JP7124786B2 - Material testing machine and control method for material testing machine - Google Patents

Description

The present invention relates to a material testing machine and a control method for the material testing machine.

A material testing machine is known in which a test object is gripped by a gripper and a load is applied to the test object.
A material testing machine includes a table, a crosshead, a table, and a pair of screw rods for raising and lowering the crosshead (Patent Document 1).
When performing a tensile test with this material testing machine, the screw neck is rotated while both ends of the test piece are gripped by the upper gripper provided on the crosshead and the lower gripper provided on the table. to raise the crosshead relative to the table and apply a load to the test piece.

In addition, in this material testing machine, a hydraulic type gripper is adopted for gripping the test piece. This material testing machine also includes a hydraulic pump for supplying pressure oil to a hydraulic cylinder for opening and closing the pair of grip teeth of the grip.

JP 2015-114116 A

In the material testing machine described in Patent Literature 1, the hydraulic pump is constantly driven during the execution of the material test in order to maintain the gripping force of the gripper on the test piece.

However, since the hydraulic pump continues to be driven while the material test is being performed, there arises a problem of consuming power to drive the hydraulic pump.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a material testing machine capable of shortening the driving time of the hydraulic power source of the gripper and reducing power consumption, and a control method of the material testing machine. intended to

A first aspect of the present invention is a material testing machine that grips a test object with grippers and applies a load to the test object, comprising a pump that supplies hydraulic oil to the grippers, the pump and the grippers. A solenoid valve arranged in an oil passage between and configured to be switchable between an open position that communicates the oil passage and a closed position that blocks the oil passage, and a pressure that detects the hydraulic pressure in the oil passage When the hydraulic pressure detected by the pressure sensor reaches the first hydraulic pressure, the electromagnetic valve is switched from the open position to the closed position. and a control unit that switches the pump from a driving state to a stopped state.

A second aspect of the present invention is a control method for a material testing machine that grips a test object with grippers and applies a load to the test object, wherein the hydraulic pressure supplied to the grippers is a first hydraulic pressure. The present invention sometimes relates to a method of controlling a materials testing machine, closing an oil passage between the gripper and the pump while maintaining the first oil pressure, and shifting the pump from a driving state to a stopped state.

According to the first aspect of the present invention, it is possible to shorten the drive time of the hydraulic power source of the gripper and reduce power consumption.

According to the sixth aspect of the present invention, the same effects as those of the first aspect of the present invention can be obtained.

It is a figure which shows typically the structure of the material testing machine of this embodiment. It is a figure which shows the structure of a hydraulic circuit. 4 is a graph showing changes in hydraulic pressure in the process of gripping a test piece with grippers. 4 is a flow chart for gripping a test piece with a gripper; 4 is a flow chart of pressurization processing and pressure maintenance processing; 4 is a flow chart for opening the grips; It is a flow chart of end processing of the material testing machine.

[1. Configuration of material testing machine]
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically showing the configuration of a material testing machine 1 according to this embodiment.
The material testing machine 1 of the present embodiment is a so-called tensile testing machine, and is a testing machine for testing mechanical properties unique to materials that determine durability against external forces such as tension and shear.

The material testing machine 1 includes a tensile testing machine main body 2 that performs a tensile test by applying a test force as a load to a test piece TP, which is a material to be tested, and a control device 10 that controls the tensile test operation of the testing machine main body 2. and

[2. Configuration of tester main body]
The testing machine main body 2 includes a table 30, a pair of screw rods 31 and 32 rotatably erected on the table 30 so as to face the vertical direction, and a cloth movable along these screw rods 31 and 32. It comprises a head 33 , a load mechanism 40 that moves the crosshead 33 to apply a load to the test piece TP, and a load cell 36 . The load cell 36 is a sensor that measures a test force, which is a tensile load applied to the test piece TP, and outputs a test force measurement signal A1 indicating the measured test force to the control device 10 . In addition, it is good also as a structure which uses one screw neck.

The pair of threaded rods 31 and 32 are ball screws, and the crosshead 33 is connected to the threaded rods 31 and 32 via nuts (not shown). The load mechanism 40 includes worm reduction gears 41 and 42 connected to the lower ends of the screw rods 31 and 32 and a servomotor 43 connected to the worm reduction gears 41 and 42 .

