Video-type non-contact extensometer and material testing machine

Abstract

To provide a video type non-contact extensometer that can easily and accurately adjust a position of a camera so that a distance between the camera and a specimen is a predetermined distance regardless of an operator.SOLUTION: A video type non-contact extensometer comprises a camera that photographs a specimen marked with marked lines at predetermined intervals. The video type non-contact extensometer measures the elongation of the specimen from the displacement of the marked lines based on photographic data photographed by the camera in a state where the position of the camera is adjusted so that a distance to the specimen becomes a predetermined distance. The video type non-contact extensometer comprises a rangefinder that is provided integrally with the camera and measures the distance to the specimen in a non-contact manner.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a video type non-contact extensometer and a material testing machine. [Background technology]

[0002] BACKGROUND ART Conventionally, a video-type non-contact extensometer that measures the elongation of a test specimen in a material testing machine has been known (see, for example, Patent Document 1). In such a video-type non-contact extensometer, for example, marked lines are placed at a predetermined interval on the surface of a test specimen, and the marked lines are photographed with a camera when a test load is applied to the test specimen. The displacement of the gauge line distance is calculated based on the photographic data of the marked lines photographed by the camera, thereby measuring the elongation of the test specimen. Here, the position of the marked lines in the photographic data is based on the position on the camera's image sensor where the marked lines are imaged by the camera lens. Therefore, if the distance between the camera and the test specimen changes, the position of the marked lines in the photographic data also changes. Therefore, a video-type non-contact extensometer is generally calibrated based on a predetermined distance, and the marked lines are photographed with the camera positioned so that the distance between the camera and the test specimen is the predetermined distance. Regarding the adjustment of the camera position, Patent Document 1 discloses that the camera is positioned relative to the test piece by adjusting the fixing position of the arm on the support and the bending degree of the arm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-47465 Summary of the Invention [Problem to be solved by the invention]

[0004] Even if a test specimen is formed to a predetermined standard, there is actually variation based on significant figures. For example, consider a case where a steel bar, as an example of a test specimen, has a predetermined diameter. In this case, when the steel bar is set in the testing machine body, the center position of the steel bar can be considered constant regardless of the steel bar, but the diameter of the steel bar varies based on significant figures. For this reason, the distance between the surface of the steel bar and the camera tends to vary for each steel bar, which can easily lead to errors in measuring elongation. Therefore, when measuring the elongation of a test specimen, it is desirable to measure the test specimen for each test specimen and adjust the position of the camera according to the measurement results.

[0005] However, in the configuration described in Patent Document 1, the camera position is adjusted by moving the camera in accordance with the graduations on a scale, etc. Therefore, the work of measuring each test object and adjusting the camera position in accordance with the graduations can easily become cumbersome. Furthermore, in a configuration where the camera is adjusted to a scale, some workers may easily misread the scale, which may prevent them from adjusting the camera position with high precision. The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a video-type non-contact extensometer that makes it easy for anyone, regardless of the operator, to easily and accurately adjust the position of the camera so that the distance between the camera and the test piece is a predetermined distance. [Means for solving the problem]

[0006] A first aspect of the present invention is a video-type non-contact extensometer that includes a camera that photographs a test specimen having marked lines at predetermined intervals, and measures the elongation of the test specimen from the displacement of the marked lines based on photographic data captured by the camera while the camera is positioned so that the distance to the test specimen is a predetermined distance, a support bar having a longitudinal shape extending in a direction approaching and moving away from the test specimen; a movement mechanism supported by the support bar, the movement mechanism including a movement member supported so as to be movable in the longitudinal direction of the support bar; and the camera fixed to the movement member. a range finder that is provided integrally with the camera and that measures the distance to the test piece in a non-contact manner; a display unit that is provided integrally with the camera and that displays the measured distance; Equipped with The moving mechanism includes a position adjustment screw that moves the moving member toward and away from the test piece relative to the support bar. This relates to a video-type non-contact extensometer.

