JP3749413B2 - Starting method of material test apparatus and material test apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a material testing apparatus, and in particular, moves a spool of a guide valve of a three-stage servo valve, and controls the hydraulic pressure supplied to a pair of ports of a cylinder of a main actuator by the movement of the spool. The present invention relates to a material testing apparatus in which a load is applied to a test body by moving a rod.
[0002]
[Prior art]
This type of three-stage servo valve is connected by a first stage servo valve, a second stage guide valve, and a third stage main actuator. The second stage guide valve is a first stage servo valve. This is equivalent to a small actuator when viewed from the valve. In recent years, material testing apparatuses using such a three-stage servo valve have been proposed. FIG. 2 is a cross-sectional view schematically showing an essential part of a material testing apparatus using such a three-stage servo valve, and will be specifically described based on FIG.
[0003]
The material testing apparatus shown in FIG. 2 includes a main actuator 60 in which a piston rod 61 reciprocates in a cylinder 62. The piston rod 61 applies a load to a test body (TP) via a load cell (L / C) 63. Has been made to give. The cylinder 62 is formed with a hydraulic port communicating with the two chambers 62 a and 62 b partitioned by the piston 61 a formed at the intermediate portion of the piston rod 61.
[0004]
These hydraulic ports communicate with a guide valve (switching valve) 70 through a pipe. The guide valve 70 includes a sleeve 71 and a main spool 72 that can move with respect to the sleeve 71. The sleeve 71 is formed with a hydraulic port that communicates with the two chambers 71 a and 71 b partitioned by both ends of the main spool 72 and communicates with the servo valve 80. The sleeve 71 is provided with a hydraulic port connected to the hydraulic unit 81 via a supply pipe 82 and a drain pipe 83. A displacement detector (differential transformer or potentiometer) 73 is connected to one end of the main spool 72. The displacement detector (differential transformer or potentiometer) 73 detects the position of the main spool 72 and outputs a detection signal as a voltage. Output as a value.
[0005]
The servo valve (S / V) 80 is connected to the hydraulic unit 81 via a supply pipe 82 and a drain pipe 83. The supply pipe 82 and the drain pipe 83 are branched to communicate with a guide valve (switching valve) 70, and a shunt valve 84 is provided in the middle of the pipe branched from the supply pipe 82. The servo valve (S / V) 80 receives an input signal Eie from a setting unit (not shown) that generates a target load signal (setting signal) Ei through an adding unit 75 and an amplifier 76.
[0006]
When starting the material testing apparatus configured in this way, first, hydraulic oil is supplied from the hydraulic unit 81 to the servo valve 80 via the supply pipe 82, and as shown in FIG. The hydraulic pressure P _S1 is raised until the rated pressure is reached, then the shunt valve 84 is opened, and the hydraulic pressure P _S2 on the guide valve 70 side is raised until the rated pressure is reached, as shown in FIG. I have to. That is, after the main spool 72 of the guide valve 70 is positioned at a mechanically neutral position and set so that the flow of pressure oil to the main actuator 60 is minimized, the hydraulic pressure on the main actuator 60 side rises. ing.
[0007]
This is because the position of the main spool 72 of the guide valve (switching valve) 70 can be monitored from the outside by an electric signal (deviation signal) Ee of the displacement detector 73 attached to the main spool 72. When the signal (deviation signal) Ee is zero, the main spool 72 of the guide valve 70 must be in the center position. The displacement detector 73 is attached to the main spool 72 so as to be so. For this reason, before the hydraulic pressure is supplied from the hydraulic unit 81 to the servo valve 80 via the supply pipe 82, the drive current does not flow to the servo valve 80 (the drive current is set to zero (Ei = 0)). In this case, it is assumed that the spool of the servo valve 80 is located at the center.
[0008]
Therefore, if the above assumption is correct, no hydraulic pressure (differential pressure) for moving the main spool 72 of the guide valve 70 is generated, so that the main spool 72 of the guide valve 70 should not move. Under such an assumption, as shown in FIG. 3A, when the hydraulic pressure P _S1 is applied, the spool 72 of the guide valve (switching valve) 70 should not move during the process of adding the hydraulic pressure P _S1. . That is, in FIG. 2, the input voltage (Eie) is initially set to zero (Eie = 0), and in this state, pressure oil is supplied from the hydraulic unit 81 to the servo valve 80 via the supply pipe 82. Since the hydraulic pressure _PS1 rises as shown in FIG. 3A, a closed loop including the servo valve 80, the guide valve 70, the displacement detector 73, the amplifier 74, the adder unit 75, and the amplifier 76 operates. The main spool 72 is balanced at the center position.
