JP6450151B2 - Power transmission belt - Google Patents

Description

  The present disclosure relates to a power transmission belt.

  2. Description of the Related Art A rubber cogged belt (cogged belt) is known as a speed change belt used in transmissions such as two-wheeled vehicles, buggies, and snowmobiles. The cogged belt is a power transmission belt in which cogs are formed at a constant pitch along the longitudinal direction of the bottom surface (inner circumference).

  The cogged belt is formed as follows, for example. First, an unvulcanized rubber sheet rolled to a predetermined thickness is press-molded to form a cogged sheet. Subsequently, the cogged sheet cut to a predetermined length is wound while fitting the cog side into a cog groove formed on the outer peripheral surface of the cylindrical vulcanization mold, and the cut surfaces are butted. Next, an unvulcanized adhesive rubber layer, a core wire, a stretched rubber layer, and the like are wound around the outer peripheral surface of the cogged sheet wound around the cylindrical vulcanization mold to form an unvulcanized slab. Subsequently, the unvulcanized slab is heated and vulcanized. After vulcanization, the vulcanized belt slab is demolded from the cylindrical vulcanization mold and cut into a ring to finish power transmission with cogs.

  There are various variations in the method of forming the cogged belt, but in any case, the compressed rubber layer on which the cogs are formed has a joining portion that abuts the cut surface. The joint portion is lower in strength than other portions of the compressed rubber layer, and cracks are likely to occur.

  In order to suppress the occurrence of cracks in the joint, it has been studied to bond an adhesive tape or a reinforcing cloth to the joint (see, for example, Patent Document 1).

JP 2002-005242 A

  However, the adhesive tape is made of soft rubber, and there is a problem in that the strength decreases conversely when entering the joint surface. Moreover, the conventional reinforcing cloth consists of canvas etc., and is only adhere | attached on the surface of the compression rubber layer. For this reason, the intensity | strength of a junction part cannot be made high enough. Such a problem may occur in other power transmission belts such as a wrapped belt.

  It is an object of the present disclosure to realize a power transmission belt with improved joint strength.

  One aspect of the power transmission belt includes an adhesive rubber layer in which a core wire is embedded, and a compression rubber layer provided on one surface of the adhesive rubber layer. The compression rubber layer includes a joint portion in which a three-dimensional fabric is embedded. Have.

  In one aspect of the power transmission belt, the three-dimensional fabric has a connecting yarn, a front knitted fabric and a back knitted fabric, the connecting yarn is a monofilament, and at least one of the front knitted fabric and the back knitted fabric is a mesh knitted fabric. It can be the ground.

  In one aspect of the power transmission belt, the compression rubber layer may have a cog portion in which cog crest portions and cog valley portions are alternately arranged.

  In this case, the junction may be provided in the cog valley.

  In one aspect of the power transmission belt, the adhesive rubber layer further includes a stretch rubber layer provided on a surface opposite to the compression rubber layer, and the stretch rubber layer has cog crests and cog troughs alternately arranged. You may have a cog part.

  One aspect of the power transmission belt may further include a surface cloth bonded to the surface of the compressed rubber layer.

  According to the power transmission belt of the present disclosure, the strength of the joint can be improved.

(A) And (b) shows the power transmission belt which concerns on one Embodiment, (a) is a partial perspective view, (b) is sectional drawing. (A)-(c) is sectional drawing which shows the structural example of a three-dimensional fabric. It is sectional drawing which shows 1 process of the manufacturing method of the power transmission belt which concerns on one Embodiment. It is sectional drawing which shows 1 process of the manufacturing method of the power transmission belt which concerns on one Embodiment. It is sectional drawing which shows 1 process of the manufacturing method of the power transmission belt which concerns on one Embodiment. It is sectional drawing which shows the modification of the power transmission belt which concerns on one Embodiment. (A) And (b) shows the modification of the power transmission belt which concerns on one Embodiment, (a) is a partial perspective view, (b) is sectional drawing. It is sectional drawing which shows the modification of the power transmission belt which concerns on one Embodiment. It is a schematic diagram which shows a belt running test machine.

