JPS60231132A - Fatigue testing apparatus - Google Patents

Abstract

PURPOSE:To stably control dynamic load to an actual use condition, in a fatigue testing apparatus for applying average load and dynamic load to an object to be tested, by generating dynamic load by a DC motor and detecting the rotary speed of said motor to compare the same with a reference value. CONSTITUTION:An object 1 to be tested is held by a fixed end 2 at the upper part thereof and by a vibration stand 4 at the lower end thereof. The internal stress of the object 1 to be tested is set to a desired value by operating the setting knob 33 of an average load motor 7 and a dynamic load motor 12 is started by a start switch 34 and the rotary speed thereof is brought to a desired value by operating a mannal setting knob 35 while a rotary speed display circuit 36 is looked. In this state, a test is performed until the object 1 to be tested is broken and the number of vibrations are cumulated and displayed by a vibration number display circuit 37. Because the motor 12 is a DC servo motor and the output of a rotary speed detector 21 is compared with that of a reference voltage generation circuit 46 by a comparing circuit 45 and controlled by a control circuit 34 so as to be made constant, dynamic load is stabilized over a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in fatigue testing equipment for mechanical elements, parts or members on which repeated stresses, tensile or compressive complex stresses act.

[Conventional technology]

Fatigue testing equipment that applies cumulative tensile or compressive stress in addition to simple repeated stress is often used, but each test specimen is tested under conditions similar to the loads under which it will actually be used. This required a fairly complex operation. For example, the West German Sienck fatigue testing device has been well known for a long time, but this device includes an automatic control device for two values, average load 2 and dynamic load, and its operation and adjustment are complex, and it is prone to failure. occurred frequently. moreover,
It required an AC/DC electric motor, and the equipment was large.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fatigue testing device that is easy to operate and adjust, can be made compact, and can perform long-term tests in a stable state.

[Means for solving problems]

The present invention provides a test object mounting jig having a fixed end at one end and a movable end at the other end, a vibrating arm connected to the movable end, and a tensile force applied to the test object in advance through the vibrating arm. an average load applying means for generating a compressive force, a means including a motor and an unbalanced weight for generating repetitive motion in the vibrating arm, and a fixed end of the test object;
A fatigue testing device equipped with a means for electrically detecting the internal stress of the test object, wherein the motor is a DC motor, a speed detector detects the rotational speed of the motor as a voltage signal, and the output voltage is manually operated. a reference voltage generation circuit that can be controlled by a reference voltage generation circuit, a comparison circuit that receives the output voltage of this reference voltage generation circuit and the voltage signal as input, and a current supplied to the motor so that the output of this comparison circuit is constant. An object of the present invention is to provide a fatigue testing device characterized by being equipped with a control circuit.

[Effect]

The device of the present invention provides one control loop that can precisely control the rotational speed of the dynamic load motor, and eliminates the need for loop control for the average load motor once it is initially set. In addition, for moving loads and electric motors, the set rotational speed is faithfully maintained, rather than based on load cell data, so that the load applied to the test object can be maintained for a long time without adjustment. can.

〔Example〕

Figure 1 shows the mechanical structure of the fatigue testing device.

In FIG. 1, the test object 1 is held at its upper part by a fixed end 2, and the internal stress of the test object 1 is transferred to the load cell 3.
detected by.

The lower movable end of the test object 1 is held on a vibrating table 4 and connected to a vibrating arm 6 via a connecting rod 5.

The average load motor 7 is a reversible motor, and the rotating shaft 8
When rotated in either the forward or backward direction, the worm gear device 9 pulls up or pushes down the rotary arm 10 as indicated by the arrow in the figure. Since the rotary arm 10 is supported at a fulcrum P shown schematically, a tensile or compressive force is applied to the test object 1 by the torsion shaft 11, via the vibrating arm 6, and by the connecting rod 5. This stress is detected by the load cell 3 and displayed via an electric circuit.

Next, an unbalanced weight 14 is attached to the tip of the rotating shaft 13 of the dynamic load motor 12, and when this rotates, the bearing 1
5, a load is repeatedly applied to the vibrating arm 6.

Here, the feature of the present invention is that the dynamic load motor 1
2 is a DC motor whose rotational speed is precisely controlled, and the average load motor 7 is not included in the closed loop of the automatic control system and is not changed after initial setting.

The control system will be explained in more detail.

FIG. 2 shows a block configuration diagram of an embodiment of the fatigue testing apparatus control system according to the present invention.

The dynamic load motor 12 is a DC servo motor with a power source of 41 AC.
Power supply current is supplied via the /DC converter 42 and the control circuit 43. The dynamic load motor 12 has a rotation speed detector 2.
1 are connected, and this output is given to one input of the comparator circuit 45. A reference input from a reference voltage generation circuit 46 is applied to the other input of the comparison circuit 45 .

This reference input is set by the manual setting knob 35.