[0009]
Here, when the positive polarity deviation signal Eie is output from the adder 75, the spool position of the servo valve 80 and the position of the main spool 71 of the guide valve 70 cause the hydraulic pressure from the supply pipe 82 to be supplied to the hydraulic port of the cylinder 62. Move to feed. When the negative polarity deviation signal Eie is output from the adding unit 74, the spool position of the servo valve 80 and the position of the main spool 71 of the guide valve 70 supply the hydraulic pressure from the supply pipe 82 to the hydraulic port of the cylinder 61. To move. By such an operation, the main actuator 60 can apply a load having a magnitude corresponding to the target load signal (setting signal) Ei to the test body (TP).
[0010]
[Problems to be solved by the invention]
However, in the material testing apparatus described above, the following troubles have actually occurred. That is, in FIG. 2, even if the input voltage is zero (Eie = 0), the position of the main spool 71 of the guide valve 70 is completely at the center, and the detection signal of the displacement detector 73 is completely zero (Ee = 0). Such a mounting relationship is difficult.
Even if the position of the spool 71 of the guide valve 70 and the mounting relationship of the displacement detector 73 are mechanically ideal, there is always a fluid imbalance of the guide valve 70 in machining. Even if the detection signal of the displacement detector 73 is mechanically zero (Ee = 0), there is a problem that such an unbalance is unavoidable in the fluid environment. .
[0011]
The present invention has been made to solve the above-described problems, and can prevent a differential pressure from being generated in the main actuator even when the pressure oil supplied to the servo valve reaches a predetermined hydraulic pressure. An object of the present invention is to provide a starting method for a material testing apparatus and to provide a material testing apparatus to which the starting method can be applied.
[0012]
[Means for solving the problems and their functions and effects]
In order to achieve the above object, the starting method of the material testing apparatus according to the present invention obtains the displacement of the main spool position of the guide valve as a voltage value and supplies pressure oil to the servo valve to bring the pressure oil to a predetermined pressure. A voltage value that does not cause a differential pressure between the pair of ports of the main actuator before reaching this value is obtained in advance, and this voltage value is stored in advance as an initial set value, and this pre-set initial set value is set when the servo valve is started. It is given as a signal.
[0013]
In this way, if the initial setting value stored in advance is given as a setting signal when the servo valve is activated, the initial setting value is set in advance so that the main actuator does not move. Then, the main actuator does not move until the pressure of the pressure oil supplied to the servo valve reaches a predetermined value and the servo valve rises. In such a state, when the hydraulic pressure is supplied to the guide valve and the hydraulic pressure of the guide valve gradually rises, the main actuator does not move. For this reason, it becomes possible to prevent an extra load from being applied to the specimen (TP) when the servo valve is started.
[0014]
On the other hand, the material testing device of the present invention includes a setting unit that applies a setting signal to the servo valve and applies a predetermined load to the test body, and an initial value setting unit that applies an initial setting signal to the servo valve when the servo valve is activated. A main spool displacement detector that obtains the displacement of the main spool position of the guide valve as a voltage value, and supplies a pressure oil to the servo valve so that the pressure oil reaches a predetermined pressure. A voltage value that does not cause a differential pressure between the two ports is obtained in advance by the main spool displacement detector, and this voltage value is stored in advance in the initial value setting unit as an initial setting value, and the previously determined and stored initial setting value is servoed. It is given when the valve starts.
[0015]
In this way, a voltage value is determined in advance so that no differential pressure is generated between the pair of ports of the main actuator until the pressure oil reaches a predetermined pressure by supplying the pressure oil, and this voltage value is set as an initial set value. When the initial value is stored in advance in the initial value setting unit and the previously determined and stored initial setting value is given when the servo valve is started, the initial setting value is set in advance so that the main actuator does not move. When the input signal is input to the main actuator, the main actuator does not move until the pressure of the pressure oil supplied to the servo valve reaches a predetermined value and the servo valve starts up. For this reason, it becomes possible to prevent an extra load from being applied to the specimen when the servo valve is started.
[0016]
A main actuator displacement detector that detects displacement of the piston rod of the main actuator and outputs a main actuator displacement detection signal; and a first addition unit that adds the main actuator displacement detection signal to the setting signal and outputs the deviation signal And a second addition unit for adding the main spool displacement detection signal to the deviation signal and outputting the deviation signal, and by giving the output signal from the second addition unit as an input signal of the servo valve, Thus, it is possible to obtain a test apparatus in which an extra load is not applied to the test body when starting up.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram schematically showing an embodiment of a material testing apparatus according to the present invention.
