JPH05106690A - High load transmitting toothed belt - Google Patents

Abstract

PURPOSE:To improve a life by burying an alamide fiber core material along a bottom part of a belt main unit of polyurethane resin having a tooth part on an internal surface, forming a reinforcing layer on the tooth part, and specifying the alamide fiber core material. CONSTITUTION:An alamide fiber core material 3 serving as a tensile material is buried along a tooth bottom part of a belt main unit 1 of polyurethane resin, having tooth parts 2 of equal pitch on an internal surface, to form a reinforcing layer 4 of fabric, knitted cloth, etc. The alamide fiber core material 3 filament- bundled from several hundreds to several thousands, so that a filament of denier 0.9 to 1.6de obtains a denier number (d) of 16.3P<2d<24.5P<2> relating to a tooth pitch P, is first twisted by first twist coefficients 1.2 to 4.2 to form a first twist thread, and by drawing to arrange the seven first twist threads to perform a ply twist in 3.2 to 4.2 by a ply twist coefficient in a reverse direction to the first twist direction, a core material total denier number D is set to 82P<2D<122P<2> to provide a core material occupation rate 75 to 95% relating to a belt width. By the above, lives for tooth part shear and belt breaking can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved high-load transmission toothed belt in which a core body of aramid fiber is embedded as a tensile body in a belt body made of polyurethane resin.

[0002]

2. Description of the Related Art Conventionally, a high-load transmission toothed belt has been used for driving a large-scale processing machine such as a machine tool or a molding machine. Conventionally, a toothed belt having a structure in which a glass fiber core body as a tensile body is embedded in rubber and the tooth surface is reinforced with a nylon woven cloth has been used. However, in recent years, there has been an increasing demand for toothed belts that can be used under higher load conditions, and in response to this, polyurethane resin, which is stronger than rubber, is used, and the core body of aramid fiber is used in the belt body of the polyurethane resin. Attempts have been made to cope with high load conditions by burying the inner part and further reinforcing the tooth part with a woven or non-woven fabric.

By the way, there are roughly two damage modes that lead to the life of a toothed belt, namely, tooth shearing and belt cutting. In order to improve the shearing life of the former tooth, it is important to increase the belt tensile modulus so that the pitch of the belt teeth can be accurately maintained even when a load is applied, and the fatigue strength of the tooth that receives the load is increased. It is necessary to. Further, in order to improve the latter belt cutting life, it is necessary to reduce the body fatigue when the belt is repeatedly wound around a small-diameter pulley and repeatedly bent.

[0004]

With regard to the above-mentioned polyurethane resin toothed belt, the core constituting the tensile body is changed from glass fiber to aramid fiber having a high elastic modulus, and the rubber of the belt main body is made of polyurethane resin. As a result, the belt tensile elastic modulus and the tooth fatigue strength are significantly improved as compared with the conventional ones, and as a result, the tooth shear life can be significantly improved.

On the other hand, however, since the core body has a high elastic modulus, the bending fatigue of the core body becomes slightly worse than in the conventional case. Therefore, the use range of the high-load polyurethane resin toothed belt is limited so that it cannot be used with a small pulley and cannot be used because the number of repeated bendings increases at high speeds. .. In particular, the restriction that it can not be used with a small pulley is a big drawback in a large processing machine, and since the pulley has to be large, there is a problem that it takes up a large space in the belt transmission system and the device itself becomes large. ..

For example, a belt transmission system may require a reduction ratio of about ⅛, and in that case, the small pulley is 1
At 8 ^T , the large pulley side also reaches 144 ^T , which requires a very large space. Therefore, in order to reduce the space, 16 ^T or 14 smaller than 18 ^T
There is an increasing demand for toothed belts that can be used in ^{T and} that are capable of high load transmission.

The present invention has been made to solve these problems, and its purpose is to improve the shear life of the tooth portion of a polyurethane resin toothed belt by improving the structure of the aramid fiber core body. At the same time, it is intended to improve the belt cutting life so that it can be used even with a small pulley smaller than 18 ^T or high rotation.

[0008]

In order to achieve the above object, it was found in the invention of claim 1 that the shearing life of the teeth is extended by increasing the belt Young's modulus. A filament denier of the aramid fiber core embedded in the toothed belt made of polyurethane resin, the total denier, the number of core twists, the core twist coefficient, the core twist coefficient, and the belt width in order to achieve both increase and flex fatigue. The occupancy rate of the body was specified.