The load mechanism 40 transmits the rotation of the servomotor 43 to the pair of screw necks 31 and 32 via the worm reduction gears 41 and 42, and the screw necks 31 and 32 rotate in synchronism, thereby rotating the crosshead 33. moves up and down along the screw necks 31 and 32.

The crosshead 33 is provided with an upper gripper 34 for gripping the upper end of the test piece TP, and the table 30 is attached with a lower gripper 35 for gripping the lower end of the test piece TP. . During the tensile test, the testing machine main body 2 grips the upper end of the test piece TP with the upper gripper 34 and the lower end of the test piece TP with the lower gripper 35, under the control of the control device 10. , a test force is applied to the test piece TP by raising the crosshead 33 .
The upper gripper 34 has a pair of gripping teeth 34a, 34b, and the lower gripper 34 has a pair of gripping teeth 35a, 35b.

[3. Configuration of control device]
The control device 10 controls the operation of the testing machine main body 2 and measures the test conditions. A PC (Personal Computer) 100, which is an external control device, is connected to the control device 10, and the PC 100 communicates with the control device 10 to set test conditions for the tensile test and instruct the start of the tensile test. , monitor the progress of the tensile test, and display and analyze the measurement data.

The control device 10 is an electronic circuit unit including a CPU (Central Processing Unit) 20, a memory 11, an interface circuit (not shown), and the like. The control device 10 includes a sensor amplifier 12 that amplifies the test force measurement signal A1 output from the load cell 36 and a servo amplifier 14 that supplies drive current to the servo motor 43 .

The control device 10 functions as a control section 21 and a measurement section 22 by executing a control program for the control device 10 stored in the memory 11 by the CPU 20 . The controller 21 executes each process in the control method of the material testing machine of the present invention. The control device 10 receives a test condition command TCd, a test start command TSc, an extensometer operation command EXc and the like transmitted from the PC 100 .

Upon receiving the test start command TSc, the control unit 21 controls the operation of the tensile test by the testing machine main body 2 according to the test condition command TCd. Test conditions such as origin adjustment, stroke range, tensile speed, etc. are specified by the test condition command TCd.

Based on the test force measurement signal A1 amplified by the sensor amplifier 12, the measurement unit 22 acquires the measured value of the test force applied to the test piece TP (hereinafter referred to as measured test force Fs). Based on the number of pulses of the elongation measurement signal A2 counted by the counter 13, the measurement unit 22 measures the upward displacement of the test piece TP from the start of the tensile test (elongation, hereinafter referred to as measurement displacement Xs). ). Measurement unit 22 then transmits measurement data Md including measurement test force Fs and measurement displacement Xs to PC 100 .

The PC 100 acquires a tensile test execution condition set by a user's operation, and transmits a test condition command TCd to the control device 10 . In addition, the PC 100 accepts the start of the tensile test instructed by the user's operation, and transmits a test start command TSc to the control device 10 . Furthermore, the PC 100 receives the measurement data Md transmitted from the control device 10, acquires the measured test force Fs and the measured displacement Xs, and displays a monitor screen showing the transition of the measured test force Fs and the measured displacement Xs. do.

The control unit 21 includes a remote controller 15 for instructing opening and closing of the upper gripper 34 and the lower gripper 35 . The remote controller 15 is provided with a close switch 151 for instructing the closing operation of the upper gripper 34 and an open switch 152 for instructing the opening operation of the upper gripper 34 . The remote controller 15 is provided with a close switch 153 for instructing the closing operation of the lower gripper 35 and an open switch 154 for instructing the opening operation of the lower gripper 35 .
Furthermore, the control unit 21 controls the motor 91 that drives the hydraulic pump 90 that opens and closes the upper gripper 34 and the lower gripper 35, and switches the hydraulic pump 90 between a stopped state and a driven state. Further, the control unit 21 switches the electromagnetic valve 86 for opening/closing the upper gripper 34 and the electromagnetic valve 186 for opening/closing the lower gripper 35 . The hydraulic pump 90 and motor 91 will be described later with reference to FIG. Solenoid valve 86 and solenoid valve 186 will be described in detail with reference to FIG.

The control device 10 has a standby switch 155 . The standby switch 155 is a button that causes the control device 10 to start and end operations.
When starting the material test by the material testing machine 1 , the user turns on the main power switch (not shown) of the material testing machine 1 and presses the standby switch 155 to activate the control device 10 . Then, the closing operation of the upper gripper 34 and the lower gripper 35 can be instructed.
When finishing the material test by the material testing machine 1 , the user presses the standby switch 155 to finish the operation of the control device 10 , and then turns off the main power of the material testing machine 1 .

