JP3322219B2 - Material testing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material testing machine having excellent responsiveness at the time of abnormality.

[0002]

2. Description of the Related Art Conventionally, a specimen is mounted in a load frame, and a load is applied to the specimen by a load cell and an operating transformer.
There is known a material testing machine that measures a load and a displacement to obtain a load-displacement characteristic of a test body. In this case, in a general material testing machine, a load is applied to a test body by a hydraulic cylinder with an operation valve.

[0003]

If any abnormality occurs in the apparatus during the test, the abnormality is sensed and an alarm is activated, and the hydraulic cylinder is stopped by stopping the hydraulic source or setting the operation valve to the neutral position. However, at that time, even if the hydraulic power source is stopped, the oil pressure does not decrease for a while, and the operating valve has a leak, so the hydraulic cylinder cannot be stopped instantaneously. The tester itself may be adversely affected. A similar effect occurs when an external abnormality such as a power failure occurs. SUMMARY OF THE INVENTION An object of the present invention is to provide a material testing machine provided with a load mechanism capable of responding immediately to an abnormality.

[0004]

In order to achieve the above-mentioned object, a material testing machine according to the present invention comprises a hydraulic cylinder to be loaded on a specimen, and a direction and an amount of hydraulic oil supplied to the hydraulic cylinder. An operating valve for controlling, a pilot check valve is provided in a hydraulic circuit between the hydraulic cylinder and the operating valve, and a sensor for detecting a device abnormality or an external abnormality is provided,
The operation of the hydraulic cylinder is stopped by closing the pilot check valve in response to the abnormality detection signal detected by this sensor. Thus, when the pilot check valve is activated by the alarm, the hydraulic oil does not flow out of the hydraulic cylinder, and the position of the hydraulic cylinder is maintained.

[0005]

FIG. 1 is an overall configuration diagram showing an embodiment of a material testing machine according to the present invention. In the drawing, reference numeral 1 denotes a tester main body for applying a compressive load or a tensile load to a test body S, which is provided with a load frame including upper and lower yokes 11, 12, support columns 13, 14, and the like. The crosshead 15 is held vertically movable. Reference numerals 2a and 2b denote a pair of jigs (chucks) for gripping the upper and lower ends of the specimen S, respectively. The upper jig 2a is connected to the crosshead 15 via the load cell 3, and the lower jig 2b is for load. Is connected to the piston rod of the hydraulic cylinder 4. The hydraulic cylinder 4 is fixed to the device fixing part. Although not shown, as means for detecting the displacement of the specimen S,
For example, a differential transformer for detecting the stroke of the hydraulic cylinder 4 is provided.

Reference numeral 5 denotes an operation valve, for example, a servo valve, which controls the direction and amount of pressurized oil supplied to the hydraulic cylinder 4 and controls the expansion and contraction of the piston. 6a and 6b are pilot check valves disposed in both flow paths between the hydraulic cylinder 4 and the servo valve 5. A normal check valve allows flow to flow only in one specific direction (from the inlet direction to the outlet direction) and shuts off the flow in the opposite direction.
A and 6b can flow in both directions by applying a pilot operation pressure. When the pilot operation pressure is cut off, the pilot check valves 6a and 6b allow the flow only in one specific direction and cut off the flow in the opposite direction. This switching operation is performed instantaneously. Pilot check valve 6
The pilot ports 6a and 6b are connected to a hydraulic pump 51, which will be described later, via an electromagnetic switching valve 7, and the pressure of hydraulic oil acting on the pilot port 6p is switched by the electromagnetic switching valve 7, so that the pilot check valves 6a and 6b Is controlled. On the other hand, the electromagnetic switching valve 7 is connected to a sensor 8 which detects an abnormality, for example, an abnormality of the apparatus itself such as generation of an excessive pressure of the pressure oil or an external abnormality such as a power failure and generates an alarm. 7 is controlled. That is, at normal times, the pressure of the hydraulic oil acts on the pilot port 6p, and the pilot check valves 6a and 6b are in an operation state in which flow in both directions is possible. However, when the sensor 8 detects an abnormality, it responds to the abnormality detection signal. The electromagnet of the electromagnetic switching valve 7 is turned off,
Pilot port 6 of pilot check valve 6a, 6b
p pressure oil is released to the tank 7a through the electromagnetic switching valve 7,
The operation state of the pilot check valves 6a and 6b is switched so that the one-way flow is shut off.

