JP2018004370A - Evaluation method and evaluation device for fatigue life of link for caterpillar band - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaluation method and evaluation device for fatigue life of a link for a caterpillar band, capable of reproducing a state of fatigue damage of a link for a caterpillar band of a practical vehicle with accuracy.SOLUTION: An evaluation method of fatigue life of links for a caterpillar band connected to each other in an annular shape, comprises: coupling both ends of a pair of opposite track links 1, 1' with a track pin 3 and a track bush 4, respectively; attaching a track plate 2 to a track plate attaching surface 15 of the pair of track links to fix the track bush; and continuously imparting rotation movement around an axis AX in reverse directions alternately, the axis being a central line passing through axial centers of the track bush and track pin and connecting between the track bush and track pin.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an evaluation method and an evaluation apparatus for estimating the fatigue life of a track link of a crawler track constituting an endless track.

In order to measure the stress distribution of the crawler belt constituting the endless track, it is desirable to measure the stress distribution of the crawler belt in the actual vehicle. However, the measurement in the actual vehicle has a problem that the apparatus becomes large and the work efficiency does not increase.
Therefore, conventionally, a method of reproducing a stress distribution generated in a track link of a crawler track by using a part of the crawler track by a bench test (a bench test) has been performed.
As a bench test like this, twisting stress is generated on the track link by alternately pushing the Amsler universal testing machine using hydraulic pressure on both ends of the shoe plate fastened with bolts etc. on the track link. A method for reproducing the maximal stress has been developed (Patent Document 1).
In addition, a track pin and a track bush are incorporated into a pair of track links, the track bush is fixed, and a rotational moment is alternately applied to the opposite track pin in the opposite direction to measure the fatigue life of the link. A method has been developed (Patent Document 2).

JP 61-280545 A Japanese Patent Laid-Open No. 11-173949

However, although the technique described in Patent Document 1 is suitable for stress measurement by static load, it is not suitable for evaluation of fatigue life because it does not apply repeated load. In addition, there is a problem that the test body requires a four-frame link and is not large and simple.
Further, as shown in FIG. 6, in an actual vehicle, the outer peripheral edge portion R1 of the bush hole 7 on the side of the track mounting surface 15 of the track link 1 is often damaged by fatigue. On the other hand, when the fatigue life is evaluated by the technique described in Patent Document 2, the state of fatigue damage in the actual vehicle is reproduced, such as the portion R2 connecting the bush hole 7 and the window hole 12 that is not damaged much in the actual vehicle is broken. I can't say. In the case of the technique described in Patent Document 2, since the track pin is held by a jig and this jig is rotated by a shaft, the stress distribution is different from that of the actual vehicle. It is considered a thing.

  Therefore, an object of the present invention is to provide a method and an apparatus for evaluating the fatigue life of an endless track link that can accurately reproduce the state of fatigue damage of the endless track link of an actual vehicle.

  The inventor studied various causes of the stress distribution different from that of the actual vehicle in the technique described in Patent Document 2, and fastened the crawler plate to a pair of track links, thereby providing the same stress distribution as that of the actual vehicle. It was found that the fatigue life (torsional fatigue strength) of the track link can be accurately evaluated. In particular, it has been found that when a tensile load is applied between the track bush and the track pin, a load situation closer to that of an actual vehicle can be reproduced.

In order to solve the above problems, the means of the present invention are as follows.
(1) A method for evaluating the fatigue life of an endless track link linked in an annular shape, wherein both ends of a pair of opposed track links are connected by a track pin and a track bush, respectively, and the pair of track links are worn. A shoe plate is attached to the plate mounting surface, the track bush is fixed, passes through the center in the axial center of each of the track bush and the track pin, and a center line connecting the track bush and the track pin is an axis. A rotational moment about the axis is applied alternately and continuously in the opposite direction.
(2) In (1), a tensile load along the axis is applied between the track bush and the track pin.
(3) Track bush fixing means for fixing a track bush for attaching a track bush for connecting one end of the pair of track links, and a second end of the track link. Rotating means for rotating a track pin for connecting a predetermined angle in both directions around an axis centering on a center line between the track pins; and the track bush fixing means, An endurance track link fatigue life evaluation apparatus, comprising: a track bush and a moving means for applying a tensile load along the axis between the track bush and the track pin.