[0007] A second aspect of the present invention is a materials testing machine comprising: a testing machine main body that applies a test load to a test specimen; a camera that photographs the test specimen having marked lines at predetermined intervals; and a video-type non-contact extensometer that measures the elongation of the test specimen from the displacement of the marked lines based on photographic data taken by the camera while the camera is positioned so that the distance to the test specimen is a predetermined distance; a support bar having a longitudinal shape extending in a direction approaching and moving away from the test specimen; a movement mechanism supported by the support bar, the movement mechanism including a movement member supported so as to be movable in the longitudinal direction of the support bar; and the camera fixed to the movement member. a range finder that is provided integrally with the camera and that measures the distance to the test piece in a non-contact manner; a display unit that is provided integrally with the camera and that displays the measured distance; The video type non-contact extensometer is provided with The moving mechanism includes a position adjustment screw that moves the moving member toward and away from the test piece relative to the support bar. Regarding material testing machines. [Effects of the Invention]

[0008] According to the first and second aspects of the present invention, since a rangefinder is integrally provided on the camera, it is easy for any operator to easily and accurately adjust the position of the camera so that the distance between the camera and the test piece is a predetermined distance. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a front view of a material testing machine according to an embodiment. [Figure 2] FIG. 1 is a plan view of a material testing machine according to an embodiment. [Figure 3] FIG. 1 is a diagram showing the main parts of a video-type non-contact extensometer. [Figure 4] FIG. 1 is a view of the main parts of a video-type non-contact extensometer as seen from the test specimen side. [Figure 5] FIG. 2 is a diagram schematically illustrating an X-axis stage. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] [1. Embodiment] Fig. 1 is a front view of a material testing machine 1 according to an embodiment, and Fig. 2 is a plan view of the material testing machine 1 according to an embodiment. The material testing machine 1 according to the embodiment is a material testing machine capable of applying a test load to a test piece T whose ends are gripped by upper and lower gripping tools 18 and 19 in a tensile direction, which is the direction in which the distance between the upper and lower gripping tools 18 and 19 widens.

[0012] The material testing machine 1 of this embodiment comprises a testing machine main body 10 that applies a test load to a test specimen T, a video-type non-contact extensometer 30 that measures the elongation of the test specimen T to which a test load is applied by the testing machine main body 10, and a control device 100 that controls the testing machine main body 10 and the like.

[0013] The testing machine main body 10 has a base 11 that is placed on the floor. A ram cylinder 12 is arranged on the base 11. The ram cylinder 12 has a ram 12A that can be raised and lowered by hydraulic pressure. A hydraulic source (not shown) is connected to the ram cylinder 12. The hydraulic pressure inside the ram cylinder 12 is measured by a pressure cell (not shown) and input to the control device 100. A rectangular plate-shaped table 13 is fixed to the upper end of the ram 12A. The table 13 can be raised and lowered by the ram cylinder 12.

[0014] As shown in Fig. 2, a pair of support columns 14 are arranged in a first diagonal direction on the table 13. An upper crosshead 15 extending in the width direction is supported across the tops of the pair of support columns 14. The pair of support columns 14 and the upper crosshead 15 rise and fall together with the table 13.

[0015] The table 13 has a pair of through holes (not shown) formed in the thickness direction in the second diagonal direction. A threaded rod 16 extending in the vertical direction is inserted into each of these through holes. The threaded rod 16 is erected on the base 11 below the table 13. A lower crosshead 17 extending in the width direction is hung across the threaded rod 16 above the table 13. The lower crosshead 17 is supported by the threaded rod 16 via a nut (not shown). When this nut is rotated by a drive source (not shown), the lower crosshead 17 moves up and down along the threaded rod 16. This allows the height of the lower crosshead 17 to be set.

[0016] The upper crosshead 15 and the lower crosshead 17 are provided with grippers 18 and 19 for gripping the test specimen T, respectively. With the lower crosshead 17 set to a predetermined height and both ends of the test specimen T gripped by the grippers 18 of the upper crosshead 15 and the grippers 19 of the lower crosshead 17, the table 13 is moved upward, whereby the upper crosshead 15 rises relative to the lower crosshead 17 and a tensile load is applied to the test specimen T. As the test specimen T, for example, a test piece, a steel bar, a deformed steel bar, etc. may be used.

