JPH11173949A - Method and apparatus for measuring fatigue life of crawler belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and correctly measure the fatigue life of a crawler belt by alternately and continuously applying a rotational moment around an axis which is a center line of track pins and applying an accumulated load. SOLUTION: A track pin 8 is rotatably fitted in pin holes formed at other ends of track links 1, 1' and caught by a holding member 9 of a U-cross section. A connecting rod 16 is moved up and down by an actuator. When the connecting rod 16 is moved up and down, a shaft 10 rotates as indicated by arrows by a predetermined angle in both directions alternately, the track pin 8 rotates by a predetermined angle in both directions about an axis of a center line and, the track links 1, 1' rotate by a predetermined angle in both directions about the center line. A stress distribution and a state of a fatigue failure of a test body (track links) are observed while the connecting rod 16 is moved up and down many times, thereby the fatigue life of the track links 1, 1' is evaluated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention reproduces a stress distribution and a crack state generated in a track link of a crawler track constituting an endless track in a state similar to that of an actual vehicle (actual machine), thereby quickly increasing the fatigue life of the crawler track. The present invention relates to a measurement method and a measurement device that can be estimated.

[0002]

2. Description of the Related Art In order to measure the stress distribution of a crawler track constituting an endless track, it is desirable to measure the stress distribution of a crawler track of an actual vehicle. was there.

For this reason, a method of reproducing a stress distribution generated in a track link of a crawler belt using a part of the crawler belt by a bench test (table bench test) has been conventionally performed.

As such a method, Japanese Patent Application Laid-Open No.
The method described in EP 0545 is known. This method uses hydraulic pressure to alternately push both ends of a track plate, which is fastened with bolts, etc., onto a track link, to generate torsional stress on the track link, thereby increasing the maximum stress of the actual vehicle. Is to reproduce.

[0005]

However, although it is possible to reproduce the maximum stress in the above method, it is difficult to continuously apply the cumulative load, so that the state of fatigue failure cannot be reproduced. there were.

The present invention has been made in view of such a point, and provides a method and apparatus for measuring the fatigue life of a crawler track capable of reproducing the same state of fatigue failure of a crawler track as that of an actual vehicle. The purpose is to:

[0007]

According to the measuring method of the present invention, there is provided a method of measuring the stress distribution and fatigue failure applied to track links of a crawler track in which a number of track links are connected endlessly, as in a real vehicle. In the method of reproducing and evaluating the state of the above, the track pin and the track bush are incorporated in the opposed track link, the track bush is fixed, and the axis centered on the center line between the track pins facing the track bush. The present invention is characterized in that a circumferential rotation moment is alternately and continuously applied to evaluate a stress distribution generated in the track link and a crack state such as a crack length.

Further, the measuring device of the present invention comprises a means for fixing a track bush for connecting one end of the opposed track link, and a track pin for connecting the other end of the track link to a center line between the track pins. Means for rotating a predetermined angle in both directions around the axis.

The present inventors have studied various methods for performing a fatigue test using only one of the right and left track links. However, this method could not solve the problem that the stress distribution to a torsional load was significantly different from that of an actual vehicle. .

[0010]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. Track bushes 2 are press-fitted and fixed to one ends of the track links 1 and 1 ′ as test specimens. The track bush 2 has upper and lower fixtures 3 and 4 having semicircular grooves formed on opposing surfaces, respectively. And is fixedly fixed.

The fixing is performed by the concave member 6 fixed on the base 5.
, The upper fixture 3 and the lower fixture 4 are placed, and the plate 7 is screwed and fixed to the upper end of the concave member 6 with a screw or the like.
This is performed by pressing the upper fixing member 3 with.

A pin hole is formed in the other end of each of the track links 1 and 1 ', and a track pin 8 is rotatably fitted in the pin hole.

The track pin 8 is gripped by a gripping member 9 having a U-shaped cross section, and a shaft 10 is connected to the gripping member 9.

At the center and rear end of the shaft 10, a base 5 is provided.
The bearing 1 is inserted into the through holes of the plates 11, 11 '
It is rotatably supported via 2.

A crank 13 is fitted and fixed to the shaft 10 between the plates 11 and 11 '.
The both ends of the shaft 15 penetrated and fixed to the lower end of a connecting rod 16 that moves up and down.

An actuator 17 is connected to the upper end of the connecting rod 16, and the connecting rod 16 is vertically moved by the actuator 17. The actuator 17 is not particularly limited as long as the connecting rod 16 can be moved up and down. For example, a fatigue tester may be used.

Since the connecting rod 16 is moved up and down, the shaft 10 is constructed as described above.
1 rotates alternately by a predetermined angle in both directions, as indicated by arrows in FIG. 1, and the track pin 8 rotates a predetermined angle in both directions about the center line A in FIG.
1 'rotates a predetermined angle in both directions around the center line.

In this way, the connecting rod 15 is moved up and down a number of times, and the stress distribution and fatigue damage of the test piece (track link) are observed to evaluate the fatigue life of the track link.

