JPH0531010B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a tensile member for a power transmission belt, and more specifically, the present invention relates to a tensile member for a power transmission belt, and specifically, it has a high initial elastic modulus, little elongation during belt use, excellent bending resistance, and a tooth member with a large coefficient of linear expansion. The present invention relates to tension bodies for belts such as belts, V-shaped belts, and multi-rib belts. (Prior Art) In recent years, belts have been required to be maintenance-free, have a long service life, and have heat resistance, in addition to the downsizing of machinery and equipment, as well as the need for less manpower and safety. In addition, due to the compactness of mechanical equipment, the conventional two-axis drive (driving one driven axis)
As many driven shafts are being replaced by multi-shaft drives (many driven shafts are simultaneously driven by a single belt), many tensile bodies are subject to bending due to the shafts, and there is a strong demand for bending resistance as well. ing. By the way, currently, glass cord or aramid (trade name) cord with a high elastic modulus is generally used for tensile materials such as toothed belts for automobiles due to meshing problems, but glass cord has a high coefficient of linear expansion, so The belt's ability to follow the thermal expansion of the engine is good, but there are some concerns about its bending fatigue properties. In addition, although aramid cord has good bending fatigue resistance, it does shrink due to heat, so when the temperature of the engine rises, the belt contracts due to the thermal expansion of the engine, pulleys, etc., and the tension of the belt increases as a result of this. This accelerates the fatigue of the tensile member, and also leads to damage to the teeth, which in turn damages the transmission itself. On the other hand, in cold climates, when the engine starts, the tension decreases, resulting in poor engagement and a jumping phenomenon, which shortens the life of the belt. In addition, polyester cords and aramid cords are mainly used for the tensile material of V-shaped belts, but especially for scooters, in addition to high speeds and high horsepower, they are used at high temperatures, so it is difficult to stabilize the belt tension at high temperatures. required. Furthermore, polyester cords, aramid cords, and glass cords are mainly used as tensile materials for multi-rib belts, but for automobiles, multi-axis belts,
Due to high temperature use and the use of aluminum engines with a large coefficient of linear expansion, there are strong requirements for hot tension and bending fatigue resistance, and especially hot tension leads to side wear of V-shaped belts and wear and deformation of the ribs of multi-ribbed belts. Each of the above-mentioned trends is gradually expanding to the fields of home appliances and general industrial machinery. As mentioned above, in addition to bending fatigue resistance, tension members for belts are strongly required to have stability in tension at the time of heating. Most of them have a negative coefficient of linear expansion, and in order to stabilize the tension during heating, an expensive and large tension stabilizing device is required. On the other hand, the 9th material has a large coefficient of linear expansion.
As shown in Figures A and B, there is a steel wire cord in which steel wire 11 is twisted around a core 12 made of steel or Manila hemp. This code is the first
It has a structure in which a steel wire 11 is wound around a core 12 as shown in Figure 9 A and B, and its cross section usually has a geometric strand structure as shown in Figure 9 A and B. ing. As for the twisted structure, an appropriate structure is now selected in relation to the physical properties of the steel wire cord, such as elasticity, rotation, deformation, flexibility, and strength utilization. However, conventional steel wire cords having the above-mentioned structure do not yet have sufficient properties as a tensile material. This means that although the temperature dependence of the tension is stable as shown in Figure 6, based on the experience of using steel wire cords as described above in toothed belts, V-shaped belts, etc., the core 12 Since the side wire such as the steel wire 11 is twisted and wound around the core and the side wire, the core and the side wire are substantially in point contact in a criss-cross pattern, so that no load is applied to the wire, which is the side wire. , when bending, a large frictional force is applied to the core, causing significant abrasion and damage to the core. Due to problems with bending characteristics, heat generation occurs when using small pulleys, and bending fatigue with small pulleys is difficult.
It is also in trouble due to the fact that it has been replaced by polyester cord, glass cord, and aramid cord. That is, current steel wire cords have problems in bending rigidity, bending fatigue resistance, belt tension reduction, running stability, belt processability, etc., and are unsuitable as belt tensile members. (Problems to be Solved by the Invention) The present invention deals with the above-mentioned actual situation, and specifically aims to take advantage of the advantages of metal fibers and improve the disadvantages thereof. Focusing on the structure, we give it appropriate physical properties as a tensile material, and greatly improve the tension at high temperatures due to thermal expansion of the engine and pulley auxiliary equipment, the decrease in tension when the engine is cooled, and the resistance to bending fatigue. The purpose is to make improvements. (Means for solving the problems) Therefore, the tensile material a of the present invention that meets the above purpose
The basic structure is shown in Figure 1, and the feature is that a large number of metal wires 1, such as steel wires, with a cross-sectional area of 7 to ^1000μ2 are aligned and twisted to form a cord. Alternatively, a cord structure may be obtained by pulling together a large number of strands, first twisting them, forming a strand (small rope) 2, and collecting a larger number of strands. In this case, no core wire is used for the cord or strand, and the twisted structure has a non-geometric cross-sectional structure with no distinction between core wires and side wires, and the cord is twisted at an angle α (see Figure 2).
8.4 to 15.3 degrees are used. Here, the twist angle α is determined in relation to the twist pitch l (mm) and the cord diameter D (mm), as shown in FIG. That is, the tensile material for belts of the present invention has a twist angle smaller than that of a normal wire cord, which increases the elastic modulus and reduces the drop in tension. It is easy to bend with respect to the pulley, has excellent abrasion resistance, and has a coefficient of linear expansion close to that of the engine, making it suitable as a tension member for belts with little difference in belt tension between hot and cold times. Generally, belt bending fatigue occurs when the belt passes through pulleys, and is caused by heat generation due to bending stress or wear of the wires due to friction between the wires. Therefore, in order to alleviate this bending stress,
A method of increasing the twist angle of the tensile rope is adopted, but since the relationship between the twist angle and the bending stress elastic modulus is as shown in Figure 7, the general twist angle α of steel wire cord is 16 degrees. The above is used. However, as the twisting angle increases, the direction of the strands is different from the tension direction of the cord, so the strength utilization rate decreases, and the difference in elongation between the side wires and the core wire causes friction between them. This causes cord wear, which increases the likelihood of cord fatigue. Therefore, the present invention is designed to reduce the size of a normal wire cord without increasing the twist angle, and to reduce the bending stress by increasing the cord twist angle (first twist angle).
is set at 8.4 to 15.3 degrees. In order to reduce the bending stress mentioned above, a twisted structure was considered, and a structure that did not distinguish between the side wires and the core wire, that is, a structure that did not use the core wire, was adopted, and the contact between the wires or strands changed from point contact to Measures have been taken to reduce cord fatigue due to line contact. Furthermore, when the diameter of the metal wire is made thinner,
The bending stress decreases in proportion to the cube of the diameter of the strand, but if the wire is made too thin, processing becomes impossible, which is undesirable, and if it exceeds 1000 ^μ2 , the rigidity increases and heat fatigue due to bending increases, so 7 A range of ~ ^1000μ2 is practically suitable. (Function) If a tensile member having the above structure is used as a belt tension member, the belt tension due to expansion of the iron engine room will not change much because the linear expansion coefficient of the metal wire itself is large. However, since the twist angle α is small, compared to conventional steel wire cords with a large twist angle, the linear expansion in the belt length direction approaches the expansion of the engine room, making it more durable than belts using conventional steel wire cords. A more uniform tension can be maintained. In addition, in the case of recent aluminum engines, the coefficient of linear expansion of Al is twice that of iron, which is much larger.
Although steel wire may not be able to follow the expansion of Al, it is easy to follow the expansion of Al if a metal fiber strand with a large linear expansion coefficient suitable for this is selected. However, although Al engines are currently in use, there are still only a few engines in use, and given that many engines are made of iron, the role of steel wire cords is sufficient to satisfy the current situation. Thus, as described above, the tensile member of the present invention is effective in maintaining tension during expansion, and since bending stress is taken into consideration by changing the wire diameter and twisting angle, it reduces cord fatigue and improves belt performance. It has a remarkable effect on improving the durability of. (Example) Hereinafter, specific configuration examples of the present invention will be explained based on the accompanying drawings, and specific test examples will also be described. FIG. 1 shows an example of the tensile body of the present invention, in which a is a tensile body with a cord structure, and 1 is a tensile body with a cross-sectional area of 7 to 7.
1000 μ ² metal wire, 2 is a strand in which a large number of the metal wires 1 are selected according to the belt to be used, aligned and pre-twisted; Twisting angle 8.4~15.3
It consists of a cord structure that is carefully twisted without using a core wire. Of course, this tensile member a may be constructed by aligning a large number of metal wires 1 and twisting them as they are to form a cord. Figures 3 to 5 show examples of belts using the tensile body constructed as described above, with Figure 3 showing a toothed belt, Figure 4 showing a V-shaped belt, and Figure 5 showing a belt with a toothed belt, and Figure 5 showing a V-shaped belt. Showing a multi-ribbed belt. In each of these figures, a is a tensile member having the above structure, 3
4 is an elastic body; 4 is an upper part covering the elastic body 3;
and a lower canvas layer, constructed by conventional means. Next, we will list test examples in which various fibers were comparatively tested based on the above-mentioned configuration examples. First, 13 strands were prepared by pre-twisting 50 steel wire strands with a cross-sectional area of 400 μ ² as samples, and a steel cord was prepared with a twisting angle of 12 degrees. A belt (timing belt with 83 teeth) was formed. Similarly, a toothed belt (same as above) using a conventional cord made of glass fiber and aramid fiber was prepared as a comparison sample. The physical properties of the tensile material in each of these samples are as follows.

