced.
On the other hand, in the method for manufacturing a power transmission belt, the protruding portion of the compressed rubber sheet is disposed on the groove-shaped portion of the mold, and in this state, the back surface of the compressed rubber sheet is heated and pressed to increase the volume. The raised portion is fully press-fitted into the groove-like portion, resulting in a flat, unvulcanized sleeve with no dents. Thereby, the occurrence of pinholes at the interface between the compressed rubber layer and the adhesive rubber layer is suppressed, and the running life of the belt is also increased.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a partial front view of a power transmission belt obtained by the method of the present invention.
In the power transmission belt 1, a cord 3 made of a cord is embedded in the upper and lower adhesive rubber layers 2a and 2b, and an extension rubber layer 6 made of a rubber layer 5a and a lower adhesive rubber are positioned above the upper adhesive rubber layer 2a. At the lower position of the layer 2b, there is a compressed rubber layer 7 in which a reinforcing cloth 4 and a rubber layer 5b are laminated. The stretch rubber layer 6 and the compression rubber layer 7 have upper and lower cog portions 11 and 12 in which cog valley portions 8 (8a) and cog mountain portions 9 (9b) are alternately arranged along the longitudinal direction of the belt at a constant pitch. Is provided. The reinforcing cloth 4 may also be laminated on the stretch rubber layer 6.

  The compressed rubber layer 7 is divided into a first layer 7a located away from the lower adhesive rubber layer 2b and a second layer 7b closely contacting the lower adhesive rubber layer 2b, and the interface between the first layer 7a and the second layer 7b is It has a gentle uneven pattern. Since the bump 9 is filled with the first layer 7a and the second layer 7b, the interface between the second layer 7b of the compression rubber layer and the lower adhesive rubber layer 2b is maintained on a flat surface, and pinholes are also generated. No cracks are generated when the belt is running.

  The first layer 7a and the second layer 7b may be the same rubber composition, and the hardness of the second layer 7b may be set larger than that of the first layer 7a, and further the second layer The amount of the short fibers 7b may be larger than that of the first layer 7a.

  At the interface 13 between the compressed rubber layer 7 and the lower adhesive rubber layer 2b, there is little unevenness and a relatively flat surface, and there is no dent in the second layer 7b. Therefore, the lower adhesive rubber layer 2b does not penetrate into the second layer 7b, and the thickness of the lower adhesive rubber layer 2b is substantially uniform over the entire belt. In addition, since the interface 13 is filled with the rubber composition, no voids such as pinholes are generated, and the occurrence of cracks is reduced during belt running.

  The shape of the belt side surface is from the top portion 14 of the stretch rubber layer 6 to the boundary position U corresponding to 90 to 100% of L, where L is the distance from the top portion 14 of the stretch rubber layer 6 to the upper end P of the core wire 3. Is a cut surface perpendicular to the top 14 of the stretched rubber layer 6, and a bias cut surface from the boundary position U to the bottom surface of the compressed rubber layer. The angle of the bias cut surface is 20 to 60 degrees, and a wide angle belt is also included. Of course, the shape of the belt side surface may be only the bias cut surface.

  As the core 3, polyester fiber, aramid fiber, and glass fiber are used, and the total number of deniers obtained by twisting together polyester fiber filament groups mainly composed of ethylene-2,6-naphthalate is 4,000 to 8, A cord subjected to adhesion treatment of 000 is preferable in order to reduce the belt slip ratio and extend the belt life. The number of upper twists of this cord is 10 to 23/10 cm, and the number of lower twists is 17 to 38/10 cm. When the total denier is less than 4,000, the modulus and strength of the cord are too low. When the total denier is more than 8,000, the belt becomes thick and the bending fatigue property is deteriorated.

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

  And as a short fiber used for the said compression rubber layer 7, it consists of fibers, such as an aramid fiber, a polyamide fiber, a polyester fiber, cotton, and the length of a fiber is about 1-10 mm although it changes with kinds of fiber. For example, aramid fibers are about 3 to 5 mm, and polyamide fibers, polyester fibers, and cotton are about 5 to 10 mm. And the direction of the short fiber in the said rubber layer is orientating in the range of 70-110 degrees, when the direction of the perpendicular direction with respect to the longitudinal direction of a belt is set to 90 degrees. The stretched rubber layer 5 may not include the short fibers 16. The adhesive rubber layers 2a and 2b may include the above short fibers, but it is preferable not to include them in consideration of adhesion to the core wire 3.