[0017] In the testing machine main body 10 according to this embodiment, an upper compression platen 20 is provided on the lower surface of the lower crosshead 17, and a lower compression platen 21 is provided on the upper surface of the table 13. A test specimen T, such as concrete, is sandwiched between the upper compression platen 20 and the lower compression platen 21, and by moving the table 13 upward, a load can be applied to the test specimen T in the compressive direction.

[0018] Fig. 3 is a diagram showing the main parts of the video non-contact extensometer 30. In Fig. 3, the main parts of the video non-contact extensometer 30 are viewed from the side of the materials testing machine 1. Fig. 4 is a diagram showing the main parts of the video non-contact extensometer 30 as viewed from the side of the test specimen T. The video-type non-contact extensometer (hereinafter referred to as "extensometer") 30 is equipped with cameras 51 and 52 that photograph a test specimen T, which has benchmark lines M1 and M2 attached at a predetermined interval. When a load is applied to the test specimen T by the testing machine main body 10, the extensometer 30 photographs the benchmark lines M1 and M2 of the test specimen T with the cameras 51 and 52, detects the positions of the benchmark lines based on the photographic data captured by the cameras 51 and 52, and measures the elongation of the test specimen T from the displacement of the benchmark lines M1 and M2. The benchmark lines M1 and M2 are provided on the test piece T by attaching a sticker bearing a mark indicating the benchmark lines M1 and M2 to the test piece T.

[0019] The extensometer 30 according to this embodiment has a pole 31 that extends in the vertical direction. The pole 31 is fixed to, for example, the floor surface. A support bar 32 that extends in the horizontal direction is supported on the pole 31. The support bar 32 is formed in a rectangular tubular shape. The support bar 32 is fixed to the pole 31 via a clamper 33. The clamper 33 is configured to be movable in the vertical direction along the pole 31 and rotatable around the pole 31. The support bar 32 is also slidable in the horizontal direction relative to the clamper 33. The clamper 33 is fixed to the pole 31 by operating a lever 33A of the clamper 33. This fixes the vertical position of the support bar 32 while preventing it from rotating relative to the pole 31. The support bar 32 is also fixed to the pole 31 at a predetermined longitudinal position.

[0020] The camera unit 50 is supported at a first longitudinal end of the support bar 32. The weight 34 is supported at a second longitudinal end of the support bar 32. The weight 34 allows the center of gravity of the weight applied to the support bar 32 to be closer to the pole 31. The weight 34 allows the elongated support bar 32 to extend horizontally, making it easier to fix the support bar 32 to the pole 31 in a stable state.

[0021] FIG. 5 is a diagram showing a schematic diagram of the X-axis stage 40. As shown in FIG. 4 and 5, an X-axis stage 40, which is an example of a movement mechanism, is provided at a first longitudinal end of the support bar 32. The X-axis stage 40 is configured to be movable in a linear direction in the horizontal direction toward and away from the test piece T. In the following, the horizontal direction toward and away from the test piece T will be referred to as the front-to-rear direction. Furthermore, the direction in which the cameras 51 and 52 move away from the test piece T will be referred to as the front, and the direction in which the cameras 51 and 52 approach the test piece T will be referred to as the rear.

[0022] The X-axis stage 40 has a housing 41. The housing 41 is fixed to the lower surface of the support bar 32. A moving stage 42, which is an example of a moving member, is supported in the housing 41 so as to be movable in the front-rear direction. In this embodiment, a dovetail groove 41A (see FIG. 4) is formed in the housing 41, and the moving stage 42 is configured to be movable in the front-rear direction along the dovetail groove 41A.

