JPH048947A - Toothed belt - Google Patents

Abstract

PURPOSE:To enhance durability by making up both each tooth rubber and a back rubber from material selected out of hydrogenerated nitrile rubber, chlorosulfonated polyethylene rubber, and alkylation chlorosulfonated polyethylene rubber, and thereby making up each core wire out of glass fiber cords which are twisted by the specified number of turns. CONSTITUTION:A toothed belt 1 includes a back rubber 4 in which a plurality of tooth rubbers 2 and a plurality of core wires 3 are embedded while being covered with cover canvas 5. Both each tooth rubber 2 and the back rubber 4 are made of, for example, hydrogenerated nitrile butadiene rubber in which hydrogen is added by more than 80% to the double bonding link of chlorosulfonated polyethylene rubber and alkylation chlorosulfonated polyethylene rubber or acrylonitrile butadiene rubber both heat resistance and aging resistance of which are improved. Each core wire 3 is made up out of glass fiber cords which are formed on the basis of the first twist number of 10.5 to 13.5 turns/10cm and the final twist number of 6.5 to 9.5 turns/10cm. By this constitution, there is little change in belt tension against running time, bending fatigue strength is hardly reduced, and durability is thereby enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a toothed belt, and more particularly to a toothed belt in which the number of twists of core wires is specified to improve belt durability.

(Prior technology) Unlike flat belts and belts, toothed belts are capable of reliable transmission without slipping, and have the advantage of not requiring lubrication compared to reliable transmission using gears or chains.
Demand has been increasing rapidly in recent years. In particular, the advancement of this technology is remarkable in the transmission drive of overdrive camshafts (OHC) in automobiles.

However, in the case of such an OHC drive, since the toothed belt is used under high load and on multiple axes, the belt is subjected to bending fatigue and is stretched. When a toothed belt used under such severe conditions is stretched by more than about 0.1%, it tends to have poor engagement with the bobbles, and tends to cause a jumping phenomenon.

The behavioral tendency of this toothed belt is influenced by the characteristics of the core wire, namely elongation and bending fatigue.

By the way, today, a glass fiber cord with high strength and low elongation is used as one of the tensile members of such toothed belts. For example, in the case of belts in automotive OHC drives, the construction of glass fiber cords is usually E
CG-150-3/11 or 3/13, number of twists 7.
0 to 10.0/10 Cm is used. For example, the number of first twists is 1.7 to 2.6/inch, and the number of first twists is 1.
A toothed belt using hydrogenated nitrile rubber with a ratio of 8 to 2.3 per inch has been proposed and is disclosed in Japanese Patent Application Laid-open No. 159827/1983.

(Problem to be Solved by the Invention) However, when the belt is run under high load and multi-axis conditions with small-diameter boobies as in the OHC drive described above, such glass fiber cords are stretched and the belt tension decreases. was causing There are various possible causes for this, but it has been found that one of them is related to the lobe configuration, especially the number of first twists.

That is, a belt using a rubber composition of hydrogenated nitrile rubber and chlorosulfonated polyethylene for the tooth rubber and back rubber, and using a glass core wire with a number of first twists of 7.0 to 10.0 times/lQcm, It contracted and the belt tension increased.

As a result, the wear of the canvas at the bottom of the belt tooth was accelerated, and cracks were more likely to occur at the root of the belt tooth.

On the other hand, those using glass core wires with a number of first twists of 14 to 18 twists/10 cm were stretched during running, resulting in a decrease in belt tension and early cracks at the tooth roots.

Thus, the present invention aims to provide a toothed belt that uses a glass fiber cord having a cord structure with low elongation and bending fatigue as a core wire, reduces fluctuations in belt tension with respect to running time, and has bending fatigue resistance. This is the purpose.

(!f! Means for Solving the Problem) That is, the present invention is characterized by having a plurality of tooth rubbers arranged along the longitudinal direction, a back rubber in which a core wire is embedded,
In the toothed belt in which the surface of the toothed rubber is covered with a cover canvas, the toothed rubber and the back rubber are made of a heat-resistant rubber composition selected from hydrogenated nitrile rubber, chlorosulfonated polyethylene rubber, and alkylated chlorosulfonated polyethylene rubber. The number of first twists is 10.5 as the core wire.
~13.5 times/10cm with 6.5 to 9.5 twists/
The point is that a glass fiber cord of 1Qcm is used.

