JPH06144310A - Rubber crawler - Google Patents

Abstract

PURPOSE:To reduce the winding rigidity, and to facilitate the winding of a rubber crawler around of a sprocket by laminating a rubber composition, in which short fibers are mixed, on steel cords, and burying them. CONSTITUTION:Steel cords 3 in the longitudinal direction are buried between cross directional metal cores 2, which are embedded in the longitudinal direction of a rubber crawler with an equal space, and the grounding surface 9, and furthermore, a rubber composition 4, in which short fibers 6 are mixed, is laminated on the steel cords 3 in the grounding surface side, and they are buried. A desirable angle of orientation of the rubber composition 4 against the center line of the short fibers 6 is 45-135 degree. In the rubber composition 4, the short fibers 6 at 2-25mm of length, which are made of metal fiber, organic fiber or inorganic fiber, are mixed at 5-40volume% of mixture ratio relative to the rubber. In spite of a high torsional rigidity and a high lateral rigidity, the winding rigidity can be lowered to eliminate the mechanical loss and improve the travelling stability and prevent the run-off of a rubber crawler from a sprocket.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber crawler used for construction vehicles, agricultural vehicles or leisure vehicles, and more specifically, it has high wrapping rigidity with respect to twisting and lateral slippage. The present invention relates to a rubber crawler which has a low height and can be easily wound around a sprocket and can be manufactured uniformly.

[0002]

2. Description of the Related Art As shown in FIG. 9A, conventionally, a steel cord 3 is rubberized between a core metal 2 and a grounding surface 9 as a reinforcing cord of a rubber crawler 1 in a circumferential direction, that is, a length direction. However, with only the steel cord in the circumferential direction, the rubber crawler may be twisted or laterally displaced by the force received from the road surface while the vehicle is running, and although it easily fits on the road surface, it does not function as a rubber crawler. In order to secure higher torsional rigidity and lateral rigidity, in addition to the steel cord 3, the bias cord 6 needs to be rubberized and additionally embedded. However, the adoption of the bias cord 6 requires a cord alignment process, a rubberizing process, and a bias cutting process in the manufacturing thereof, resulting in variations in the process and an excessive amount of time and labor, resulting in a cost disadvantage. . Also, by adding a bias cord, it was possible to secure high torsional rigidity and lateral rigidity as a rubber crawler, and as a result, the winding rigidity around the sprocket became higher and the mechanical loss also increased. In addition, as shown in the enlarged view of FIG.
The contact area with the rubber 4 is not so large, and the bias cord 6 and the rubber 4 may be separated from each other, that is, separation may occur due to the use in a harsh condition in rough land traveling.

[0003]

However, the adoption of the bias cord requires a cord alignment process, a rubberizing process, and a bias cutting process in the production thereof, which results in variations in the process and is too time-consuming. , Was a cost disadvantage. Further, by adding a bias cord, it was possible to secure high torsional rigidity and lateral rigidity as a rubber crawler. As a result, the rigidity of winding around the sprocket was increased, and the mechanical loss was increased.
In the present invention, in order to solve the above-mentioned problems of the prior art, there is no variation and is uniform, easy to manufacture, and the torsional rigidity and lateral rigidity are high, but the winding rigidity is reduced. (EN) A rubber crawler having the contradictory properties of facilitating winding around a sprocket.

[0004]