[0023] A position adjustment screw 43 is provided on the housing 41. The position adjustment screw 43 includes a knob portion 43A and a threaded shaft portion 43B extending forward from the knob portion 43A. The position adjustment screw 43 is rotatably supported by the housing 41. The position adjustment screw 43 is supported so as to be immovable relative to the housing 41 in the axial direction of the position adjustment screw 43, i.e., the front-to-rear direction. The threaded shaft portion 43B of the position adjustment screw 43 is fitted into a threaded hole 42B of the moving stage 42. The threaded hole 42B is formed in a columnar threaded hole portion 42A provided in the moving stage 42. When an operator grips the knob portion 43A and rotates the position adjustment screw 43 forward or backward, the moving stage 42 moves forward or backward.

[0024] A position fixing screw 44 is provided on the housing 41. The position fixing screw 44 includes a knob portion 44A and a threaded shaft portion 44B extending from the knob portion 44A. The threaded shaft portion 44B extends in a direction intersecting the threaded shaft portion 43B of the position adjustment screw 43. The threaded shaft portion 44B is threaded into the housing 41, and the tip of the threaded shaft portion 44B is configured to be able to move toward and away from the moving stage 42. When an operator grips the knob portion 44A and screws in the position fixing screw 44, the threaded shaft portion 44B comes into contact with the moving stage 42, and the position of the moving stage 42 in the front-to-rear direction is fixed.

[0025] A camera unit 50 is integrally supported on the moving stage 42. The camera unit 50 is integrally provided with cameras 51 and 52 and a range finder 53 that measures the distance to the test piece T in a non-contact manner. 3 and 4, camera unit 50 of this embodiment has a pair of upper and lower cameras 51, 52. The pair of upper and lower cameras 51, 52 are fixed to moving stage 42 via a frame 54 extending in the vertical direction. Cameras 51, 52 are supported at both upper and lower ends of frame 54, respectively.

[0026] In this embodiment, the pair of upper and lower cameras 51, 52 have the same configuration. The cameras 51, 52 are arranged with the lenses 51A, 52A facing the test piece T. The pair of upper and lower cameras 51, 52 are arranged so that the distances from the lenses 51A, 52A to the test piece T are the same distance D1. By moving the moving stage 42 with the position adjustment screw 43, the distances to the test piece T for the pair of upper and lower cameras 51, 52 can be set to the same distance D1. Furthermore, the cameras 51, 52 can photograph the marked lines M1, M2 when they are separated by the same distance D1 from the test piece T. Note that the extensometer 30 in this embodiment is calibrated based on a predetermined distance D0. In other words, when the cameras 51, 52 are positioned so that the distance D1 between the cameras 51, 52 and the test piece T is the predetermined distance D0, the positions of the marked lines M1, M2 can be detected with high accuracy.

[0027] The upper camera 51 photographs the specimen T within a predetermined range including the upper marked line M1. The lower camera 52 photographs the specimen T within a predetermined range including the lower marked line M2. As a result, even if the specimen T is extended and the marked lines M1 and M2 move, the marked lines M1 and M2 are photographed by the cameras 51 and 52. The photographed data from the cameras 51 and 52 is transmitted to the control device 100 via a signal cable (not shown).

[0028] The camera unit 50 has a rangefinder 53. The rangefinder 53 measures the distance to the test piece T in a non-contact manner. The rangefinder 53 is fixed to the moving stage 42 via a folded plate-shaped frame 55. More specifically, the frame 55 has a side surface 55A extending along the frame 54. The side surface 55A is disposed to the side of the frame 54, which extends vertically. The rangefinder 53 is fixed to the side surface 55A by a pair of front and rear square frame-shaped fixing members 56, 56. The rangefinder 53 is disposed in the center between the upper camera 51 and the lower camera 52. The rangefinder 53 is provided integrally with the cameras 51, 52 and is provided near the cameras 51, 52. The rangefinder 53 in this embodiment is a laser rangefinder. The rangefinder 53 irradiates the test piece T with laser light L having a small spot diameter and measures the distance to the test piece T based on the reflected laser light L.

