JP5109948B2 - Material testing machine - Google Patents

Description

The present invention relates to wood charge tester you load test force to specimen using an electromagnetic actuator.

2. Description of the Related Art Conventionally, a vibration apparatus or a material testing machine that applies a test force to a specimen by using an electromagnetic actuator using an electromagnetic force is known. Among electromagnetic actuators that use electromagnetic force, a small electromagnetic actuator uses a permanent magnet to form an excitation unit. On the other hand, a large electromagnetic actuator is provided with an exciting coil in an exciting part, and a necessary magnetic flux density is achieved by the exciting coil. In any type of electromagnetic actuator, by supplying a drive current to the movable coil, a test force (load) is applied to the specimen through a piston rod that works in conjunction with the movable coil bobbin (Patent Document 1).
JP 2004-205337 A

However, in an electromagnetic actuator having an excitation coil, it is necessary to operate the excitation unit as an electromagnet, so that a current for achieving a magnetic saturation state is generally continuously supplied.
As a result, not only the test force that is actually required is large, but also the excitation unit not only consumes a large amount of power continuously, but also causes a malfunction or malfunction that causes a large current to flow through the moving coil. In some cases, excessive test force suddenly occurs, which is dangerous from the viewpoint of safety.

A material testing machine according to the present invention is a material testing machine for loading a test piece with a test force generated by an electromagnetic actuator having an exciting coil and a moving coil, and a piston rod attached to the moving coil and a predetermined grip. In the attaching step of attaching the test piece to the piston rod using a tool and the ending step of removing the test piece from the piston rod, the excitation is performed in order to generate a thrust force sufficient to move the piston rod up and down. The first excitation control means for generating the first magnetic flux density by the coil and the second excitation step by the excitation coil so that a predetermined test force can be obtained at the stage of executing the test on the test piece. It characterized in that it comprises a second excitation control means for generating a magnetic flux density, the.
Here, the first excitation control means and the second excitation control means are provided in an applied voltage setting means for controlling a magnetic flux density by changing a DC voltage applied to the excitation coil, or provided in the excitation coil. In addition, tap switching means for selecting any one of the plurality of taps can be provided.

According to the present invention, since it is constituted appropriately changing the magnetic flux density to be generated by the exciting coil in accordance with the state of the wood charge test, not only eliminate unnecessary power consumption caused by the excitation coil, due to failure or malfunction Unexpected excessive test force can be prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Embodiment 1>
FIG. 1 is an overall configuration diagram of a material testing machine using an electromagnetic actuator according to an embodiment of the present invention. This material testing machine includes a testing machine main body 10 that applies a test force to the test piece TP, and a feedback control system 60 that controls the testing machine body. The feedback control system 60 includes a target signal generating unit 30 that generates a target signal of a test force applied to the test piece TP, and a feedback control unit 50 that generates a drive signal for the electromagnetic actuator 12 provided in the testing machine main body unit 10. And are included.

  The tester main body 10 has an electromagnetic actuator 12 supported by a frame 11. FIG. 2 is an explanatory diagram showing a schematic configuration of the electromagnetic actuator 12. The electromagnetic actuator 12 drives the piston rod 13A in the vertical direction. That is, in the electromagnetic actuator 12, the exciting part 73 provided with the movable coil 71 mounted on the cylindrical movable part 70 and the exciting coil 72 for generating a predetermined magnetic flux density is accommodated. The piston rod 13 </ b> A is fixed to the movable portion 70.

  When a current flows through the exciting coil 72 and a magnetic flux density B is generated, a driving force I is passed through the movable coil 71 to generate a thrust F in the movable portion 70, and the piston rod 13A fixed to the movable portion 70 A vertical thrust F is transmitted.

When the length of the movable coil 71 is L, the thrust F is expressed by the following equation.
F = I ・ B ・ L
That is, a thrust F proportional to the current I of the movable coil is transmitted to the piston rod 13A.

  A displacement sensor 14 (see FIG. 1) is attached to the frame 11. The displacement sensor 14 detects the displacement amount of the piston rod 13 </ b> A and outputs it to the feedback control unit 50.

  Below the piston rod 13A, an upper grip 38, a test piece TP, a lower grip 40, a connecting rod 13B, and a load sensor 16 (for example, a load cell) are provided. The load sensor 16 detects a test force and detects a feedback control unit 50. Output to.

  The target signal generation unit 30 is set by setting the necessary information such as the average value of the waveform, amplitude, frequency, displacement, and test force by the operator (or other control device) according to the purpose of the material test. A target signal corresponding to the information is output.