Therefore, according to the present invention, in the rubber crawler in which the lengthwise steel cord is embedded between the widthwise core metal embedded at equal intervals in the lengthwise direction and the grounding surface, the steel It is characterized in that a rubber composition in which short fibers are mixed and laminated on a cord is embedded. For details, 2m
A metal fiber, an organic fiber, or an inorganic fiber short fiber having a length of m to 25 mm is 45
Oriented at an orientation angle of 135 degrees to 135 degrees, these short fibers have a mixing ratio of 5% to 4% with respect to rubber.
The rubber composition mixed so as to have a volume% of 0%,
It is arranged on the grounding surface side of the steel cord, between the steel cord and the core metal, or on both sides with the steel cord sandwiched. This means that by arranging the short fibers with a directivity at an orientation angle of 45 to 135 degrees with respect to the length direction, that is, the center line, the twisting and lateral rigidity are high, but the winding This is based on a new finding that the rigidity can be lowered to facilitate the winding around the sprocket by the aligned mixing of the short fibers into the rubber composition. A rubber composition mixed with steel cords or short fibers may be divided and arranged on both sides in the width direction with a center line, that is, a row of holes for sprocket engagement interposed therebetween. At this time, the orientation angles of the short fibers of the rubber composition that are divided and arranged may be symmetrical with respect to the center line so as to contradict each other.

[0005]

In the present invention, the rubber composition in which the short fibers such as the metal fibers, the organic fibers or the inorganic fibers are mixed is manufactured by the roll extrusion process, so that the short fibers can be relatively easily and uniformly oriented. In addition to what was possible,
The thus-processed rubber composition is bias cut so that the short fibers have an orientation angle of 45 to 135 degrees, laminated on a steel cord, and embedded in a rubber crawler to bias cut the conventional steel cord. Compared to the laminated ones, we were able to realize an epoch-making rubber crawler that is comparable in torsional rigidity and lateral rigidity, but has low winding rigidity and can be easily wound around a sprocket. This twist rigidity and lateral rigidity are comparable to each other, but the characteristic that the winding rigidity can be made low to facilitate winding around the sprocket is especially true between the ground contact part and the sprocket, that is, a relatively long straight line. This is a very important characteristic for a rubber crawler that continuously runs between a portion and a suspended portion having a large curvature.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention, in which a lengthwise steel cord 3 is embedded between a widthwise cored bar 2 and a grounding surface 9 embedded at equal intervals in the lengthwise direction of a rubber crawler 1, Further, the rubber composition 4 in which the short fibers 6 are mixed is embedded by being laminated on the ground surface side of the steel cord 3. The orientation angle of the rubber composition 4 with respect to the center line of the short fibers 6 is preferably in the range of 45 degrees to 135 degrees as in the second embodiment described later, and both sides in the width direction sandwiching the center line, that is, the row of holes for sprocket engagement. Rubber composition divided into left and right parts 4 ₁ , 4 ₂
The orientation angles of the respective short fibers may be symmetrical with respect to the center line so as to be opposite to each other. As shown in FIG. 7 (A), short fibers 6 of metal fiber, organic fiber or inorganic fiber having a length of 2 mm to 25 mm are mixed so that the mixing ratio with respect to rubber is 5% to 40% by volume. The rubber composition 4 so that the thickness of the rubber composition 4 is successively reduced by the rollers 7 and 7 and the rollers 8 and 8, and the rubber composition 4 to be processed is pulled in the extrusion direction (arrow A direction). Extrude by applying tension. Since the final thickness of the rubber composition is usually about 2 mm to 5 mm, it has been found that when the length of the short fibers is equal to or larger than the thickness of the rubber composition, that is, 2 mm to 25 mm, it is easy to align. By doing so, the short fibers that have been oriented randomly in the rubber composition will be aligned in the extrusion direction. FIG. 7 (A) shows a side view of the short fibers, that is, a vertically aligned state, and FIG.
Shows the state in plan view, that is, the left and right aligned state of the short fibers as viewed from above.

FIG. 8 shows a method of bias cutting the rubber composition produced by the extrusion process described in FIG. With respect to the extrusion direction of the rubber composition,
For example, bias cut with 45 degree cutting lines C1 and C2,
By embedding the cut rubber composition in the rubber crawler such that the middle line L of the widths of the cutting lines C1 and C2 coincides with the circumferential center line L of the rubber crawler, the orientation direction of the short fibers becomes 45 degrees. That is, the reinforcing layer is arranged.

