JP3106108B2 - Tensile body for belt and transmission belt - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension member used for various power transmission belts and a power transmission belt using the same.

[0002]

2. Description of the Related Art Aramid tensile members for power transmission belts are generally known (see JP-A-54-9347 and JP-A-56-105135). Most of the aramid filaments used in such belt tensile members have a thickness of 1.5 denier. The tensile member for a belt is generally provided in a spiral shape.

[0003]

The demands on the market for power transmission belts have become increasingly severe in recent years. In particular, there is a demand to reduce the width of the power transmission belt in order to save space for power transmission means in various machines and devices. When the width of the power transmission belt is reduced, the number of spiral windings of the tensile member is reduced accordingly, so that the load applied to the tensile member increases. Therefore, there is a problem that the tensile member is fatigued early. .

Accordingly, the present invention is to improve the bending fatigue resistance of the power transmission belt so that the power transmission belt can withstand a heavy load.

[0005]

Means for Solving the Problems The present inventor has been working from an early stage.
We started a study on the fatigue mechanism of the tensile body formed by aramid filaments, and found that one of the causes of this fatigue was filament wear. That is, when the belt is bent at the pulley, relative displacement between the filaments occurs inside the tensile member, whereby the filaments rub against each other and wear, and therefore, the tensile member fatigues. . Such a phenomenon is more remarkable as the load applied to the tensile body is higher. Particularly, when the yarns constituting the tensile body cross each other and are in contact with each other, one yarn intersects with the other yarn. It has been found that since the yarn is bent and stretched with the fulcrum as a fulcrum, the filament constituting the yarn is greatly worn. It can be said that the property of the aramid filament that tensile strength in the longitudinal direction is high but weak in bending appears.

The invention of this application has been made based on the above-mentioned elucidation of the cause of fatigue of the tensile member. In a tensile member for an aramid belt, the tensile member is formed by a braid. And 3.0 to 5.0 in the yarns constituting the braid.
It is characterized by using denier aramid filament.

That is, although the yarns constituting the braid cross each other and are in contact with each other, the thickness of the aramid filament constituting the crossed yarns is set to 3.0 denier or more, and the thickness is made larger than before. There is a feature of the present invention in this respect. This prevents the cross contact between the aramid filaments caused by the crossing of the yarns from becoming strong and sharp. That is, it is possible to prevent the surface pressure at the intersection contact portion between the aramid filaments from lowering and to prevent the bending radius (R) from being reduced when bending and elongating. As a result, abrasion at the intersection contact portions of the aramid filaments is suppressed, and the tensile strength of the tensile body is increased.

[0008] Even in a tensile body made of a plied yarn, the filaments constituting the yarn will come into cross contact with each other. Therefore, when an aramid filament is applied to this, it is necessary to increase the thickness as described above. Although there is significance, in the invention of this application, the tensile body is limited to that made of braid because high tensile strength is obtained in the case of the braid and high load transmission in which the wear fatigue is a problem. Because it is suitable.

Regarding the above braid, it is advantageous to use a four-strand braid in order to obtain a high tensile strength.

[0010] The tensile member for a belt according to the invention of the present application is:
The transmission belt can be generally used, and among them, an endless tension band, and a plurality of blocks disposed around the entire circumference at a constant pitch in the longitudinal direction of the tension band and coupled to the tension band, Suitable for use as a so-called block belt tensile member. This is because such a block belt is generally used as a high-load transmission belt such as a continuously variable transmission belt.

In the case of such a block belt, the tension band is formed by wrapping a tension member provided in a spiral shape so as to extend in the longitudinal direction of the belt and to make a pitch in the width direction of the belt, and is wrapped with a rubber material. The belt tension member as described above is used for the tension member.

[0012]

Therefore, according to the invention of this application, in the tensile body for an aramid belt, the tensile body is formed by a braid, and the yarn constituting the braid is 3.0 to 3.0.
Since 5.0 denier aramid filament was used,
Abrasion at the cross contact portions of the aramid filaments can be suppressed, the bending fatigue resistance can be increased, and the durability of the power transmission belt, particularly a high-load power transmission belt, can be improved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a tension member 11 for a belt according to the present invention. this is,
The yarn 12 is formed by a round braid made by using four yarns 12, and the yarn 12 is formed by a bundle of 3.0 to 5.0 denier aramid filaments.

The following processing is performed on the above-mentioned rounded braid before being used as a tensile member on the transmission belt. That is, a sub-coat layer is formed on the surface by immersing the round braid in a liquid adhesive mainly containing an isocyanate compound,
Next, a second coat layer is formed on the sub-coat layer by dipping in an RFL liquid (liquid adhesive containing resorcinol-formalin latex as a main component), and then dipped in a rubber paste to form the second coat layer. A topcoat layer is formed on the layer.