  The feedback control unit 50 amplifies the load signal detected by the load sensor 16 and outputs it, a displacement amplifier 52 that amplifies and outputs the displacement signal detected by the displacement sensor 14, and the load amplifier 51. A changeover switch 53 for selectively taking out one of the output load signal and the displacement signal output from the displacement amplifier 52, the target signal supplied from the target signal generator 30, and the changeover switch 53. A subtraction unit 54 that calculates a deviation (control deviation) from the signal, a PID control signal output unit 55 that outputs a PID control signal based on the calculated deviation, and a drive current of the electromagnetic actuator 12 by amplifying the PID control signal The power amplifier 57 is provided.

  Next, the control operation by the feedback control unit 50 will be described. When the changeover switch 53 selects whether to perform load feedback control or displacement feedback control, a load signal from the load amplifier 51 or a displacement signal from the displacement amplifier 52 is sent to the subtractor 54.

  By subtracting the load signal or displacement signal negatively from the target signal from the target signal generator 30, the subtractor 54 calculates a deviation (control deviation). The PID control signal output unit 55 has gain coefficients set in advance for each of the P, I, and D components, and calculates a feedback gain by calculating each of these coefficients and the deviation calculated by the subtracting unit 54 to perform PID control. Output a signal.

What has been described above is the process of controlling the drive current of the movable coil 71. Next, control of the magnetic flux density generated by the exciting coil 72 will be described.
The excitation current control circuit 65 shown in FIG. 1 is a circuit that controls the magnitude of the current flowing through the excitation coil 72. More specifically, as shown in FIG. 3, a DC constant voltage source 77 and an amplifier 79 are installed inside the electromagnetic actuator 12, and gain control of the amplifier 79 is performed by the excitation current control circuit 65. In other words, the excitation current is controlled by directly controlling the voltage applied to the excitation coil 72. However, since the magnitude of the excitation current and the magnetic flux density are not in a linear relationship, it is preferable to previously store the relationship between the excitation current of the excitation coil 72 and the magnetic flux density in a table or the like.

  The magnetic flux density generated by the exciting coil 72 is switched according to the operation mode, that is, the state of the material test. For example, in the preparatory stage of the material test (= attachment stage of the test piece TP), an electromagnetic force sufficient to raise and lower the piston rod 13A and grip the test piece TP with the upper grip 38 and the lower grip 40 is electromagnetic. It may be generated from the actuator 12. As a result, not only can the power consumption in the exciting coil 72 be reduced, but even if a large voltage or the power supply voltage itself is applied to the movable coil 71 due to some failure and an excessive force is instantaneously generated, there is a danger to the operator. In addition, it is possible to minimize damage to equipment and the like.

  In the stage where the material test is performed (= test execution stage), the gain of the amplifier 79 is increased to set the magnetic flux density so that the rated test force can be obtained. Since the test piece TP is simply removed after the material test is completed, the gain of the amplifier 79 is reduced so that a magnetic flux density equivalent to the preparation stage of the material test can be obtained.

  As described above, in addition to switching the magnetic flux density in each execution stage of the material test, it is possible to control the magnetic flux density according to the test conditions in the execution stage of the material test. That is, the magnetic flux density can be changed so that a thrust suitable for the test force applied to the test piece TP can be obtained.

-Actions and effects of the first embodiment-
(1) According to the first embodiment, in the electromagnetic actuator 12 including the excitation coil 72 instead of the permanent magnet, the excitation control for generating the first magnetic flux density by the excitation coil 72 in the preparation stage and the end stage of the material test. In the test execution stage in which the material test is performed, the excitation coil 72 performs excitation control for generating the second magnetic flux density (first magnetic flux density <second magnetic flux density). In addition to eliminating waste of power consumption, it is possible to prevent the occurrence of an unpredictable excessive test force due to a failure or malfunction.
(2) Even when the test force itself (= test condition) applied to the test piece TP is changed, the magnetic flux density generated by the exciting coil 72 is appropriately changed to improve power saving and safety. Can do.

-Modification in Embodiment 1-
(1) In order to accurately control the excitation current I _L flowing through the exciting coil 72, as shown in FIG. 4, it is also possible for the gain variable setting to a DC voltage V ₀ using amplifiers is sufficiently large It is.

  (2) As shown in FIG. 5, it is also possible to directly change the number of windings n by providing a plurality of taps in the exciting coil 72 and switching these taps. For this switching, a mechanical relay or a stationary switching element can be used.

  (3) It is also possible to perform a fatigue test by vibrating the test piece TP using the electromagnetic actuator 12 described so far. That is, in the target signal generator 30 (see FIG. 1), the test force corresponding to the excitation condition is generated by setting the maximum displacement, the maximum speed, and the maximum acceleration when the test piece TP is repeatedly loaded. Is possible.