FIG. 2 shows a second embodiment of the present invention.
In the example of (A), similarly to the first embodiment shown in FIG. 1, the rubber composition 4 is divided into left and right parts on both sides in the width direction with the center line L, that is, the row of holes for sprocket engagement interposed therebetween. ₁ ,
4 _2, in which were stacked disposed embedded between the width direction of the core metal 2 and the steel cord 3 which is embedded at equal intervals in the longitudinal direction of the rubber crawler 1. As shown in FIG. 2C, the orientation angle of the short fibers 6 in each of the rubber compositions 4 ₁ and 4 ₂ with respect to the center line L (the same as the length direction of the steel cord 3) is 45 to 135 degrees. The range is preferable, and the orientation angles thereof may be symmetrical with respect to the center line so as to be opposite to each other, or may be in the same direction. Figure 2
In the example of (B), the rubber composition 4 is composed of one wide band. In this case, a row of sprocket holes is provided on the line along the center line L of the rubber composition 4.

FIG. 3 shows a third embodiment, in which the rubber composition 4 is composed of one wide band and is laminated between the core metal 2 and the steel cord 3 and is in contact with the steel cord 3. An example in which the rubber compositions 5 ₁ and 5 ₂ are laminated and arranged left and right on both sides in the width direction between the ground and the ground, that is, an example in which the rubber compositions are arranged above and below, that is, inside and outside with the steel cord 3 sandwiched therebetween. Is. Of course, as shown in FIG. 3 (B), the rubber composition 5 arranged between the steel cord 3 and the grounding surface may be composed of one wide band. Also,
The inner and outer rubber compositions sandwiching the steel cord 3 may be divided into left and right parts on both sides in the width direction, and may be arranged in layers.
As shown in FIG. 3 (C), the rubber compositions 4 ₁ and 4 ₂ divided into left and right may be arranged above the core metal 2, that is, on the inner peripheral surface side. Then, in these cases, the orientation directions of the short fibers 6 may be the same direction, or may be symmetrical with respect to the center line so as to be opposite to each other.

As described above, according to the present invention, a rubber composition in which short fibers such as metal fibers, organic fibers or inorganic fibers are mixed is produced by roll extrusion, so that the short fibers can be homogeneously and relatively easily formed. In addition to being able to have directionality, the rubber composition processed by this is bias cut so that the short fibers have an orientation angle of 45 to 135 degrees and laminated on a steel cord to form a rubber. By embedding it in the crawler, a rubber crawler having excellent characteristics as shown below was obtained.

As shown in FIG. 4B, a torsional rigidity is compared by applying a predetermined rotational moment, that is, a torque T to the rubber crawler around the center line and measuring the torsion angle θ. It became like. In other words, the twist angle θ for the same torque T was smaller in the present invention than in the conventional bias structure. That is, it is understood that the torsional rigidity is high.

Next, looking at the lateral rigidity, FIG. 5 (B)
As shown in Fig. 5 (A), the loads F, F, F are applied in the lateral direction of the rubber crawler in a direction that causes lateral displacement as shown in Fig. 5A.
For the displacement for a given load, as shown in
In the present invention, it was smaller than that of the conventional bias structure. That is, it can be seen that the lateral rigidity is also high.

Further, in order to measure the winding rigidity of the rubber crawler 1 around the sprocket 10, the load F required to wind the rubber crawler 1 around the sprocket 10 having the radius R is measured as shown in FIG. Figure 6
As shown in (A), in the present invention, it was smaller than that of the conventional bias structure. That is, it has been found that the winding rigidity can be reduced despite the high torsional rigidity and lateral rigidity. This is because the short fibers are arranged with an orientation angle of 45 to 135 degrees with respect to the length direction, that is, the center line, and the short fibers are aligned with the rubber composition. As a result of the mixing, the short fibers are skillfully superposed vertically and horizontally, and as a result, the contact area between the rubber composition and the short fibers is much larger than that of the conventional steel cord bias structure. Very expensive. This means that the surface pressure between the rubber composition and the short fibers is reduced and the external force resistance performance becomes extremely high, resulting in keeping the torsional rigidity and lateral rigidity high. Furthermore, by arranging the short fibers with a directionality at an orientation angle of 45 to 135 degrees with respect to the length direction, that is, the center line, the length direction of the short fibers is set to the rubber crawler length direction. Since it wraps around the sprocket in a tilted state, the ratio of the rubber composition that has entered between the short fibers is significantly higher than that of the conventional steel cord bias structure, and the wrapping rigidity is increased. Can be suppressed to a value sufficiently lower than that of the conventional structure.