  The reinforcing cloth 4 is a cloth woven in plain weave, twill weave, satin weave, etc. made of cotton, polyester fiber, nylon or the like, and is a canvas whose warp and weft crossing angle is about 90-120 °. 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 formaldehyde into a latex. Examples of the latex used here include chloroprene, styrene / butadiene / vinylpyridine terpolymer, hydrogenated nitrile, and NBR.

  Next, the steps of the method for manufacturing the power transmission belt will be described with reference to FIGS.

  FIG. 2 shows an example of a method for manufacturing the power transmission belt 1, in which a reinforcing cloth is formed on a forming die in which protrusions and grooves are provided alternately.

  That is, in the molding of the reinforcing cloth 40, a rubber adhesive, which is a rubber paste, is applied to the surface of the projecting portion 42 of the molding die 41 (with a cylindrical mother die attached to the mold) by spraying, brushing, rollers, or the like. After that, the reinforcing cloth 40 that has been subjected to the bonding process or not yet processed is pulled out and placed on the surface of the protrusion 42. After the pinion roll 50 is lowered and it is confirmed that the tooth portion 52 is in the groove-like portion 43 of the forming die 41, the forming die 41 is rotated and the reinforcing cloth 40 positioned on the front protruding portion 42a is attached to the pinion roll. Pressing at the bottom surface 51, and then engaging the tooth portion 52 of the pinion roll 50 with the groove-like portion 43 of the mold 41 and bringing the tooth tip end surface 44 into contact with the groove-like bottom surface 45 of the mold 41 for pressure deformation. . The pinion roll 50 rotates with the rotation of the mold 41.

  Then, by pressing the reinforcing cloth 40 in the adjacent rear protrusion 42b with the bottom surface 51 of another adjacent pinion roll, the reinforcing cloth 40 is completely stretched along one groove-like part 43 without stretching. Deformation is repeated in sequence, and the reinforcing cloth 40 is molded so as to be in close contact with the entire periphery of the mold 41. In the case of the present embodiment, when one tooth portion 52 of the pinion roll 50 is in the groove-like portion 43 of the molding die 41, the tooth portion 52 of the other pinion roll 50 does not press the reinforcing cloth 40. The cloth 40 does not stretch or float. While repeating this, the entire surface of the mold 41 is coated up to 1-4 plies. Then, the end of the reinforcing cloth 40 is cut by a cutter and attached to the forming die 41.

  Note that in the molding of the reinforcing cloth 40, it is not necessary to use the pinion roll as described above, and a rod that fits into the groove-shaped portion may be used.

  The rubber-based adhesive used here is obtained by dissolving various rubber compounds in a solvent such as methyl ethyl ketone (MEK) and toluene and mixing them, and the adhesion of the reinforcing cloth 40 to the mold 41 surface is obtained. Well.

  Subsequently, as shown in FIG. 3, both end faces of the unvulcanized compressed rubber sheet 55 in which the layer 55a provided with the raised portion 55c and the flat layer 55b are laminated are inclined in the thickness direction (normally bebe cut). What is said is wound around a forming die 41 on which the reinforcing cloth 40 is formed. In this case, the raised portion 55 c needs to be disposed on the groove-like portion 43 of the mold 41. This is because the raised portion 55c having a volume is fully press-fitted into the groove-like portion 43 to finish a flat unvulcanized sleeve having no dent portion.

  As the compressed rubber sheet 55, a layer 55a provided with raised portions and a flat layer 55b are laminated and integrated. The layer 55a provided with the raised portion and the flat layer 55b may be the same rubber composition, and the hardness of the layer 55a provided with the raised portion may be set larger than that of the flat layer 55b. . Further, the amount of short fibers added to the layer 55a provided with the raised portions may be larger than that of the flat layer 55b. By doing in this way, the rubber | gum flow of the layer 55a which provided the protruding part in the shaping | molding process is blocked | prevented, and the sheet | seat 55 for compressed rubber can fully be press-fit in the groove-shaped part 43 by maintaining hardness.

Then, after abutting the cut surfaces of the compressed rubber sheet 55, the surfaces of the cut surfaces are lightly pressed with a pressure jig (not shown) and joined, and then heated with a heating press (not shown). To form a joint (not shown). The heating and pressing conditions are a temperature of 80 to 120 ° C., a surface pressure of 1 to ² kg / cm ² , and a time of 10 to 30 seconds. The joint is usually positioned at the groove 43 of the mold 41. When the position of the joint comes to the projecting portion 42, the joint comes to the belt cog valley portion, so that cracking is likely to occur.

