JPH063244B2 - Toothed belt - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a toothed belt having improved durability.

(Prior Art) A conventional toothed belt uses glass fiber, aramid fiber, carbon fiber, steel cord, etc., which have a small elongation as a tensile body, and this tensile body is made of an elastic body such as polyurethane resin or chloroprene. The embedded one is used as a base, and an uneven tooth surface is formed on one side of this base, and the tooth surface and the tooth surface of the toothed pulley mesh with each other to drive power from one toothed pulley to the other toothed pulley. Is to be transmitted to.

The tooth flanks of such toothed belts have been covered with cloth to protect the tooth flanks and to increase the durability of the toothed belt. As the material of this stretchable fabric, fibers having excellent wear resistance and fatigue resistance are used. Further, as this cloth, stretchable processed yarn is used to have elasticity in the longitudinal direction of the tooth surface and to stabilize the shape of the tooth surface during manufacturing of the toothed belt.

Compared to flat belts and V-belts, such toothed belts have more reliable power transmission, and have come to be used in many industrial fields including automobiles. Recently, high speed, high load, high temperature and severe conditions It has also been tried to use. Under such conditions, the belt is severely deteriorated, and in particular, due to the shear stress in the portion of the toothed belt that comes into contact with the tooth tips of the toothed pulley, a crack is generated in that portion, and eventually the tooth body is destroyed. The reality is that the life of the toothed belt is shortened.

A false twisted yarn has been used as the elastic processed yarn used for the toothed belt.However, the false twisted yarn generally has a drawback that the life of the toothed belt is short because the degree of polymerization is low and the strength is low. It was

(Problems to be Solved by the Present Invention) It is an object of the present invention to provide a toothed belt having a long service life by ameliorating the above defects of the prior art.

(Technical Means for Solving Problems) The present invention has the following configuration in order to achieve the above object. That is, the configuration of the present invention is a toothed belt having a belt body made of an elastic resin having a tensile body and a tooth surface made of the elastic resin on one surface, and the tooth surface being covered with a cloth. In the above, as the cloth, a polyurethane-based elastic yarn is used as a core yarn, and the strength around the core yarn is 6.5 g /
A stretchable fabric composed of a covered elastic yarn composed of a sheath yarn obtained by winding a synthetic fiber yarn of d or more in a coil shape,
The toothed belt is characterized in that the stretchable cloth has a stress of 10 kg / 3 cm or less at 50% elongation and a stress of 20 kg / 3 cm at 70% elongation.

Further, the toothed belt of the present invention is the core of the covered elastic yarn, which comprises a core yarn made of polyurethane-based elastic yarn constituting the stretchable fabric and a sheath yarn formed by winding a synthetic fiber yarn in a coil shape. The yarn is arranged in the longitudinal direction of the belt.

The present invention will be described in more detail.

FIG. 1 is a partial sectional view of a toothed belt according to the present invention.

In FIG. 1, reference numeral 1 denotes a stretchable cloth which covers the surface of the tooth surface 2 of the toothed belt 10. This stretchable fabric has a sheath yarn in which a polyurethane elastic yarn is used as a core yarn in the longitudinal direction of the tooth flank 2 and a synthetic fiber yarn having a strength of 6.5 g / d or more is wound around the core yarn in a coil shape. It is made of a woven fabric in which covered elastic yarns are arranged.

As is clear from FIG. 1, the tensile body 3 of the toothed belt 10
Is embedded in an elastic body 4 such as synthetic rubber or polyurethane resin. The elastic body 4 has tooth bodies 5 projected on one surface at equal intervals, and a concave tooth groove 6 is formed between the tooth bodies 5.

Usually, the tensile body 3 is made of glass fiber, aramid fiber, polyamide fiber, polyester fiber, carbon fiber, steel wire or the like which has a small elongation.

The stretchable cloth 1 has high strength, wear resistance, and fatigue resistance in order to cover the surfaces of the tooth body 5 and the tooth groove 6 on one side to maintain the tooth profile of the toothed belt 10. To be
Furthermore, it is important that the tooth body of the toothed belt of this cloth has an accurate tooth profile that matches the tooth profile of the mold, and therefore it is required to have elasticity according to the injection of the elastic body. A woven fabric is generally used as such a fabric structure.

In the present invention, in order to achieve such stretchability, a yarn having a specific structure is adopted. That is, FIG. 2 and FIG. 3 are schematic views schematically showing the structure of the coated elastic yarn 11 used in the present invention.
(B) shows a state at the time of relaxation.

The covered elastic yarn 11 is a covered elastic yarn in which a polyurethane-based elastic yarn is used as a core yarn 12 and a sheath yarn 13 is wound around the core yarn 12 in a coil shape. The one shown in FIG. 2 has a sheath yarn 13 around the core yarn.
Is wound around Z twist. On the other hand, as shown in FIG. 3, a sheath yarn 13 is wound around the core yarn 12 in the Z twist direction, and a sheath yarn 13 'is further wound around the S twist direction.

As the sheath yarn of such a coated elastic yarn, the strength is 6.5 g / d.
High-strength yarn made of the above synthetic fibers is adopted. As such fibers, for example, polyamide fibers, polyester fibers, polyvinyl alcohol alcohol fibers, aromatic polyamide fibers, etc. are used.

The above-mentioned coated elastic yarn uses polyurethane elastic yarn as a core yarn,
The high-strength synthetic fiber described above can be wound around the core yarn with a covering machine in a stretched state. The degree of elasticity of the covered elastic yarn depends on the stretch ratio of the polyurethane elastic yarn used for the core yarn during covering, the yarn length of the sheath yarn, and the number of windings per unit length.