[Table] Each of the above sample belts was then suspended between an iron driving pulley with 20 teeth and an iron driven pulley with 40 teeth.
When driven at 7200 rpm, as shown in Fig. 6, the belt tension of the conventional comparison belt using cords made of glass fibers and aramid fibers increased as the ambient temperature increased, but the belt tension of the present invention without core wires increased as the ambient temperature increased. In addition, the tension of the belt using steel wire cord with a small twist angle was maintained constant. In addition, in order to investigate the relationship between the twist angle, bending stress elastic modulus, and belt strength residual ratio, we used a steel wire cord tensile member having a conventionally commonly used core wire for the toothed belt using the tensile member of the present invention. A toothed belt to be used was prepared, and both were suspended between a driving pulley with 20 teeth and a driven pulley with 40 teeth and driven at 7200 rpm in the same manner as described above. The results are shown in Figures 7 and 8. Regarding the relationship between the twist angle and the bending stress elastic modulus, stress is large in conventional steel wire cords with a large twist angle; It has been found that the small steel wire cord of the present invention has low stress and can be used satisfactorily for small pulley diameters. On the other hand, the relationship between the twist angle and the remaining belt strength is less than 60% with the conventional Suriel wire cord, but when the present invention is used, it is less than 60%.
It maintains 60 to 70%, indicating that wear fatigue is low. As described above, products using the steel wire cord tensile body according to the present invention have generally better physical properties than conventional tensile bodies, and are fully compatible with the currently required belt performance. It is approved to do so. (Effects of the Invention) As explained above, the present invention does not use a core wire, the twisting angle is smaller than before, and the cross-sectional area of each constituent metal wire is defined within a specific range, and this is used as a belt. By using a tensile material, the belt has good flexibility, and even though it uses metal wire, it can be used for pulleys with small pulley diameters, and the metal wire itself has wear and fatigue. In addition, since metal wires with a large coefficient of linear expansion are used, they can easily follow expansion caused by temperature rises in engines, drive devices, etc., and reduce belt tension. It exhibits a remarkable effect in that it can maintain uniformity and provide stable driving.