That is, according to the present invention, an aramid fiber core body as a tensile body is embedded along the above-mentioned tooth bottom portion in a belt main body made of polyurethane resin having tooth portions at equal pitch intervals on the inner surface, and the tooth portion is woven. In a high-load transmission toothed belt on which a reinforcing material layer such as cloth, knitted fabric, or non-woven fabric is formed, a filament having a filament denier of 0.9 de to 1.6 de is used for a belt tooth pitch P (unit: mm). 1
A ply-twisted yarn obtained by plying several hundreds to thousands of filament bundles with a plying factor of 1.2 to 4.2 to obtain a denier number d of 6.3P ² <d <24.5P ² , The seven twists are aligned and the upper twist coefficient is 3.2 to the opposite direction to the lower twist direction.
By twisting at 4.2, the total number of core denier D is 82.
P ² <a D <122P ^2, and embedded along the tooth bottom portion is 75% to 95% Traction occupancy for the belt width.

According to the second aspect of the present invention, the aramid fiber core has a high tensile strength by imparting a higher tension to one of the seven twisted lower twisted yarns than the other six twisted twisted yarns. Six other ply-twisted yarns are twisted around one of the center ply-twisted yarns.

In the invention of claim 3, the belt tooth height h is
(Unit: mm) is 1.00 for pulley groove depth H (Unit: mm)
H <h <1.02H.

[0012] In the invention of claim 4, the aramid fiber core is made of aramid fiber having a crystal orientation angle of about 9 ° by heat drawing.

[0013]

According to the first aspect of the present invention, the aramid fiber core has a ply-twisted yarn obtained by bundling hundreds to thousands of filaments having a filament denier of 0.9 de to 1.6 de and ply-twisted. Since the upper twist coefficient of the lower twist yarn is 3.2 to 4.2, the Young's modulus of the belt and the bending fatigue resistance can be made compatible with each other.

At this time, the ply twist coefficient of the ply twisted yarn is 1.2.
Therefore, it is possible to prevent the belt from meandering due to the deterioration of the balance of the twisting of the core itself and to prevent the decrease of the belt Young's modulus due to the increase of the lower twist coefficient.

Further, since seven lower twisted yarns are aligned and twisted first, it is possible to improve bending fatigue while securing the belt Young's modulus. Further, regarding the pitch P of the belt tooth portion, the number d of denier of the lower twisted yarn in the aramid fiber core is 16.3P ² <d <24.5P ² ,
Since the total number of core denier D is 82P ² <D <122P ² , the belt Young's modulus and the bending fatigue property can be compatible with each other by these limits.

Further, the core body occupancy ratio to the belt width is 75
Since it is ˜95%, a sufficient elastic modulus can be obtained, delamination is less likely to occur between the tooth portion and the tensile body layer, and the shearing life of the tooth portion can be extended.

As described above, by increasing the belt Young's modulus, it is possible to improve both the shearing life of the tooth portion and the bending fatigue resistance, and to improve the shearing life of the tooth portion in the high load transmission toothed belt made of polyurethane, The belt cutting life can be improved to enable use with a small pulley or high rotation.

According to the second aspect of the present invention, the aramid fiber core is formed by twisting one of the bundled seven twisted yarns to give a higher tension than the other six twisted yarns. ,
The one undertwisted yarn having a high tension is always located at the center of the core body, and the other six undertwisted yarns are uniformly twisted around it. As a result, the shape of the core is stable, and the six surrounding ply-twisted yarns are twisted in good alignment with respect to the strength, and the deterioration or variation in the strength is reduced. Moreover, since one central plied yarn is straight, the elastic modulus can be increased and the elongation can be suppressed.

In the invention of claim 3, the belt tooth height h is
Is 1.00H <h <1.02H with respect to the pulley groove depth H, it is possible to obtain a normal meshing state by contacting the belt tooth bottom with the pulley tooth top with initial tension being applied to the belt. Therefore, the bending fatigue property can be improved.

In the invention of claim 4, since the orientation angle of the crystal of the aramid fiber in the core body is about 9 °, the above respective effects can be effectively obtained.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a toothed belt B for high load transmission according to an embodiment of the present invention. This belt B has basically the same structure as a conventional toothed belt and has a pitch P on the inner surface. A belt body 1 having tooth portions 2, 2, ... Is provided, and a core body 3 as a tensile body is provided along the bottom portion of each tooth portion 2 of the belt body 1.
Is buried. Belt body 1 has JIS / A hardness of 85
The core body 3 is aramid fiber, which is made of polyurethane resin having a temperature of 90 ° to 93 °. A reinforcing material layer 4 made of woven cloth, knitted cloth, non-woven cloth or the like is formed on each tooth 2.

