CN110879171B

CN110879171B - Material testing machine

Info

Publication number: CN110879171B
Application number: CN201910837427.XA
Authority: CN
Inventors: 泷本辽介
Original assignee: Shimadzu Corp
Current assignee: Shimadzu Corp
Priority date: 2018-09-05
Filing date: 2019-09-05
Publication date: 2022-08-19
Anticipated expiration: 2039-09-05
Also published as: JP2020038143A; CN110879171A; JP7103086B2

Abstract

Provided is a material testing machine provided with a dimension measuring device capable of confirming whether foreign matter exists between a pair of dimension measuring indenters during zero point correction before measuring the dimension of a test piece. The size measuring device includes a control unit having a memory, an arithmetic unit, and a communication unit. The size of each test piece measured by the size measuring device is transmitted to the control device via the communication unit. The memory includes a determination unit as a functional block, the determination unit determining whether or not there is a deviation between a zero point at the time of the previous zero point correction and an output value of the gauge at the time of bringing the pair of size measurement indenters into contact with each other before the measurement of the size of the test piece. If it is determined by the function of the determination unit that there is a deviation from the previous zero point, it is suspected that a foreign object is interposed between the sizing indenters, and the control unit sends a test stop command to the control device to terminate the sizing operation.

Description

Material testing machine

Technical Field

The present invention relates to a material testing machine including a dimension measuring device for measuring a dimension of a test piece, among material testing machines for continuously testing a large number of test pieces.

Background

Among material testing machines that perform material tests, there are those called robots that continuously test a large number of test pieces. In such a material testing machine, if a plurality of test pieces are stored in the storage, the test pieces can be automatically and continuously taken out from the storage, the size of the test pieces can be measured, the material test of the test pieces can be performed, the test pieces can be collected, and the test data can be processed (see patent document 1).

The stress generated when a tensile or compressive test force is applied to the test piece is obtained by dividing the test force applied to the test piece by the cross-sectional area of the test piece. The test piece was measured by the following procedure: in order to determine the cross-sectional area of the test piece, the width and thickness of both end portions and the central portion between the standard points of the test piece were measured by a dimension measuring apparatus. The following structure is adopted: a pair of arms each supporting a size measuring indenter is brought close to each other by driving of a motor, and a test piece is held between the pair of size measuring indenters, and the thickness of the test piece is measured by a gauge (see patent document 2).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 9-229836

Patent document 2: japanese patent laid-open publication No. 2011-13061

Disclosure of Invention

Problems to be solved by the invention

Before the measurement of the dimensions of each test piece, the zero point calibration of the gauge was performed by bringing a pair of dimensional measurement indenters into contact with each other. Then, the output value of the zero-point-corrected gauge is the amount of change from the zero point. When the zero point correction is performed in a state where foreign matter (for example, metal chips or the like at the time of processing a test piece) enters between the sizing indenters, the sizing data is deviated by an amount corresponding to the thickness of the foreign matter, and the thickness of the test piece cannot be accurately measured. In a material testing machine called an automaton, since operations of carrying in a test piece to a dimension measuring device, dimension measurement of the test piece in the dimension measuring device, and carrying out of the test piece from the dimension measuring device are automatically performed, even if a foreign substance adheres to a dimension measuring indenter in the middle of a continuously performed material test and zero point correction is performed in a state where a foreign substance exists between a pair of dimension measuring indenters, the test is continued. As a result, the test data includes stress data based on the cross-sectional area calculated with inaccurate dimensions, thereby impairing the accuracy of the material test.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a material testing machine including a dimension measuring device capable of confirming whether or not a foreign object is present between a pair of dimension measuring indenters at the time of zero point calibration before measuring the dimension of a test piece.

Means for solving the problems

A first aspect of the present invention is a material testing machine including a dimension measuring device for measuring a dimension of a test piece, the dimension measuring device including: a pair of sizing indenters in contact with the test strip; a pair of arms that support the pair of sizing indenters, respectively; a drive mechanism that moves the pair of arms toward and away from each other; a detector connected to either one of the pair of arms, for detecting a thickness of the test piece when the test piece is held between the pair of sizing indenters; and a control unit that performs zero-point correction with the output value of the detector when the pair of size measuring indenters are brought into contact with each other as a zero point, wherein the control unit includes a determination unit that determines whether there is a deviation between the output value of the detector when the pair of size measuring indenters are brought into contact with each other before the size of the test piece is measured and the zero point at that time, and when the determination unit determines that there is a deviation between the output value of the detector and the zero point at that time, the control unit does not perform zero-point correction on the output value of the detector and ends the size measuring operation.