The material testing apparatus of this embodiment includes a main actuator 10 in which a piston rod 11 reciprocates in a cylinder 12, and one end of the piston rod 11 is a test body (TP) via a load cell (L / C) 13. The other end is connected to an actuator displacement detector (for example, a differential transformer) 14 that outputs a voltage value corresponding to the position of the piston rod 11.
[0018]
The cylinder 12 is formed with a hydraulic port communicating with the two chambers 12a and 12b partitioned by the piston 11a formed at the intermediate portion of the piston rod 11. The actuator displacement detector 14 detects the displacement of the piston rod 11 and outputs a displacement signal (voltage) SK ₁ . The displacement signal SK ₁ is amplified by an amplifier 17 having an amplification factor α and then input to a first adder 18 described later.
A switching valve (guide valve) 20 is connected to the hydraulic port, and the guide valve 20 includes a sleeve 21 and a main spool 22 that is movable with respect to the sleeve 21. The sleeve 21 is formed with a port that communicates with two chambers 21 a and 21 b partitioned by both ends of the main spool 22 and is connected to the servo valve 30.
[0019]
The sleeve 21 is formed with a port connected to a supply pipe 32 and a drain pipe 33 connected to the hydraulic unit 31, and a shunt valve 34 is provided between the port and the supply pipe 32. . A main spool displacement detector (for example, a differential transformer) 23 is connected to one end of the main spool 22, and the main spool displacement detector 23 detects a displacement of the main spool 22 and detects a displacement signal (voltage) SK _2. Is output. The displacement signal SK ₂ is amplified by an amplifier 26 having an amplification factor β and then input to a second adder 28 described later.
[0020]
The servo valve (S / V) 30 includes a sleeve (not shown) and a pilot spool movable with respect to the sleeve, and a pair of ports connected to ports communicating with the two chambers 21a and 21b of the guide valve are provided. Is formed. A pair of ports connected to a supply pipe 32 and a drain pipe 33 connected to the hydraulic unit 31 are provided. The servo valve (S / V) 30 receives a signal S obtained by amplifying a deviation SE between an input signal SEi and a displacement signal SK ₂ described later by an amplifier 29 having an amplification factor of Ka.
[0021]
Here, the material test apparatus of the present embodiment includes a zero cancel unit 15 that sets an output signal from the actuator displacement detector 14 to 0 when the material test apparatus is activated, and a setting unit 19 that generates a target displacement signal E _i. And an initial value setting unit 25 for generating an initial displacement signal E _adj .
Also, a first addition unit 18 that adds a target displacement signal E _i from the setting unit 19 and a signal obtained by amplifying the displacement signal SK ₁ to the amplifier 17 and outputs a deviation signal SE _i thereof, and the deviation signal A variable amplifier 27 for amplifying SE _i , a second adder 28 for adding the input signal SE _i and the displacement signal SK ₂ amplified by the amplifier 26 and outputting the deviation signal SE, and the deviation signal SE And an amplifier 29 for applying the input signal S to the servo valve 30.
Furthermore, the addition unit 16 that adds the output signal output from the zero cancel unit 15 and the output signal from the actuator displacement detector 14 at the time of starting the material testing apparatus is output from the initial value setting unit 25 at the same time. And an adder 24 for adding the output signal from the main spool displacement detector 23.
[0022]
The actuator displacement detectors (e.g., Sa働trans) 14 displaced detect and output a displacement signal SK ₁ corresponding to the load applied to the test body (TP) by the actuator 10, the displacement signal SK ₁ After being amplified by the amplifier 17, it is applied to the − input of the first adder 18. On the other hand, the target displacement signal E _i from the setting unit 19 is input to the + input of the first addition unit 18, and this deviation SE _i (E _i −SK ₁ ) is output from the first addition point 18.
[0023]
Further, the main spool displacement detector (e.g., Sa働trans) 23 outputs the detection to the displacement signal SK ₂ a displacement of the main spool 22 of the guide valve 20, after amplifying the displacement signal SK ₂ by the amplifier 26, This is applied to the negative input of the second adder 28. On the other hand, the deviation SE _i (E _i −SK ₁ ) is input to the + input of the second adder 28 after being amplified by the amplifier 27, and the deviation SE (SE _i −SK ₂ ) is input from the second adder 28. Is output. Further, the deviation signal SE output from the second adder 28 is amplified by the second amplifier 29 and then applied to the servo valve 30 as the control signal S.