[4. Grip hydraulic circuit]
FIG. 2 shows the configuration of the hydraulic circuit.
The hydraulic circuit 65 includes a hydraulic pump 90 , an electromagnetic valve 86 , and a pair of hydraulic cylinders 72 and 77 forming the upper gripper 34 .
The solenoid valve 86 is of the so-called double solenoid type, which is a three-position solenoid valve having an open position 87 , a closed position 88 and an ejection position 89 .
At the closed position 88 , which is the neutral position, communication between the hydraulic pump 90 and the oil passage 83 is cut off, and the oil passage 85 communicates with the hydraulic tank 95 .

When the electromagnetic valve 86 is switched to the open position 87 on the right in the drawing, the hydraulic pump 90 and the oil passage 83 are communicated, and the oil passage 85 is communicated with the hydraulic tank 95 .
At this time, hydraulic pressure is supplied to the closing side oil chambers 75, 80 of the pair of hydraulic cylinders 72, 77, the pistons 73, 78 move, and the grip teeth 34a, 34b protrude.
The gripping teeth 34a, 34b are provided with a rack and pinion mechanism 71 to synchronize the operations of the gripping teeth 34a, 34b.

When the electromagnetic valve 86 is switched to the discharge position 89 on the left in the drawing, the hydraulic pump 90 and the oil passage 85 are communicated, and the oil passage 83 is communicated with the hydraulic tank 95 .
At this time, hydraulic pressure is supplied to the opening side oil chambers 76, 81 of the pair of hydraulic cylinders 72, 77, the pistons 73, 78 move, and the grip teeth 34a, 34b retract.
At this time, the action of the rack and pinion mechanism 71 synchronizes the operations of the grip teeth 34a and 34b.

A pressure sensor 84 is connected to an oil passage 83 that connects the solenoid valve 86 and the closed-side oil chambers 75 and 80 of the pair of hydraulic cylinders 72 and 77 to detect the oil pressure in the oil passage 83 . An accumulator 82 for accumulating pressure is connected to the oil passage 83, and the inside of the oil passage 83 can be maintained at a predetermined oil pressure (first oil pressure).
In this embodiment, the solenoid valve 86, the accumulator 82, the closed-side oil chambers 75 and 80 of the pair of hydraulic cylinders 72 and 77, and the oil passage 83 form a closed oil passage circuit to prevent internal leakage. The hydraulic circuit is considered to be as small as possible.

When the solenoid valve 86 switches to the discharge position 89 and the oil passage 83 communicates with the hydraulic tank 95, the pressure accumulated inside the hydraulic cylinders 72 and 77 is released at the same time when the solenoid valve 86 is switched.
In this embodiment, since a hydraulic system that minimizes internal leakage is employed, the oil inside the hydraulic cylinders 72 and 77 and the oil inside the accumulator 82 is released from the state where the first oil pressure P1 is applied to the hydraulic tank 95 at atmospheric pressure. , the flow rate at the time of release is too large and may exceed the allowable flow rate of the oil filter 94 . Therefore, a flow rate control valve 93 is provided in the oil passage 92 before the oil filter 94 to suppress the increase in the flow rate when the oil filter 94 is opened and to keep the flow rate within the allowable flow rate of the oil filter 94 .
The hydraulic circuit of the lower gripper 35 uses the hydraulic oil discharged from the hydraulic pump 90, and its configuration is the same as that of the upper gripper 34. Therefore, the hydraulic circuit of the lower gripper 35 is Description is omitted.

[5. Opening/closing operation of the grip]
Next, the opening/closing operation of the upper grip 34 will be described.
The opening/closing operation of the upper gripper 34 is performed by switching the supply destination of the hydraulic oil discharged from the hydraulic pump 90 by the electromagnetic valve 86 .