The feature of the present invention lies in the structure of the aramid fiber core body 3 which constitutes the above-mentioned tensile body.
That is, the total denier number D of the aramid fiber core body 3
(Denier) is the tooth pitch P of the toothed belt B (unit: mm)
, 82P ² <D <122P ² . The filament bundle denier number d (unit denier) is
Similarly, the range is 16.4P ² <d <24.4P ² .
This filament bundle is ply-twisted with a ply-twist coefficient of 1.2 to 4.2 to form a ply-twisted yarn 3a.
As shown in FIGS. 3 and 4, 7 pieces of a are aligned and twisted in the opposite direction to the lower twist with an upper twist coefficient of 3.2 to 4.2, and the total denier number D is within the above range. To do. The core body 3 is embedded along the bottom of the tooth portion 2 at an occupation rate of 75 to 95%.

In the aramid fiber core body 3, one of the seven twisted lower twisted yarns 3a, 3a, ... Is given a higher tension than the other six twisted yarns and is twisted upward. ,
As shown in FIG. 4, one under-twisted yarn 3a with a high tension center
The other six ply-twisted yarns 3a, 3a, ... Are twisted around.

FIG. 2 shows a toothed pulley 11 around which the toothed belt B is wound. The pulley 11 has tooth portions 12, 12, ... Groove portion 13 in which the belt tooth portion 2 is meshed between 12
Are formed. And the groove depth H of this pulley 11
With respect to (unit mm), the height h (unit mm) of the tooth portion 2 of the belt B is set to 1.00H <h <1.02H.

Further, more preferably, the aramid fiber used has a crystal orientation angle of about 9 ° by heat drawing.

The reasons for limiting the above numerical values will be described in detail below in order. First, the hardness of the polyurethane resin forming the belt body 1 is set to 85 ° to 93 °. In order to extend the durable life of the belt B under high load conditions, the polyurethane resin is required to have sufficient strength.
However, if the hardness exceeds 93 °, the belt is likely to be cracked on the back surface of the belt due to repeated winding around the small pulley, and there is a risk of belt breakage due to the progress of the crack. Further, when the hardness is less than 85 °, the strength of the tooth portion is insufficient and the durable life is shortened. Therefore, the hardness of the polyurethane resin needs to be 85 ° to 93 °.

The core body 3 uses aramid fiber. Since the aramid fiber has a higher elastic modulus than the glass fiber, the pitch of the belt teeth can be more accurately maintained when a load is applied.

Further, the fatigue strength of the tooth portion 2 can be increased by providing the belt tooth portion 2 with the reinforcing material layer 4 such as a woven fabric, a knitted fabric or a non-woven fabric.

FIG. 6 shows the load durability evaluation results by changing the belt Young's modulus. The test apparatus has the configuration shown in FIG. 5, in which a toothed belt B is wound between a pair of toothed pulleys 11, 11. In the belt B, the pitch P of the tooth portions 2 is P = 14 mm, the hardness of the polyurethane resin of the belt body 1 is 90 °, the tooth portions 2 are reinforced with a non-woven fabric, and the tooth portions 2 have an arcuate tooth shape. An h having a h = 4.65 mm, an aramid fiber core 3 and a tooth number of 100 ^T was used. Further, each pulley 11 is 28 ^T −28 ^T and has a tooth groove depth H of H = 4.95 mm. The pulley rotation speed was 1900 rpm, the load torque was 15 kgfm, and the belt width was 15 mm and 12 mm. The belt Young's modulus variable is the total denier of the aramid fiber core body,
The twisting coefficient and the heat drawing treatment were used. All body pitches are 2.5 mm. The twisting coefficient TM is expressed by the following equation.