Note that a signal is obtained in advance so that the piston rod 11 of the main actuator 10 does not move when pressure oil is supplied from the hydraulic unit 31 to the servo valve 30 via the supply pipe 32. The signal E _adj is preset in the initial value setting unit 25.
[0024]
Next, how to obtain the initial displacement signal E _adj will be described. First, with the shunt valve 34 closed, the set value Ei of the setting unit 19 is set to 0, and the output signal SK ₁ from the actuator displacement detector 14 is set to 0 by the zero canceling unit 15 and the first addition is performed. The output of the unit 18 is set to 0. In this state, after setting the set value of the initial value setting unit 25 to an arbitrary level, the shunt valve 34 is opened so that the pressure oil from the hydraulic unit 31 can flow into the main actuator 10.
[0025]
As a result, the main spool 22 is displaced according to a set value of an arbitrary level set in the initial value setting unit 25, and a differential pressure (Pa−Pb or Pa−Pb or between the chambers 12a and 12b of the main actuator 10 is accompanied by this displacement. Pb-Pa) occurs, and the piston rod 11 is displaced. In this state, the initial value setting unit until the piston rod 11 of the main actuator 10 is not displaced, that is, until no differential pressure (Pa-Pb or Pb-Pa) occurs between the chambers 12a and 12b of the main actuator 10. 25 set values are changed. When such operation is repeated and the piston rod 11 of the main actuator 10 is not displaced, this level is set in the initial value setting unit 25 as the initial displacement signal E _adj .
Thus, an initial displacement signal E _adj can be obtained, and the piston rod 11 of the main actuator 10 can be prevented from moving by using the initial displacement signal E _adj when starting the material testing apparatus. Become.
[0026]
Next, the operation of the material testing apparatus configured as described above will be described below.
First, after placing the test body (TP) on the table, when a power switch provided in a control device (not shown) is pressed to turn it on, the hydraulic pressure is supplied from the hydraulic unit 31 via the supply pipe 32 to the servo valve 30. Will be supplied to. At the same time, the initial value setting unit 25 sends an initial displacement signal E _adj . The actuator displacement detector 14 and the main spool displacement detector 23 output detection signals until the pressure P _S1 of the pressure oil supplied to the servo valve 30 rises to a predetermined value as shown in FIG. Therefore, the displacement signals SK ₁ and SK ₂ are not input to the first adder 18 and the second adder 28.
[0027]
Therefore, the initial value setting unit 25 sends the initial displacement signal E _adj, the initial displacement signal E _adj is inputted outputs a signal SE (= E _adj) in the second addition unit 28, the signal SE (= E _adj ) is input to the amplifier 29 to output a signal S (= E _adj ), and this signal S (= E _adj ) is applied to the servo valve 30.
[0028]
By the way, the initial displacement signal E _adj sent from the initial value setting unit 25 is set in advance so that the piston rod 11 of the main actuator 10 does not move, so that the signal S (= E _adj ) is sent to the servo valve 30. When input, the pressure rod pressure P _S1 supplied to the servo valve 30 reaches a predetermined value as shown in FIG. 3A, and the piston rod 11 of the main actuator 10 moves until the servo valve 30 rises. Things will disappear. In such a state, the shunt valve 34 is opened, and the hydraulic pressure is supplied to the guide valve 20. As shown in FIG. 3B, the hydraulic pressure _PS2 of the guide valve 20 gradually rises. As a result, the piston rod 11 of the main actuator 10 does not move.
[0029]
When the hydraulic pressure _PS2 of the guide valve 20 rises in such a state, the target displacement signal E _i is sent from the setting unit 19 and the actuator displacement detector (differential transformer) 14 and the main spool are sent. The displacement detector (differential transformer) 23 outputs displacement signals SK ₁ and SK ₂ , respectively. As a result, signals corresponding to the adders 18 and 28 are input, the deviation signal SE _i is output from the first adder 18, the deviation signal SE is output from the second adder 28, and the deviation signal SE is Amplified by the amplifier 29 to output a signal S, which is applied to the servo valve 30.
[0030]
When the positive polarity deviation signal SE is output from the second adder 28, the spool position of the servo valve 30 and the position of the spool 21 of the guide valve 20 change the hydraulic pressure from the supply pipe 32 to the chamber 12 a of the cylinder 12. It moves so that it may supply to the hydraulic port connected to. Further, when a negative polarity deviation signal SE is output from the second adder 29, the spool position of the servo valve 30 and the position of the spool 21 of the guide valve 20 transfer the hydraulic pressure from the supply pipe 32 to the chamber 12 b of the cylinder 11. It moves to supply to the hydraulic port that communicates. By such an operation, the actuator 10 can apply a load having a magnitude corresponding to the target displacement signal E _i to the test body (TP).