That is, the expansion / contraction ratio of the covered elastic yarn can be arbitrarily selected by appropriately selecting the draw ratio of the core yarn and the winding number of the sheath yarn of a unit length.

When forming such a covered elastic yarn, the sheath yarn may be wound in either the right-handed or left-handed manner, or may be first wound in one direction and then wound in the opposite direction to cover the double-wrapped elastic yarn. It can also be a thread. Since the double-wrapped covered elastic yarn cancels the torque due to the winding of the sheath yarn, the yarn can be easily handled.

As the sheath yarn of the coated elastic yarn used in the present invention, a synthetic fiber yarn having a strength of 6.5 g / d or more is used, but if the strength is less than 6.5 g / d, the shear stress of the belt tooth body is reduced. Has a low retention rate, and a sufficient belt life cannot be obtained.

When forming a stretchable fabric that covers the tooth surface of the toothed belt using the above-mentioned coated elastic yarn, the structure of the fabric may be arbitrary, but the stretchability of the fabric is that the stress at 50% elongation is 10 kg / 3.
It is necessary to use those having a stress of not more than cm and a stress at 70% elongation of not more than 20 kg / 3 cm. That is, when a toothed belt is molded with a stretchable cloth having a stress greater than this, the stretchability of the cloth is insufficient, so the adhesion between the cloth and the tooth profile deteriorates, and the moldability and peeling resistance of the tooth profile are reduced. The problem of being damaged occurs.

The toothed belt is usually manufactured as follows.

First, the stretchable fabric is wound around a cylindrical mold with the direction of stretch along the circumferential surface. A cord of a tensile body is spirally wound on it, and an unvulcanized rubber sheet having a constant thickness is further wound on the cord, and then a known press-fitting method is used to apply pressure and heat from the outside to form a cylindrical mold. Press rubber into the tooth space. When press-fitting this rubber, depending on the shape of the tooth profile, the stretchable fabric is 50
It is ˜70% stretchable, fully conformable to the mold and cures under the correct shape.

The present invention will be further described below with reference to examples.

(Example) Example 1 A coated elastic yarn was manufactured by using a covering machine using "Operon" yarn (polyurethane elastic yarn manufactured by Toray DuPont) 140D as a core yarn. High-strength nylon 66 yarn (strength 9.2 g / d) 420D for sheath yarn, and air-entanglement-treated high-strength nylon 66 high-strength yarn (strength 6.5 g / d)
Two types of 420D were used.

The covering conditions were such that the "operon" yarn was stretched 3.5 times and the sheath yarn was wound around 200 times / m.

On the other hand, nylon 66 false twisted yarn (strength 5.5g /
d) 140D / 3 was used.

The above three types of yarns are used for wefts and nylon 66 for the warp
210D filament yarn was used to make a twill weave with a woven structure of 2/2, and the woven density after relaxation was 150 warps / 5 cm and weft 140 warps / 5 cm.

The elongation stress of the obtained cloth at 50% elongation and 70% elongation in the weft direction was measured, and the results are shown in Table 1.

Using the above-mentioned three types of stretchable fabrics, the stretchable fabrics are wound by a known press-fitting molding method so that the wefts are arranged in the direction of the tooth surface of the cylindrical mold, and the cord of aromatic polyaramid fiber is wound thereon. The vulcanized rubber sheets were arranged, and an unvulcanized rubber sheet was placed thereon, heated from outside to press the rubber into the tooth spaces of the cylindrical mold, and vulcanized to prepare a toothed belt.

The number of modules of the toothed belt manufactured was 20. This toothed belt was cut into a width of 4 cm.

The toothed belt thus obtained was subjected to a pulsating load of 50 tons and a driving side rotation speed of 1500 r. p. A running test was performed at m for 200 hours, the shearing force of the tooth body before and after running was measured, and the retention rate was obtained.

Table 1 shows the results of the running test.

As is clear from Table 1, the toothed belt according to the present invention shows markedly improved shear stress and retention rate as compared with the conventional belt using false twisted yarn.

(Effect of the present invention) The present invention uses a synthetic fiber having a high degree of polymerization and a high strength, which has not been conventionally applied to a toothed belt, for coating the tooth surface, thereby significantly improving the durability of the tooth surface. That is what I got.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a toothed belt according to the present invention. FIG. 2 and FIG. 3 are schematic views schematically showing the structure of the covered elastic yarn used in the present invention. 1: Stretchable cloth, 2: Tooth surface 3: Tensile body, 4: Elastic body, 5: Tooth body, 6: Tooth groove, 11: Coated elastic yarn, 12: Core yarn, 13 and 13 ′: Sheath yarn

Claims (2)

[Claims] 1. A toothed belt having a tension member and made of an elastic resin, and a toothed belt having a tooth surface made of an elastic resin on one surface, and the tooth surface being covered with a cloth. As the cloth, a polyurethane elastic yarn is used as a core yarn, and a covered elastic yarn is formed by a sheath yarn in which a synthetic fiber yarn having a strength of 6.5 g / d or more is wound around the core yarn in a coil shape. Stretchable fabric, wherein the stretchable fabric has a stress at 50% elongation of 10 kg / 3 cm or less and a stress at 70% elongation of 2
A toothed belt characterized by using a fabric of 0 kg / 3 cm. 2. A covered elastic yarn comprising a core yarn made of a polyurethane-based elastic yarn constituting a stretchable fabric and a sheath yarn formed by winding a synthetic fiber yarn in a coil shape around the core yarn. The toothed belt according to claim (1), wherein the toothed belt is arranged in the direction.