TM = t · d ^1/2 / K where t: the number of twists per inch d: Denier of cord K: Material constant (68 for aramid fiber) PPTA (polyparaphenylene terephthalamide fiber) for aramid fiber The crystal orientation angle OA is about 15 ° and the crystal orientation angle OA is about 9 ° by heating and stretching the crystal at about 5 °. The belt Young's modulus was measured by attaching a 28 ^T- 28 ^T pulley to a tensile tester, winding the belt B around the pulley, and pulling at a speed of 50 mm / min. Since the belt B does not have a uniform cross-section, for convenience sake, the value AE obtained by multiplying the elastic modulus E by the cross-sectional area A is defined as the belt Young's modulus. Body 3
Are filament denier 1.4de and 2.25d
Two types were used, the one of e. The structure of the core body 3 is such that the filament bundle obtained by bundling the above filaments has the above twist coefficient T
An undertwist was used in M, and several of these undertwisted yarns were aligned and twisted in the opposite direction to the undertwist with the same twist coefficient TM as the undertwist coefficient. As shown in FIG. 6, the belt endurance life is dramatically improved by increasing the Young's modulus.

Next, FIG. 7 shows the results of evaluation of bending fatigue.
The test apparatus at this time is basically the same as that shown in FIG. 5, in which both pulleys 11 and 11 are arranged vertically and a belt tension is applied by applying a weight of 80 kgf to one pulley 11. The pulley 11 was 18 ^T- 18 ^T , the belt width was 15 mm, the pulley rotation speed was 3600 rpm, and the vehicle was run without load. Others are the same as those in the test of FIG. 6, and two types of core body twisting coefficient TM = 3.4 and 4.8 were performed. As shown in FIG. 6, the strength after bending shows a sharp tendency to decrease from around 10 ⁷ times of bending.
There are various usage conditions in the market, but about 10 ⁸ to 2 ×
About 10 ⁸ times is a standard. Therefore, in order for the belt B to travel without being cut, there is no problem as long as it has a strong holding ratio of about 50% at 10 ⁸ times. From the decreasing tendency of the bending fatigue property shown in FIG. 7, if the strength retention of about 80% is obtained at 2 × 10 ⁷ times, the strength retention of 50% can be estimated at 10 ⁸ times. Therefore, a strong retention rate of 80% at 2 × 10 ⁷ times is considered as one index.

Based on this idea, the twisting coefficient TM = 4.
8 can also be used with 18 ^T pulleys. However, as shown in FIG. 6, when the twisting coefficient TM = 4.8, the belt Young's modulus is insufficient, and thus the shearing life of the tooth portion is low.
Thus, it is understood that the belt Young's modulus and the bending fatigue property must be made compatible by selecting an appropriate core body specification in order to use the small pulley while improving the belt life.

In order to achieve both the belt Young's modulus and bending fatigue resistance, the twisting coefficient of the core is set to TM = 3.2 to 4.2. FIG. 8 shows changes in the belt Young's modulus and bending fatigue resistance due to changes in the twist coefficient. As shown in FIG. 8, when the twist coefficient TM = 2.0, the Young's modulus is high, but the bending fatigue resistance is very low. Further, when the twisting coefficient TM = 4.8, the bending fatigue resistance is high, but the Young's modulus is low. In order to achieve both Young's modulus and bending fatigue resistance, the twist coefficient is TM = 3.2.
It must be in the range of 4.2. In the test shown in FIG. 8, the upper twist and the lower twist were performed in opposite directions with the same twist coefficient. In the case of rubber belts, the wear between the lower twisted yarns has a large effect on the decrease in strength.Therefore, if the upper and lower twists are twisted in the opposite directions, the crossing angle of the filaments between the lower twisted yarns will increase and it will be more easily worn. Although there is a problem, in the case of a polyurethane resin belt, the polyurethane resin is sufficiently filled between the ply-twisted yarns, and the strength decrease due to the wear of the ply-twisted yarns hardly occurs. Does not affect much. As an example, when the lower twisted yarn denier number is 4500 denier, the upper twisted number is 5, the upper twisted coefficient TM = 3.4 and the lower twisted state is not used, and the bending fatigue property is examined under the same conditions as in FIG. Met. The vertical twisting coefficient TM = 3.4 shown in FIG. 8 had a tenacity retention of 60%, so it can be seen that the lower twisting coefficient has little effect. However, the larger the lower twist coefficient, the lower the belt Young's modulus tends to be. Therefore, the maximum twist coefficient should be the same as the maximum twist coefficient. On the other hand, if it is too small, the balance of the twist of the core itself becomes unbalanced, which may cause the belt to meander. Therefore, the lower twist factor is TM =
It is set between 1.2 and 4.2.