The R for forming the second coat layer
The FL liquid is obtained by mixing an initial condensate of resorcinol and formalin with latex, and a high adhesive strength is obtained when the molar ratio of resorcinol to formalin is in the range of 1: 0.5 to 3. The prepolymer of resorcinol and formalin is mixed with latex such that the resin content is 2 to 30 parts by weight based on 100 parts by weight of the rubber content of the latex. The solid content of this RFL solution is 5 to 40%.

As the latex, styrene-butadiene-vinylpyridine terpolymer, chlorosulfonated polyethylene (CSM), nitrile rubber (NB)
R), hydrogenated nitrile rubber (H-NBR), epichlorohydrin, styrene butadiene rubber (SBR), chloroprene rubber (CR), chlorinated butadiene, olefin-
Latex such as vinyl ester copolymer, natural rubber (NR) or a mixture thereof can be used.

As the rubber paste for forming the top coat layer, a rubber composition having excellent adhesion between the tensile member and a rubber wrapping the tensile member or a canvas in contact with the tensile member is employed. You. That is, as the rubber paste, although it depends on the material of the mating member to be bonded, for example, chloroprene (C
R), chlorosulfonated polyethylene (CSM), alkylated chlorosulfonated polyethylene (ACS)
M), one or more rubber compositions selected from among hydrogenated nitrile rubber (H-NBR), a mixed polymer of a hydrogenated nitrile rubber (H-NBR) and an unsaturated carboxylic acid metal salt, and the like. A resin-based solution in which a resin component and an additive are mixed is preferable.

(Regarding Power Transmission Belt) FIG. 2 shows an example of a power transmission belt using the tension member 11 for a belt. This transmission belt has a pair of endless tension bands 1, 1 arranged in parallel on the left and right, and fitting portions 7a, 7a opened laterally on both sides thereof. A plurality of blocks 7 which are fitted with the left and right tension bands 1 and 1 at a constant pitch in the longitudinal direction of the tension band 1 and are arranged over the entire circumference of the tension band 1. V-belt. This V-belt is not shown, but
Each of them is wound around two drive-side and driven-side shift pulleys composed of a fixed sheave and a movable sheave, and is used to form a belt-type continuously variable transmission.

Each of the tension bands 1 includes an upper rubber layer 2, a lower rubber layer 3, and a tension member 11 provided between the two rubber layers 2, 3. Layer 5 and lower fabric layer 6 are provided integrally on the lower surface of lower rubber layer 3, respectively. The tensile member 11 is provided in a spiral shape extending in the belt longitudinal direction and having a pitch in the belt width direction. The upper surface of each tension band 1 has a number of concave upper surface grooves 1a extending in the belt width direction, and the lower surface has a number of arcuate lower surface grooves 1b extending in the belt width direction. Are arranged at predetermined pitches and correspond to up and down (inside and outside).

On the other hand, each of the blocks 7 has a substantially trapezoidal shape, and both side surfaces thereof are formed with sliding portions 8, 8 which are in sliding contact with the groove surface of the speed change pulley. In each of the left and right sides of each block 7, there is formed a slit-shaped fitting portion 7a which is open on the side surface and penetrates in the belt longitudinal direction.
On the upper surface (belt outer peripheral side) of the fitting portion 7a, a protruding ridge 9a having a convex cross section for engaging with the upper surface groove 1a of the tension band 1 is provided. On the other hand, on the lower surface of the fitting portion 7a (on the inner peripheral side of the belt), a protruding ridge 9b having an arc-shaped cross section that engages with the lower surface groove 1b of the tension band 1 is provided.

(Another Example of Transmission Belt) FIG. 3 shows another example of a transmission belt using the tension member 11 for a belt. This transmission belt is a toothed belt, and the belt tension member 11 is provided in a spiral shape extending in the belt longitudinal direction and having a pitch in the belt width direction. A plurality of back rubbers 22 continuously provided on the outer peripheral side of the tension member 11 over the entire periphery of the belt are joined, and a plurality of rubber members are arranged on the inner peripheral side of the tension member 11 at a predetermined pitch in the longitudinal direction of the belt. Are bonded. The toothed rubber side of the transmission belt is covered with a tooth cloth 25. Each tooth rubber 23 is slightly swelled so that the front and rear surfaces in the longitudinal direction of the belt become arc-shaped.

For the back rubber 22 and the tooth rubber 23, a rubber composition containing chloroprene rubber as a main raw material is used. In the tooth cloth 25, a 6,6 nylon yarn is used for the yarn arranged to extend in the belt width direction, and a 6,6 nylon wooly processed yarn is used for the yarn arranged to extend in the belt longitudinal direction. It was used.