  As shown in FIG. 1, the power transmission belt of this embodiment includes an adhesive rubber layer 110 in which a core wire 112 is embedded, and a compressed rubber layer 120 provided on one surface of the adhesive rubber layer 110. The compression rubber layer 120 has cog ridges 121 and cog valleys 122 alternately arranged along the circumferential direction, and has a joint 125 in which a three-dimensional fabric 140 is embedded. . In FIG. 1, an extended rubber layer 130 is provided on the surface of the adhesive rubber layer 110 opposite to the compressed rubber layer 120.

  The adhesive rubber layer 110, the compressed rubber layer 120, and the stretched rubber layer 130 may have a composition corresponding to the required belt characteristics. Examples of raw rubber components for the adhesive rubber layer 110, the compression rubber layer 120, and the stretch rubber layer 130 include natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, hydrogenated acrylonitrile butadiene rubber, butyl rubber, Ethylene-α-olefin elastomers such as chlorosulfonated polyethylene rubber, urethane rubber, ethylene propylene rubber, and ethylene propylene diene rubber (EPDM) can be used.

  The adhesive rubber layer 110, the compressed rubber layer 120, and the stretch rubber layer 130 may contain various compounding agents as necessary. Examples of the compounding agent include a crosslinking agent (for example, sulfur and organic peroxide), an anti-aging agent, a processing aid, a plasticizer, a reinforcing material such as carbon black, and a filler.

  The compressed rubber layer 120 and the stretched rubber layer 130 may contain short fibers. The short fibers can be, for example, polyamide short fibers, vinylon short fibers, aramid short fibers, polyester short fibers, and cotton short fibers. The short fiber can have a length of 0.2 mm to 5.0 mm and a fiber diameter of 10 μm to 50 μm, for example. The short fiber may be produced by, for example, cutting a long fiber that has been subjected to an adhesive treatment to be heated after being immersed in a resorcin-formalin-latex (RFL) treatment solution or the like into a predetermined length along the length direction. The short fibers may be blended as necessary, and may not be blended. When forming the rubber sheet to be the compression rubber layer 120 and the stretch rubber layer 130, the short fibers can be oriented in the required direction by adjusting the amount of short fibers. The adhesive rubber layer 110 preferably contains no short fibers. However, short fibers may be blended.

  The core 112 may be appropriately selected according to the required belt characteristics. For example, an organic fiber such as an aramid fiber, a polyester fiber, a polyamide fiber, or a rayon fiber, a glass fiber, or an inorganic fiber such as steel that is bound in a cord shape can be used.

  The core 112 may be preprocessed. The pretreatment of the core wire 112 may be performed, for example, by immersing the core wire 112 in an RFL processing solution and baking it, and then immersing in a rubber paste and drying by heating if necessary. The immersion and baking in the RFL treatment liquid can be repeated a plurality of times as necessary. For example, the rubber paste can be obtained by dissolving the same rubber as that used in the rubber composition constituting the adhesive rubber layer 110 in toluene or the like.

  The three-dimensional fabric 140 is a knitted fabric having a three-layer structure in which a front knitted fabric 141 and a back knitted fabric 142 are connected by a connecting yarn 143 as shown in FIGS. The front knitted fabric 141 and the back knitted fabric 142 are arranged so as to have a substantially constant interval. The connecting yarn 143 only needs to connect the front knitted fabric 141 and the back knitted fabric 142. For example, loop stitches may be formed in the front knitted fabric 141 and the back knitted fabric 142. A structure in which the knitted fabric 142 is hooked on the knitted fabric 142 may be adopted. If necessary, the connecting thread 143 may be disposed in an inclined manner or may be disposed so as to cross in an X shape. By connecting the connecting yarn 143 back and forth between the front knitted fabric 141 and the back knitted fabric 142, a predetermined space can be maintained between the front knitted fabric 141 and the back knitted fabric 142. The three-dimensional fabric 140 can be formed by, for example, a double Russell weave.