Next, the reason why the number of twists on the core is set to 7 will be described. FIG. 9 is a graph showing the change characteristics of the belt Young's modulus and bending fatigue resistance with respect to the change in the number of twists in the core. 284 total denier to remove other factors
The twist coefficient is T
Fixing M = 3.4, filament denier 1.4d
The number of ply-twisted yarns was changed by fixing to e and changing the ratio of the number of ply-twisted yarns and the number of denier of the ply-twisted yarn (filament number). In general, three twisted strands are most often used as a twisted core body for an aramid fiber transmission belt. This is the most stable construction for undertwisted yarns,
This is because the twisted yarn is well aligned, and as a result, the strength and the fluctuation of the elastic modulus are small and the reliability is excellent. The next most stable number is 5 twists. This five-ply twist has a fairly stable structure, though not so much as a three-ply twist, and is therefore used in part. Furthermore, with regard to 6-strands and more, the conventional cords are not comfortable to sit in, so they are extremely unstable and the alignment of the lower twisted yarns is poor. It was thought that it was not suitable as a tension member for a belt. However, according to the present inventor, in reality, only 7-ply twist is an exception, and it is found that not only these problems do not occur, but also bending fatigue resistance is significantly better than that within 5 ply twist. That is, as shown in FIG. 3, the 7-strand has a stable cross-sectional shape, and the sitting of the cord is extremely good. However, at that time, as in the case of less than 5 twists, in order to improve the alignment of all the lower twisted yarns 3a, 3a, ..., the same tension is applied to the 7 lower twisted yarns 3a, 3a ,. If this is done, the most stable center plied yarn 3a moves in and out to the outside, and becomes unstable on the contrary, which may cause a problem such as a decrease in strength. Therefore, in this embodiment, of the seven undertwisted yarns 3a, the same tension is applied to six yarns to improve the alignment, while the remaining one undertwisted yarn 3a has a higher tension than the other six yarns. To increase
Twisting is performed in that state. By doing so, as shown in FIG. 4, one ply-twisted yarn 3a to which high tension is applied is always located at the center of the core body, and six ply-twisted yarns 3a,
3a, ... Are twisted uniformly. As a result, the shape of the core body is stable, and the six surrounding twisted yarns 3a, 3a, ...
Since they are twisted in a well-aligned manner, the decrease in strength and variation are reduced. Further, since one central plied yarn is straight, the elastic modulus can be increased and the elongation can be suppressed.
In FIG. 9, in the case of 7 twists, 7 lower twisted yarns 3a, 3
When all of a, ... Are aligned with the same tension (shown by the solid line in the figure), six are aligned with the same tension, and the remaining one plied yarn 3a is given twice the tension of the other. (Indicated by the same broken line), the latter one has a higher elastic modulus than the former and also has a good bending fatigue property.

Next, FIG. 10 shows a graph of the change characteristics of the belt Young's modulus and bending fatigue resistance due to the change of filament denier. In order to remove other factors, the total denier number D is fixed at 28400 denier, and the twist coefficient TM is T.
M = 3.4, the number of upper twists was fixed at 5, and the number of lower twist filaments was changed to make the number of lower twist yarn denier uniform so that the filament denier was varied. As shown in Figure 10,
2.1d for filament denier of 1.4de
The retention rate is as high as 12% compared to that of e. It can be seen from FIG. 10 that the filament denier is preferably 1.6 de or less. However, when the filament denier is less than 0.9 de, a stable denier cannot be obtained in the production of fibers,
Practically unusable due to lack of reliability. Therefore, the filament denier is selected to be 0.9 to 1.6 de.

Next, FIG. 11 shows a graph of change characteristics of bending fatigue property due to change of belt tooth height. At this time, the specifications of the core are fixed to filament denier 1.4 de, lower twist yarn denier number 5680 de, lower twist coefficient TM = 3.4, upper twist number 5, twist coefficient TM = 3.4, and only belt tooth height. It was a variable. In contrast to the design in which there is a gap of 6% with respect to the tooth height h as shown in FIG. 11, the retention rate of 12% is improved at ± 0%. If it is further compressed by 1%, it will be improved by 8%. When the belt tooth height is made higher than the pulley groove depth, the belt B is statically
When the belt is wound around the pulley 11, the tooth tip contact occurs and the belt tooth bottom part floats up from the pulley tooth top part. However, if the compression ratio is within 2%, the initial tension is applied to cause the belt to sink and come into contact. It will be a good mesh. However, if the belt tooth height is increased by 2% or more, the belt will be in a floating state even if the initial tension is applied, and the PLD (pitch line difference) will not match, resulting in poor meshing between the belt and the pulley. Will end up. Therefore, the belt tooth height h is preferably in the range of 1.00H <h <1.02H with respect to the pulley groove depth H. Up to now, most of the polyurethane resin toothed belts have been set to H> h, but by setting the above range, the bending fatigue property can be improved.