[0014]

As described above, according to the present invention, a rubber composition in which a short fiber such as a metal fiber, an organic fiber or an inorganic fiber is mixed is produced by roll extrusion, so that no special step is required. In addition to the fact that it is possible to uniformly give orientation to the short fibers by a relatively simple process and it is extremely advantageous in terms of cost, in addition to this, the rubber composition processed by the short fibers is 45 degrees to 135
Bias cut to a degree of orientation angle and laminated on a steel cord and embedded in a rubber crawler, resulting in aligned mixing of short fibers into the rubber composition, compared to that of a conventional bias structure. Despite the high torsional rigidity and lateral rigidity, the winding rigidity can be reduced to eliminate mechanical loss, improve running stability, and effectively prevent the rubber crawler from separating from the sprocket. Compared to the conventional steel cord that is bias cut to form a rubberized cord layer, the composition of mixing short fibers into the rubber composition significantly reduces the occurrence of separation from short rubber fibers, that is, separation. An excellent and rare rubber crawler was provided.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a first embodiment of the present invention.

FIG. 2 is a partial sectional view and a schematic plan view showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view and a schematic plan view showing a third embodiment of the present invention.

FIG. 4 is a graph showing twist characteristics of a rubber crawler.

FIG. 5 is a graph showing lateral rigidity of a rubber crawler.

FIG. 6 is a graph showing the winding rigidity of a rubber crawler.

FIG. 7 is a side view and a plan view in which a rubber composition mixed with short fibers is extruded.

FIG. 8 is a view showing a bias cut of a rubber composition mixed with short fibers.

FIG. 9 is a conventional example in which a steel bias cord is embedded.

[Explanation of symbols]

 1 Rubber Crawler 2 Core Bar 3 Steel Cord 4 Rubber Composition 5 Rubber Composition 6 Short Fiber 7 Roller 8 Roller 9 Grounding Surface 10 Sprout C1 Bias Cut Line C2 Bias Cut Line L Center Line

Claims (7)

[Claims] 1. A rubber crawler in which a longitudinal steel cord is embedded between a widthwise cored bar embedded at equal intervals in the longitudinal direction and a grounding surface, the rubber crawler being laminated on the steel cord,
A rubber crawler in which a rubber composition mixed with short fibers made of metal fibers, organic fibers or inorganic fibers is embedded. 2. Short fibers have a fiber length of 2 mm to 25 m.
The rubber crawler according to claim 1, wherein m is a mixing ratio of 5 to 40% by volume with respect to the rubber composition, and the orientation direction of the fibers is 45 degrees to 135 degrees with respect to the center line. 3. The rubber crawler according to claim 2, wherein the rubber composition mixed with the short fibers is embedded between the steel cord and the core metal or between the steel cord and the grounding surface. 4. The rubber composition in which short fibers are mixed is embedded between the steel cord and the core metal or between the inner peripheral surface side of the core metal and between the steel cord and the ground surface. 2. The rubber crawler according to 2. 5. The rubber crawler according to claim 3, wherein the rubber composition is divided into left and right parts on both sides in the width direction with the center line interposed therebetween. 6. The rubber crawler according to claim 4, wherein one of the rubber compositions is divided into left and right parts on both sides in the width direction with the center line interposed therebetween. 7. The orientation angle of the short fibers of the rubber composition, which are divided into left and right parts on both sides in the width direction with the center line sandwiched, are symmetrical with respect to the center line so as to be opposite to each other. The rubber crawler according to claim 5.