  According to the present invention, it is possible to obtain an evaluation method and an evaluation apparatus for the fatigue life of an endless track link that can accurately reproduce the state of fatigue damage of the endless track link of an actual vehicle.

It is a disassembled perspective view which shows the component of a part (single piece) of the endless track used for this invention. It is a perspective view which shows the fatigue life evaluation apparatus of the endless track link which concerns on embodiment of this invention. FIG. 3 is a plan view of FIG. 2. FIG. 3 is a side view of FIG. 2. It is a figure which shows the twist angle of a shaft. It is a figure which shows the site | part of the fatigue damage of the track link in a real vehicle and the conventional fatigue evaluation apparatus.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1 is an exploded perspective view showing components of a part (single frame) of an endless track used in the present invention, and FIG. 2 is a perspective view showing a fatigue life evaluation device for an endless track link according to an embodiment of the present invention. 3 is a plan view of FIG. 2, and FIG. 4 is a side view of FIG.

  As shown in FIG. 1, the track link 1 for the endless track used in the present invention (same for the track link 1 ′) is substantially elliptical, and a pin hole 11 is provided at one end (right end in FIG. 1). A bush hole 7 is provided at the other end (left end in FIG. 1). Further, two window holes 12 are provided between the pin hole 11 and the bush hole 7 in order to attach the shoe plate 2 side by side. A screw hole 14 for inserting the bolt 5 is formed in the inner surface of the window hole 12. In addition, in the case of a small endless orbital band, there is one in which the window holes are connected to form one. The bolt 5 is for attaching the crawler plate 2.

Then, the track bush 4 is fitted (press-fitted) between the bush holes 7, 7 'of the pair of left and right track links 1, 1'. On the other hand, the track pin 3 is fitted (press-fitted) into the pin holes 11 and 11 ′ of the pair of track links 1 and 1 ′. The track pin 3 is rotatable with respect to the pin holes 11 and 11 '.
Further, by inserting bolts 5 into the screw holes 14 of the pair of left and right endless track bands 1, 1 ′ and the mounting holes 21 provided in the shoe plate 2 and fastening them with nuts 6, the endless track band links One crawler plate 2 is fixed to a crawler plate attachment surface 15 which is the lower surface of 1 and 1 '.
An assembly composed of these components is a single piece 30, and a number of single pieces 30 are connected in a ring shape to form an endless track. This single piece 30 is used as a specimen of the present invention.
The pitch P of each track link 1 is the distance between the center of the bush hole 7 and the center of the pin hole 11, and the pitch P is used to express the size of the link.

As shown in FIG. 2, the endurance track link fatigue life evaluation apparatus 100 according to the embodiment of the present invention includes a base 101 and a track bush 4 of a single piece 30 placed on the base 101. The track bush fixing means 50 for fixing, the rotating means 60 for rotating the track pin 3 of the single piece 30 in both directions around the axis AX, and the moving means 70 for moving the track bush fixing means 50 in the axis AX direction. And.
As shown in FIG. 3, the axis AX passes through the centers P1 and P2 of the center of the track bush 4 and the track pin 3 of the single piece 30 and connects the track bush 4 and the track pin 3 with each other. It is.

The track bush fixing means 50 includes a base portion 51 placed on the base 101 so as to be movable in the axial center AX direction, an upper fixture 53a and a lower fixture 53b placed on the base portion 51, a base And a presser 55 disposed above the portion 51 and the upper fixture 53a.
The upper fixing tool 53a and the lower fixing tool 53b each have a semicircular groove formed on the opposing surface, and the track bush 4 is sandwiched between the grooves. Then, the presser 55 is fixed to the base portion 51 with a screw or the like, and the upper fixture 53a is pressed with the presser 55, whereby the track bush 4 is firmly fixed between the upper fixture 53a and the lower fixture 53b. .