When closing the upper gripper 34 , the hydraulic pump 90 is driven and hydraulic oil is supplied to the solenoid valve 86 . The solenoid valve 86 is switched from the closed position 88 to the open position 87 while the hydraulic oil is being supplied. As a result, the oil passage 83 is connected to the closed side oil chambers 75 and 80 , and hydraulic oil from the hydraulic pump 90 is supplied to the closed side oil chambers 75 and 80 . At the open position 87, hydraulic pressure is supplied to the closed-side oil chambers 75, 80 of the pair of hydraulic cylinders 72, 77, so that the grip teeth 34a, 34b protrude and the test piece TP is gripped. Hydraulic oil in the open side oil chambers 76 and 81 passes through an oil passage 85 and is discharged to a hydraulic tank 95 .

When opening the upper gripper 34 , the hydraulic pump 90 is driven and hydraulic oil is supplied to the solenoid valve 86 . The electromagnetic valve 86 is switched from the closed position 88 to the discharged position 89 while the hydraulic oil is being supplied. As a result, the oil passage 85 is connected to the open side oil chambers 76 and 81 , and hydraulic oil is supplied from the hydraulic pump 90 to the open side oil chambers 76 and 81 . At the ejection position 89, hydraulic pressure is supplied to the opening side oil chambers 76, 81 of the pair of hydraulic cylinders 72, 77, the grip teeth 34a, 34b are retracted, and the test piece TP is released. Hydraulic oil in the closed side oil chambers 75 and 80 passes through the oil passage 85 and is discharged to the hydraulic tank 95 .

The case of gripping the test piece TP will be described along with the time change of the oil pressure of the oil passage 83 .
FIG. 3 is a graph showing changes in the hydraulic pressure P in the oil passage 83 in the process of gripping the test piece TP with the upper gripper 34. As shown in FIG. 3, the vertical axis indicates the hydraulic pressure P in the oil passage 83, and the horizontal axis indicates the time T. As shown in FIG. The hydraulic pressure of the oil passage 83 is substantially the same as the hydraulic pressure of the closed-side oil chamber 75 and the hydraulic pressure of the closed-side oil chamber 80 .
First, at time T1, the user presses the close switch 151 . When the close switch 151 is pressed, the hydraulic pump 90 is driven and the electromagnetic valve 86 is switched to the open position 87 according to instructions from the control section 21 .
As a result, hydraulic oil is supplied to the oil passage 83, and the oil pressure P in the oil passage 83 changes from "zero" to the oil pressure P0. The hydraulic pressure P0 is the pressure of hydraulic oil discharged when the pressure on the discharge side of the hydraulic pump 90 is atmospheric pressure, and is, for example, 1 to 2 MPa.

At time T2, the grip teeth 34a, 34b and the test piece TP come into contact. As a result, the hydraulic pressure P in the oil passage 83 rises.
At time T3, when the hydraulic pressure P becomes the second hydraulic pressure P2, the electromagnetic valve 86 is switched to the closed position 88 according to the instruction from the control unit 21, and the driving of the hydraulic pump 90 is stopped. The inside of the oil passage 83 is maintained at the second oil pressure P2, and the gripping force of the upper gripper 34 corresponds to the second oil pressure P2. The second oil pressure P2 is, for example, 3-6 Mpa.
The second hydraulic pressure P2 is not a large pressure, and the user can finely adjust the position of the test piece TP clamped by the upper gripper 34 .

At time T4, when the user presses the close switch 151 again, the hydraulic pump 90 is driven and the electromagnetic valve 86 is switched to the open position 87 according to the instruction from the control section 21. FIG. The hydraulic pressure P in the oil passage 83 rises.
When the hydraulic pressure P reaches the first hydraulic pressure P1, the electromagnetic valve 86 is switched to the closed position 88 according to the instruction from the control unit 21, and the driving of the hydraulic pump 90 is stopped after a certain period of time. Even if the hydraulic pump 90 stops, the test piece TP is gripped with a gripping force corresponding to the first hydraulic pressure P1. The first hydraulic pressure P1 is, for example, 500 Mpa.

When the solenoid valve 86 is switched to the open position 87, the oil passage 83 is closed and the pressure of the working oil in the closing side oil chambers 75, 80 is maintained.
In this state, even if the working oil in the closed side oil chambers 75, 80 leaks into the open side oil chambers 76, 81, the working oil in the accumulator 82 is supplied to the oil passage 83, and the closed side oil chamber 75 , 80 is maintained.
Since the hydraulic pump 90 is stopped during the material test in this manner, the influence of noise generated by the hydraulic pump 90 during the material test can be suppressed.
Also, when the test piece TP is gripped, the close switch 151 is pressed at time T1 to perform the first closing operation. At time T4, the close switch 151 is pressed, and the second closing operation is performed. As a result, erroneous operations when gripping the test piece TP can be suppressed.