The above glass fiber cord is ECG-150・3/6～3/
It consists of 13 components.

FIG. 1 is a cross-sectional perspective view of a toothed belt according to the present invention,
A toothed belt 1 has a plurality of toothed rubbers 2 along the belt longitudinal direction.
and a back rubber 4 in which a core wire 3 made of glass fiber cord is embedded.
A cover canvas 5 is attached to the surface of the tooth rubber 2.

The tooth rubber 2 and the back rubber 4 are made of chlorosulfonated polyethylene rubber (C5M), alkylated chlorosulfonated polyethylene rubber (AC5M), or hydrogenated acrylonitrile in which 80% or more of the double bond of acrylonitrile-butadiene rubber is hydrogenated. It is butadiene rubber (referred to as hydrogenated nitrile rubber, expressed as H-NBR), and is a rubber with improved heat aging resistance.

A magnesium oxide-aluminum oxide solid solution is added to the chlorosulfonated polyethylene rubber to improve heat resistance.
Aluminum oxide solid solutions are generally Mgo, 7Alo, 3
01.15, and a specific example is Kyowa Chemical Industry■
There are KW-2000, KW-2100, etc. manufactured by KW-2000 and KW-2100.

The amount of the acid acceptor added is chlorosulfonated polyethylene 1
1 to 50 parts by weight, preferably 4 to 2 parts by weight per 00 parts by weight
In this case, if the magnesium oxide-aluminum oxide solid solution is less than 1 part by weight, the hydrogen chloride generated during crosslinking cannot be sufficiently removed, so the number of crosslinking points in the chlorosulfonated polyethylene decreases, resulting in less than 1 part by weight. This results in a toothed belt that lacks heat resistance and is prone to early cracking. On the other hand, if the amount exceeds 50 parts by weight, the Mooney viscosity becomes extremely high, causing processing problems. Therefore, in the rubber composition used for the toothed belt of the present invention, a magnesium oxide-aluminum oxide solid solution is added to chlorosulfonated polyethylene within the above range in order to improve belt life and satisfy processability. The most preferred is

Further, the alkylated chlorosulfonated polyethylene rubber is made of low density polyethylene having a linear molecular structure with a chlorine content of 15 to 45 wt% and a sulfur content of 0.5 to 2.5 wt%.
This is a chlorosulfonated polyethylene rubber that has been chlorosulfonated to a range of wt%. This AC5M
Since it has an alkyl side chain, the crystallinity of the main chain polyethylene is reduced and it has rubber-like properties. In addition, since crystallization is difficult to occur even in the low temperature region (-10° C. or lower), rubber elasticity is maintained and excellent cold resistance is achieved.

The cover canvas 5 can be made of a plain woven fabric, a twill woven fabric, a satin woven fabric, etc. that is stretchable in the weft direction (the longitudinal direction of the belt). Among them, in the case of plain weave canvas, the weft 5a and the warp 5b
Since the weft yarns 5a and warp yarns 5b are alternately stacked in a cross-layered manner, wave-shaped intersections of the weft yarns 5a and the warp yarns 5b are formed continuously in the weft and warp directions. On the other hand, when twill weave or satin weave canvas is used, the weft and warp yarns each form wave-shaped intersections every other yarn, and there are fewer wavy intersections than normal plain-weave canvas, and rubber is used not only between the yarns but also between the intersections. When used in the belt teeth, direct contact between the warp and weft yarns during belt flexibility can be avoided and the belt life can be improved, which is preferable.

Additionally, in order to further increase the stretchability, the plain weave canvas, twill weave canvas, or satin weave canvas may be covered with other low-oriented polyester synthetic fiber yarns as a knitted fabric.

First, the cover canvas 5 is made of weft yarns 5 that make up the fabric.
a% The surface of the warp threads 5b is coated with an adhesive layer made of a cured product of RFL liquid, isocyanate solution, or epoxy solution.

The above cover canvas is made of polyamide fiber, polyester fiber,
The material is aromatic polyester fiber, etc. Specifically, the weft threads 5a of the cover canvas are stretchable, and woolly threads obtained by crimping filament threads of nylon 6 or 6.6 nylon are used, and the warp threads 5b are nylon 6 or nylon 6.6 crimped. 6 nylon filament yarn is used.