  At least one of the front knitted fabric 141 and the back knitted fabric 142 can be a knitted fabric having a plurality of openings knitted into a through-hole structure such as a mesh knitted fabric. Thereby, rubber | gum can penetrate | invade easily in the structure | tissue of the three-dimensional fabric 140, and it can reinforce more firmly. The front knitted fabric 141 and the back knitted fabric 142 are not particularly limited, but the woven shape in a plane can be a polygonal shape such as a quadrangular shape or a hexagonal shape, a circular shape, or the like. The front knitted fabric 141 and the back knitted fabric 142 may have the same knitting structure or different knitting structures.

  The connecting thread 143 has a woven shape on the elevation surface as a parallel shape as shown in FIG. 2 (a), a cross shape as shown in FIG. 2 (b), or as shown in FIG. 2 (c). It can be combined. In the case shown in FIG. 2A, the monofilaments arranged in parallel have the same winding direction. In the case shown in FIG. 2B, the filaments are arranged in parallel so that the winding direction is alternately right-handed and left-handed. In the case shown in FIG. 2 (c), for example, two rows of right-handed and left-handed monofilaments are arranged in parallel. Alternatively, one set of the right winding and the left winding of the first winding pitch and a set of monofilaments having different winding pitches may be arranged in parallel.

  The fibers forming the front knitted fabric 141 and the back knitted fabric 142 are not particularly limited, and any of natural fibers and synthetic fibers can be used. For example, it can be formed of cotton, cupra, rayon, cellulose fiber, polyester fiber, polyamide fiber, polyacrylonitrile fiber, or the like. Among these, polyester fibers such as polyethylene terephthalate, polymethylene terephthalate, and polybutylene terephthalate are preferable. These fibers may be in any form such as raw yarn, blended yarn, blended yarn or false twisted yarn.

  The connecting yarn 143 is not particularly limited, and can be, for example, a polyester fiber, a polyamide fiber, a polyacrylonitrile fiber, or the like. Among them, polyester fibers such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate, and polyamide fibers such as nylon are preferable, and polyethylene terephthalate and polytrimethylene terephthalate are particularly preferable. As the connecting yarn 143, either a multifilament yarn or a monofilament yarn can be used, and among these, a monofilament yarn is preferable. The diameter of the connecting thread 143 can be about 0.05 mm to 0.3 mm.

The thickness of the three-dimensional fabric 140 can be about 2 mm to 20 mm, and preferably about 2 mm to 3.5 mm. Density of solid fabric 140 may be a 0.02g / cm ³ ~0.2g / cm ³ order. The compression elastic modulus of the three-dimensional fabric 140 can be about 20 N / mm to 200 N / mm. Specific weight of the three-dimensional fabric 140 may be a 100g / m ² ~2000g / m ² approximately.

  In FIG. 1, the three-dimensional fabric 140 is embedded only in the vicinity of the joint portion 125, but may be embedded over the entire compressed rubber layer 120.

  The three-dimensional woven fabric 140 may be used as it is, or may be used after pretreatment with an RFL solution, rubber paste, or the like.

  A cover cloth may be provided on at least one surface of the compressed rubber layer 120 and the stretched rubber layer 130. The cover cloth may be a canvas made of aliphatic polyamide fiber, cotton, a mixed fiber thereof, a mixed fiber of cotton and polyester fiber, and an aromatic polyamide fiber. The canvas may be treated with an RFL solution and rubber glue and used as a rubberized canvas.

  The power transmission belt of this embodiment can be formed as shown in FIGS. First, a sheet for a compressed rubber layer having a predetermined thickness to be the compressed rubber layer 120 is prepared, and a cogged sheet 120 </ b> A having a cog portion 123 is formed. The cogged sheet 120A may be formed by, for example, a flat plate press or a cogged cylindrical mold.