  (4) The electromagnetic actuator 12 described with reference to FIGS. 1 to 5 can also be used in a microhardness meter for measuring the local hardness of a material to be tested or a substrate.

<Embodiment 2>
The first embodiment described above relates to the configuration and control mode of the material testing machine, but it is also possible to configure the vibration device using the electromagnetic actuator 12 shown in FIGS. That is, it is possible to take out only the electromagnetic actuator 12 and the exciting current control circuit 65 and vibrate a specimen (not shown) through the piston rod 13A. The mounting position of the load cell (not shown) is appropriately set according to the mode of vibration.

  In other words, in the second embodiment, the excitation coil 72 repeatedly applies the test force generated by the electromagnetic actuator 12 having the movable coil 71 and the excitation coil 72 to the specimen (not shown). There is provided an excitation current control circuit 65 that switches between a first excitation mode for generating a magnetic flux density of 2 and a second excitation mode for generating a second magnetic flux density by the excitation coil 72 according to the state of the excitation test. The state of the vibration test is the test conditions for setting the maximum displacement, maximum speed and maximum acceleration applied to the specimen, or the stage during the vibration test preparation stage, the stage during the vibration test, or the stage after the vibration test is completed. Can be specified according to the processing stage.

-Actions and effects of the second embodiment-
(1) According to the second embodiment, in the electromagnetic actuator 12 provided with the excitation coil 72 instead of the permanent magnet, the excitation coil 72 generates the first magnetic flux density at the preparation stage and the end stage of the excitation test. In the test execution stage in which the control is performed and the excitation test is performed, the excitation coil 72 performs excitation control for generating the second magnetic flux density (first magnetic flux density <second magnetic flux density). In addition to eliminating the waste of power consumption caused by the failure, it is possible to prevent the occurrence of an unpredictable excessive test force due to a failure or malfunction.

-Modification in Embodiment 2-

(1) As in the first embodiment, by the output voltage V ₀ which DC voltage source as shown in FIG. 3 to variable amplification, it is possible to vary the magnetic flux density. Further, in order to accurately control the excitation current I _L flowing through the exciting coil 72, as shown in FIG. 4, the DC voltage V ₀ variably setting it is also possible to use the gain is sufficiently large amplifier is there.

  (2) Furthermore, as shown in FIG. 5, it is also possible to directly change the number of windings n by providing a plurality of taps in the exciting coil 72 and switching these taps.

The above description is merely an example, and the present invention is not limited to the above-described embodiments and modifications unless the features of the present invention are impaired.
It is also possible to combine the embodiment and one of the modified examples, or to combine the embodiment and a plurality of modified examples.
It is possible to combine the modified examples in any way.
Furthermore, other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

1 is an overall configuration diagram of a material testing machine using an electromagnetic actuator according to an embodiment of the present invention. 2 is an explanatory diagram showing a schematic configuration of an electromagnetic actuator 12. FIG. 4 is a circuit diagram for controlling the magnitude of a current flowing through an exciting coil 72. FIG. 4 is a circuit diagram for controlling the magnitude of a current flowing through an exciting coil 72. FIG. 4 is a circuit diagram for controlling the magnitude of a current flowing through an exciting coil 72. FIG.

Explanation of symbols

TP Test piece 10 Test machine body 11 Frame 12 Electromagnetic actuator 13A Piston rod 14 Displacement sensor 16 Load sensor 30 Target signal generator 38 Upper gripper 40 Lower gripper 50 Feedback control unit 51 Load amplifier 52 Displacement amplifier 53 Changeover switch 54 Subtraction Unit 55 PID control signal output unit 57 power amplifier 60 feedback control system 65 excitation current control circuit 70 movable unit 71 movable coil 72 excitation coil 73 excitation unit 73
80 Tap switching control circuit

Claims (2)

In a material testing machine for loading a test piece with a test force generated by an electromagnetic actuator having an excitation coil and a moving coil,
A piston rod attached to the moving coil;
In order to generate a thrust force sufficient to move the piston rod up and down in an attaching step of attaching the test piece to the piston rod using a predetermined gripping tool and an ending step of removing the test piece from the piston rod. a first excitation control means for generating a first magnetic flux density by the exciting coil,
A second excitation control means for generating a second magnetic flux density by the excitation coil so that a predetermined test force can be obtained at a stage of performing a test on the test piece ;
A material testing machine comprising: The material testing machine according to claim 1 ,
The first excitation control means and the second excitation control means are applied voltage setting means for controlling magnetic flux density by changing a DC voltage applied to the excitation coil, or a plurality of taps provided in the excitation coil. A material testing machine which is a tap switching means for selecting any one of the above.

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