JPH0544608Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement of a so-called wrapped V-belt in which the outer circumferential surface of a belt core is covered with an outer covering canvas.

(Prior Art) In general, agricultural V-belts used for power transmission in agricultural machines such as combines, rice transplanters, and tractors are constantly exposed to mud, sand, dust, water, etc. For this reason, wrapped V-belts are widely used, which have a structure in which the outer peripheral surface of a belt core made of rubber is covered with canvas or the like.

Further, in most cases, this type of V-belt uses a back tension pulley mechanism for the purpose of applying tension for power transmission. That is, in this tension pulley mechanism, a tension pulley having a rotation axis parallel to the rotation axes of the two pulleys is arranged between the driving and driven pulleys, and the tension pulley allows the tension pulley to be wound between the driving and driven pulleys. By pressing the back side of the hung V-belt, tension is applied to the V-belt and power is transmitted between the driving and driven pulleys.

By the way, when wrapping an outer canvas around the belt core of a wrapped V-belt, the beginning and end of the winding, that is, the joining edge, are usually cut along the grain of the canvas (the direction along the warp or weft of the canvas). has been done. There are usually two types of angles that the canvas threads make with respect to the longitudinal direction of the belt: 45° or 60°.
Both are cut along the grain of the canvas.

In addition, the outer canvas is generally made by coating a base fabric with rubber and then bias-cutting and splicing, but the bias-cut splices are also made in the direction along the grain of the canvas. There is.

(Problem to be solved by the invention) However, in recent years, as agricultural machinery has become more compact and has improved performance, the conditions for using agricultural V-belts have become even more severe. Due to the increase in V-belts, the rise in ambient temperature, etc., a reduction in durability due to cracks in the compression members of wrapped V-belts in particular has become a major problem.

In other words, in the case of an outer canvas cut along the grain of the canvas as described above, under so-called reverse bend conditions using the back tension pulley, the stress caused by distortion due to belt bending is absorbed by the fabric at the cut part. The weaving threads (only one of the warp threads or the weft threads) that intersect with the cutting line of the upper cloth in the lower cloth are intensively received. As a result, cracks occur early from the threads at the cut portion, reducing the durability of the belt. This is similar to a general phenomenon in which, for example, when a certain member is in a discontinuous state, stress concentrates on the discontinuous portion and destruction progresses.

The present invention was developed in view of the above, and its purpose is to improve the cut shape of the joint part of the outer covering canvas used in wrapped V-belts.
Even when used as an agricultural V-belt or the like under reverse bend conditions using a back tension pulley, the purpose is to disperse stress concentration at the joints of the outer covering canvas and to suppress the occurrence of cracks at the joints.

(Means for solving the problem) To achieve this purpose, the solution of the present invention is as follows:
The edge portion of the outer covering canvas as a joint is not cut in the direction along the thread of the canvas, but the cutting angle is shifted by a predetermined angle from the angle of the thread.

Specifically, the configuration of the present invention includes a belt core body having an inverted trapezoidal cross section, and a belt core body such that the edges of the belt core body are overlapped along the longitudinal direction of the belt and there is at least one overlapping portion. In a wrapped V-belt, which is provided with an outer covering canvas that is covered from the outer peripheral side of the belt and joined to the outer peripheral surface, the cutting line and thread of the edge of the canvas that is above the overlapping part of the outer covering canvas is θ ₁ is the angle of intersection between the warp and weft of the canvas with respect to the longitudinal direction of the belt, and in the direction perpendicular to the longitudinal direction of the belt, 5°≦θ ₁ ≦{(180−θ)/2 −5}°, and in the direction along the belt longitudinal direction, it shall be set in the range of 5°≦θ ₁ ≦ (1/2) and {90−(180−θ)/2}°, respectively. do.

For example, as shown in FIG. 1, in a V-belt in which the angle of the threads with respect to the longitudinal direction of the belt is 60°, the intersection angle θ between the warp and weft is θ=120°, and in that case,
For the direction perpendicular to the belt longitudinal direction, 5°≦
It is set in the range of θ ₁ ≦25°, and in the direction along the belt longitudinal direction, in the range of 5°≦θ ₁ ≦30°.

(Function) With the above configuration, in the present invention, the cutting line of the upper cloth at the overlapping part of the outer covering canvas is deviated from the thread, so that the upper cloth of the lower cloth covered by the cloth at the cut part is cut. When the weaving threads in the portions that intersect with the lines are subjected to stress, the stress is received by both the warp and weft threads of the canvas, and the stress is dispersed.
As a result, cracks do not occur in the outer covering canvas, and the durability of the belt can be improved.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 2 shows the overall structure of a V-belt A according to an embodiment of the present invention, and this V-belt A includes an endless belt core 1 and an outer covering canvas 6 covering the outer peripheral surface of the belt core 1. Be prepared. The above belt core 1
The cushion layer 2 forming the bottom rubber and the tensile band layer 3 are formed to have an inverted trapezoidal cross section, and the tensile band layer 3 has core cords 4, 4, . . . and the core cords 4. , 4, . . . are embedded in the adhesive rubber layer 5.

On the other hand, in the outer covering canvas 6, the warp threads 7, 7, ... and the weft threads 8, 8, ... are arranged at θ=120° with respect to the longitudinal direction of the belt.
A plain weave canvas woven with an intersection angle of The belt is coated from the outer circumferential side so as to become one, and is joined to the outer circumferential surface of the belt.