[0029] The camera unit 50 includes a digital display 57. The digital display 57 digitally displays the distance measured by the rangefinder 53. The digital display 57 is configured with a liquid crystal display or the like. The digital display 57 is provided integrally with the cameras 51 and 52. In this embodiment, the digital display 57 is provided on the rangefinder 53. The digital display 57 is exposed on the side between the fixing members 56. The operator can recognize the distance from the test specimen T to the camera 51 from the digitally displayed distance. Furthermore, because the digital display 57 is integrated with the cameras 51 and 52, it is easy to align the positions of the cameras 51 and 52 while looking at the digital display 57. In particular, because the position adjustment screw 43 is located near the digital display 57, it is possible to operate the position adjustment screw 43 while looking at the digital display 57. Furthermore, compared to adjusting the positions of the cameras 51 and 52 according to scales, this makes it easier to prevent the operator from making reading errors.

[0030] In this embodiment, the rangefinder 53 is positioned offset forward by a distance D2 relative to the cameras 51 and 52. Here, the digital display unit 57 displays the distance D1+D2 from the rangefinder 53 to the test piece T, but the digital display unit 57 may be configured to display the distance D1 by subtracting the distance D2 from the distance D1+D2.

[0031] Camera unit 50 of this embodiment is made up of cameras 51 and 52, rangefinder 53, frames 54 and 55, fixing member 56, digital display unit 57, etc. Cameras 51 and 52, rangefinder 53, and digital display unit 57 can move in the front-to-rear direction together with moving stage 42. Since moving stage 42 is mounted on the underside of support bar 32, camera unit 50, which tends to be heavy, is mounted below support bar 32.

[0032] A lighting fixture 60 is provided on the opposite side of the support bar 32 from the camera unit 50. The lighting fixture 60 is fixed via a frame 61. The frame 61 is fixed to the upper surface of the support bar 32. The lighting fixture 60 extends in the vertical direction. The lighting fixture 60 illuminates the benchmark lines M1 and M2 of the test piece T. Because the lighting fixture 60 is provided on the opposite side of the support bar 32 from the camera unit 50, the light from the lighting fixture 60 is less likely to be obstructed regardless of the positions of the cameras 51 and 52 of the camera unit 50. A light shielding plate 62 (see FIG. 2) is disposed on the back surface of the testing machine main body 10. The light shielding plate 62 can, for example, prevent indoor illumination light from entering the cameras 51 and 52, thereby preventing erroneous detection of the positions of the marked lines M1 and M2.

[0033] 1, a control device 100 that controls each part of the materials testing machine 1 is arranged next to the testing machine main body 10. The control device 100 is a device that centrally controls the materials testing machine 1, and is connected to the testing machine main body 10 and the extensometer 30 so that signals can be sent and received between them. The signals received by the control device 100 from the testing machine main body 10 and the extensometer 30 include measurement signals for the oil pressure of the ram cylinder 12, video signals from the cameras 51 and 52, and appropriate signals required for control and testing. The signals sent by the control device 100 to the testing machine main body 10 and the extensometer 30 include control signals for the hydraulic cylinder, control signals for a drive source (not shown) for raising and lowering the lower crosshead 17, and other appropriate signals required for control and testing.

[0034] The control device 100 includes a computer, which includes a processor such as a CPU (Central Processing Unit) or MPU (Micro-Processing Unit), a memory device such as a ROM (Read Only Memory) or RAM (Random Access Memory), a storage device such as an HDD (Hard Disk Drive) or SSD (Solid State Drive), and an interface circuit for connecting the control device 100 and various peripheral devices. The processor executes computer programs stored in the memory device or storage device, thereby realizing various functions of the materials testing machine 1.

[0035] In this embodiment, the control device 100 controls the materials testing machine 1 upon receiving an input operation to start a test. That is, the control device 100 controls the testing machine main body 10 to apply a test load to the specimen T. The control device 100 also calculates the elongation of the specimen T. Specifically, the control device 100 acquires video signals, i.e., image data, from the cameras 51 and 52. The control device 100 detects the positions of the benchmark lines M1 and M2 based on the image data. The control device 100 calculates the displacement of the benchmark lines M1 and M2 based on the positions of the benchmark lines M1 and M2 and the positions of the benchmark lines M1 and M2 at the start of the test. The control device 100 also calculates the displacement of the gauge length, i.e., the elongation of the specimen T, based on the initial gauge length, the displacement of the upper gauge length M1, and the displacement of the lower gauge length M2.

