JP5986508B2 - Rubber crawler - Google Patents

Description

  The present invention relates to a rubber crawler.

Generally, a rubber crawler includes a crawler main body formed endlessly by a rubber elastic body, and a tensile body extending along the crawler circumferential direction in the crawler main body.
In recent years, for example, as shown in Patent Document 1 below, by forming a portion of the crawler body located on the inner peripheral side of the tensile body with a rubber elastic body having a loss factor of 0.15 or less, low Rubber crawlers with improved fuel efficiency have been proposed.

JP-A-6-24367

  However, in the conventional rubber crawler, while reducing fuel consumption, the cut resistance may be reduced.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a rubber crawler that can achieve low fuel consumption while maintaining cut resistance.

  In order to solve the above problems and achieve such an object, the rubber crawler of the present invention is a rubber crawler including a crawler body formed endlessly by a rubber elastic body, and the rubber elastic body includes: The loss elastic modulus at 60 ° C. is less than 3 MPa, and the loss elastic modulus at −20 ° C. is 70 MPa or more.

  According to the present invention, the loss elastic modulus at 60 ° C. is less than 3 MPa, and the loss elastic modulus in the temperature range (low strain rate range) of the crawler body during running of the rubber crawler can be kept low. It is possible to reduce the bending resistance at the time of traveling, and it is possible to reduce fuel consumption, and the loss elastic modulus at −20 ° C. is 70 MPa or more, and the loss elastic modulus in the high strain rate region Can be improved and cut resistance can be improved.

  According to the rubber crawler according to the present invention, fuel consumption can be reduced while maintaining cut resistance.

Hereinafter, an embodiment of a rubber crawler according to the present invention will be described.
The rubber crawler includes a crawler body formed endlessly by a rubber elastic body, a tensile body extending along the crawler circumferential direction in the crawler body, and a core bar embedded in the crawler body. ing.
The rubber elastic body has a loss elastic modulus at 60 ° C. of less than 3 MPa and a loss elastic modulus at −20 ° C. of 70 MPa or more. That is, the loss elastic modulus of this rubber elastic body is small in the high temperature range where the strain rate is low, and is large in the low temperature range where the strain rate is high. When the rubber crawler runs, the surface temperature of the crawler main body is about 20 ° C. to 80 ° C., but the bending resistance of the rubber crawler decreases as the loss elastic modulus in this temperature range decreases.
In the crawler body, if the thickness (for example, about 7.5 mm) of the outer peripheral side rubber body located on the outer peripheral side of the tensile body is, for example, about 25% or more of the thickness (for example, about 30 mm) of the crawler body. Further, bending resistance and cut resistance are further improved.

The rubber elastic body is made of a material containing carbon or the like but not containing NR at all. The glass transition temperature of the rubber elastic body is about −50 ° C. to −30 ° C.
The loss elastic modulus was measured using a spectrometer (Rheograph Solid L-IR) manufactured by Toyo Seiki Seisakusho. The test piece had a thickness of 2 mm, a width of 5 mm, and a length of 30 mm. The condition was 15 Hz ± 2%.

Here, in the crawler body, one of the outer peripheral side rubber body and the inner peripheral side rubber body located on the inner peripheral side of the tensile body is formed of the same rubber elastic body as the current one, and the other A plurality of types of rubber crawlers formed of rubber elastic bodies as shown in Table 1 were formed, and bending resistance and falling weight cut depth (cut resistance) were measured for each rubber crawler.
First, the bending resistance is measured by winding a rubber crawler with a force of about 19.6 kN between a driving wheel having an outer diameter of about 414 mm and a driven wheel having an outer diameter of about 410 mm. The wheel was rotated at 93 rpm. At this time, the strain generated in the drive shaft directly connected to the drive wheel was measured, and the bending resistance (N · m) of the rubber crawler was calculated based on the measured value. The width of the crawler body was about 450 mm.
The results are shown in Table 1. In Table 1, the case where the bending resistance was less than 250 N · m was marked as “◯”, and the case where the bending resistance was 250 N · m or more was marked as “X”. As a result, it was confirmed that if the loss elastic modulus at about 60 ° C. is less than 3 MPa, the bending resistance can be suppressed to less than 250 N · m.

Next, the measurement of the cutting depth of the falling weight is performed by measuring a weight having a blade edge angle of 60 degrees and a blade edge width of 5 cm at the tip, and a weight of 30 kg. This was done by measuring the depth of cut formed in a rubber material having a thickness of about 3 cm when it was naturally dropped from the height position.
The results are shown in Table 1. In Table 1, the case where the cut depth was less than 10 mm was marked as ◯, and the case where the cut depth was 10 mm or more was marked as x. As a result, it was confirmed that the cut depth can be suppressed to less than 10 mm when the loss elastic modulus at about −20 ° C. is 70 MPa or more.

Next, as an example, a rubber crawler having a crawler body made of a rubber elastic body having a loss elastic modulus at 60 ° C. of 2.24 MPa and a loss elastic modulus at −20 ° C. of 77.26 MPa is prepared. As a comparative example, a rubber crawler having a crawler body made of a rubber elastic body having a loss elastic modulus at 60 ° C. of 2.62 MPa and a loss elastic modulus at −20 ° C. of 38 MPa was prepared.
In the examples, SBR alone was adopted as the main material of the rubber elastic body, and in the comparative example, a material containing 15 wt% NR and 85 wt% SBR was adopted as the main material of the rubber elastic body.
Then, when each rubber crawler was mounted on a vehicle and the rubber crawler when the concrete road surface, the rocky place, and the crushed stone road were run for about 150 hours in total for each of the same time was visually confirmed, It was confirmed that there were fewer examples than the comparative examples.

  As described above, according to the rubber crawler according to the present embodiment, the loss elastic modulus at 60 ° C. is less than 3 MPa, and the temperature of the crawler body during the running of the rubber crawler (low strain rate range). The loss elastic modulus is kept low, the bending resistance at the time of running of the rubber crawler can be reduced, the fuel consumption can be reduced, and the loss elastic modulus at −20 ° C. is 70 MPa or more. Moreover, the loss elastic modulus in the high strain rate region is increased, and the cut resistance can be improved.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the entire crawler body does not have to be formed of the rubber elastic body. Among the crawler body, the outer peripheral side rubber body positioned on the outer peripheral side of the tensile body and the inner side positioned on the inner peripheral side of the tensile body. At least one of the peripheral rubber bodies may be formed of the rubber elastic body.

  Low fuel consumption can be achieved while maintaining cut resistance.

Claims (1)

A rubber crawler comprising a crawler body formed endless by a rubber elastic body,
The rubber elastic body has a loss elastic modulus at 60 ° C. of less than 3 MPa and a loss elastic modulus at −20 ° C. of 70 MPa or more.