The outer covering canvas 6 is formed with a 1-ply portion of only the lower cloth 6a and a 2-ply portion in which the upper cloth 6b is overlapped on the lower cloth 6a. 6b is cut at a predetermined angle θ ₁ with respect to the angle of the threads of the canvas. That is,
Angle θ ₁ between the cutting line 6c of the edge of the canvas 6b above the overlapping portion of the outer covering canvas 6 and the thread grain.
The intersection angle between the warp threads 7 and the weft threads 8 of the canvas with respect to the belt longitudinal direction is θ = 120°, and in the direction perpendicular to the belt longitudinal direction, 5°≦θ ₁ ≦ {(180
-θ)/2-5}°, that is, in the range of 5°≦θ ₁ ≦25°, and in the direction along the belt longitudinal direction,
5°≦θ ₁ ≦(1/2)・{90−(180−θ)/2}°,
That is, they are each set in the range of 5°≦θ ₁ ≦30°.

Therefore, in the above embodiment, the V-belt A is put into a reverse bend state by the back tension pulley, and the upper cloth 6 of the outer covering canvas 6
The upper cloth 6b of the lower cloth 6a covered by b
When stress is applied to the weaving yarn at the portion intersecting the cutting line 6c, the cutting line 6c of the upper cloth 6b of the outer covering canvas 6 is 5°≦θ ₁ ≦25° from the thread in the direction orthogonal to the longitudinal direction of the belt. The _above stress is applied to the warp threads ₇ , 7,
. . . and the weft threads 8, 8, . . . and the stress is dispersed. Therefore, cracks do not occur in the outer covering canvas 6, and thus the durability of the belt A can be improved.

In the above embodiment, as the outer covering canvas 6, a plain weave canvas was used in which warp threads 7, 7, ... and weft threads 8, 8, ... were woven at an intersection angle of θ = 120° with respect to the longitudinal direction of the belt. However, the warp threads 7, 7, ... and the weft threads 8, 8, ...
You may also use a plain weave canvas woven with ... at an intersection angle of θ = 90° with respect to the longitudinal direction of the belt. In that case, the angle θ ₁ between the cutting line 6c of the outer covering canvas 6 and the thread of the canvas is 5° in the direction orthogonal to the longitudinal direction of the belt.
It is set in the range of ≦θ ₁ ≦40°, and in the range of 5°≦θ ₁ ≦22.5° in the direction along the longitudinal direction of the belt.

Finally, a specific example will be explained. The outer canvas is woven with the warp and weft at an intersection angle of θ = 120° with respect to the longitudinal direction of the belt, and similarly, θ = 90°.
2. Using outer covering canvas woven at the intersection angle of
For types of V-belts A ₁ and A ₂ , the angle θ ₁ between the cutting line of the outer covering canvas and the thread of the canvas is 0 to 30° in the direction orthogonal to the belt longitudinal direction.
We prepared a large number of test V-belts that were changed within the range of
When the running time of the belt until the occurrence of a crack was measured using the pulley type transmission shown in FIG. 4, the results shown in FIG. 3 were obtained. The above pulley type transmission has a driving pulley _P1 , a driven pulley _P2 ,
It includes a back tension pulley _P3 arranged between both pulleys _P1 and _P2 , and the driving pulley _P1 has an effective diameter of 103 mm and is driven to rotate at a rotation speed of 2500 rpm. Also, the effective diameter of driven pulley P ₂ is 174.5
mm, with a load of 7.5 HP. Further, the back tension pulley P ₃ has a diameter of 100 mm, and applies a tension load of 20 kg to the V-belts A ₁ and A ₂ .

As is clear from FIG. 3, if the angle θ ₁ between the cutting line of the outer covering canvas and the thread of the canvas is approximately in the range of 5 to 25° in the direction orthogonal to the belt longitudinal direction, two types of V-belts can be used. In both A ₁ and A ₂ , the belt running time before cracking was significantly longer than that of a conventional belt, indicating that the effect of the present invention was well exhibited.

(Effects of the invention) As explained above, according to the invention, in the wrapped V-belt in which the outer covering canvas is attached to the outer peripheral surface of the belt core, the overlapping portion of the outer covering canvas along the longitudinal direction of the belt By cutting the edge of the upper cloth at a predetermined angle with respect to the angle of the threads of the canvas, the part of the lower cloth covered by the cut cloth intersects with the cutting line of the upper cloth. Both the warp and weft of the canvas can receive the stress and disperse the stress, thereby suppressing the occurrence of cracks in the outer covering canvas and improving the durability of the wrapped V-belt.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, with FIG. 1 being an enlarged plan view of the inner circumferential side of the V-belt, and FIG. 2 being a perspective view of the V-belt seen from the inner circumferential side. FIG. 3 is a characteristic diagram showing the time required to generate a crack with respect to a change in the cutting angle at the cut portion of the outer covering canvas, and FIG. 4 is a schematic diagram of the pulley type transmission used for the test. A... V-belt, 1... Belt core, 6... Outer canvas, 6a... Lower cloth, 6b... Upper cloth, 6c
...cutting line, 7...warp thread, 8...weft thread.

Claims (1)

[Claims for Utility Model Registration] A belt core body having an inverted trapezoidal cross section, and a belt core body formed around the outer circumference of the belt such that the edges thereof are overlapped along the belt longitudinal direction and there is at least one overlapped portion. A wrapped V-belt comprising an outer covering canvas which is covered from the side and joined to the outer circumferential surface, wherein the line between the cutting line and the thread of the edge of the upper side of the overlapping portion of the outer covering canvas is The angle θ ₁ is 5°≦θ ₁ ≦{(180−θ)/2−5 in the direction orthogonal to the belt longitudinal direction, where θ is the intersection angle between the warp and weft of the canvas with respect to the belt longitudinal direction. }°, and in the direction along the longitudinal direction of the belt, it is set in the range of 5°≦θ ₁ ≦ (1/2) {90−(180−θ)/2}° Wrapped V-belt.