In the hydraulic circuit of the servo valve 5, a hydraulic pump 51 for supplying pressure oil and a hydraulic tank 53 are inserted in series, and the hydraulic pump 51 is driven by a motor 52. The hydraulic pump 51 is also connected to the electromagnetic switching valve 7 as described above. Reference numeral 9 denotes a control unit, which includes, in addition to a control circuit of the entire apparatus, a waveform generation circuit that generates a load pattern waveform corresponding to a load pattern input from the test condition input unit.

In the normal operation of the above-described device, the electromagnet of the electromagnetic switching valve 7 is ON, so that the operating pressure acts on the pilot check valves 6a and 6b, and the check valve 6
The servo valves 5a and 6b can flow in both directions, and the servo valve 5 is controlled in accordance with a load pattern waveform generated from a waveform generating circuit in the control unit 9, and the hydraulic oil acting on the hydraulic cylinder 4 up and down accordingly. The pressure oil direction and the pressure oil amount change to move the position of the piston rod. This position is detected by the above-mentioned displacement detector, and the load value acting on the specimen S is detected by the load cell 3, and the respective detection signals are amplified and A / D
The converted, load-displacement characteristic graph is displayed on the display device and recorded on the recorder.

When an abnormality is detected by the sensor 8 during the material test, an alarm for abnormality detection is generated from the sensor 8,
In response, the electromagnetic switching valve 7 releases the pilot operation pressure to the tank 7a, and switches the operation state of the pilot check valves 6a, 6b to a state (shown in the drawing) in which the flow from the hydraulic cylinder 4 to the servo valve 5 is cut off. Thus, the flow of hydraulic oil from the hydraulic cylinder 4 to the servo valve 5 is instantaneously shut off. Accordingly, the operating position of the hydraulic cylinder 4 is maintained in a state when the abnormality is detected, and therefore, even if an abnormality occurs, the test body S and the test machine main body are prevented from being adversely affected.

During the occurrence of an abnormality, the operation of the hydraulic pressure source is temporarily stopped. When the cause of the abnormality is eliminated, the abnormality signal from the sensor 8 disappears, and the electromagnetic switching valve 7 is also returned to a state where it can be returned. The test may be continued if the abnormality disappears in a very short time and does not affect the test results.However, depending on the degree of the abnormality, the cause of the abnormality is clarified and the recovery procedure is completed. May be configured to hold the entire hydraulic system in a stopped state.

[0011]

As described above, according to the present invention, even when an abnormality occurs in the apparatus itself or externally during the test, the pilot check valve is activated by the alarm generated by the abnormality detection sensor, Hydraulic oil no longer flows from the hydraulic cylinder, the position of the hydraulic cylinder is maintained, and adverse effects on the test object S and the test machine main body are prevented.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing one embodiment of a material testing machine of the present invention.

[Explanation of symbols]

 1 Test machine body 2a Upper jig 2b Lower jig 3 Load cell 4 Hydraulic cylinder 5 Servo valve 6a Pilot check valve 6b Pilot check valve 7 Electromagnetic switching Valve 7a ... oil flow direction 7b ... oil flow direction 8 ... sensor 9 ... control unit 11 ... yoke 12 ... yoke 13 ... support column 14 ... support column 15 ... cross head 51 ... hydraulic pump 52 ... Motor 53 ... Hydraulic tank

Continuation of the front page (56) References JP-A-10-38779 (JP, A) JP-A-8-304249 (JP, A) JP-A-57-24840 (JP, A) JP-A-4-2944 (JP) JP-A-2-268247 (JP, A) JP-A-59-85940 (JP, U) JP-A-57-88202 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB G01N 3/02 G01N 3/08 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A hydraulic cylinder for applying a load to a test body,
An operating valve that controls the direction and amount of hydraulic oil supplied to the hydraulic cylinder is provided.A pilot check valve is provided in the hydraulic circuit between the hydraulic cylinder and the operating valve, and a device abnormality or external abnormality is detected. A material testing machine, comprising: a sensor for detecting, and closing a pilot check valve in response to an abnormality detection signal detected by the sensor to stop the operation of the hydraulic cylinder.