Next, FIG. 12 shows a graph of the belt Young's modulus and flex fatigue due to changes in the total denier number D of the body.
To remove other factors, filament denier 1.
The core total denier number D was changed by changing the number of denier of the lower twisted yarn denier by fixing 4 de, the number of upper twists 5, the twist coefficient TM = 3.4, the belt tooth height to 5.00 mm. Further, considering that a large number of core bodies can be embedded per unit width by reducing the total number D of core bodies, the occupation rate of the core body is fixed to about 85%. The occupancy ratio is a ratio of the core body portion to the belt width, and the occupancy ratio (%) = (Cp / Cd) × 100 where Cp: core body pitch Cd: core body diameter (mm) It The core body diameter Cd is Cd = 2 {16 × D / (π ³ × 9 × 10 ³ × S)} 1/2, where D: total denier S: specific gravity (1.44 to 1.47 for PPTA) ) Is calculated. This occupancy rate of the body is set to 75 to 95%. That is, when the occupancy rate is 75% or less, a sufficient elastic modulus cannot be obtained, while when the occupancy rate is more than 95%, delamination is likely to occur between the tooth portion 2 and the tensile body layer, and conversely the tooth portion shear life is increased. Is shortened.

Returning again to FIG. 12, regarding the belt Young's modulus, if the total denier number D is 16,000 denier or more, the Young's modulus can be maintained at 7500 kgf / 15 width or more, so that a high tooth shear life can be maintained. On the contrary, regarding the bending fatigue property, if the total denier number D is 24000 or less, the strength retention is about 80%, so that a retention of 50% can be estimated even after 10 ⁸ times of bending. Therefore, 14mm
With a pitched toothed belt, the total number of core denier D is D = 1
It is set in the range of 6000 to 24000 denier. Further, since the number of upper twisted yarns is 5, the denier number d of the lower twisted yarn is set in the range of d = 3200 to 4800.

Even if the toothed belt is of the same type, there are several tooth pitches which differ depending on the load torque. For example, tooth pitches of 11 mm, 8 mm, 5 mm, 3 mm, etc. have been industrialized in addition to the above 14 mm. In the case of improving the toothed belt core body, the above-mentioned twisting coefficient can be applied to any pitch, but the above-mentioned total denier number D and lower twist yarn denier number d are set according to each pitch. Is. INDUSTRIAL APPLICABILITY The present invention is not intended only for a toothed belt having a pitch of 14 mm, but is improved by increasing the belt Young's modulus and improving the bending fatigue property at any pitch so that the belt can be used in a smaller pulley. is there. In general, when the pitches of the same type of toothed belt are different, the belt shape changes in a substantially similar manner in proportion to the pitch. Therefore,
The total denier number D and the lower twisted yarn denier number d can be generalized by the square of the belt pitch P × a constant.

Therefore, the total number of denier D is D = 16000 for the 14 mm pitch toothed belt as described above.
Generalized by ~ 24000 denier, 82P ² <D
It is set within the range of <122P ² . Similarly, the number of denier of the lower twisted yarn is 14 mm pitch and d = 3200 to 4800d.
generalized by e, 16.3P ² <d <24.5P ²
It is set in the range of.

For example, in the case of a toothed belt having a pitch of 8 mm,
The total denier number D is set to D = 5200 to 7800 de, and the lower twist yarn denier number d is set to d = 1050 to 1560 denier.

In the toothed belt B configured as described above, it is possible to improve both the shearing life of the tooth portion 2 and the bending fatigue resistance by increasing the belt Young's modulus, and to improve the shearing life of the tooth portion of the belt. At the same time, it is possible to improve the cutting life and enable use with a small pulley or high rotation.

(Specific Examples) In order to explain that the present invention is very effective, the evaluation results of load durability and bending fatigue resistance are shown for several comparative examples including the present invention example and the conventional example. In the load durability evaluation test, the belt width was varied under the same conditions as in FIG. In the bending fatigue evaluation test, the number of pulley teeth was 18 ^T- 18 ^T , 22 ^T- 22 ^T , 2
The variable was 8 ^T- 28 ^T, and the other conditions were the same as those in FIG.