The measurement of the stress distribution can be performed using a known stress detecting means. For example, a strain gauge may be attached to the surface of the track links 1 and 1 '.

As shown in FIG. 4, the torsion angle of the shaft 9 is preferably ± 14 ° or less, more preferably ± 3 ° or less, and the torsional torque is ± 4tf · m or less (± 20tf or less). Is good.

The track link to be tested according to the present invention is not particularly limited.
216 pitch T / L.

As the test object of the present invention, a device in which a track pin and a track bush are incorporated in a pair of right and left track links (hereinafter abbreviated as L / A) is generally used. However, the measurement may be performed with other components incorporated.

Next, the results of functional tests of the fatigue life measuring apparatus of the present invention shown in FIGS. 1 to 3 will be described. As a test piece, 216 pitch L / A was used.

(1) Measurement of Stress Distribution A torsion torque of 1.6 tf · m (load 8 tf) was repeatedly applied to the specimen, and the stress distribution generated on the track link was measured.

As a result, as shown in FIG. 5, a relatively large stress was generated in each portion of the outer surface of the track link,
As shown in FIG. 6, no significant stress was generated on the inner surface. This matches the state of the actual vehicle. still,
The numbers in FIGS. 5 and 6 indicate the magnitude of the stress (unit is kgf /
mm ² ), where the positive symbol represents tension, the negative symbol represents compression, and the arrows visually represent the magnitude and direction of the stress.

(2) Measurement of Relationship between Load and Stress A repeated load of −8 to +8 tf was applied, and the stress generated in each of the portions 1 to 5 on the outer surface of the track link in FIG. 7 was measured. The relationship between the applied load and the generated stress is shown in the graph of FIG. As shown in FIG. 7, it was confirmed that the stress was substantially linear with respect to the load in each of the measured portions 1 to 5.

(3) Fatigue Test Fatigue tests were performed on the three specimens shown in Table 1 below at the torsion torque, torsion angle and number of repetitions (N) shown in Table 1 below. The length of the crack generated on the outer surface of the track link is shown in Table 1 below, and the state of occurrence of the crack is shown in FIG.

[0028]

[Table 1]

As shown in FIG. 8, the crack occurrence position is the window hole on the bush side, which is almost the same as the damage situation in the actual machine.

In the present invention, the track pins connecting the opposite track links are rotated by a predetermined angle in both directions around the axis centered on the center line between the track pins. Since the torsion state similar to that of the actual vehicle is reproduced, it is considered that the stress distribution and fatigue damage of the specimen can almost reproduce the aspect of the actual machine.

[0031]

According to the present invention, since a cumulative load can be continuously applied, not only the stress distribution of the track link but also the state of fatigue failure can be reproduced by a bench test in a state similar to that of an actual vehicle. Problems that could not be solved by the conventional measuring device and measuring method of this kind can be solved. As a result, the fatigue life of the crawler belt can be measured quickly and accurately by using the measuring device or the measuring method of the present invention.

[0032]

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a measuring device of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a side view of FIG. 1;

FIG. 4 is a view showing a crank section of the present invention.

FIG. 5 is an outer side view of a track link showing a measurement result of a stress distribution.

FIG. 6 is an inner side view of a track link showing a measurement result of a stress distribution.

FIG. 7 is a graph showing a relationship between a torsional load and a stress generated in a track link.

FIG. 8 is an outer side view showing a crack generation state of a track link by a fatigue test.

[Explanation of symbols]

 1, 1 'track link 2 track bush 8 track pin 9 gripping member 10 shaft 13 crank 14 crank lever 16 connecting rod 17 actuator

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[Procedure amendment]

[Submission date] December 18, 1997

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

[0028]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyuki Takeno 5th-9th, Yobancho, Chiyoda-ku, Tokyo Topy Industries, Ltd.

Claims (5)

[Claims] In a method for evaluating the state of stress distribution and fatigue damage applied to track links of a crawler track in which a number of track links are connected in an endless ring by reproducing a state similar to that of an actual vehicle, the opposite track links are used. A track pin and a track bush are incorporated into the track bush, the track bush is fixed, and a rotational moment about an axis centered on a center line between the track pins facing the track bush is continuously and alternately applied in opposite directions. And evaluating a crack state such as a crack length generated in the track link. 2. The measuring method according to claim 1, wherein the rotational moment is applied by rotating the shaft of the jig holding the track pin in both forward and reverse directions. 3. The measuring method according to claim 1, wherein the shaft is rotated by ± 14 ° or less. 4. A means for fixing a track bush connecting one end of an opposed track link, and a track pin connecting the other end of the track link in both directions around an axis centered on a center line between the track pins. Means for rotating the crawler belt by a predetermined angle. 5. A shaft provided with a jig for gripping said track pin, a crank externally fitted and fixed to said shaft,
The measuring device according to claim 4, further comprising a connecting rod connected to a lever of the crank, wherein the track pin is rotated in both forward and reverse directions by moving the connecting rod up and down.