JP3526747B2 - 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 provided with a detachment control mode capable of stably positioning a chuck displaced by an actuator when a specimen is attached to and detached from a pair of chucks.

[0002]

[Related Background Art] A material testing machine for measuring a load applied to a specimen such as a metal material and a displacement (elongation) generated in the specimen while applying a load such as compression or tension to the specimen is
Schematically, for example, it is configured as shown in FIG.
That is, in the material testing machine, the specimens S, which are various kinds of samples, are chucked between the frame 2 and the actuator 3 formed of a hydraulic cylinder via the load cell 1.
0, and the actuator 3 is driven by using the pressure oil (hydraulic pressure) applied from the hydraulic pressure source 4 via the servo valve 5, thereby applying a load to the sample S. That is, roughly, the chuck 1 of the tester main body
It is configured to apply a load, displacement, or strain to the sample S mounted between 0 and 10 via a hydraulic servo system.

However, the load (actual load) applied to the sample S by the above load is detected by the load cell 1, and the displacement generated in the sample S by the application of the load is the operation amount of the actuator 3 (displacement amount). ) Is detected by the displacement meter 6, and the strain generated in the sample S due to the application of the load is detected by the strain gauge 7 attached to the sample S. The control unit 8 configured by a microcomputer or the like inputs the loads, displacements, and strains detected as described above, and, for example, the deviation between the actual load detected by the load cell 1 and the load target value is zero (0). The operation of the servo valve 5 is feedback-controlled via the servo amplifier 9 so that With such a feedback control system, the hydraulically driven actuator 3 is servo-controlled to adjust the load (load) or displacement applied to the sample S.

Incidentally, the feedback control system (electrohydraulic servo circuit) for the hydraulic servo valve 5 formed by the control section 8 is selectively operated via a switch 21 which is switched according to a control mode, as shown in FIG. 2, for example. The load control system A and the displacement control system B set to 1 are provided.

The load control system A includes a process (hydraulic servo system) 2 including the servo valve 5 and the actuator 3.
As the control amount in 2, the actual load K applied to the sample S is detected through the detection amplifier 23 (load measuring unit), and the deviation Δe _K from the control target value R _K is detected by the deviation device 24. Looking for. Then, under the control of the controller 25 having a predetermined control gain, the control output value U _K is obtained so that the deviation Δe _K becomes zero (0), and the operation of the process 22 is performed.
Specifically, the displacement amount of the actuator 3 is controlled.

Further, the displacement control system B uses the process 2
As the control amount of 1, the actual displacement H of the actuator 3 is detected via the detection amplifier 26 (displacement measuring unit), and the deviation Δe _H from the control target value R _H is obtained by the deviation device 27.
Then, under the control of the controller 28 having a predetermined control gain, the control value U _{K is} set so that the deviation Δe _H becomes zero (0).
To control the operation of the process 22.

Under such feedback control, for example, the operation (displacement amount) of the actuator 3 is controlled while changing the control target values R _K and R _H to apply a load to the sample S and measure the load. By investigating the relationship between the load and the displacement measured via the section and the displacement measuring section, the material characteristics of the sample S can be obtained.

[0008]

By the way, when the specimen S is mounted between the chucks 10 of the material testing machine constructed as described above, the specimen S is not subjected to an excessive load, and It is important that the specimen S is in a state in which an unintended load is not applied when the mounting is completed. Further, when the test piece S is removed from between the chucks 10 after the test, the load applied to the test piece S is set to zero (0), and the operation of the actuator 3 is displacement-controlled. It is desirable to do it in the state.
For example, the load applied to the sample S is monitored under a displacement control system in which the displacement of the actuator 3 is used as a control amount, and when the load is detected, the target displacement value is set to zero (0). It is desirable to mount the sample S on the chuck 10 or remove it from the chuck 10 while correcting the above.

However, when the rigidity of the test piece S is very high, a large load is likely to be applied to the test piece S even if the chuck 10 is slightly displaced. Therefore, even if the displacement target value is corrected by the minimum correction amount, There is a problem that it becomes difficult to reduce the applied load to zero (0) and the control becomes unstable.

In addition, when the test piece S is broken by a long-term test such as a fatigue test, it is not always zero (0) due to the drift generated in the load measuring section and the weight of the test piece S added to the load cell 1. The load control system may act so as to set the load to zero (0) while detecting the measured load that is not 0). When such a situation occurs, there arises a problem that, for example, broken specimens S collide with each other, or the actuator 3 operates excessively up to the limit of its operating range.

The present invention has been made in consideration of the above circumstances, and its purpose is to control the position of the chuck by controlling the operation of the actuator in order to attach / detach the specimen to / from the tester main body. (EN) Provided is a material testing machine having a control function capable of stably executing the above.