All the belts were toothed belts having a pitch of 14 mm, the number of teeth was 100 ^T , and the tooth profile was an arcuate tooth profile. Inventive Examples and Comparative Examples 1 to 3 are polyurethane resin belts, all of which have a hardness of 90 °, and the core body is aramid fiber.

The core of the present invention is made of PPTA, and aramid fibers having an orientation angle OA of about 9 ° are used by heating and stretching about 5% of a raw yarn having a crystal orientation angle OA = about 15 °. This is marketed under the trade name of "Kevlar 49" by Toray Dupont Kevlar.) The filament denier was 1.4 denier, and the number d of denier of the lower twisted yarn was d = 4560 denier (four commercially available yarns having a denier of 1140 de were bundled and used). This was twisted under with a twisting coefficient of TM = 3.4, and twisted with 5 twists and TM = 3.4. The core pitch was 2.2 mm and the occupation rate was 88%.

The core of Comparative Example 1 is an aramid fiber having a crystal orientation angle OA of 9 °, which is the same as that of the present invention. Its filament denier is 1.4 de, and the number of denier of the twisted yarn is d = 568.
0 de (1420 de × 4), number of twists 5, twist coefficient TM = 3.4, core pitch Cp = 2.5 mm, occupancy 8
It was set to 5%. The core of Comparative Example 2 has a crystal orientation angle OA = 1.
1. Filament denier with 5 ° aramid fiber (trade name “Kevlar 29” manufactured by Toray-Dupont Kevlar).
25 de, number of denier of twisted yarn d = 4500 de (22
50 de × 2), the number of twists is 5, the twist coefficient TM = 4.
8, core pitch Cp = 2.5 mm, occupancy rate is 76%.
The core of Comparative Example 3 has a yarn denier of 1140 denier,
Number of lower twists 4, Number of upper twists 5, Twisting coefficient TM = 3.4,
Occupancy rate was 86% at the core pitch Cp = 2.2 mm.

Comparative Example 4 is a rubber belt, and the core is glass fiber, which is widely and generally used.

FIG. 13 shows a graph of load durability when the width of each belt varies. As shown in FIG. 13, in comparison with the commercially available rubber belt of Comparative Example 4, the present invention example and Comparative Examples 1 to 1
No. 3 has a very long durable life. This is because the belt main body is made of polyurethane resin having high fatigue strength, and the teeth are fiber-reinforced. Furthermore, in the example of the present invention and the comparative example 2, the durable life is several times longer than that of the comparative example 4. This is because the belt Young's modulus was significantly increased. Further, the example of the present invention is slightly inferior to the comparative example 1, but exhibits substantially the same durability. The inventive example and the comparative example 2 have Young's moduli close to each other, and as a result, endurance life is also near.

FIG. 14 is a graph showing the bending fatigue resistance of each belt due to the variable number of pulley teeth. As shown in FIG. 14, in the example of the present invention, even with the 14 ^T pulley, the strength retention is 8 at 2 × 10 ⁷ times.
Since it is 0% or more, about 50% is estimated even at 10 ⁸ times, and even a small 14 ^T pulley can be used without any problems.

Thus, since only the example of the present invention has a long endurance life of shearing teeth and good bending fatigue, it is proved that it can be used with a small pulley of 14 ^T or less and under a high load condition. Was given.

[0051]

As described above, according to the first aspect of the present invention, the aramid fiber core body as a tensile body is embedded along the tooth bottom portion in the belt main body made of polyurethane resin, and the tooth portion is woven. In a high load transmission toothed belt having a reinforcement layer such as cloth, the filament denier is 0.9 de
A belt tooth pitch P
A filament bundle in which hundreds to thousands are bundled so that the denier number d is 16.3P ² <d <24.5P ² with respect to (unit mm) is twisted with a twisting factor of 1.2 to 4.2. The total number of denier D of the core body is 82P ² <D <by arranging 7 of the obtained ply-twisted yarns and plying them in a direction opposite to the ply-twisting direction with a ply-twisting coefficient of 3.2 to 4.2. Since the aramid fiber core body of 122P ² is formed and the aramid fiber core body is embedded along the tooth root portion at a core body occupation ratio of 75 to 95% with respect to the belt width, the tooth portion is increased by increasing the belt Young's modulus. For both high load transmission made of polyurethane that has both improved shear life and improved flex fatigue, has a long tooth shear life, and has high flex fatigue, and can be suitably used even for small pulleys of 14 ^T and high rotation. A toothed belt can be realized.