  Next, as shown in FIG. 3, the cogged sheet 120 </ b> A is cut into a predetermined number of cog crests 121 and cog troughs 122, and wound around a cylindrical vulcanization mold 161 having grooves. At this time, the cog mountain portion 121 is aligned with the groove portion of the vulcanization mold 161. The solid fabric 140 is arranged in advance in the vulcanizing mold 161, and both ends of the cogged sheet 120A are butted so that the butted portion 125A is positioned on the solid fabric 140.

  Next, as shown in FIG. 4, the adhesive rubber layer sheet 110 </ b> A that becomes the adhesive rubber layer 110 is wound on the cogged sheet 120 </ b> A, the core wire 112 is spun, and the adhesive rubber layer sheet 110 </ b> B is wound. Further, a stretch rubber layer sheet 130A, which becomes the stretch rubber layer 130, is wound to form a cylindrical rubber slab.

  As shown in FIG. 5, a cylindrical belt molded body is formed by covering a rubber slab with a sleeve (not shown) and vulcanizing. The butted portion 125 </ b> A of the cogged sheet 120 </ b> A becomes a joint portion 125 reinforced by the three-dimensional fabric 140. A power transmission belt is formed by removing the cylindrical belt molded body from the vulcanizing mold 161 and cutting it.

  If the butt portion 125A of the cogged sheet 120A is vulcanized and bonded as it is, the strength of the joint portion 125 may be lower than other portions of the compressed rubber layer 120 due to various factors during butt and vulcanization bonding. . However, in the present embodiment, the three-dimensional fabric 140 is disposed in the butt portion 125A, the butt portion 125A is vulcanized and bonded, and the three-dimensional woven fabric 140 is embedded in the obtained joint portion 125. Since the three-dimensional fabric 140 reinforces the joint 125, the strength at the joint 125 can be improved. The three-dimensional fabric 140 has voids having a three-dimensional network structure, and the rubber composition that becomes the compressed rubber layer 120 enters the voids during vulcanization. For this reason, therefore, the three-dimensional fabric 140 and the compressed rubber layer 120 are bonded to each other much more firmly than when the canvas or the like is used as the reinforcing cloth. Therefore, a greater reinforcing effect can be obtained.

  Gas is generated when the butt portion 125A is vulcanized and joined. If the gas generated in the butted portion 125A cannot be released sufficiently, a cavity is formed in the joint portion 125, and the joint strength may be reduced. By embedding the three-dimensional fabric 140 having a large number of voids in the joint portion 125, the gas intervening in the butting portion 125A can be easily released through the three-dimensional fabric 140 at the time of joining, so that the joint portion 125 is firmly joined. be able to.

  In the case where the cover rubber is provided on the compressed rubber layer 120, for example, when pressing is performed to form a cog on the sheet for the compressed rubber layer, the canvas is attached to form a cogged sheet with the canvas. When a cover cloth is provided on the stretch rubber layer 130, the canvas may be wound after the stretch rubber layer sheet 130A is wound.

  In FIG. 1, the three-dimensional fabric 140 is embedded on the surface side of the compressed rubber layer 120. Normally, cracks are generated from the surface side of the compressed rubber layer 120 toward the core wire 112 side. Therefore, the three-dimensional fabric 140 for reinforcement may be embedded in the surface side of the compressed rubber layer 120.

  In FIG. 1, the joint portion 125 is provided in the cog valley portion 122. However, any portion may be provided as long as the compressed rubber layer 120 can be joined. For example, it may be provided in the cog mountain portion 121. In addition, a plurality of joint portions 125 may be provided. In FIG. 1, the junction 125 has a right angle with the core 112. However, the angle formed with the core 112 can be in the range of about 60 ° to 90 °.