[0012]

In order to achieve the above-mentioned object, the present invention provides a pair of chucks which are provided to face each other and hold a specimen, an actuator for driving one of these chucks back and forth, and this actuator. And a feedback control means for controlling the operation of the actuator in accordance with the load applied to the specimen by the displacement of the actuator or the displacement of the actuator, and in particular, the feedback control means includes the actuator
When you attach and remove the specimen from the chuck by driving
The displacement change of the actuator and the load change applied to the specimen
Means for determining the elasticity change of the specimen from
Displacement control means for controlling the operation of the actuator according to the displacement of the actuator and its target value when the elastic change of the sample is not detected, and the elastic change of the sample.
When the oxidization is detected, the load applied to the specimen becomes zero.
It is characterized in a detachable control and a load control means for controlling operation of the actuator to the provision of the mode so that.

That is, according to the present invention, when controlling the operation of the actuator when the specimen is attached to or detached from the chuck,
If the elasticity change of the specimen is detected ,
The load of the actuator is controlled so that the applied load is zero, and when the elastic change of the specimen is not detected, the actuator is displacement-controlled in accordance with the displacement target value, so that the rigidity of the specimen is concerned. the <br/> the chuck to a predetermined mounting and dismounting position without, easily, and is characterized in that as accurately locate.

According to a preferred aspect of the present invention, as described in claim 2, when the test piece is attached to or detached from the chuck, the displacement control means and the load control means are selected by judging the elastic change of the test piece. It is characterized by operating in. In other words, by monitoring the elasticity change in the specimen, the load state of the specimen can be easily and accurately determined to switch the control mode for the actuator to the load control mode or the displacement control mode described above. I am trying.

Further, when the actuator comprises a ram for displacing the chuck by receiving hydraulic pressure to displace the position of the chuck, the hydraulic servo valve for supplying and discharging the hydraulic pressure to and from the ram is actuated. The feedback control means is realized as an electrohydraulic servo circuit for controlling.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a material testing machine according to an embodiment of the present invention will be described with reference to the drawings, in particular, load control when mounting / removing a specimen between chucks. The material testing machine according to this embodiment is basically configured to control the operation of the actuator 3 to apply a load to the sample S mounted between the chucks 10 as shown in FIG. As a control means, a feedback control system forming an electrohydraulic servo control circuit as shown in FIG. 2 is provided.

The feature of this material testing machine is that the test piece S is attached and detached between the pair of chucks 10, 10.
When the chuck 10 position-controlled by the actuator 3 is positioned at a predetermined chucking position (attachment / detachment position), the operation of the actuator 3 is controlled according to the control procedure shown in FIG. 3, for example. In particular, when executing this control, the displacement of the actuator 3 and thus the displacement of the chuck 10 is monitored, and the load applied to the specimen S mounted between the chucks 10 or 10 or attached to the chuck 10 in accordance with the displacement of the chuck 10. It is characterized in that the control mode is switched to the load control mode or the displacement control mode depending on whether or not the load applied to the sample S changes with the displacement of the actuator 3 while observing.

That is, the attachment / detachment mode set when attaching / detaching the sample S to / from the chucks 10, 10 detects the change in the load while measuring the load applied to the sample S as shown in FIG. At the same time [step S1], while measuring the displacement of the actuator 3 (chuck 10), a change in the displacement (displacement amount) is detected [step S2]. The detection of these load changes and displacement changes is
[Pre-load], [Pre-displacement] measured one sampling cycle before, [Current load], measured at the current sampling time,
This is done by subtracting each [current displacement].
Then, in accordance with the detected load change and displacement change, the specimen S is moved along with the displacement of the actuator 3 as described later.
It is determined whether or not the load applied to [Step S3
~ S6], displacement control [step S7] or load control [step S8] for the actuator 3 is selectively executed.

In the displacement control for the actuator 3, the deviation between the set displacement target value and the actually measured actual displacement of the actuator 3 is set to zero (0), in other words, the displacement of the actuator 3 is changed. This is performed by feedback controlling the operation of the servo valve 5 described above under the displacement control system B so that the displacement target value is obtained. Further, in the load control for the actuator 3, the target load value is set to zero (0), and the deviation from the actual load applied to the sample S according to the displacement of the actuator 3 under the load control system A is calculated, This is done by feedback controlling the operation of the servo valve 5 so that the load becomes zero (0).