[0036] Next, the operation of this embodiment will be described. When measuring elongation with the extensometer 30, the test specimen T is set with its upper and lower ends gripped by grippers 18 and 19. Also, benchmark lines M1 and M2 are marked on the test specimen T at a predetermined interval. The operator adjusts the positions of the cameras 51 and 52 so that the distance D1 between the test object T and the cameras 51 and 52 becomes the preset distance D0.

[0037] Here, in the extensometer 30, the distance D1 between the test specimen T and the cameras 51, 52 has a significant effect on the measurement accuracy. For example, if the preset distance D0 is set to 500 mm and the distance D1 between the test specimen T and the cameras 51, 52 deviates from the distance D0 by 1 mm, an error of approximately 1 / 500, or 0.2%, will occur. Therefore, in order to suppress errors in measurements with the extensometer 30, it is important to accurately align the distance D1 between the test specimen T and the cameras 51, 52 with the calibrated preset distance D0.

[0038] In this embodiment, the rangefinder 53 is provided integrally with the cameras 51 and 52. This allows an operator to easily and accurately recognize the distance D1 between the cameras 51 and 52 and the test piece T using the rangefinder 53. This makes it easier for an operator to align the cameras 51 and 52 while recognizing whether the distance D1 between the cameras 51 and 52 and the test piece T is equal to the distance D0 based on the rangefinder 53, and makes it easier to adjust the positions of the cameras 51 and 52 so that the distance D1 between the cameras 51 and 52 and the test piece T is equal to the distance D0. In particular, the rangefinder 53 measures the distance D1 between the test piece T and the cameras 51 and 52 after the test piece T is set in the testing machine main body 10. This eliminates the need to measure the size of the test piece T to align the cameras 51 and 52 before setting them, making the testing operation easier.

[0039] In this embodiment, digital display units 57 are provided integrally with cameras 51 and 52, and distance D1 is digitally displayed near cameras 51 and 52. This makes it easy to adjust the positions of cameras 51 and 52 while looking at the digitally displayed distance D1.

[0040] In this embodiment, the camera unit 50 is configured to be movable by the X-axis stage 40. Therefore, the positions of the cameras 51 and 52 can be moved in the forward and backward directions with high precision. Furthermore, for example, large adjustments to the positions of the cameras 51 and 52 can be made by changing the clamp position of the support bar 32, and fine adjustments to the positions of the cameras 51 and 52 can be made using the position adjustment screws 53. Therefore, when continuously testing test specimens T of a predetermined standard, it is possible to roughly adjust the positions of the cameras 51 and 52 by changing the clamp position of the support bar 32 to match the predetermined standard, and then finely adjust the positions of the cameras 51 and 52 using the position adjustment screws 53 to match variations in the size of the test specimens T.

[0041] Furthermore, in this embodiment, the distance meter 53 is a laser distance meter. Therefore, the distance D1 to the test piece T is measured with high precision using the laser light L with a small spot diameter, making it easier to align the camera position with high precision. In particular, when the test piece T has an uneven surface, such as a deformed steel bar, the small spot diameter of the laser distance meter makes it easy to determine which of the uneven surfaces of the uneven surface is being measured. Therefore, elongation can be measured with high precision compared to when it is difficult to determine which of the uneven surfaces is measuring the distance D1. The distance meter 53, which is a laser distance meter, is suitable as the distance meter in the extensometer 30 of the material testing machine 1.

[0042] When the operator adjusts the positions of the cameras 51 and 52 so that the distance D1 between the test specimen T and the cameras 51 and 52 is a predetermined distance D1 based on the distance meter 53, the operator inputs an operation to start the test into the control device 100. As a result, a tensile load is applied to the test specimen T in the testing machine main body 10. Furthermore, the extensometer 30 measures the elongation based on the photographed data of the benchmark lines M1 and M2. Because the distance D1 between the test specimen T and the cameras 51 and 52 is accurately matched to the distance D0, the elongation of the test specimen T can be easily detected with little measurement error.