When the material test is finished and the material testing machine 1 is stopped, the control section 21 executes a termination process.
In this case, the solenoid valve 86 is switched from the closed position 88 to the exhaust position 89 while the hydraulic pump 90 remains stopped. As a result, the closed-side oil chambers 75 and 80 and the accumulator 82 are connected to the hydraulic tank 95 through the oil passage 83, the hydraulic oil is discharged to the hydraulic tank 95, and the pressure in the closed-side oil chambers 75 and 80 and the accumulator 82 increases. comes out.
A flow control valve 93 is provided in the oil passage 92 connected to the hydraulic tank 95, and the flow control valve 93 suppresses sudden outflow of hydraulic oil.

[6. Control flow for closing the grip]
A control flow for closing the upper grip 34 will be described.
FIG. 4 is a flow chart for gripping the test piece TP with the upper gripper 34. FIG. FIG. 5 is a flow chart of pressurization processing and pressure maintenance processing. FIG. 6 is a flow chart for opening the upper gripper 34. As shown in FIG.
As shown in FIG. 4, in step S1, the control unit 21 determines whether or not the closing switch 151 of the grip is pressed. If the close switch 151 is pressed, the controller 21 performs pressurization processing in step S2.
As shown in FIG. 5, the control unit 21 drives the hydraulic pump 90 in step S21, and the control unit 21 switches the electromagnetic valve 86 to the open position 87 in step S22.

After the pressurization process is performed in step S2 of FIG. or not.
If the inside of the oil passage 83 is lower than the second oil pressure P2 (step S3; NO), the process returns to step S3. When the oil passage 83 is at the second oil pressure P2 (step S3; YES), in step S4, pressure maintenance processing is performed to maintain the pressure in the closing side oil chambers 75, 80 at the second oil pressure P2.
In the pressure maintenance process, as shown in FIG. 6, in step S23, the control unit 21 switches the solenoid valve 86 to the closed position 88, and in step S24, the control unit 21 determines whether or not a predetermined time has elapsed, After the elapse of time (step S24; YES), the process stops driving the hydraulic pump 90 in step S25.
The close switch 151 is a switch that is continuously pressed in steps S1 to S4. As a result, even when the close switch 151 is kept pressed, the pressure in the close side oil chambers 75, 80 is maintained at the second oil pressure P2.

As shown in FIG. 4, in step S5, the controller 21 determines whether the close switch 151 of the upper grip 34 has been pressed. If the close switch 151 is pressed (step S5; NO), the process returns to step S5, and if the close switch 151 is not pressed (step S5; YES), the process proceeds to step S6.
In step S6, the control section 21 determines whether or not the close switch 151 of the upper grip 34 has been pressed again. If the close switch 151 is pressed again (step S6; YES), the controller 21 performs pressurization processing in step S7.
As shown in FIG. 5, the control unit 21 drives the hydraulic pump 90 in step S21, and the control unit 21 switches the electromagnetic valve 86 to the open position 87 in step S22.

Next, at step S8 in FIG. 4, the control unit 21 determines from the detection value of the pressure sensor 84 whether or not the pressure of the working oil in the oil passage 83 is the set first oil pressure P1.
If it is determined that the inside of the oil passage 83 is lower than the first oil pressure P1 (step S8; NO), the process returns to step S8. When it is determined that the oil passage 83 is at the first oil pressure P1 (step S8; YES), in step S9, pressure maintenance processing is performed to maintain the pressure in the closing side oil chambers 75 and 80 at the first oil pressure P1. done.
In the pressure maintenance process, as shown in FIG. 6, the controller 21 switches the electromagnetic valve 86 to the closed position 88 in step S23. After it is determined that the time has passed (step S24; YES), the process stops driving the hydraulic pump 90 in step S25.
The close switch 151 is a switch that must be kept pressed in steps S6 to S9. As a result, even when the close switch 151 is kept pressed, the pressure in the close side oil chambers 75, 80 is maintained at the first oil pressure P1.