The rotating means 60 includes a gripping member 61 having a U-shaped cross section for gripping the top and bottom of the track pin 3, a shaft 63 a concentric with the shaft center AX, and a side opposite to the gripping member 61. A crank lever 63L fitted and fixed to the end of the shaft 63a, a connecting rod 65 fixed to the crank lever 63L, and an actuator (not shown) 67 connected to the upper end of the connecting rod 65. The gripping member 61 corresponds to “a jig for gripping the track pin”.
The central portion and the rear end (crank 63b side) of the shaft 63a are rotatably supported by through holes of support portions 103a and 103b provided upright on the base 101 through bearings (not shown).
Further, both ends of a shaft 65a that penetrates and fixes the crank lever 63L are rotatably fixed to the lower end of a connecting rod 65 that moves up and down.
The actuator 67 is not particularly limited as long as the connecting rod 65 can be moved up and down. For example, a fatigue tester may be used.

  The moving means 70 is formed along the axis AX direction of the base 101 and has a dovetail rail 71 on which the base portion 51 of the track bush fixing means 50 is placed, and pulls the base portion 51 in the axis AX direction. And a tensile load loading mechanism 72 that does not.

Since it is configured as described above, when the connecting rod 65 is moved up and down by the actuator 67, the shaft 63a is rotated by a predetermined angle in both directions around the axis AX (arrow direction in FIG. 2) via the crank lever 63L. It has become.
As a result, the track pin 3 rotates by a predetermined angle in both directions around the axis AX, and the track links 1 and 1 'rotate by a predetermined angle in both directions around the axis AX.
In this way, the connecting rod 65 is moved up and down many times, the stress distribution of the specimen (track link) and the state of fatigue failure are observed, and the fatigue life of the track link is evaluated.
The stress distribution can be measured using a known stress detection means. For example, a strain gauge may be attached to the surface of the track link 1, 1 '.

In the present invention, the crawler plate 2 is attached to the single piece 30, so that the crawler belt can be twisted in the same condition as the actual vehicle, compared with the case where the crawler plate 2 is not attached. Lifetime (torsional fatigue strength) can be accurately evaluated.
The track plate 2 is not restricted except for the track links 1 and 1 '.

  In particular, when the track bush fixing means 50 is moved away from the rotating means 60 along the axis AX by the moving means 70 and a tensile load along the axis AX is applied between the track bush 4 and the track pin 3, The load situation closer to that of a real vehicle can be reproduced.

  As shown in FIG. 5, the twisting stress (load amplitude) applied to the track pin 3 can be set by adjusting the twisting angle of the shaft 63a (stroke of the crank 63b). Can be measured.

It goes without saying that the present invention is not limited to the above-described embodiment, but extends to various modifications and equivalents included in the spirit and scope of the present invention.
The crawler plate attached to the track link may be a simulated crawler plate (a plate having the same bending rigidity and torsional rigidity in the longitudinal direction) instead of the actual vehicle. The length of the crawler plate may be equal to or greater than the distance (width) between the pair of track links 1 and 1 ′, and both ends may be cut off.

1, 1 'Track link 2 Track plate 3 Track pin 4 Track bush 15 Track plate mounting surface 50 Track bush fixing means 60 Rotating means 61 Jig (gripping member)
63a shaft 63b crank 63L crank lever 65 connecting rod 70 moving means 72 tensile load loading mechanism AX shaft center

Claims (3)

A method for evaluating the fatigue life of links for endless tracks connected in a ring,
The opposite ends of a pair of track links are connected by track pins and track bushes, respectively, and the footwear is attached to the footwear mounting surface of the pair of track links.
Fixing the track bush,
The track bush and the track pin pass through the center at the center in the axial direction, and rotational moments around the axis centering on the center line connecting the track bush and the track pin are alternately applied in the opposite directions alternately. A method for evaluating the fatigue life of a link for an endless track.   The fatigue life evaluation method for an endless track link according to claim 1, wherein a tensile load along the axis is applied between the track bush and the track pin. A track bushing fixing means for fixing a track bushing to which one end of the pair of track links is connected, the trackboards being attached to the shoeboard mounting surfaces of the pair of track links facing each other;
Rotating means for rotating a track pin connecting the other end of the track link by a predetermined angle in both directions around an axis centering on a center line between the track pins;
Moving means for applying a tensile load along the axis between the track bush and the track pin by moving the track bush fixing means away from the rotating means along the axis;
An apparatus for evaluating the fatigue life of a link for an endless track band, comprising:

Images