The switching between the displacement control and the load control for the actuator 3 is carried out by checking whether the displacement change is zero (0) based on the displacement change obtained as described above, that is, whether the actuator 3 is displaced. It is started to determine whether or not [step S3]. This determination is performed in order to prevent a calculation error in obtaining the elasticity change of the sample S described below, that is, so-called zero crack. Then, the load change obtained as described above is divided by the displacement change, and the elastic change of the sample S is obtained as the calculation result [step S5]. When the displacement of the actuator 3 is not detected, that is, when the actuator 3 is not displaced under the displacement control or the load control described above, the displacement change of the actuator 3 is forcibly set to [1]. S4], which prevents zero cracking in the calculation.

If the elastic change of the sample S is obtained as described above, then it is judged whether or not the elastic change exceeds the preset judgment threshold value α [step S6]. . This determination focuses on the fact that, when a load is applied to the sample S due to the displacement of the actuator 3, the elastic characteristics of the sample S change depending on the load regardless of the rigidity of the sample S. is there. When a load is applied to the sample S based on such determination of elastic displacement, the above-mentioned load control mode is set [step S8], and the actuator is set so that the load is zero (0). 3 load control. On the other hand, in spite of the displacement of the actuator 3, when the load on the sample S is not detected, that is, when the elastic displacement is not detected, the chuck 1 displaced by driving the actuator 3 is moved.
0 has not reached the specified attachment / detachment position, or the specimen S
Since there is no load on the specimen S as a result of the specimen S being broken as shown in the tensile test as a result of the absence of the specimen itself, the displacement control mode described above is set in this case. [Step S7]. Then, the operation of the actuator 3 is controlled under each of these control modes to control the displacement of the actuator 3 and thus the position of the chuck 10.

Thus, according to the present material testing machine that controls the position of the chuck 10 by controlling the operation of the actuator 3 under such a procedure, the test piece S is mounted between the chucks 10 and the test is performed. In order to carry out the operation, when the actuator 3 is operated to position the chuck 10 at a predetermined chucking position, first, a displacement amount up to the chucking position is given as a displacement target value with reference to the initial position (origin position) of the actuator 3. . When the mounting mode is started in this state, the chucks 10, 10 are sufficiently separated from each other at first, so that even if the position of the lower chuck 10 is displaced due to the displacement of the actuator 3, the chuck 10, A load (load) is not applied to the sample S provided between 10 pieces. Therefore, the actuator 3 is displacement-controlled according to the displacement target value.

Then, the lower chuck 10 comes close to the chucking position, and the specimen S is placed between the chucks 10, 10.
In the state of being held, there is a risk that an unintended load is applied to the sample S with the displacement of the actuator 3. However, when such a load is detected from the elasticity change described above, the control for the actuator 3 is switched from the displacement control described above to the load control, and the load is made zero (0), that is, removed. The operation of the actuator 3 is controlled so as to load. As a result, the chuck 10 is positioned at a position where an unintended load is not applied to the sample S. In such an unloaded state, the specimen S is mounted between the chucks 10 and 10. Then, with the above-mentioned unloaded position of the actuator 3 as the measurement origin, the specimen S mounted between the chucks 10, 10
The material test for is started.

On the other hand, when the material test is completed, the position control of the chuck 10 is performed so as to remove the sample S from between the chucks 10, 10. In this case,
Since a predetermined load is applied to the sample S along with the operation of the actuator 3 described above, the operation of the actuator 3 is first controlled so that this load is zero (0). Specifically, from the change in elasticity of the sample S obtained as described above, when the elasticity of the sample S is detected, the load applied to the sample S is set to zero (0). The operation of the actuator 3 is controlled (load control). The position of the actuator 3 when the load becomes zero (0) is set as the position of the chuck 10 for removing the sample S from between the chucks 10, 10, and the sample S is removed in this state.

However, if the test piece S is broken by the tensile test or if the test piece S is crushed by the compression test, the test piece S is no longer used when the operation of the actuator 3 is controlled as described above. Since no load is applied to the sample S and the load itself is not detected, the elasticity change obtained as described above is zero. Therefore, in this case, the displacement control of the actuator 3 is performed according to the preset displacement target value without performing the load control described above, and after the chuck 10 is positioned at the predetermined position,
The specimen S is removed from the chucks 10, 10.

As described above, according to the material testing machine having the control mode in which the operation of the actuator 3 is controlled to attach / detach the sample S between the chucks 10, 10, the sample S is subjected to an undesired load. The sample S can be attached to and removed from the chuck 10 without being added. Particularly, even under the test condition that the rigidity of the sample S is high and a large load is applied to the sample S even if the actuator 3 is slightly displaced, the sample S can be easily and surely mounted. . Then, it becomes possible to perform a highly accurate material test with the unloaded state as the test start condition. Moreover, since the displacement of the actuator 3 is controlled until the load applied to the sample S is detected, the operation of the actuator 3 can be efficiently controlled.