[7. Control flow for opening the grip]
FIG. 7 is a flow chart of termination processing of the material testing machine 1 .
As shown in FIG. 7, in step S11, the control unit 21 determines whether the open switch 152 is pressed. If the open switch 152 is pushed, the hydraulic pump 90 is driven in step S12, and the electromagnetic valve 86 is switched to the discharge position 89 in step S13. As a result, hydraulic oil is supplied to the open side oil chambers 76 and 81, and the grip teeth 34a and 34b of the upper gripper 34 are opened.
Then, in step S14, after a predetermined time has passed by the timer, in step S15, pressure maintenance processing is performed to maintain the pressure in the closing side oil chambers 75 and 80 at the hydraulic pressure P0.

In the pressure maintenance process, as shown in FIG. 6, the controller 21 switches the electromagnetic valve 86 to the closed position 88 in step S23. After it is determined that the time has passed (step S24; YES), the process stops driving the hydraulic pump 90 in step S25.
The open switch 152 is a switch that must be kept pressed in steps S11 to S15. As a result, even when the open switch 152 is kept pressed, the pressure in the closing side oil chambers 75, 80 is maintained at the oil pressure P0.

[8. mode]
It will be appreciated by those skilled in the art that the exemplary embodiments described above are specific examples of the following aspects.

(Section 1)
The material testing machine according to one aspect is a material testing machine that grips a test object with grippers and applies a load to the test object, comprising a pump that supplies hydraulic oil to the grippers, the pump and the grippers. A solenoid valve arranged in an oil passage between and configured to be switchable between an open position that communicates the oil passage and a closed position that blocks the oil passage, and a pressure that detects the hydraulic pressure in the oil passage a sensor; and a control unit that switches the solenoid valve from an open position to a closed position and shifts the pump from a driving state to a stopped state when the hydraulic pressure detected by the pressure sensor reaches a first hydraulic pressure.

According to the material testing machine described in item 1, the power consumption of the material testing machine can be suppressed because the pump is stopped during the material test while maintaining the hydraulic pressure for gripping the test object in the gripper.

(Section 2)
In the material testing machine according to item 1, an accumulator configured to maintain the first hydraulic pressure may be provided in the oil passage between the gripper and the solenoid valve.

According to the material testing machine described in item 2, even if hydraulic fluid between the gripper and the solenoid valve leaks, the hydraulic pressure for gripping the test object is maintained in the gripper. Thereby, the power consumption of the material testing machine can be suppressed.

(Section 3)
In the material testing machine according to item 1 or item 2, the control unit may stop the pump after a predetermined time has elapsed from the point at which an instruction signal for switching the electromagnetic valve from the open position to the closed position is output. .

According to the material testing machine described in item 3, the solenoid valve is closed before the pressure from the pump drops, suppressing the hydraulic oil between the grip and the solenoid valve from returning to the pump side, Such hydraulic pressure is maintained.

(Section 4)
In the material testing machine according to any one of items 1 to 3, the control unit switches the switching position of the solenoid valve to a discharge position for discharging hydraulic oil in the oil passage, and then executes termination processing. You can

According to the material testing machine described in item 4, when the material testing machine is stopped, the pressure in the oil passage between the gripper and the pump is released to prevent damage to consumables such as packing.

(Section 5)
5. The material testing machine according to any one of items 1 to 4, further comprising a closing operation instruction section for instructing a closing operation of the gripper, wherein the control section receives an instruction to close the oil. At the time when the inside of the passage becomes the second hydraulic pressure lower than the first hydraulic pressure, the electromagnetic valve is switched from the open position to the closed position, the driving of the pump is stopped, and when an instruction to perform the closing operation is received again. , the solenoid valve may be switched from the closed position to the open position, and the pump may be driven until the inside of the oil passage reaches the first oil pressure.

According to the material testing machine described in item 5, when the grippers start gripping the test object and before reaching the set pressure for the material test, the hydraulic pressure is once maintained and the grippers grip the test object. can be confirmed. Also, the position of the test object can be finely adjusted. Furthermore, it is possible to suppress erroneous operations in closing the grip.

(Section 6)
A control method for a material testing machine according to one aspect is a control method for a material testing machine that grips a test object with a gripper and applies a load to the test object, wherein the hydraulic pressure supplied to the gripper is a first hydraulic pressure. When , the oil passage between the gripper and the pump is closed while maintaining the first oil pressure, and the pump is shifted from the driving state to the stopped state.

According to the control method of the material testing machine described in item 6, the power consumption of the material testing machine can be suppressed. Since the pump is stopped while the test object is gripped by the grips, the influence of noise due to pump operation during material testing is suppressed.