In addition, the weft 5a is a mixed yarn of a spun yarn containing at least 40% by weight, preferably 50% by weight or more, of aromatic polyamide fibers and urethane elastic yarn, and the warp 5b is a mixture of aliphatic fibers, such as The filament yarn is made of polyester, nylon 6, nylon 6.6, nylon 4.6, nylon 4.6, polyamide such as polyvinyl alcohol, polyethylene, polypropylene, etc., and this structure is made by aligning 3 to 25 monofilaments of 10 to 50 deniers. It is possible to use a multifilament yarn which is twisted at 5 to 30 times/10 (J), or which is made by bundling or twisting 100 to 200 aromatic polyamide filaments of 1 to 6 deniers.

The reason why spun yarn of aromatic polyamide fiber is used is that it blends well with the urethane elastic yarn, makes the thickness of the canvas constant, and improves heat resistance and abrasion resistance. Otherwise, heat resistance and abrasion resistance will not be improved. In addition, in this cover canvas, a highly rigid yarn is used for the weft, and a correspondingly high rigid yarn is used for the warp, so the balance between the weft and warp is maintained, resulting in a canvas of uniform thickness. For this reason, the cover canvas has a smooth thickness, the resulting belt has a uniform PLD value, and the belt life is improved. Furthermore, since this cover canvas has abrasion resistance and sufficient strength, it sufficiently protects the tooth portion and prevents cracks and chipping of the root portion of the tooth.

The structure of the glass fiber cord, which is the core wire 8, is such that three strands each made of a large number of alkali-free glass filaments each having a diameter of 9μ or 9 to 10μ are gathered together and twisted 10.5 to 13.5 times/10.5 to 13.5 times. It is a cord that is first twisted to 10 cm to make a child rope, and then 13 of these child ropes are collected and final twisted in the opposite direction to the first twist with a number of final twists of 6.5 to 9.5 times/10 cm.Specifically, ECG150 -3/6~3/13
It is.

Glass fiber cords are subjected to RFL treatment and overcoat treatment, and the RFL liquid is a mixture of latex with an initial condensate of resorcin and formalin, and in this case, the molar ratio of resorcin and formalin is 1:0.5 to 3. It is preferable to increase the adhesion force.

In addition, the initial condensate of resorcinol and formalin is mixed with latex so that the resin content is 2 to 30 parts by weight per 100 parts by weight of the rubber content of the latex, and the total solid concentration is 5 to 40%. Adjusted to concentration.

The above latex is a styrene/butadiene/vinylpyridine terpolymer, chlorosulfonated polyethylene, H
- Latexes such as NBR, epichlorohydrin, natural rubber, SBR, chloroprene rubber, and olefin-vinyl ester copolymers.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Three ECG150 glass core wires were aligned and the first
After soaking in the RFL treatment solution shown in the table, drying, and baking,
The number of first twists was varied as shown in Table 2, and the number of first twists was 8.0±0.5 times71 by aligning 11 or 13 twists.
The cord was twisted at 0 cm, immersed in a rubber paste shown in Table 3, and heat treated to obtain a glass fiber cord having a structure of ECG150-3/11.3/13.

Table 1 On the other hand, the cover canvas uses 6.6 nylon woolly processed yarn for the weft and industrial 6.6 nylon for the warp, and the thickness on the cross section of the belt is 0.25 and 0°30. A material with a 2\ twill weave structure was used that had been adhesively treated to match the tooth rubber.

For the tooth rubber and back rubber, rubber compositions containing hydrogenated nitrile rubber and chlorosulfonated polyethylene rubber as main raw materials shown in Table 4 were used.

A toothed belt was manufactured using the above materials by a conventional press-fitting method. The resulting belt has a tooth pitch of 9°525ml
ZA tooth type, number of teeth is 88, belt width is 19.1
It is mm.

The produced belt was run in a 3-axis rotation test, and 100
The remaining strength of the belt after running for 0 hours was determined, and the presence or absence of cracks at the root of the teeth was examined, as well as the state of wear of the cover canvas. The results are shown in Table 2.

In addition, the relationship between belt running time and belt tension is shown in Figs. 2 and 3. In this case, the belt tension is measured after the belt is run for a predetermined time in the three-axis rotation test, and then the belt and the device are cooled to room temperature. It was measured using a belt tension gauge after cooling.

Note that the three-axis rotation test has a driving pulley (teeth 18), one driven pulley (number of teeth 36), and a tension pulley (diameter 52 mm) between both pulleys. The running conditions were an ambient temperature of 120°C and a drive boolean rotation speed of 6000r.
pm, the rotation speed of the driven boolean is 3000 rpm, the load is 5 horsepower, and the initial tension is 15 kgf.