The second aspect of the invention further includes a control device that controls a tester main body having a load mechanism that applies a test force to the test piece, and a transport mechanism that transports the test piece from the dimension measurement device to the tester main body, wherein when the determination unit determines that there is a deviation between the output value of the detector when the pair of dimension measurement indenters are brought into contact with each other before the dimension of the test piece is measured and a zero point at that time, the control unit of the dimension measurement device transmits a stop signal to the control device, and the control device stops transport of the test piece by the transport mechanism.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the first aspect of the invention, the dimension measuring device determines whether or not there is a deviation between the output value of the detector when the pair of sizing indenters are brought into contact with each other before the dimension of the test piece is measured and the zero point at that time, and therefore it is possible to confirm whether or not there is a foreign object between the pair of sizing indenters before the zero point correction before the dimension measurement of the test piece is performed. Further, the user can easily know the state where the foreign matter has entered between the size measuring indenters based on the determination result of the determination section. Further, when the output value of the detector when the pair of sizing indenters are brought into contact with each other before the measurement of the size of the test piece deviates from the zero point at that time, the zero point correction is not performed and the sizing operation is ended, so that it is possible to prevent the occurrence of a large deviation in the sizing data. This can prevent an abnormality in the test result due to an abnormality in the dimension measurement data.

According to the second aspect of the invention, when the determination unit of the size measuring device determines that there is a deviation between the output value of the detector when the pair of size measuring indenters are brought into contact with each other before the size of the test piece is measured and the zero point at that time, it is suspected that foreign matter has entered between the size measuring indenters, and therefore a stop signal is transmitted to the control device, and the control device stops the conveyance of the test piece by the conveyance mechanism, and therefore, the automatic operation of the material testing machine can be stopped, and the test result with abnormal output can be prevented from being output. In addition, by stopping the automatic operation, waste of the test piece and waste of the test time can be reduced.

Drawings

Fig. 1 is a schematic diagram of a material testing machine according to the present invention.

Fig. 2 is a block diagram showing a main electrical configuration of the material testing machine including the dimension measuring device 3.

Fig. 3 is a perspective view of the sizing device 3 viewed from obliquely above the right.

Fig. 4 is a schematic cross-sectional view of the periphery of the measurement jig 41 in the measurement device 3.

Fig. 5 is a flowchart illustrating the sizing operation.

Description of the reference numerals

1: a testing machine main body; 2: a storage room; 3: a sizing device; 4: a conveying mechanism; 5: disassembling the device; 11: a crosshead; 12: a frame; 14: an upper clamp; 15: a lower clamp; 16: a load sensor; 17: a control device; 18: a base; 19: a camera; 21: an input display unit; 25: a drive mechanism; 31: a sizing indenter; 32: an upper arm; 33: a lower arm; 34: a checking fixture; 35: a cylinder; 36: a cylinder; 37: a cylinder; 41: a sizing clip; 71: a memory; 72: an image processing unit; 73: a test control unit; 74: a conveying control part; 75: a communication unit; 76: an arithmetic device; 77: a storage device; 80: a control unit; 81: a memory; 82: a determination unit; 83: a motor control unit; 85: a communication unit; 86: an arithmetic device; TP: and (3) testing the test piece.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. Fig. 1 is a schematic diagram of a material testing machine according to the present invention. Fig. 2 is a block diagram showing a main electrical configuration of the material testing machine provided with the dimension measuring device 3.

The material testing machine comprises: a storage 2 for storing a plurality of test pieces TP in a stacked manner; a dimension measuring device 3 for measuring the thickness of the test piece TP; and a tester main body 1 that performs a tensile test. The material testing machine automatically and continuously performs a tensile test on a plurality of test pieces TP by taking out the test pieces TP piece by piece from the storage 2 by the action of a transport mechanism 4 (see fig. 2) such as a robot arm, placing the test pieces TP at a test position of the testing machine main body 1 after passing through the dimension measuring device 3, and performing the test.