[9. Other embodiments]
In the above embodiment, a three-position solenoid valve 86 is shown, but a two-position solenoid valve 87 and closed position 88 is used. A release valve for releasing the pressure in the oil passage 83 may be provided. Instead of switching the solenoid valve 86 to the discharge position 89 in the above embodiment, the two-position solenoid valve may be closed and the release valve may be opened to release the pressure in the oil passage 83 . As a result, the electromagnetic valve can be made simpler.

Although the pressure sensor 84 is provided in the oil passage 83 between the hydraulic pump 90 and the upper gripper 34 in the above embodiment, the pressure sensor 84 may be provided in the closing side oil chamber 75 of the upper gripper 34 . Thereby, the pressure for gripping the test object can be detected with higher accuracy.

In the above-described embodiment, when the controller 21 receives an instruction to close the solenoid valve 86 from the open position 87 when the inside of the oil passage 83 reaches the second oil pressure P2 lower than the first oil pressure P1. It was switched to the closed position 88 and the drive of the hydraulic pump 90 was stopped. However, even if the solenoid valve 86 is held at the open position 87 and the hydraulic pump 90 is driven until the inside of the oil passage 83 reaches the first oil pressure P1 when the controller 21 receives the instruction for the closing operation. good. Thereby, the material testing machine 1 can be easily controlled.

In the above embodiment, the material testing machine 1 that performs a tensile test is shown as a material testing machine, but the present invention applies a test force to the test piece TP and measures the physical change that occurs in the test piece TP. It can be widely applied to material testing machines. For example, the present invention can be applied to a material testing machine that performs compression tests, bending tests, peeling tests, fatigue tests, and the like.

Reference Signs List 1 material testing machine 15 remote controller 21 control section 34 gripper 65 hydraulic circuit 72 hydraulic cylinder 75 closing side oil chamber 76 opening side oil chamber 77 hydraulic cylinder 80 closing side oil chamber 81 opening side oil chamber 82 accumulator 83 oil passage 84 pressure sensor 86 Solenoid valve 87 Open position 88 Closed position 89 Discharge position 90 Hydraulic pump 91 Motor 95 Hydraulic tank 151 Close switch 152 Open switch 153 Close switch 154 Open switch 155 Standby switch P1 First hydraulic pressure P2 Second hydraulic pressure

Claims (6)

A material testing machine that grips a test object with a grip and applies a load to the test object,
a pump that supplies hydraulic oil to the gripper;
a solenoid valve arranged in an oil passage between the pump and the gripper, and configured to be switchable between an open position communicating with the oil passage and a closed position blocking the oil passage;
a pressure sensor that detects the hydraulic pressure in the oil passage;
switching the electromagnetic valve to the open position, starting to drive the pump, and switching the electromagnetic valve from the open position to the closed position when the hydraulic pressure detected by the pressure sensor reaches a first hydraulic pressure; a control unit that shifts the pump from a driving state to a stopped state;
material testing machine. An accumulator configured to maintain the first hydraulic pressure is provided in the oil passage between the gripper and the solenoid valve,
The material testing machine according to claim 1. The control unit stops the pump after a predetermined time has elapsed from the time when an instruction signal for switching the solenoid valve from the open position to the closed position is output.
The material testing machine according to claim 1 or 2. The control unit switches the switching position of the solenoid valve to a discharge position for discharging hydraulic oil in the oil passage, and then executes a termination process.
The material testing machine according to any one of claims 1 to 3. A closing operation instruction unit for instructing the closing operation of the grip,
The control unit moves the solenoid valve from the open position to the closed position when the inside of the oil passage becomes a second oil pressure lower than the first oil pressure when receiving a first instruction to close. After switching, the driving of the pump is stopped, and when a second closing operation instruction is received, the solenoid valve is switched from the closed position to the open position, and the inside of the oil passage reaches the first oil pressure. driving the pump to
A material testing machine according to any one of claims 1 to 4. A control method for a material testing machine that grips a test object with a grip and applies a load to the test object,
When the hydraulic pressure supplied to the gripper becomes the first hydraulic pressure,
closing the oil passage between the gripper and the pump while maintaining the first hydraulic pressure;
A method of controlling a material testing machine, wherein the pump is changed from a driving state to a stopped state.

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