  In FIG. 1, the three-dimensional fabric 140 is embedded on the surface side of the compressed rubber layer 120 so as to intersect the bonding surface of the bonding portion 125. However, as shown in FIG. 6, the three-dimensional fabric 140 may be embedded in the thickness direction of the compressed rubber layer 120. The power transmission belt shown in FIG. 6 can be formed as follows. After cutting the cogged sheet 120A to a predetermined length, the three-dimensional fabric 140 is attached to one end face of the cogged sheet 120A. The cogged sheet 120A is wound around the vulcanization mold 161 from the end face side to which the three-dimensional fabric 140 is attached, and the opposite end face is abutted against the end face to which the three-dimensional fabric 140 is attached. Thereafter, it can be formed in the same manner as the power transmission belt shown in FIG.

FIG. 1 shows a cogged belt in which a cog portion (lower cog portion) 123 is provided only on the compressed rubber layer 120 side. However, as shown in FIG. 7 , it may be a double cogged belt in which an upper cog portion 133 in which cog mountain portions 131 and cog valley portions 132 are alternately arranged is provided also on the stretched rubber layer 130 side. Also in the case of a double cogged belt, the three-dimensional fabric 140 may be embedded in the thickness direction of the compressed rubber layer 120 as shown in FIG.

  In the present disclosure, the cogged belt has been described, but the same configuration can be applied to a ribbed belt or the like.

  Hereinafter, the present disclosure will be described in detail with reference to examples, but the present disclosure is not limited to only these examples.

<Belt running test>
As shown in FIG. 9, a belt running tester equipped with a driving pulley and a driven pulley made of a pulley having a pulley diameter of 80 mm was used. After the evaluation belt was wound around the running test machine, a load of 1000 N was applied to the driven pulley, and a running test was performed under the conditions of room temperature and rotation speed of 4900 rpm. The time from the start of running to the occurrence of cracks in the joint was evaluated. Moreover, about the crack which generate | occur | produced, the failure rank was evaluated on the following references | standards.
Rank A: Line-shaped crack.
Rank B: Cracks of 1/5 or less of the distance from the valley of the compressed rubber layer to the core wire.
Rank C: A crack of 1/2 or less of the distance from the valley of the compressed rubber layer to the core wire.
Rank D: Cracks reaching the core from the valley of the compressed rubber layer.
Rank E: Cogs in the compressed rubber layer are missing or broken down.

<Belt for evaluation>
-Rubber composition-
The adhesive rubber layer sheet, the compressed rubber layer sheet, and the stretch rubber layer sheet were each formed from a rubber compound containing chloroprene (CR) rubber as a rubber component. The rubber compound had a general compounding composition for a transmission belt, and carbon black, zinc oxide, magnesium oxide, a vulcanization accelerator, an anti-aging agent, and a processing aid / plasticizer were compounded. Short fibers (aromatic polyamide) were blended in the compressed rubber layer sheet and the stretch rubber layer sheet. The thicknesses of the adhesive rubber layer sheet, the compressed rubber layer sheet, and the stretch rubber layer sheet were 0.4 mm, 0.7 mm, and 0.7 mm, respectively.

-Solid fabric-
As a three-dimensional fabric, Fusion AKE64030 manufactured by Asahi Kasei Fibers Co., Ltd. was used. The three-dimensional fabric was used without being treated.

-Canvas-
As the canvas, a mixed canvas of polyester and cotton was used. The thickness was 0.7 mm, and it was used after being treated with an RFL solution and rubber paste.

-Core wire-
Polyethylene terephthalate was used for the core wire. For the core wire, the step of immersing in the RFL treatment solution was repeated a plurality of times, and thereafter, the core wire was immersed in rubber paste and dried by heating, and then wound up and used.

Example 1
The compressed rubber layer sheet was pressed to form a cogged sheet. The obtained sheet with cogs was cut at the cog valley so as to have a predetermined length.