According to the second aspect of the present invention, the aramid fiber core is twisted by twisting one of the seven twisted plied yarns having a higher tension than the other six plied yarns, Since the other 6 ply-twisted yarns are twisted around one high ply-twisted yarn, the shape of the core is stabilized and the 6 ply-twisted yarns around the core are aligned well and the strength is reduced. It is possible to reduce unevenness and variation, and to keep one ply-twisted yarn at the center straight to increase elastic modulus and suppress elongation.

Further, according to the invention of claim 3, the belt tooth height h is 1.00H <h <with respect to the pulley groove depth H.
Since it is 1.02H, it is possible to obtain a normal meshing state between the belt groove portion and the pulley tooth portion, and it is possible to further improve the bending fatigue property.

Further, according to the invention of claim 4, the orientation angle of the crystal of the aramid fiber in the core body is set to about 9 °, so that the above effect can be effectively obtained.

[Brief description of drawings]

FIG. 1 is a front view partially showing a toothed belt according to an embodiment of the present invention.

FIG. 2 is a front view showing a part of a pulley.

FIG. 3 is a cross-sectional view showing a 7-strand core body.

FIG. 4 is a perspective view showing a 7-strand core body.

FIG. 5 is a schematic view of a belt tester.

FIG. 6 is a characteristic diagram showing a relationship between a change in Young's modulus of a belt and durability.

FIG. 7 is a characteristic diagram showing evaluation of bending fatigue resistance.

FIG. 8 is a characteristic diagram showing the relationship between the change in the twisting coefficient of the core and the belt Young's modulus and bending fatigue resistance.

FIG. 9 is a characteristic diagram showing the relationship between the change in the number of twists in the core and the belt Young's modulus and bending fatigue resistance.

FIG. 10 is a characteristic diagram showing the relationship between the change in core filament denier and the belt Young's modulus and flex fatigue.

FIG. 11 is a characteristic diagram showing a relationship between changes in belt tooth height and bending fatigue resistance.

FIG. 12 is a characteristic diagram showing the relationship between changes in the total denier of the body and belt Young's modulus and flex fatigue.

FIG. 13 is a characteristic diagram showing a relationship between changes in belt width and load durability in a specific example of the present invention.

FIG. 14 is a characteristic diagram showing a relationship between changes in the number of pulley teeth and bending fatigue resistance in a specific example of the present invention.

[Explanation of symbols]

 B Toothed belt 1 Belt body 2 Tooth portion 3 Core body 3a Twisted yarn 4 Reinforcement layer 11 Toothed pulley P Pitch of tooth portion d Number of lower twisted yarn denier D Total number of core denier h Belt tooth height H Pulley groove depth

Claims (4)

[Claims] 1. A aramid fiber core body as a tensile body is embedded along a root portion of a belt body made of a polyurethane resin having tooth portions at equal pitch intervals on its inner surface, and the tooth portion is woven or knitted cloth. In a toothed belt for high load transmission having a reinforcing material layer such as a non-woven fabric, the aramid fiber core has a filament denier of 0.
A filament having a size of 9 de to 1.6 de is applied to a belt tooth pitch P (unit: mm) of 16.3 P ² <d <24.5.
The ply-twisted yarn obtained by plying several hundred to several thousand filament bundles having a denier number d of P ^{2 with} a ply-twisting factor of 1.2 to 4.2 is aligned with the ply-twisting direction. Is twisted in the opposite direction with a twisting coefficient of 3.2 to 4.2, so that the total denier number D of the core body is 82P ² <D <122P ² and the core body occupancy ratio to the belt width is 75 ~ 9
A toothed belt for high load transmission, which is buried at 5% along the tooth bottom. 2. An aramid fiber core is obtained by applying a higher tension to one of the seven twisted plied yarns than the other six twisted yarns and twisting the yarn under the center of the high tensioned yarn. 6. A structure in which six other twist yarns are twisted around a twist yarn.
Toothed belt for high load transmission described. 3. The belt tooth height h (unit: mm) is 1.00H <h <1.02H with respect to the pulley groove depth H (unit: mm). High-load transmission toothed belt. 4. The toothed belt for high load transmission according to claim 1, 2 or 3, wherein the aramid fiber core is made of aramid fiber whose crystal orientation angle is about 9 ° by heat drawing. ..