A pair of frames 12 are provided upright on a base 18 of the tester body 1, and a pair of screws synchronously rotated by a drive mechanism 25 (see fig. 2) are disposed in the frames 12. The screw is screwed to a nut provided in the crosshead 11, and the crosshead 11 is raised and lowered by the rotation of the screw. The raising and lowering operation of the crosshead 11 is controlled by a controller 17 connected to the tester main body 1.

The tester body 1 has the following structure: the crosshead 11 is connected to an upper jig 14 via a load sensor 16 for detecting a test force, a lower jig 15 is disposed on a base 18, and when both ends of a test piece TP are gripped by the upper jig 14 and the lower jig 15, the crosshead 11 is raised to perform a tensile test on the test piece TP. A camera 19 for measuring the extension of the test piece TP is disposed on the frame 12.

The test piece TP is transported from the storage 2 to a holding position (test position) where the test piece TP is held by an upper chuck 14 and a lower chuck 15 of the tester body 1 by a transport mechanism 4 such as a transport arm or a belt conveyor, the transport mechanism 4 holding the test piece TP by suction with a suction pad. The operation of the conveyance mechanism 4 is controlled by a control device 17.

The control device 17 is connected to the drive mechanism 25 of the tester body 1, the transport mechanism 4 for transporting the test piece TP from the storage 2 to the tester body 1 via the size measuring device 3, the size measuring device 3 for measuring the size of the test piece TP, and the detaching device 5 for detaching the test piece TP after the test from the upper jig 14 and the lower jig 15, and is used for controlling an automatic test for continuously performing a test on a large number of test pieces TP. The control device 17 includes: a memory 71 such as ROM and RAM; an arithmetic device 76 such as an MPU or a CPU; a storage device 77 for storing data such as test results; and a communication unit 75 that communicates with an externally connected device such as the size measuring apparatus 3 according to a predetermined communication protocol. The memory 71, the communication unit 75, the arithmetic device 76, and the storage device 77 are connected to each other via a bus 79. In fig. 2, the programs stored in the memory 71 are represented as functional blocks. The memory 71 includes: an image processing unit 72 that processes the image acquired from the camera 19; a test control unit 73 that generates a control amount of the drive mechanism 25 for moving the crosshead 11 up and down to execute a material test; and a transport controller 74 for controlling the transport mechanism 4 for transporting the test pieces TP.

When the test piece TP is held by the upper and

lower grips

14 and 15, the crosshead 11 is raised under the control of the controller 17 in the tester main body 1, and a tensile load is applied to the test piece TP. The drive mechanism 25 for moving the crosshead 11 functions as a load mechanism of the present invention. The test force at this time is detected by a load sensor 16 disposed in the crosshead 11, and a detection signal thereof is transmitted to the control device 17. The image acquired by the camera 19 is input to the control device 17, and the stretch of the test piece TP obtained by the image processing is displayed on the input display unit 21. The input display unit 21 is a liquid crystal display device provided with a touch panel, and also functions as an input device operated by a user when inputting test conditions.

When the test piece TP breaks, the control of the control device 17 stops the raising of the crosshead 11, and the tensile test is completed. Thereafter, the broken test piece TP held by the upper and

lower grips

14 and 15 is detached from the upper and

lower grips

14 and 15 by the detaching device 5.

Fig. 3 is a perspective view of the sizing device 3 viewed from obliquely right above. In fig. 3, a structure for measuring the thickness of the test piece TP is particularly illustrated. Fig. 4 is a schematic cross-sectional view of the periphery of the size measuring clip 41 in the size measuring apparatus 3.

The size measuring apparatus 3 has the following structure: a pair of size measuring clamps 41 for gripping the test piece TP to measure the thickness of the test piece TP, and an upper arm 32 and a lower arm 33 for supporting the pair of size measuring indenters 31, respectively, are arranged. A pair of sizing clamps 41 are connected to the

air cylinders

36, 37. A gauge 34 used for measuring the thickness of the test piece TP is attached to the upper arm 32. Further, a cylinder 35 is connected to the lower arm 33, and the cylinder 35 is used to raise the lower arm 33, thereby causing the pair of size measuring indenters 31 to sandwich the test piece TP. The pair of sizing jigs 41 are provided with holes through which the pair of sizing rams 31 supported by the upper arm 32 and the lower arm 33 pass, and the tip of the sizing ram 31 on the upper arm 32 side is disposed at the same position as the test piece contact surface of the upper sizing jig 41. The lower arm 33 moves up and down by the operation of the air cylinder 35, and thereby the tip of the sizing ram 31 on the lower arm side moves up and down in the hole of the sizing clamp 41 on the lower side. When the pair of size measuring indenters 31 are caused to grip the test piece TP, the pair of size measuring grips 41 lightly grip the test piece TP by the operation of the

air cylinders

36 and 37, and then the lower arm 33 is raised by the operation of the air cylinder 35 to press the pair of size measuring indenters 31 against the test piece TP.