  One ply of a resin film or release paper made of polymethylpentene or polyethylene terephthalate, which is a release material 56, having excellent heat resistance and release properties along the surface of the layer 55a provided with the raised portions 55c of the compressed rubber sheet 55. It is wound and overlapped and joined, and is surrounded by a pressing member 66 having a flat inner surface. The pressing material 66 is a sheet body or a cylindrical body, and for example, a rubber jacket is applied.

Subsequently, the process proceeds to a molding process for the compressed rubber sheet 55. In this rubber sheet molding step, for example, a vulcanization can can be used. In this case, after covering the outer side of the pressing material 66 with a rubber jacket 57 as a steam blocking material, the molding die 41 is placed in a vulcanizing can, and the temperature is 160 to 180 ° C. and the external pressure is only 0.1 to 0.9 MPa. Then, molding is performed for about 5 to 10 minutes to form an unvulcanized sleeve 60 having a cog 59 as shown in FIG. Even if it molds with a vulcanizing can, the joint part of the sleeve 60 does not crack.
Needless to say, the molding is not a vulcanized can, and the outside of the compressed rubber sheet 55 may be heated and pressurized by a pressure band, a press method, or the like.

  As shown in FIG. 4, when the compressed rubber sheet 55 heated and pressurized flows into the groove-like portion 43, the unvulcanized sleeve 60 is pressed into the groove-like portion 43 by the pressing material 66. At the same time, since the volume is compensated, the cog portion 59 is formed with a flat unvulcanized sleeve on the back surface that does not generate a dent portion that penetrates deeply from the back surface 61. Thereby, generation | occurrence | production of the pinhole in the interface of a compression rubber layer and an adhesive rubber layer is suppressed, and the running life of a belt also becomes long.

  A belt molded body is produced on the back surface of the compressed rubber layer 70 produced by the method shown in FIG. That is, it shows a state in which a belt molded body is produced on the back surface of the molded compression rubber layer 70. The molding die 41 is mounted on a molding machine (not shown), and the cord 71 made of a cord is connected to the compression rubber layer. 70 (back surface 61 of the sleeve 60) is wound in a spiral, and then an adhesive rubber sheet 72 for forming an adhesive rubber layer, an elastic rubber sheet 73 for forming an elastic rubber layer, an upper surface reinforcing cloth 74, and an air vent 75 are sequentially wound. Thus, a belt molded body 76 is produced. Then, the molding die 41 taken out from the molding machine is placed on the support base, and the cylindrical mother die 77 is inserted. The surface of the projecting portion 78 and the groove portion 79 of the cylindrical mother die 77 is covered with a woven fabric such as nylon.

  The air vent 75 used here is a resin film made of polymethylpentene or polyethylene terephthalate, which is excellent in heat resistance and releasability, like the release material 56. However, it is not always necessary to use the air vent 75.

  Subsequently, the mold 41 is transferred to a vulcanizing can and vulcanized by a normal method. After vulcanization, the cylindrical mother die 77 and then the cylindrical belt sleeve are extracted from the molding die 41.

  The air venting material 75 wound around the surface of the upper surface reinforcing cloth 74 suppresses stagnation of air at the time of forming the cog mountain portion, improves the flow, and accurately forms the cog mountain shape.

  Next, a belt sleeve is attached to the mantle, and a cogged belt 1 is manufactured by cutting the belt sleeve to a predetermined width with a cutter. In addition, the belt sleeve is cut at a right angle to a predetermined width, finished into a single belt having a rectangular cross section, and attached to a biaxial pulley and rotated while rotating the belt side surface from the boundary position U to the bottom surface of the compressed rubber layer. The power transmission belt 1 can be finished by cutting the bias with a pair of cutters to remove ring debris.

Example 1
As a core wire, a 1,500 denier aramid fiber (trade name: Twaron) is twisted 2 × 3 by twisting it upside down at an upper twist number of 19.7 times / 10 cm and a lower twist number of 15.8 times / 10 cm. An unprocessed code with a total denier of 9,000 was prepared. Next, this untreated cord was pre-dipped with an isocyanate-based adhesive, then dried at about 170 to 180 ° C., immersed in an RFL solution, and then subjected to a stretching and heat setting treatment 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.

  The compression rubber layer and the stretch rubber layer are made of a rubber composition made of chloroprene rubber containing aramid short fibers (25 parts by weight with respect to 100 parts by weight of rubber), and the adhesive rubber layer is made of chloroprene rubber containing no short fibers. A rubber composition was used.