Control circuit 43 and comparison circuit 45 are configured into one unit. Further, the output of the rotational speed detector 21 is connected to a vibration frequency display circuit 37 and a rotational speed display circuit 36 that indicate the cumulative value of the rotational speed.

On the other hand, the average load motor 7 is set using the manual setting knob 33 by this average load setting circuit 49.

The output signal of the load cell 3 that detects the internal stress of the test object 1 is displayed on an internal stress display circuit 32 using an analog display, and is connected to a rupture detection circuit 50 that detects that the test object 1 has broken.

The output of this breakage detection circuit 50 is supplied to an alarm device 51 and a power supply circuit 41.

Next, a method of operating the fatigue testing apparatus of this embodiment will be explained.

After attaching the test object 1 to the test equipment, open the lower lid 31 of the operation panel 22, operate the setting knob 33 of the average load motor 7 while looking at the internal stress display circuit 32, and check the inside of the test object 1. Set the stress to the desired value.

Next, the dynamic load motor 7 is started by the start switch 34, the manual setting knob 35 is operated, and a desired value is obtained while looking at the rotation speed display circuit 36 on the digital display. If the value displayed on the internal stress display circuit 32 is inappropriate at this time, the setting knob 33 is adjusted again to the desired value.

When the above operations are completed, the lower lid 31 is closed and the test is continued. As a result, the number of vibrations is cumulatively displayed on the vibration number display circuit 37. This display is truncated if it is less than 100 times.

In this state, the test is continued in the same state until the test object 1 breaks.

When the test object 1 exceeds its fatigue limit and ruptures, the signal current from the load cell 3 indicates the rupture value, so the rupture detection circuit 50 sends a power release command to the power source 41 to open the circuit, and alarm device 51 Activate.

At this time, by reading the display value of the vibration frequency display circuit 37, the fatigue limit value of the test object 1 can be known.

When this device was prototyped and tested, it was found that if the rotational speed of the dynamic load motor 12 is precisely controlled and kept constant, the test object
It was found that the load applied to can be kept constant over a long period of time and a good fatigue test can be performed.

The above embodiment has a structure that handles small materials as test objects, but based on the same principle, crankshafts and axle shafts can be , torsion springs, and any other member can be designed, and the present invention can be implemented with these as well.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain an apparatus that performs tests in a stable state for a long period of time. Furthermore, since the device of the present invention has a simple control system, there are few adjustment points and the operation is easy. Furthermore, the device of the present invention eliminates the need for a large control device such as a motor generator that was found in conventional devices.
The equipment has become smaller and more economical.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the mechanical structure of a fatigue testing device according to an embodiment of the present invention. FIG. 2 is a block diagram of a device control system according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Test object, 2... Fixed end, 3... Load cell, 4... Vibration table, 5... Connecting rod, 6... Vibrating arm, 7... Average load morph, 8...Rotating axis, 9...
Worm gear device, 10... Movable arm, 11... Torsion shaft, 12... Dynamic load motor, 13... Rotating shaft, 1
4... Unbalanced weight, 15... Bearing, 16...
Additional weight, 21... Rotation speed detector, 22... Operation panel, 31... Lower lid, 32... Internal stress display circuit,
33.35... Manual setting knob, 34... Start switch, 36... Rotation speed display circuit, 37... Vibration frequency display circuit, 41... Power supply, 42... AC/DC converter, 43... Control circuit, 45... Comparison circuit,
46...Reference voltage generation circuit, 49...Average load setting circuit, 50...Breakage detection circuit, 51...Alarm device. Patent Applicant Hino Motors Co., Ltd. Agent Patent Attorney Nao Ide Takashi Engraving of the drawing (no changes to the content) Procedural amendment 29th year of the Showa era, published by the Japan Patent Office τ Kazuo Wakasugi, 1, case description No. Patent Application No. 86979 (1982) 2. Title of the invention: SE to SE, % 43, Relationship with the case of the person making the amendment: Patent applicant 4, agent (1) Supplement the attached power of attorney (2) Engraving of drawings (no changes in content) 9. List of attached documents (11. 1 power of attorney (2) 1 drawing)

Claims (1)

[Claims] (1) A test object mounting jig whose one end is a fixed end and the other end is a movable end, a vibrating arm connected to the movable end, and a tensile force applied to the test object in advance through the vibrating arm. means for applying an average load to generate a compressive force, means including a motor and unbalanced weight to generate repetitive motion in the vibrating arm, and a fixed end of the test object to apply internal stress of the test object. A fatigue testing device equipped with an electrical detection means, wherein the motor is a DC motor, a speed detector that detects the rotational speed of the motor as a voltage signal, and a standard that allows the output voltage to be controlled by manual operation. A voltage generation circuit, a comparison circuit that receives the output voltage of the reference voltage generation circuit and the voltage signal as input, and a control circuit that controls the current supplied to the motor so that the output of the comparison circuit is constant. A fatigue testing device characterized by the following: