Material testing machine, control method of material testing machine, control device of material testing machine, and control program of material testing machine

Abstract

To properly determine chuck abnormality during execution of a material test.SOLUTION: A tensile testing machine 1 that performs a tensile test by applying a test force F in a vertical direction to a test piece TP includes a determination unit 513 that determines a chuck abnormality in a gripper 21,22 that grips the test piece TP based on a modulus of elasticity EY of the test piece TP determined by a test force detection value FD in the vertical direction applied to the test piece TP and an elongation detection value ED in the vertical direction of the test piece TP.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a materials testing machine, a control method for a materials testing machine, a control device for a materials testing machine, and a control program for a materials testing machine. [Background technology]

[0002] BACKGROUND ART Conventionally, various techniques relating to grippers have been known for use in material testing machines such as tensile testing machines. For example, Patent Document 1 discloses that the tooth surfaces of the gripping teeth of a gripping tool have coarse file marks in the area that clamps the tip of the test piece, and fine file marks in the area that clamps the side closer to the center of the test piece. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-102692 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it has been difficult to determine chuck abnormalities with conventional material testing machines such as the tensile testing machine described in Patent Document 1.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a materials testing machine that is capable of determining chuck abnormalities, a control method for a materials testing machine, a control device for a materials testing machine, and a control program for a materials testing machine. [Means for solving the problem]

[0006] A material testing machine according to a first aspect of the present invention is a material testing machine that performs a material test by applying a test force in a predetermined direction to a specimen held by a gripping tool, and is equipped with a judgment unit that judges a chuck abnormality in the gripping tool that holds the specimen based on the elastic modulus of the specimen, which is determined by the test force in the predetermined direction applied to the specimen and the amount of deformation of the specimen in the predetermined direction.

[0007] A control method for a materials testing machine according to a second aspect of the present invention is a control method for a materials testing machine that performs a materials test by applying a test force in a predetermined direction to a specimen gripped by a gripping tool, and includes a judgment step of judging a chuck abnormality in the gripping tool that grips the specimen based on the elastic modulus of the specimen, which is determined by the test force in the predetermined direction applied to the specimen and the amount of deformation of the specimen in the predetermined direction.

[0008] A control device for a materials testing machine according to a third aspect of the present invention is a control device for a materials testing machine that performs a materials test by applying a test force in a predetermined direction to a specimen gripped by a gripping tool, and is equipped with a judgment unit that judges a chuck abnormality in the gripping tool that grips the specimen based on the elastic modulus of the specimen, which is determined by the test force in the predetermined direction applied to the specimen and the amount of deformation of the specimen in the predetermined direction.

[0009] A control program for a materials testing machine according to a fourth aspect of the present invention is a control program for a materials testing machine that performs a materials test by applying a test force in a predetermined direction to a specimen gripped by a gripping tool, and causes a processor to function as a judgment unit that judges a chuck abnormality in the gripping tool that grips the specimen based on the elastic modulus of the specimen, which is determined by the test force in the predetermined direction applied to the specimen and the amount of deformation of the specimen in the predetermined direction. [Effects of the Invention]

[0010] The materials testing machine according to the first aspect of the present invention, the control method for the materials testing machine according to the second aspect of the present invention, the control device for the materials testing machine according to the third aspect of the present invention, and the control program for the materials testing machine according to the fourth aspect of the present invention determine a chuck abnormality in a gripping tool that grips a specimen based on the elastic modulus of the specimen, which is determined by the test force applied to the specimen in a predetermined direction and the amount of deformation of the specimen in the predetermined direction. Therefore, chuck abnormalities in the gripping tool can be properly determined. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a tensile testing machine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a main body control device. [Figure 3] FIG. 10 is a side view showing an example of a chuck abnormality. [Figure 4] FIG. 10 is a screen diagram showing an example of a stress-strain curve display screen. [Figure 5] 10 is a flowchart showing an example of processing by the main body control device. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, this embodiment will be described with reference to the drawings.

[0013] [1. Configuration of fatigue testing machine] FIG. 1 is a diagram showing an example of the configuration of a tensile tester 1 according to this embodiment. FIG. 1 shows an X-axis, a Y-axis, and a Z-axis which are perpendicular to each other. The X-axis and the Y-axis are parallel to the horizontal direction. The Z-axis is parallel to the vertical direction. The X-axis indicates the left-right direction. The Y-axis indicates the front-back direction. The Z-axis indicates the up-down direction. The positive direction of the X-axis is the right direction. The positive direction of the Y-axis is the forward direction. The positive direction of the Z-axis is the upward direction.

[0014] The tensile tester 1 of this embodiment applies a test force F in the vertical direction to a test piece TP to perform a tensile test to measure the mechanical properties of the sample. The test force F is, for example, a tensile force. The up and down directions correspond to an example of a "predetermined direction." The tensile testing machine 1 comprises a testing machine main body 2 that applies a test force F to a test piece TP, which is the material to be tested, to perform a tensile test, a control unit 3 that controls the tensile testing operation by the testing machine main body 2, and a display mechanism 60. The test piece TP corresponds to an example of a "specimen." The tensile tester 1 corresponds to an example of a "material testing machine."

[0015] As shown in FIG. 1, the testing machine main body 2 is configured by forming a load frame on a base 26 using a pair of support columns 28 and 29 and a yoke 13, and fixing a crosshead 10 to the support columns 28 and 29.

[0016] A hydraulic actuator 18 is disposed on the base 26, and a lower grip 22 for gripping the lower end of the test piece TP is attached to a piston rod 181 of the hydraulic actuator 18. An upper grip 21 for gripping the upper end of the test piece TP is attached to the crosshead 10 via a load cell 14. The test piece TP is attached to the lower grip 22 and the upper grip 21 so that the central axis of the test piece TP is parallel to the Z axis. The lower gripping tool 22 and the upper gripping tool 21 correspond to an example of a “gripper.” Therefore, in the following description, the lower gripping tool 22 and the upper gripping tool 21 may be referred to as gripping tools 21, 22.

[0017] The hydraulic actuator 18 has its piston rod 181 extended and retracted by a servo valve 20, which controls the direction and amount of pressure oil. As a result, the gap between the upper grip 21 and the lower grip 22 expands and contracts, and a test force F is applied to the test piece TP fixed between the upper grip 21 and the lower grip 22. The stroke of the hydraulic actuator 18, i.e., the displacement of the test piece TP, is detected by a differential transformer 19 attached to the hydraulic actuator 18.

[0018] The load cell 14 is a sensor that measures the test force F, which is the tensile load applied to the test piece TP, and outputs a test force measurement signal SG1 to the control unit 3. The differential transformer 19 is a sensor that measures the displacement amount of the test piece TP and outputs a displacement measurement signal SG2 corresponding to the displacement amount to the control unit 3. The load cell 14 corresponds to an example of a "test force sensor."

[0019] An extension sensor 15 is disposed on the test piece TP. For example, a dumbbell-shaped test piece formed with a constricted center is used as the test piece TP. The extension sensor 15 is a sensor that measures the vertical distance between a pair of reference points on the test piece TP to measure the amount of extension E in the vertical direction and outputs an extension measurement signal SG3 to the control unit 3. The pair of reference points are disposed above and below the constricted region of the test piece TP. The extension sensor 15 corresponds to an example of a "deformation amount detector."

[0020] In this embodiment, a case will be described in which the extension sensor 15 measures the extension amount E, but the extension amount E may also be measured by a camera. In this case, the camera is disposed, for example, in the positive direction of the Y axis with respect to the test piece TP. The camera measures the extension amount E by measuring the distance between the reference points. Reference point marks are formed at the reference points of the test piece TP. The camera measures the extension amount E in the vertical direction by measuring the distance between the reference point marks.

[0021] The control unit 3 includes a signal input / output device 40 and a main body control device 50. The signal input / output device 40 constitutes an input / output interface circuit that transmits and receives signals to and from the testing machine main body 2, and in this embodiment has a first sensor amplifier 42, a second sensor amplifier 43, a third sensor amplifier 45, and a servo amplifier 44.

[0022] The first sensor amplifier 42 is an amplifier that amplifies the test force measurement signal SG1 output by the load cell 14 to generate a test force detection value FD, and outputs the test force detection value FD to the main body control device 50. The second sensor amplifier 43 amplifies the displacement measurement signal SG2 output by the differential transformer 19 and outputs a displacement measurement signal A3 indicating the displacement detection value XD to the main body control device 50 as a digital signal. The third sensor amplifier 45 is an amplifier that amplifies the extension measurement signal SG3 output by the extension sensor 15 to generate an extension detection value ED, and outputs the extension detection value ED to the main body control device 50. The servo amplifier 44 is a device that controls the servo valve 20 under the control of the main body control device 50. The main body control device 50 calculates an instruction value dX based on, for example, the test force detection value FD and the test force target value TF, and transmits an instruction signal A4 indicating the instruction value dX to the servo valve 20. The test force detection value FD corresponds to an example of a "test force in a predetermined direction." The detected elongation value ED corresponds to an example of the "amount of deformation in a predetermined direction."

[0023] Based on operations from the user, the main body control device 50 controls the operation of the testing machine main body 2. Furthermore, the main body control device 50 causes the testing machine main body 2 to carry out a tensile test. In this embodiment, the “user” includes an operator who operates the testing machine main body 2 .

[0024] The main body control device 50 includes a computer having a storage device such as a hard disk drive (HDD) or a solid state drive (SSD), an interface circuit with the signal input / output device 40, and various electronic circuits. An A / D converter is provided in the interface circuit with the signal input / output device 40, and the analog test force measurement signal SG1, displacement measurement signal SG2, and extension measurement signal SG3 are converted into digital signals by the A / D converter.

[0025] The display mechanism 60 is communicably connected to the main body control device 50 and displays various information. The display mechanism 60 also includes a display 61 such as an LCD (Liquid Crystal Display), and the display mechanism 60 displays various images on the display 61.

[0026] [2. Configuration of the main control device] Next, the configuration of the main body control device 50 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the main body control device 50 according to this embodiment. The main body control device 50 is configured by, for example, a personal computer. The main body control device 50 includes a control unit 50A. The control unit 50A also includes a processor 51 and a memory 52. The processor 51 includes a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), and the like. The memory 52 is configured by a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The memory 52 stores a control program 521. The main body control device 50 corresponds to an example of a "control device."

[0027] The main body control device 50 is not limited to a personal computer, and may be configured with one or more appropriate circuits such as integrated circuits such as IC chips and LSIs. The main body control device 50 may also be configured with, for example, a tablet computer or a smartphone.

[0028] As shown in FIG. 2, the control unit 50A includes a test execution unit 511, a calculation unit 512, a determination unit 513, a stop unit 514, a display control unit 515, and a detection result storage unit 522. Specifically, the processor 51 executes a control program 521 stored in the memory 52, thereby functioning as a test execution unit 511, a calculation unit 512, a determination unit 513, a stop unit 514, and a display control unit 515. In addition, the processor 51 executes the control program 521 stored in the memory 52, thereby causing the memory 52 to function as a detection result storage unit 522.

[0029] The detection result storage unit 522 stores the test force detection value FD, the elongation detection value ED, the stress σ, the strain ε, and the elastic modulus EY in association with each other. The test force detection value FD and the elongation detection value ED are acquired by the calculation unit 512 and stored in the detection result storage unit 522 by the calculation unit 512. The stress σ, the strain ε, and the elastic modulus EY are calculated by the calculation unit 512 and stored in the detection result storage unit 522 by the calculation unit 512.

[0030] The test execution unit 511 executes the tensile test. The test execution unit 511 controls the testing machine main body 2, for example, by PID (Proportional-Integral-Differential) control so that the test force detection value FD coincides with the test force target value TF. For example, the test execution unit 511 controls the hydraulic actuator 18 based on the test force detection value FD so that the test force F becomes the test force target value TF. In other words, the test execution unit 511 calculates an instruction value dX based on the test force detection value FD and the test force target value TF, and transmits an instruction signal A4 indicating the instruction value dX to the servo valve 20 of the hydraulic actuator 18.

[0031] In this embodiment, a case will be described in which the test execution unit 511 controls the hydraulic actuator 18 so that the test force detection value FD becomes the test force target value TF, but the embodiment is not limited to this. The test execution unit 511 may also control the hydraulic actuator 18 so that the elongation detection value ED becomes the elongation target value TE, which is the target value for the elongation amount E. Furthermore, the test execution unit 511 may also control the hydraulic actuator 18 so that the displacement detection value XD becomes the displacement target value, which is the target value for the displacement amount. Furthermore, if the test piece TP breaks during the execution of the tensile test, the test execution unit 511 causes the testing machine main body 2 to terminate the execution of the tensile test.

[0032] The calculation unit 512 acquires the test force detection value FD while the tensile test is being performed. The test force detection value FD is a detection value of the test force F applied to the test piece TP by the testing machine main body 2. The calculation unit 512 acquires the test force detection value FD output from the load cell 14 via the first sensor amplifier 42. The calculation unit 512 acquires the test force detection value FD, for example, at a predetermined cycle. The predetermined cycle is, for example, 1 msec. The calculation unit 512 stores the acquired test force detection value FD in the detection result storage unit 522.

[0033] Furthermore, when the calculation unit 512 acquires the test force detection value FD, it calculates the stress σ applied to the test piece TP from the test force detection value FD. The calculation unit 512 calculates the stress σ (N / m 2 ) is calculated. The calculation unit 512 stores the calculated stress σ in the detection result storage unit 522. σ=FD / ST (1) Here, the area ST is, for example, the cross-sectional area between the gauge points of the test piece TP when the test piece TP is not deformed. The area ST is the cross-sectional area of ​​the cross section parallel to the horizontal plane between the gauge points of the test piece TP in FIG. 1. In other words, the area ST is the cross-sectional area of ​​the test piece TP in the initial state between the gauge points in the direction perpendicular to the tensile direction.

[0034] The calculation unit 512 acquires the detected elongation value ED while the tensile test is being performed. The detected elongation value ED is a detected value of the amount of elongation of the test piece TP. The calculation unit 512 acquires the detected elongation value ED output from the elongation sensor 15 via the third sensor amplifier 45. The calculation unit 512 acquires the detected elongation value ED, for example, at a predetermined cycle. The predetermined cycle is, for example, 1 msec. The calculation unit 512 stores the acquired detected elongation value ED in the detection result memory unit 522.

[0035] Furthermore, when the calculation unit 512 acquires the detected elongation value ED, it calculates the strain ε of the test piece TP from the detected elongation value ED. The calculation unit 512 calculates the strain ε, for example, by the following equation (2). The calculation unit 512 also stores the calculated strain ε in the detection result storage unit 522. ε=ED / LT (2) Here, the length LT is, for example, the length between the gauge points of the test piece TP when the test piece TP is not deformed. The length LT is the vertical distance between the two gauge points of the test piece TP in FIG. 1. In other words, the length LT is the distance in a direction parallel to the tensile direction between the two gauge points in the initial state.

[0036] Furthermore, the calculation unit 512 calculates the modulus of elasticity EY of the test piece TP while the tensile test is being carried out. For example, the calculation unit 512 calculates the stress σ and the strain ε and stores them in the detection result storage unit 522, and then calculates the modulus of elasticity EY of the test piece TP. For example, the calculation unit 512 calculates the slope of the stress-strain curve GA by the least squares method based on the multiple stresses σ and multiple strains ε stored in the detection result storage unit 522, and calculates the modulus of elasticity EY (N / m 2 The calculation unit 512 stores the calculated elastic modulus EY in the detection result storage unit 522. The calculation unit 512 calculates an approximate straight line of the multiple stresses σ and multiple strains ε in the stress-strain diagram by the least squares method. The approximate straight line is expressed by the following equation (3). σ=A×ε+B (3) The coefficient A indicates the slope of the approximation line and corresponds to the elastic modulus EY, and the coefficient B indicates the intercept of the approximation line.

[0037] The determination unit 513 determines whether there is a chuck abnormality in the grippers 21, 22 that grip the test piece TP based on the elastic modulus EY. In this embodiment, the determination unit 513 determines whether there is a chuck abnormality in the grippers 21, 22 that grip the test piece TP based on the elastic modulus EY, for example, while a tensile test is being performed. The determination unit 513 determines whether there is a chuck abnormality in the grippers 21, 22, for example, when the calculation unit 512 calculates the elastic modulus EY.

[0038] The determination unit 513 determines a chuck abnormality when the strain ε calculated by the calculation unit 512 is included in the elastic region ARE determined based on the material of the test piece TP. The elastic region ARE is the range of strain ε within which the test piece TP undergoes elastic deformation. In other words, the determination unit 513 does not determine a chuck abnormality when the strain ε calculated by the calculation unit 512 is not included in the elastic region ARE determined based on the material of the test piece TP.

[0039] Furthermore, a determination area ARD may be used instead of the elastic area ARE. The determination area ARD is included in the elastic area ARE. The determination area ARD is a narrower area than the elastic area ARE. The determination area ARD is a range of strain ε within which the determination unit 513 determines whether the chuck is abnormal. In this case, the determination unit 513 determines that there is a chuck abnormality when the strain ε calculated by the calculation unit 512 is included in the determination area ARD. In other words, the determination unit 513 does not determine that there is a chuck abnormality when the strain ε calculated by the calculation unit 512 is not included in the determination area ARD.

[0040] The determination unit 513 determines that a chuck abnormality has occurred when the elastic modulus EY calculated by the calculation unit 512 is greater than a preset upper limit value AM or smaller than a preset lower limit value AN. In the present embodiment, the determination unit 513 determines that a chuck abnormality has occurred when, for example, during a tensile test, the elastic modulus EY calculated by the calculation unit 512 is greater than a preset upper limit value AM or smaller than a preset lower limit value AN. The determination unit 513 determines that a chuck abnormality has occurred when, for example, when the calculation unit 512 calculates the elastic modulus EY of the test piece TP, the elastic modulus EY calculated by the calculation unit 512 is greater than a preset upper limit value AM or smaller than a preset lower limit value AN. The upper limit value AM and the lower limit value AN are set by a user, for example, based on the material of the test piece TP. The "user" is, for example, a requester who requests the execution of a tensile test on the test piece TP using the tensile tester 1. The "user" is, for example, an administrator who manages the execution of a tensile test on the test piece TP using the tensile tester 1 in response to a request from the requester.

[0041] Here, chuck abnormality means that the test piece TP is not properly fixed in the gripping tools 21, 22. Chuck abnormality includes, for example, a case where the test piece TP is fixed in the gripping tools 21, 22 while tilted in the front-to-rear direction. This case will be further explained with reference to FIG. 3. Chuck abnormalities also include cases where the test piece TP slips relative to the gripping tools 21 and 22 during a tensile test. This phenomenon is called "chuck slippage." In this case, the test force detection value FD is temporarily held at a value smaller than the test force target value TF, making it impossible to perform the tensile test normally. Also, in this case, the test force detection value FD is temporarily held at a value smaller than the test force target value TF, so the elastic modulus EY calculated by the calculation unit 512 may become smaller than the lower limit AN. If the elastic modulus EY calculated by the calculation unit 512 becomes smaller than the lower limit AN, the determination unit 513 determines that a chuck abnormality has occurred.

[0042] When the determination unit 513 determines that there is a chuck abnormality while the tensile test is being performed, the stopping unit 514 stops the operation of the tensile test by the tensile tester 1. When the determination unit 513 determines that there is a chuck abnormality, the stopping unit 514, for example, causes the test performing unit 511 to end the performance of the tensile test by the tensile tester 1.

[0043] During the tensile test, the display control unit 515 displays the stress-strain curve GA on the display 61. The stress-strain curve GA is a curve that shows the relationship between the stress σ and the strain ε during the tensile test, where the horizontal axis shows the strain ε and the vertical axis shows the stress σ. The stress strain curve GA is further explained with reference to FIG.

[0044] Furthermore, the display control unit 515 causes the display 61 to display the upper limit AM and lower limit AN of the elastic modulus EY in the display area of ​​the stress-strain curve GA. Furthermore, the display control unit 515 causes the display 61 to display at least one of the elastic region ARE and the judgment region ARD in the display region of the stress-strain curve GA. The upper limit value AM and the lower limit value AN will be further explained with reference to FIG. The elastic area ARE and the decision area ARD will be further explained with reference to FIG.

[0045] Next, a case where the test piece TP is fixed to the gripping tools 21 and 22 in a state inclined in the front-rear direction will be described with reference to Fig. 3. Fig. 3 is a side view showing an example of a chuck abnormality. In Fig. 3, the test piece TP is fixed to the gripping tools 21 and 22 in a state inclined in the front-to-rear direction by an angle θ. The center line CL indicates the center line extending in the up-and-down direction of the gripping tools 21 and 22. The center line CLT indicates the center line extending in the longitudinal direction of the test piece TP. 3, the upper end of the test piece TP is fixed in a position shifted rearward, i.e., in the negative direction of the Y axis, relative to the upper grip 21. Also, the lower end of the test piece TP is fixed in a position shifted forward, i.e., in the positive direction of the Y axis, relative to the lower grip 22. As a result, the test piece TP is fixed between the grips 21 and 22 in a state in which it is tilted forward and backward by an angle θ.

[0046] On the other hand, the extension sensor 15 is configured to measure the extension amount E of the test piece TP in the vertical direction, that is, in the Z-axis direction. Therefore, when the test piece TP is fixed to the gripping tools 21 and 22 while tilted in the forward and backward directions by an angle θ, the elongation amount E detected by the elongation sensor 15 will be smaller than the actual elongation amount ER of the test piece TP.

[0047] The relationship between the amount of elongation E detected by the elongation sensor 15 and the amount of elongation ER of the actual test piece TP is expressed by the following formula (4). E = ER × cos(θ) (4) For example, when the angle θ is 30 degrees, the value of cos(θ) is approximately 0.87. As a result, the elastic modulus EY calculated by the calculation unit 512 becomes larger than the preset upper limit value AM, and the determination unit 513 may determine that the chuck is abnormal.

[0048] [3. Stress-strain curve display screen] Next, a stress-strain curve display screen displayed on the display 61 by the display control unit 515 will be described with reference to Fig. 4. Fig. 4 is a screen diagram showing an example of a stress-strain curve display screen 700. The stress-strain curve display screen 700 is displayed on the display 61 of the display mechanism 60 by the display control unit 515, for example.

[0049] 4, the stress-strain curve display screen 700 includes a graph G1 showing an example of a stress-strain curve GA of the test piece TP. The horizontal axis of the stress-strain curve GA represents the strain ε, and the vertical axis represents the stress σ. The graph G1 is a curve showing the relationship between the stress σ and the strain ε when the test piece TP is subjected to a tensile test.

[0050] As shown in Figure 4, the horizontal axis indicates the elastic region ARE and the plastic region ARP. The elastic region ARE indicates the region of strain ε where the test piece TP undergoes elastic deformation. The plastic region ARP indicates the region of strain ε where the test piece TP undergoes plastic deformation. In this way, the test piece TP undergoes elastic deformation from the start of the tensile test until the strain ε reaches a predetermined value, and then undergoes plastic deformation when the strain ε reaches the predetermined value εC or more. In other words, the material of the test piece TP is such that the test piece TP undergoes elastic deformation from the start of the tensile test until the strain ε reaches the predetermined value εC, and then undergoes plastic deformation when the strain ε reaches the predetermined value εC or more. The material of the test piece TP is, for example, a metal such as iron, aluminum, or titanium.

[0051] As shown in graph G1, in the elastic region ARE, the elastic modulus EY of the test piece TP is constant, so the stress-strain curve GA changes linearly. Also, as shown in graph G1, in the plastic region ARP, the stress-strain curve GA changes to a complex shape.

[0052] As shown in FIG. 4, the horizontal axis indicates the judgment area ARD. The judgment area ARD indicates the range of strain ε at which the judgment unit 513 judges the chuck to be abnormal. The judgment area ARD is included in the elastic area ARE and is narrower than the elastic area ARE. The judgment area ARD is the range of strain ε from a lower limit value to an upper limit value. The lower limit value is greater than "0" and the upper limit value is less than a predetermined value εC. The judgment area ARD is set by a user. The "user" is, for example, a requester who requests the execution of a tensile test on a test piece TP using the tensile tester 1. The "user" is, for example, an administrator who manages the execution of a tensile test on a test piece TP using the tensile tester 1 in response to a request from a requester.

[0053] 4 also shows a line segment LM indicating an upper limit AM of the elastic modulus EY and a line segment LN indicating a lower limit AN of the elastic modulus EY. In FIG. 4, when the strain ε is included in the determination area ARD, the determination unit 513 determines that there is a chuck abnormality. When the elastic modulus EY is greater than the upper limit AM or less than the lower limit AN, the determination unit 513 determines that there is a chuck abnormality.

[0054] FIG. 4 shows graph G2 and graph G3. Graph G2 shows an example of the change in the elastic modulus EY when the test piece TP is fixed between the gripping tools 21 and 22 while tilted in the front-to-rear direction, as described with reference to Fig. 3. As shown in graph G2, the elastic modulus EY calculated by the calculation unit 512 is greater than the upper limit value AM, and the determination unit 513 determines that there is an abnormality in the chuck.

[0055] Graph G3 shows an example of the change in the elastic modulus EY when the test piece TP slips relative to the gripping tools 21, 22 during the tensile test. As shown in graph G3, the elastic modulus EY calculated by the calculation unit 512 is greater than the lower limit AN, and the determination unit 513 determines that there is an abnormality in the chuck.

[0056] In this embodiment, the determining unit 513 determines that the chuck is abnormal when the elastic modulus EY is greater than the upper limit value AM or smaller than the lower limit value AN, but the embodiment is not limited to this.

[0057] The determination unit 513 may determine that the chuck is abnormal, for example, when the strain ε is included in the determination area ARD and the coordinates (ε, σ) constituting the stress-strain curve GA of the test piece TP are not included in the normal area ARK. The coordinates (ε, σ) are defined by the strain ε calculated by the calculation unit 512 from the elongation detection value ED and the stress σ calculated by the calculation unit 512 from the test force detection value FD. As shown in Figure 4, the normal area ARK is a rectangular area defined by the range between the line segment LN indicating the lower limit value AN of the elastic modulus EY and the line segment LM indicating the upper limit value AM of the elastic modulus EY in the strain ε judgment area ARD.

[0058] In this case, since there is no need to calculate the elastic modulus EY, the processing of the main body control device 50 can be simplified.

[0059] [4. Processing of the main control device] Next, the processing executed by the main body control device 50 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing an example of the processing executed by the main body control device 50. 5, the determination unit 513 determines that a chuck abnormality exists when the strain ε is included in the determination region ARD. For convenience, the test execution unit 511 starts the tensile test before step S101.

[0060] 5, first, in step S101, the calculation unit 512 acquires the test force detection value FD output from the load cell 14 via the first sensor amplifier 42. The calculation unit 512 also stores the acquired test force detection value FD in the detection result storage unit 522. Next, in step S103, the calculation unit 512 calculates the stress σ applied to the test piece TP from the test force detection value FD. The calculation unit 512 also stores the calculated stress σ in the detection result storage unit 522.

[0061] Next, in step S105, the calculation unit 512 acquires the detected extension value ED output from the extension sensor 15 via the third sensor amplifier 45. The calculation unit 512 also stores the acquired detected extension value ED in the detection result storage unit 522. Next, in step S107, the calculation unit 512 calculates the strain ε of the test piece TP from the detected elongation value ED. The calculation unit 512 also stores the calculated strain ε in the detection result storage unit 522.

[0062] Next, in step S109, the display control unit 515 causes the display 61 to display the stress-strain curve GA. Next, in step S111, the determination unit 513 determines whether or not the strain ε calculated in step S107 is included in the determination area ARD. If the determination unit 513 determines that the strain ε is not included in the determination area ARD (step S107; NO), the process returns to step S101. If the determination unit 513 determines that the strain ε is included in the determination area ARD (step S107; YES), the process proceeds to step S113.

[0063] Then, in step S113, the calculation unit 512 calculates the slope of the stress-strain curve GA as the elastic modulus EY (N / m2) by the least squares method based on the multiple stresses σ and multiple strains ε stored in the detection result storage unit 522. Next, in step S115, the determining unit 513 determines whether the elastic modulus EY calculated in step S113 is equal to or greater than the lower limit AN and equal to or less than the upper limit AM. If the determining unit 513 determines that the elastic modulus EY is not equal to or greater than the lower limit AN and not equal to or less than the upper limit AM (step S115; NO), the process proceeds to step S117. Then, in step S117, the determination unit 513 determines that the chuck is abnormal, and the stopping unit 514 causes the test execution unit 511 to stop the operation of the tensile test by the testing machine main body 2 and terminate the execution of the tensile test by the testing machine main body 2. Thereafter, the processing ends.

[0064] If the determining unit 513 determines that the elastic modulus EY is equal to or greater than the lower limit AN and equal to or less than the upper limit AM (step S115; YES), the process proceeds to step S119. Then, in step S119, the determining unit 513 determines that there is no chuck abnormality, and causes the test executing unit 511 to continue the operation of the testing machine main body 2 to perform the tensile test.

[0065] Next, in step S121, the test execution unit 511 determines whether the tensile test has ended. If the test execution unit 511 determines that the tensile test has not been completed (step S121; NO), the process returns to step S101. If the test execution unit 511 determines that the tensile test has been completed (step S121; YES), the process then ends.

[0066] Step S115 corresponds to an example of a "determination step."

[0067] [5. Aspects and Effects] It will be understood by those skilled in the art that the above-described embodiment is a specific example of the following aspects.

[0068] (Section 1) The material testing machine according to this embodiment is a material testing machine that applies a test force in a predetermined direction to a specimen held by a gripping tool to perform a material test, and is equipped with a judgment unit that judges a chuck abnormality in the gripping tool that holds the specimen based on the elastic modulus of the specimen, which is determined by the test force in the predetermined direction applied to the specimen and the amount of deformation of the specimen in the predetermined direction.

[0069] According to the material testing machine described in paragraph 1, chuck abnormalities in the gripping tool that grips the test specimen are determined based on the elastic modulus of the test specimen, which is determined by the test force applied to the test specimen in a specified direction and the amount of deformation of the test specimen in the specified direction. Therefore, chuck abnormalities can be properly determined.

[0070] (Section 2) In the material testing machine described in paragraph 1, the judgment unit judges that the chuck is abnormal if the elastic modulus is greater than a preset upper limit value or smaller than a preset lower limit value.

[0071] According to the material testing machine described in paragraph 2, if the modulus of elasticity is greater than a preset upper limit value or less than a preset lower limit value, it is determined that the chuck is abnormal. Therefore, by setting the upper and lower limits to appropriate values, chuck abnormalities can be determined appropriately.

[0072] (Section 3) The material testing machine according to paragraph 1 or 2 further comprises a stopping unit that stops the operation of the material test when the determining unit determines that there is a chuck abnormality while the material test is being performed.

[0073] According to the material testing machine described in paragraph 3, when a chuck abnormality is determined during the material test, the operation of the material test is stopped. Therefore, the specimen can be prevented from undergoing plastic deformation, and the specimen determined to have a chuck abnormality can be reused for material testing.

[0074] (Section 4) The material testing machine described in paragraph 1 is equipped with a test force sensor that detects the test force and a deformation amount detector that detects the deformation amount, and is equipped with a calculation unit that, during the material test, calculates the stress applied to the specimen from the test force, calculates the strain of the specimen from the deformation amount, and calculates the slope of the stress-strain curve as the elastic modulus based on the stress and the strain using the least squares method.

[0075] According to the material testing machine described in paragraph 4, the stress applied to the specimen is calculated from the test force, the strain of the specimen is calculated from the deformation amount, and the slope of the stress-strain curve is calculated as the elastic modulus based on the stress and strain using the least squares method. Therefore, the elastic modulus of the test specimen can be calculated appropriately.

[0076] (Section 5) In the material testing machine described in paragraph 4, the judgment unit judges that the chuck is abnormal when the detected value of the strain is included in an elastic region determined based on the material of the test piece.

[0077] According to the material testing machine described in paragraph 5, if the detected value of strain is included in the elastic region determined based on the material of the test piece, a chuck abnormality is determined. Therefore, the chuck abnormality is judged based on the elastic modulus while the test piece is in a state of elastic deformation, and therefore the chuck abnormality can be judged appropriately.

[0078] (Section 6) The material testing machine according to claim 4 or 5 further comprises a display control unit that displays the stress-strain curve while the material test is being performed.

[0079] According to the material testing machine described in paragraph 6, a stress-strain curve is displayed while a material test is being carried out. This allows the user to visually check the stress-strain curve while the material test is being carried out, thereby improving user convenience.

[0080] (Section 7) In the material testing machine described in item 6, the display control unit displays the upper limit and lower limit of the elastic modulus in the display area of ​​the stress-strain curve.

[0081] According to the material testing machine described in item 7, the upper and lower limits of the elastic modulus are displayed in the display area of ​​the stress-strain curve. Therefore, by comparing the stress-strain curve with the upper and lower limits of the modulus of elasticity during a material test, the user can visually identify any abnormalities in the chuck, thereby improving user convenience.

[0082] (Section 8) The control method for a materials testing machine according to this embodiment is a control method for a materials testing machine that applies a test force in a predetermined direction to a specimen gripped by a gripping tool to perform a materials test, and includes a judgment step of judging a chuck abnormality in the gripping tool that grips the specimen based on the elastic modulus of the specimen, which is determined by the test force in the predetermined direction applied to the specimen and the amount of deformation of the specimen in the predetermined direction.

[0083] According to the control method for a materials testing machine described in paragraph 8, the same effects as those of the materials testing machine described in paragraph 1 can be achieved.

[0084] (Section 9) The control device of a materials testing machine in this embodiment is a control device for a materials testing machine that performs a materials test by applying a test force in a predetermined direction to a specimen gripped by a gripping tool, and is equipped with a judgment unit that judges a chuck abnormality in the gripping tool that grips the specimen based on the elastic modulus of the specimen, which is determined by the test force in the predetermined direction applied to the specimen and the amount of deformation of the specimen in the predetermined direction.

[0085] According to the control device for a materials testing machine described in paragraph 9, the same effects as those of the materials testing machine described in paragraph 1 can be achieved.

[0086] (Section 10) The control program for a materials testing machine according to this embodiment is a control program for a materials testing machine that applies a test force in a predetermined direction to a specimen held by a gripping tool to perform a materials test, and causes a processor to function as a judgment unit that judges a chuck abnormality in the gripping tool that holds the specimen based on the elastic modulus of the specimen, which is determined by the test force applied to the specimen in the predetermined direction and the amount of deformation of the specimen in the predetermined direction.

[0087] According to the control program for a materials testing machine described in paragraph 10, the same effects as those of the materials testing machine described in paragraph 1 can be achieved.

[0088] [6. Other embodiments] The tensile testing machine 1 according to this embodiment is merely an example of an embodiment of a material testing machine according to the present invention, and can be modified and applied as desired within the scope of the present invention.

[0089] In this embodiment, a case will be described in which the material testing machine is a tensile testing machine 1, but the embodiment is not limited to this. The material testing machine may apply a load to a test piece and perform a material test to measure the mechanical properties of the test piece. For example, the material testing machine may be a compression testing machine, a fatigue testing machine, or a torsion testing machine.

[0090] In addition, in this embodiment, a case where the specimen is a test piece TP will be described, but the embodiment is not limited to this. The specimen may be, for example, a plate-like member that is not machined into a dumbbell shape, or a cylindrical member.

[0091] Furthermore, in the present embodiment, the determination unit 513 determines whether there is a chuck abnormality in the grips 21, 22 that grip the test piece TP based on the elastic modulus EY while the tensile test is being performed, but the embodiment is not limited to this. The determination unit 513 may determine whether there is a chuck abnormality in the grips 21, 22 that grip the test piece TP based on the elastic modulus EY. For example, the determination unit 513 may determine whether there is a chuck abnormality in the grips 21, 22 that grip the test piece TP based on the elastic modulus EY before the tensile test is performed. In this case, a test force F that elastically deforms the test piece TP may be applied before the tensile test is performed.

[0092] In addition, in the present embodiment, the tensile tester 1 is described as having the main body control device 50 and the display mechanism 60 as separate bodies, but the embodiment is not limited to this. For example, the main body control device 50 and the display mechanism 60 may be configured as an integrated body.

[0093] In addition, in the present embodiment, the case where the main body control device 50 includes the test execution unit 511, the calculation unit 512, the determination unit 513, the stop unit 514, the display control unit 515, and the detection result storage unit 522 has been described, but the embodiment is not limited to this. For example, the display mechanism 60 may include at least one of the calculation unit 512, the determination unit 513, the stop unit 514, the display control unit 515, and the detection result storage unit 522. For example, the display mechanism 60 may include the display control unit 515.

[0094] 2 indicates a functional configuration, and the specific implementation form is not particularly limited. In other words, it is not necessary to implement hardware corresponding to each functional unit individually, and it is of course possible to implement a configuration in which a single processor executes a program to realize the functions of multiple functional units. Furthermore, some of the functions realized by software in the above embodiments may be realized by hardware, or some of the functions realized by hardware may be realized by software.

[0095] 5 are divided according to the main processing content to make it easier to understand the processing of the main body control device 50. There is no limitation to the way the processing units are divided or the names shown in the flowchart of FIG. 5, and the processing units can be divided into more processing units depending on the processing content, or one processing unit can be divided to include more processes. Furthermore, the processing order of the above flowchart is not limited to the example shown in the figure.

[0096] 2, in this embodiment, the processor 51 included in the main body control device 50 executes a control program 521 stored in the memory 52. ​​This control program 521 can also be recorded on a computer-readable recording medium. The recording medium can be a magnetic or optical recording medium or a semiconductor memory device. Specifically, examples include portable or fixed recording media such as flexible disks, HDDs, CD-ROMs (Compact Disk Read Only Memory), DVDs, Blu-ray (registered trademark) discs, magneto-optical disks, flash memories, and card-type recording media. The recording medium may also be a non-volatile storage device such as RAM, ROM, or HDD, which is an internal storage device provided in the main control device 50. The control program 521 may also be stored in a server device or the like, and the control program 521 may be downloaded from the server device to the main control device 50. [Explanation of symbols]

[0097] 1. Tensile testing machine (material testing machine) 2 Testing machine body 3. Control Unit 14 Load cell (test force sensor) 15 Expansion sensor (deformation detector) 18 Hydraulic Actuator 19 Differential transformer 20 Servo valve 21 Upper grip (part of grip) 22 Lower gripper (part of gripper) 40 Signal input / output device 50 Main control device (control device) 50A control unit 51 processors 511 Testing Department 512 Calculation Unit 513 Judgment section 514 Stop part 515 Display control unit 52 memory 521 Control Program 522 detection result storage unit 60 Display mechanism 61 Display AM upper limit AN lower limit ARE Elastic Area ARD judgment area ED Elongation detection value (deformation amount) EY Elastic Modulus FD Test force detection value (test force) TP test piece (specimen) σ stress ε strain

Claims

1. A material testing machine that performs a material test by applying a test force in a predetermined direction to a specimen gripped by a gripping tool, a determination unit that determines a chuck abnormality in a gripping tool that grips the specimen based on the elastic modulus of the specimen, which is determined by the test force applied to the specimen in the predetermined direction and the deformation amount of the specimen in the predetermined direction, Material testing machine.

2. The determination unit determines that the chuck is abnormal when the elastic modulus is greater than a preset upper limit value or less than a preset lower limit value.

2. The material testing machine according to claim 1.

3. a stopping unit that stops the operation of the material test when the determining unit determines that the chuck is abnormal during the material test; 3. A material testing machine according to claim 1 or 2.

4. a test force sensor for detecting the test force; a deformation amount detector that detects the deformation amount; Equipped with a calculation unit that calculates a stress applied to the specimen from the test force during the material test, calculates a strain of the specimen from the deformation amount, and calculates a slope of a stress-strain curve as the elastic modulus by a least squares method based on the stress and the strain; 2. The material testing machine according to claim 1.

5. the determination unit determines that the chuck is abnormal when the detected value of the strain is included in an elastic region determined based on the material of the test piece.

5. A material testing machine according to claim 4.

6. a display control unit that displays the stress-strain curve while the material test is being performed; 6. A material testing machine according to claim 4 or claim 5.

7. the display control unit displays an upper limit value and a lower limit value of the elastic modulus in a display area of ​​the stress-strain curve.

7. A material testing machine according to claim 6.

8. A method for controlling a materials testing machine that applies a test force in a predetermined direction to a specimen gripped by a gripper to perform a materials test, comprising: a determination step of determining a chuck abnormality in a gripping tool that grips the specimen based on an elastic modulus of the specimen determined by a test force applied to the specimen in the predetermined direction and a deformation amount of the specimen in the predetermined direction, How to control a materials testing machine.

9. A control device for a materials testing machine that applies a test force in a predetermined direction to a specimen gripped by a gripper to perform a materials test, a determination unit that determines a chuck abnormality in a gripping tool that grips the specimen based on the elastic modulus of the specimen, which is determined by the test force applied to the specimen in the predetermined direction and the deformation amount of the specimen in the predetermined direction, Material testing machine control device.

10. A control program for a materials testing machine that applies a test force in a predetermined direction to a specimen gripped by a gripper to perform a materials test, The processor, a determination unit that determines a chuck abnormality in a gripping tool that grips the specimen based on the elastic modulus of the specimen, which is determined by the test force applied to the specimen in the predetermined direction and the deformation amount of the specimen in the predetermined direction; Control program for materials testing machine.

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