(Manufacturing method of the toothed belt)
It can be formed by a general press-fitting method. That is, a rubber mold canvas for the tooth cloth is wound around a cylindrical mold having a tooth groove shape of the transmission belt on the outer peripheral surface, and a round braided cord as a tensile body is spirally wound thereon.
Further, an unvulcanized rubber sheet for forming back rubber and tooth rubber is wound thereon. Then, by placing this in an autoclave and pressing from the outside, a part of the unvulcanized rubber sheet is extruded from between adjacent cords of the tensile member to the rubberized canvas side to mold the rubberized canvas into a mold. After the vulcanization treatment, the molded product that has been released is cut into a predetermined width, and then the inner peripheral side and the outer peripheral side are turned upside down. Obtain an attached belt.

The rubber constituting the above-mentioned belt body is not particularly limited, but may be any rubber used for general power transmission belts, for example, natural rubber (NR), styrene butadiene rubber (SBR), nitrile Rubber (NB
R), hydrogenated nitrile rubber (H-NBR), chloroprene rubber (CR), chlorosulfonated polyethylene rubber (CSM), ethylene propylene rubber (EPDM, EP
M), butadiene rubber (BR), fluoro rubber (FPM)
And the like.

A canvas can be provided on the surface of the backing rubber 22. As the canvas, it is preferable to use a woven fabric having elasticity in the longitudinal direction of the toothed belt.
It is desirable that the treatment is performed stepwise with a combination of an epoxy resin solution, an isocyanate resin solution, an RFL solution, and a rubber paste. Further, instead of the rubber glue treatment, it is also possible to use coating such as rubber coating or topping. Such a woven fabric is treated with an adhesive or rubber as described above, and then formed into a back rubber 22 at the time of forming a belt.
Adhesive with the rubber that makes up. The canvas is preferably woven by combining fibers selected from polyamide fibers, polyester fibers, aromatic polyamide fibers, and the like.

The tension member for a belt according to the present invention is not limited to the above-mentioned block belt and toothed belt, but may be used for other V-belts, flat belts, ribbed belts and the like.

(Comparative test) Using aramid filaments having different deniers, the number of sets was 25 times / 10 cm 4
A braided braid (four round braided braids) was made, and these were used as belt tensile members to produce a toothed belt shown in FIG. 3, and a belt running test was performed to compare the bending fatigue resistance. Each braid was 1000 denier thick. The tooth pitch of the test belt is 8 mm, and the belt width is 12 mm.

FIG. 4 shows the procedure of a belt running test. It consists of four large pulleys (60 mm in diameter) 31
The test belt 21 is wound around four small pulleys (diameter 30 mm) 32 disposed between the adjacent large pulleys 31, and a predetermined load is applied to the test belt A with the weight W at 5500 rpm. To run. First, the initial strength of each test belt was obtained, and then the remaining strength after bending 1 × 10 ⁸ times (the number of times passing through the small pulley 32) was measured.
00 / initial strength). Table 1 and FIG. 5 show the results obtained by selecting several types of loads W and conducting tests. In Table 1, DW indicates the magnitude of the load per denier, and was obtained by the following equation.

DW = W (g) / 1000 (de) where "de" represents denier.

[0031]

[Table 1]

When the load is small, the effect of the thickness of the aramid filament on the residual strength of the belt, that is, on the bending fatigue resistance, is small. I'm doing it.
On the other hand, in the case of aramid filaments having a thickness of 3.0 denier or more, a decrease in residual strength is hardly observed even under a high load. From this fact, it can be seen that when the thickness of the aramid filament is set to 3.0 denier or more, a special effect can be obtained in improving the bending fatigue resistance of the belt tensile member and, consequently, the transmission belt.

[Brief description of the drawings]

FIG. 1 is a front view showing a tension member for a belt.

FIG. 2 is a perspective view in partial cross section showing an example of a toothed belt.

FIG. 3 is a partially sectional perspective view showing another example of the toothed belt.

FIG. 4 is a front view showing a point of a belt running test.

FIG. 5 is a graph showing the results of a comparative test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tension belt 7 Block 11 Tensile body for belt 12 Yarn

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16G 1/00-5/20 D04C 1/00-7/00 D07B 1/00-9/00

Claims (4)

(57) [Claims] 1. A tension member for an aramid belt, comprising:
A tensile member for a belt, wherein the tensile member is formed of a braid, and the yarn constituting the braid is formed of an aramid filament having a denier of 3.0 to 5.0. 2. The tension member for a belt according to claim 1, wherein the braid is a four-strand braid. 3. A power transmission belt comprising the belt tensile body according to claim 1 or 2. 4. The power transmission belt according to claim 3, wherein an endless tension band, and a plurality of blocks arranged over the entire circumference at a constant pitch in a longitudinal direction of the tension band and connected to the tension band. Wherein the tension band has a tension member extending in the belt longitudinal direction and spirally provided so as to cut the pitch in the belt width direction, and a rubber material wrapping the tension member. A transmission belt, wherein the tension member is formed by the belt tension member according to claim 1 or 2.