The gauge 34 is a linear gauge including a sensor for detecting the displacement amount of the spindle and a digital counter, and measures the displacement amount by bringing a measuring piece at the tip of the spindle into contact with an object to be measured. The gauge 34 functions as a thickness detector: by performing zero point correction while the pair of sizing indenters 31 are in contact with each other, the displacement amount from the zero point when the pair of sizing indenters 31 are in contact with the test piece TP is measured as the thickness of the test piece TP. The size measuring ram 31 of the upper arm 32 may also serve as the measuring tool of the gauge 34, or the thickness may be measured by bringing the measuring tool into contact with the test piece TP at a position other than the pair of size measuring rams 31. In the present embodiment, the gauge 34 is connected to the upper arm 32 side, but may be connected to either the upper arm 32 or the lower arm 33.

Referring again to fig. 2, the sizing device 3 includes a control unit 80, and the control unit 80 includes a memory 81 such as a ROM or a RAM, an arithmetic unit 86 such as an MPU or a CPU, and a communication unit 85 that performs data communication with the control device 17. The memory 81, the arithmetic device 86, and the communication unit 85 are connected to each other via a bus 89. The size measuring device 3 is connected to the control device 17, and the measured size of each test piece TP is transmitted to the control device 17 via the communication unit 85. The control unit 80 is connected to the gauge 34 and the cylinder 35. In fig. 2, a program executed by the arithmetic device 86 and stored in the memory 81 is represented as a functional block. The memory 81 includes, as functional blocks, a determination unit 82 and a motor control unit 83, the determination unit 82 determining whether or not there is a deviation between the output value of the gauge 34 when the pair of size measuring indenters 31 are brought into contact with each other before the size of the test piece TP is measured and the zero point at that time, and the motor control unit 83 controlling the operation of the air cylinder 35.

Next, an operation of measuring the size of the test piece TP by the size measuring apparatus 3 configured as described above will be described. Fig. 5 is a flowchart illustrating the sizing operation. The flowchart shown in fig. 5 shows the operation for measuring the size of 1 test piece TP.

When an automatic test for continuously testing a plurality of test pieces TP is started, the size measuring apparatus 3 performs the following steps: it is confirmed whether or not foreign matter is present between a pair of the sizing indenters 31 that contact the test pieces TP in order to measure the thickness of the respective test pieces TP. First, the lower arm 33 is moved closer to the upper arm 32 by driving the air cylinder 35, and the pair of sizing rams 31 are brought into contact with each other (step S1). The output value of the gauge 34 when the pair of sizing rams 31 are brought into contact with each other is input to the control unit 80, and it is determined by the function of the determination unit 82 whether or not there is a deviation from the zero point at the time of the previous zero point correction, that is, the current zero point (whether or not there is a foreign object between the pair of sizing rams 31) (step S2). Before the start of the automatic test, the user wipes the sizing ram 31 with a soft cloth or the like in advance to remove foreign matter and the like, and performs zero point correction at least once before the start of the first sizing operation for the first test piece TP.

A threshold value is set for the zero point, and whether or not there is a foreign object is determined based on whether or not there is a deviation, depending on whether or not the output value of the gauge 34 exceeds the threshold value. Here, as the threshold value, the measurement data in a state where the foreign matter is sandwiched between the size measuring indenters 31 is empirically several μm to several tens μm, and therefore, a value that can be tolerated as a measurement error, for example, a value of 1 μm on the negative side, 5 μm on the positive side, or the like is set in accordance with the material of the test piece TP and the state of processing. If the deviation (difference) between the output value of the gauge 34 and the zero point at that time exceeds the threshold value, it is judged that a foreign object is present because it is suspected that a foreign object is interposed between the sizing rams 31 (step S2). Then, the control unit 80 separates the pair of size measuring heads 31 by moving the lower arm 33 away from the upper arm 32 by driving the air cylinder 35, and transmits a test stop signal to the control device 17 (step S7), thereby ending the size measuring operation.