After the material test, the chucks 10, 10
When removing the sample S from the above, since the actuator 3 is displaced to a position where the load applied to the sample S is zero, the removal can be performed smoothly. Further, if the specimen S is fractured or crushed due to the execution of the material test, the displacement control is executed instead of the load control, and the chuck 10 is set at a predetermined position. Even under the circumstances, the specimen S can be easily removed from the chuck 10. That is, when the sample S is broken, only displacement control for the actuator 3 is executed. Therefore, when the specimen S breaks, the load is no longer detected and the load control system runs out of control, which causes the actuator 3 to be excessively displaced, or the specimen S bisected by the fracture collides with each other and breaks. The problem that the cross section is damaged is not caused.

In particular, as described above, the control mode is switched while observing the fracture and crushing of the sample S as the elasticity change in the sample S, so that the operation of the actuator 3 can be appropriately controlled. In addition, it is possible to realize sufficiently accurate operation control of the actuator 3 without setting the resolution of the displacement control to be particularly high and increasing the control gain thereof.

The present invention is not limited to the above embodiment. In the embodiment, the actuator 3 driven by hydraulic pressure is taken as an example of the displacement driving means of the chuck 10 and the operation of the hydraulic servo valve 5 for driving the actuator 3 is feedback-controlled. However, the actuator 3 is moved forward and backward by an electric motor. It is also possible to use a driven cylinder or a moving table mechanism. Further, here, the chuck 10 is moved up and down by the actuator 3, but a pair of chucks 10, 10
Can be similarly applied to a horizontal type material testing machine in which the test pieces S are horizontally opposed to each other and are laterally displaced to apply a load to the sample S.

Further, when the load applied to the specimen S is detected and the control mode is switched from the displacement control to the load control, the judgment threshold value can be set in multiple stages. That is, when only a light load is detected, the above-described displacement control and load control are switched with a control mode in which the displacement target value is only corrected so that the load is zero. Is also possible. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

[0031]

As described above, according to the present invention, the operation of the actuator is controlled in order to mount the specimen on the chuck of the tester main body or to remove the specimen from the chuck after the test is completed. When variably setting the position of, depending on whether or not a load is applied to the specimen during displacement of the actuator, displacement control of the actuator is performed unless a load is detected, and if a load is detected, Since the load of the actuator is controlled so as to remove the load, the position of the actuator, that is, the position of the chuck for attaching / detaching the test piece, can be accurately adjusted without increasing the resolution of displacement control. Can be set well. Therefore, the effect that the controllability of the actuator can be enhanced simply and effectively can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a material testing machine.

FIG. 2 is a diagram showing a schematic configuration of an electrohydraulic servo control system for controlling the operation of a ram.

FIG. 3 is a diagram showing a chuck mode control procedure showing a characteristic control function in the material testing machine according to the embodiment of the present invention.

[Explanation of symbols]

1 load cell 3 actuators 5 servo valve 8 control unit 9 Servo amplifier 10 chuck S specimen A load control system B displacement control system

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-142438 (JP, A) JP-A-11-72422 (JP, A) JP-A-2-302647 (JP, A) JP-A-5- 142127 (JP, A) JP-A-7-55672 (JP, A) JP-A-8-101109 (JP, A) JP-A-63-82339 (JP, A) Jitsukaihei 1-87235 (JP, U) Actual development Sho 59-85937 (JP, U) Actual development Sho 63-92238 (JP, U) Actual development Sho 64-48657 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 3/00-3/62 JISST file (JOIS)

Claims (3)

(57) [Claims] 1. A pair of chucks, which are provided so as to face each other and hold a specimen, an actuator that drives one of these chucks to move forward and backward, a load applied to the specimen by displacement of the actuator, or a load of the actuator. Feedback control means for controlling the operation of the actuator according to the displacement;
And a feedback control means for driving the actuator to supply the chuck.
When attaching and detaching the sample, the displacement change of the actuator
The elasticity change of the specimen can be determined from the change in the load applied to the specimen.
And a displacement control means for controlling the operation of the actuator according to the displacement of the actuator and its target value, when the elastic change of the specimen is not detected, and when the elastic change of the specimen is detected, For the specimen
A mode of attachment / detachment control having a load control means for controlling the operation of the actuator so that the applied load becomes zero
A material testing machine characterized by being equipped . 2. The material testing machine according to claim 1, wherein the displacement control means and the load control means are selectively driven by comparing an elastic change of the specimen with a predetermined determination threshold value. 3. The actuator receives a hydraulic pressure to perform a displacement operation to displace the position of the chuck, and the feedback control means controls the operation of a hydraulic servo valve for supplying and discharging the hydraulic pressure to and from the actuator. 2. The material testing machine according to claim 1, comprising an electro-hydraulic servo circuit that operates.