Margins below Table 4 Nitrile hydrogenation manufactured by Nippon Zeon Co., Ltd. Mutoisobrobyl-N'-phenyl-P-phenylenediamine dioctyl sebacate Tetramethylthiuram disulfide N-cyclohexyl-2 benzothiazyl sulfenamide Manufactured by Electrochemical Co., Ltd. Chlorosulfonated polyethylene nickel dibutyl dithiocarbamate dimetamethylene thiuram tetrasulfide N,N''-m
-phenylene dimaleimide Thus, Na1l and 1V
With K16 toothed belts, the adhesive agent on the glass fiber cords deteriorates quickly due to the increased tension during running, resulting in lower residual strength and greater wear on the cover canvas. On the other hand, in the belt on floor 5, NQ10, the load variation on the teeth increased due to the decrease in tension, and cracks occurred at the root of the teeth on the front side in the direction of travel. NO3,3, according to the present invention
It is understood that belts Nos. 4, 7, 8, and 9 maintain good tension, do not generate cracks at the dedendum due to load fluctuations, and have good residual strength and abrasion resistance of the cover canvas.

Example 2 As the glass core wire, the number of first twists is the same as in Example 1: 12 times/10
cm, E with number of twists 8.0±0.5 times/10cm
A glass fiber cord having a construction of CG 150-3/13 was used.

On the other hand, for the cover canvas, 6.6 nylon is used as the warp.
21 made of 7 strands of 30 denier monofilament.
0 denier monomulti yarn was twisted in the S direction at a rate of 15 turns/lQcm, and the weft was stretched 2°0 to 4.0 times as the spun yarn made of the material and thickness shown in Table 5. Urethane elastic threads are joined together in the S direction at a rate of 15 times/10 cm, and these are woven as a 2/2 twill weave.
The woven canvas was shrunk to 40 to 55% of the woven width using a wince or circular machine. Then, it is treated with RFL liquid (resorcinol-formalin-latex adhesive treatment liquid) conventionally used as an adhesive treatment agent, and further impregnated with rubber glue dissolved in an at solvent with the same rubber composition as the main body of the toothed belt. After drying, this was used as a cover canvas for a toothed belt.

As the tooth brim and the back rubber, bum compositions containing hydrogenated nitrile rubber as the main raw material shown in Table 4 were used.

The same belt as in Example 1 was made using these materials,
The remaining strength after running for 1,000 hours under the same test conditions, the state of crack occurrence at the root of the teeth, and the state of wear of the cover canvas were examined.

These results are shown in Table 5.

No. Cx: Conex (manufactured by Kijinsha) Table SD: Urethane elastic thread 4° In this way, the belt using the core wire and cover canvas is
The tension is maintained well after 500 hours, no cracks occur at the tooth base due to load fluctuations, and the remaining strength and abrasion resistance of the cover canvas are good.

(Effects) As described above, in the toothed belt according to the present invention, the number of first twists of the core glass fiber cord is 10.5 to 13.5 times/10
Since the number of ply twists per cm is 6.5 to 9.5 times/lQcm, fluctuations in belt tension with respect to running time are small, and bending fatigue of the belt is less likely to occur.Furthermore, cracks at the tooth base are less likely to occur, making the belt can improve the durability of

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional perspective view of a toothed belt according to the present invention, and FIGS. 2 and 3 are graphs showing the relationship between running time of the toothed belt and belt tension. 1... Toothed belt 2... Tooth rubber 3... Core M
4... Back rubber 5... Cover canvas patent applicant Mitsuboshi Belting Co., Ltd.

Claims (1)

[Claims] 1. A toothed belt that has a plurality of toothed rubbers arranged along the length and a back rubber in which a core wire is embedded, and a cover canvas is coated on the surface of the toothed rubbers, wherein the toothed rubber and the back rubber A heat-resistant rubber composition selected from hydrogenated nitrile rubber, chlorosulfonated polyethylene rubber, and alkylated chlorosulfonated polyethylene rubber is used as the core wire, and the upper twist is twisted with a number of first twists of 10.5 to 13.5 times/10 cm. A toothed belt characterized by using a glass fiber cord having a twist count of 6.5 to 9.5 times/10 cm.