[Brief explanation of the drawing]

Fig. 1 is a partial schematic diagram showing one example of the tensile body according to the present invention, Fig. 2 is a diagram explaining the twisting angle, and Figs. 3 to 5 are parts showing examples of each belt using the above-mentioned tensile body. A perspective view, Fig. 6 is a chart showing the relationship between belt tension and temperature, Fig. 7 is a chart showing the relation between twist angle and belt bending stress elastic modulus, and Fig. 8 is a chart showing the relationship between twist angle and belt strength remaining ratio. A diagram showing the relationship between
B is a sectional view showing a cross section of each example of a conventional tensile body, and FIGS. 10A and B are explanatory views showing the twisted shape of the tensile body in FIG. a... Tensile body, 1... Metal wire, 2... Strand, α... Twisting angle.

Claims (1)

[Scope of Claims] 1. A tensile member for power transmission belts made of a large number of metal wires arranged and twisted, the tensile member having a cross-sectional area of 7.
A large number of metal strands of ~ ^1000μ2 are aligned and twisted to form a cord, or a large number of metal strands are aligned to form a strand, and an appropriate number of these strands are further collected and twisted to form a cord. , and the cord or strand of the tensile body does not have a core wire, the twisted structure has a non-geometric cross section with no distinction between the core wire and the side wires, and the cord twist angle of the tensile body is 8 to 15.3. A tensile material for power transmission belts, which is characterized by a high tensile strength. 2. A tensile member for a power transmission belt according to claim 1, wherein the metal wire is a steel wire.