  A cylindrical mold having alternating protrusions and grooves is mounted on a spindle with a mold having a perfect circular cross section, and rubber paste prepared by dissolving chloroprene rubber composition with methyl ethyl ketone is the surface of the protrusion. Painted by spraying on. Then, the reinforcing cloth was sandwiched between the molding die and the pinion roll, and one ply was laminated while molding the molding die and the pinion roll while synchronously rotating.

Subsequently, one sheet for compressed rubber having ridges with pitch intervals between the groove portions was cut to a bias, and this was wound on a reinforcing cloth of a molding die. In this case, the raised portion of the compressed rubber sheet was disposed so as to be on the groove-shaped portion of the cylindrical matrix. Then, the end surfaces of the compressed rubber sheet were butted together and the joint portion was lightly joined with a stitcher, and then further bonded using a heating press (temperature 100 ° C., surface pressure 1-2 kg / cm ² , 15 seconds).

  Thereafter, a polymethylpentene film (release material) having a thickness of 0.05 mm is wound around the surface of the compressed rubber sheet by 1 ply, and further a pressing material (S3M wide toothed belt) having teeth and grooves alternately is surrounded. A rubber jacket is put on the outside and placed in a vulcanizing can, and the compressed rubber sheet is projected on the cylindrical mother mold by heating and pressing conditions (temperature 170 ° C., external pressure 0.8 MPa only for about 7 minutes). And an unvulcanized sleeve having a back surface having a concavo-convex pattern surface having no dent portion and a cog portion.

  Further, a belt molded body is produced by winding a core wire, an adhesive rubber sheet, a stretch rubber sheet, and a reinforcing cloth on the back surface of the unvulcanized sleeve (the surface of the compressed rubber layer) in order, and forming a protruding portion and a groove shape. Cylindrical mother molds and jackets having alternating parts were sequentially covered, and the mold was placed in a vulcanizing can and vulcanized under normal conditions to obtain a belt sleeve. This sleeve was cut into a V shape by a cutter to finish a scooped cogged belt.

  In the obtained belt, the interface between the cogging portion of the compressed rubber layer and the lower adhesive rubber layer is a flat surface, and the thickness of the lower adhesive rubber layer is reduced without the lower adhesive rubber layer entering the cog mountain portion. The thickness was almost uniform over the entire circumference. Furthermore, even when observed with the naked eye, no voids such as pinholes were observed in the compressed rubber layer because it was filled with the rubber composition. Further, the interface between the first layer and the second layer of the compressed rubber layer was a gentle uneven pattern.

The present invention relates to a power transmission for a snowmobile, a scooter and a low edge cogged belt including a low edge double cogged belt used as a snowmobile, a scooter and a general industrial speed change belt. It is a manufacturing method of a belt.

It is a partial front view of the power transmission belt obtained by the manufacturing method of the present invention. It is a manufacturing process which concerns on this invention, and is a process which shows the state which has shape | molded the reinforcement cloth on the shaping | molding die. The manufacturing process which concerns on this invention, and shows the process before winding the sheet | seat for compressed rubber around a shaping | molding die, and producing an unvulcanized sleeve. The cross section of the produced unvulcanized sleeve is shown. The process which produces a belt molded object on the back surface of the unvulcanized sleeve (compression rubber layer) which was the manufacturing process which concerns on this invention, and is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power transmission belt 2a Upper adhesive rubber layer 2b Lower adhesive rubber layer 3 Core wire 6 Stretch rubber layer 7 Compressed rubber layer 40 Reinforcement cloth 41 Molding die 43 Grooved portion 55 Compression rubber sheet 55a Layer 55b provided with a raised portion Flat Na layer 55 ridge 60 unvulcanized sleeve 61 back surface 66 pressing material

Claims (2)

It is a method for producing a power transmission belt in which a core wire is interposed between a compression rubber layer and an extension rubber layer, and a cog portion is provided at least on the compression rubber layer.
A sheet for compressed rubber having ridges at predetermined intervals on the back as a material to become a compressed rubber layer is wound around a mold having alternating protrusions and grooves, and the ridges above the groove Placed in
Pressurizing the compressed rubber sheet under heating to form an unvulcanized sleeve having a flat back surface with a cog,
After producing a belt molded body by winding at least a material to be a core wire and a stretched rubber layer around the back surface of the sleeve,
The belt molded body is heated and pressurized to be vulcanized,
A method of manufacturing a power transmission belt characterized by the above. A sheet for compressed rubber having ridges on the back at predetermined intervals is a laminate of a layer provided with ridges and a flat layer, and the layer provided with the ridges has a higher hardness than that of the flat layer. 2. The method for producing a power transmission belt according to claim 1 .

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