  A cylindrical vulcanization mold having a groove and a width of 27 cm was prepared. The cut sheet with cogs was wound around a vulcanization mold so that the cog crests corresponded to the grooves, and the ends were butted together. In a position corresponding to the butt surface of the vulcanization mold, a three-dimensional woven fabric sheet was disposed so as to straddle the butt surface. The three-dimensional fabric was cut into a width of 1.6 cm and a length of 27 cm.

  Next, the first adhesive rubber layer sheet is wound on the cogged sheet, the core wire is wound, the second adhesive rubber layer sheet is wound, the stretch rubber layer sheet provided with the cogs is wound, and the cylinder A rubber slab was formed.

  Next, a rubber slab was covered with a sleeve and vulcanized at 160 ° C. for 35 hours to obtain a cylindrical belt molded body. The obtained belt molded body was removed from the vulcanization mold and cut into a predetermined width to obtain a power transmission belt of Example 1. The outer peripheral length of the power transmission belt was 902 mm, the upper width was 25 mm, and the thickness was 12.6 mm. The height of the lower cog provided in the compressed rubber layer was 6.1 mm, and the pitch was 9.5 mm. The height of the upper cog provided in the stretched rubber layer was 2.8 mm, and the pitch was 8.3 mm.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that the reinforcing member was not disposed at the butt portion.

(Comparative Example 2)
The same procedure as in Example 1 was performed except that a polyester and cotton mixed canvas was used instead of the three-dimensional fabric.

  Table 1 summarizes the results of belt running tests of the examples and comparative examples. In the case of Example 1 in which the joint portion was reinforced with the three-dimensional fabric, the time until the occurrence of cracks was 890 hours, and compared with the case of Comparative Example 1 in which the joint portion was not reinforced (359 hours), cracks were observed. The time until the occurrence was about 2.5 times longer. Moreover, compared with the case of the comparative example 2 (765 hours) which reinforced the junction part with the canvas, it became about 1.2 times longer. Furthermore, in Example 1 in which the joint portion was reinforced with a three-dimensional fabric, the generated cracks were small compared to Comparative Example 1 in which the joint was not reinforced and Comparative Example 2 in which the canvas was used. In Example 1, the time until a crack occurred in a portion other than the joint portion of the compressed rubber layer was 890 hours, and the failure rank of the generated crack was B. Thus, in Example 1, the intensity | strength of the junction part improved to the same extent as the other part.

110 Adhesive rubber layer 110A Adhesive rubber layer sheet 110B Adhesive rubber layer sheet 112 Core wire 120 Compressed rubber layer 120A Cogged sheet 121 Cog mountain part 122 Cog valley part 123 Cog part 125 Joint part 125A Butt part 130 Stretch rubber layer 130A Stretch Sheet for rubber layer 131 Cog mountain part 132 Cog valley part 133 Upper cog part 140 Three-dimensional woven fabric 141 Front knitted fabric 142 Back knitted fabric 143 Connecting yarn 161 Vulcanization mold

Claims (6)

An adhesive rubber layer in which a core wire is embedded; and a compression rubber layer provided on one surface of the adhesive rubber layer, the compression rubber layer being a joint portion in which a three-dimensional fabric having a three- dimensional network structure is embedded Having a power transmission belt.   The three-dimensional woven fabric has a connecting yarn, a front knitted fabric and a back knitted fabric, the connecting yarn is a monofilament, and at least one of the front knitted fabric and the back knitted fabric is a mesh knitted fabric. Item 4. The power transmission belt according to Item 1.   The power transmission belt according to claim 1, wherein the compression rubber layer has a cog portion in which a cog crest portion and a cog valley portion are alternately arranged.   The power transmission belt according to claim 3, wherein the joint portion is provided in the cog valley portion.   The adhesive rubber layer further includes a stretch rubber layer provided on a surface opposite to the compression rubber layer, and the stretch rubber layer has a cog portion in which a cog crest portion and a cog trough portion are alternately arranged. The power transmission belt according to claim 3 or 4.   The power transmission belt according to claim 1, further comprising a surface cloth bonded to a surface of the compressed rubber layer.

Images