[0031]
As is clear from the above, in the present invention, the initial displacement signal E _adj sent from the initial value setting unit 25 is set in advance to a value that does not move the piston rod 11 of the main actuator 10. When a signal S (= E _adj ) is input to 30, the pressure P _S1 of the pressure oil supplied to the servo valve 30 becomes a predetermined value as shown in FIG. 3A, and the servo valve 30 starts up. The piston rod 11 of the main actuator 10 does not move. In this state, when the hydraulic pressure is supplied to the guide valve 20 and the hydraulic pressure _PS2 of the guide valve 20 gradually rises as shown in FIG. The piston rod 11 does not move.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an embodiment of a material testing apparatus according to the present invention.
FIG. 2 is a diagram schematically showing a conventional material testing apparatus.
FIG. 3 is a diagram showing a relationship between a start time when a servo valve is started and the hydraulic pressure of the servo valve, and a relationship between a start time when the guide valve is started and a hydraulic pressure of the guide valve.
[Explanation of symbols]
TP ... Test body 10 ... Actuator 11 ... Piston rod 12 ... Cylinder 13 ... Load cell (L / C)
14 ... Actuator displacement detector (differential transformer)
DESCRIPTION OF SYMBOLS 15 ... Zero cancellation part 16 ... Addition part 17, 26, 27, 29 ... Amplifier 18 ... 1st addition part 19 ... Setting part 20 ... Guide valve 21 ... Sleeve 22 ... Spool 23 ... Main spool displacement detector (differential transformer)
24 ... Addition unit 25 ... Initial value setting unit 28 ... Second addition unit 30 ... Servo valve (S / V)
31 ... Hydraulic unit 32 ... Supply piping 33 ... Drain piping

Claims (4)

A three-stage servo valve composed of a servo valve, a guide valve, and a main actuator is provided. After the pressure oil reaches a predetermined pressure by supplying pressure oil to the servo valve, the pressure oil is supplied to the guide valve. A material test in which a main spool of the guide valve is moved and pressure oil supplied to a pair of ports of the cylinder of the main actuator is controlled to move a piston rod in the cylinder to apply a load to the test body. A method of starting the device,
While obtaining the displacement of the main spool position of the guide valve as a voltage value,
The pressure value of the displacement of the main spool position is obtained in advance so that no differential pressure is generated between the pair of ports of the main actuator until the pressure oil is supplied to the servo valve and the pressure oil reaches a predetermined pressure. , This voltage value is stored in advance as an initial set value,
A starting method for a material testing apparatus, wherein the initial setting value obtained in advance is given as a setting signal when the servo valve is started. A three-stage servo valve composed of a servo valve, a guide valve, and a main actuator is provided. After the pressure oil reaches a predetermined pressure by supplying pressure oil to the servo valve, the pressure oil is supplied to the guide valve. The main spool of the guide valve is moved to control the pressure oil supplied to a pair of ports of the cylinder of the main actuator, and the piston rod in the cylinder is moved to apply a load to the specimen. A testing device,
A setting unit for giving a predetermined load to the test body by giving a setting signal to the servo valve;
An initial value setting unit for giving an initial setting signal to the servo valve when the servo valve is activated;
A main spool displacement detector for obtaining a displacement of the main spool position of the guide valve as a voltage value;
The main spool displacement detector obtains in advance a voltage value at which no differential pressure is generated between the pair of ports of the main actuator until pressure oil is supplied to the servo valve and the pressure oil reaches a predetermined pressure. This voltage value is stored in advance in the initial value setting unit as an initial setting value, and the initial setting value obtained and stored in advance is applied when the servo valve is started. A main actuator displacement detector that detects a displacement of the piston rod of the main actuator and outputs a main actuator displacement detection signal;
A first addition unit that adds the main actuator displacement detection signal to the setting signal and outputs a deviation signal thereof;
A second addition unit that adds the main spool displacement detection signal to the deviation signal and outputs the deviation signal;
3. The material testing apparatus according to claim 2, wherein an output signal from the second adder is given as an input signal of the servo valve. When the piston rod of the main actuator is at an arbitrary position in a stationary state and the set value of the setting unit is set to 0, a signal is output so that the output of the first adding unit becomes 0 4. The material testing apparatus according to claim 2, wherein a zero cancel unit is provided between the main actuator displacement detector and the first addition unit.

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