The control device 17 that has received the test stop signal stops the conveyance of the test piece TP by the conveyance mechanism 4. To stop the automatic test. After that, the control device 17 performs a warning for making the user aware of the test stop as necessary. The warning may be a warning message or error content displayed on the input display unit 21, or may be a warning by voice. Before resuming the test, the user wipes the sizing indenter 31 with a soft cloth or the like to remove foreign matter. After that, the test was restarted.

Before the test piece TP is loaded into the sizing device 3, the pair of sizing rams 31 are brought into contact with each other (step S1), and if there is no deviation between the output value of the gauge 34 and the zero point at that time and it is determined that no foreign matter is present (step S2), the control unit 80 performs zero point correction at the position of the contact (step S3). In the zero point correction, the zero point is updated by setting the value detected in step S2 to zero. That is, the value of the digital counter of the gauge 34 at this time is set to zero. Thereafter, the test piece TP is carried from the storage 2 to the size measuring device 3 by the carrying mechanism 4 (step S4), and size measurement is performed (step S5). In the dimension measurement, the position where the test piece TP is gripped by the dimension measuring clamp 41 is moved in the horizontal direction, whereby the thickness of a plurality of points is measured. Thereafter, the test piece TP is carried out of the size measuring apparatus 3 to the tester body 1 (step S6), and the size measurement of the test piece TP is completed. The dimension measurement data of each test piece TP is transmitted to the control device 17 via the communication unit 85, is stored in the storage device 77 as a part of the test data, and is used for calculation of the stress in the tensile test in the tester main body 1.

In a material testing machine called an automaton, in general, zero point correction is performed before dimension measurement for all test pieces TP one by one from the viewpoint of maintaining the accuracy of the test, and therefore, in the present embodiment, the determination of whether or not foreign matter is present by the determination unit 82 is performed before zero point correction. However, depending on the material, the determination unit 82 may determine whether or not foreign matter is present at a frequency of one test piece TP per several test pieces TP.

In a conventional material testing machine called an automatic machine, there are cases where: the user cannot notice that foreign matter enters between the pair of sizing indenters 31 during zero point calibration, and the tensile test data of the plurality of test pieces TP becomes abnormal values from the middle. In the present invention, since it is checked whether or not the output value of the gauge 34 does not greatly deviate from the zero point before the zero point correction as a function of the dimension measuring device 3, the user can easily notice that a foreign object enters between the pair of dimension measuring indenters 31, and can quickly deal with the problem of maintaining the accuracy of the dimension measuring data used for the stress calculation. In addition, in the present embodiment, since the automatic test is continued without detecting an abnormality, waste of the test piece TP and waste of the test time can be reduced.

In the above-described embodiment, the structure of the tester body 1 supports the tensile test, but the structure is not limited to this. The present invention can be applied to an automatic machine that performs other tests such as a material testing machine that continuously performs a bending test on a plurality of test pieces TP.

Claims

1. A material testing machine having a dimension measuring device for measuring a dimension of a test piece, the material testing machine being characterized in that,

the size measuring device comprises:

a pair of sizing indenters in contact with the test strip;

a pair of arms that support the pair of sizing indenters, respectively;

a drive mechanism that moves the pair of arms toward and away from each other;

a detector connected to one of the pair of arms, the detector detecting a thickness of the test piece when the test piece is held between the pair of size measuring indenters; and

a control unit that performs zero-point correction with the output value of the detector when the pair of sizing indenters are brought into contact with each other as a zero point,

wherein the control unit has a determination unit that determines whether or not there is a deviation between an output value of the detector when the pair of size measuring indenters are brought into contact with each other before the size of the test piece is measured and a zero point at the time when zero point correction was performed last time,

when the determination unit determines that there is a deviation between the output value of the detector and the zero point at that time, the control unit terminates the size measurement operation without performing zero point correction on the output value of the detector.

2. The material testing machine according to claim 1,

the test apparatus further comprises a control device for controlling a test apparatus main body having a load mechanism for applying a test force to the test piece and a transport mechanism for transporting the test piece from the dimension measurement device to the test apparatus main body,

the control unit of the dimension measuring device transmits a stop signal to the control unit when the determination unit determines that there is a deviation between the output value of the detector and a zero point at the time when the pair of dimension measuring indenters are brought into contact with each other before the dimension of the test piece is measured,

the control device stops the conveyance of the test piece by the conveyance mechanism.