[0043] Therefore, in this embodiment, it is easier to suppress dimensional errors of the test specimen T, adjustment errors by the worker, etc., and it is possible to significantly reduce elongation errors compared to when the rangefinder 53 is not integrated into the cameras 51 and 52.

[0044] [2. Modifications] The above-described embodiment merely exemplifies one aspect of the present invention, and any modifications and applications are possible without departing from the spirit of the present invention.

[0045] In the above-described embodiment, the testing machine body 10 of the material testing machine 1 is exemplified as being configured to apply a load to the test specimen T by hydraulic control, but the configuration of the extensometer 30 of this embodiment can be applied to a material testing machine that applies a load to the test specimen T in any manner, such as a configuration in which a threaded rod is driven by an electric motor to apply a load to the test specimen T.

[0046] In the above-described embodiment, a configuration in which a pair of cameras 51 and 52 are provided, one above the other, has been described, but the number of cameras is not limited to two. One camera, or three or more cameras, may be used. Furthermore, in the above-described embodiment, a configuration in which the upper camera 51 captures an image near the upper marked line M1 and the lower camera 52 captures an image near the lower marked line M2 has been described, but a configuration in which cameras capture both the upper and lower marked lines M1 and M2 may also be used. Furthermore, a configuration in which cameras with different angles of view and different field of view ranges are used for capturing images may also be used. In other words, the configuration of the cameras is not particularly limited as long as they are capable of measuring the elongation of a test specimen using marked lines.

[0047] In the above-described embodiment, a configuration has been described in which the distance meter 53 is a laser distance meter. A laser distance meter is desirable for an extensometer because the spot diameter of the laser light is small, but instead, a non-contact distance meter such as an ultrasonic distance meter or an infrared distance meter may be used.

[0048] In the above-described embodiment, the position adjustment screw 43 is configured to be operated by an operator, but the position adjustment screw 43 may be electrically controlled. For example, the distance data measured by the rangefinder 53 may be input to the control device 100, and the control device 100 may control the electric motor to rotate the position adjustment screw 43 based on the distance data so that the distance D1 between the cameras 51 and 52 and the test piece T becomes a predetermined distance D0.

[0049] In the above-described embodiment, the camera unit 50 is supported by the pole 31 fixed to the floor, but it may be fixed to the testing machine main body 10. For example, it may be configured such that the support bar 32 is clamped to the threaded rod 16.

[0050] In the above-described embodiment, the calculation of the elongation of the extensometer 30 is performed by the control device 100 that controls the testing machine main body 10. However, the extensometer 30 may be provided with its own control device separate from the control device 100, and the photographic data from the cameras 51 and 52 may be sent to the extensometer 30's own control device, and the calculation of the elongation may be performed by the extensometer 30's own control device.

[0051] It will be understood by those skilled in the art that the exemplary embodiments and variations described above are examples of the following aspects.

[0052] (Section 1) A video-type non-contact extensometer according to one embodiment includes a camera that photographs a test specimen having markings at predetermined intervals, and measures the elongation of the test specimen from the displacement of the markings based on the photographic data captured by the camera when the camera is positioned so that the distance to the test specimen is a predetermined distance. The video-type non-contact extensometer may also include a rangefinder that is integral with the camera and measures the distance to the test specimen non-contact.

[0053] According to the video-type non-contact extensometer described in paragraph 1, a distance meter is integrally provided on the camera, so that the camera position can be easily and accurately adjusted so that the distance between the camera and the test piece is the specified distance, regardless of the operator.

[0054] (Section 2) The video type non-contact extensometer described in paragraph 1 may further include a display unit that digitally displays the measured distance, and the display unit may be provided integrally with the camera.

[0055] According to the video-type non-contact extensometer described in paragraph 2, it is easy to align the camera position while looking at the display. In addition, since it is a digital display, it is easy to prevent misreading by the operator.

[0056] (Section 3) The video-type non-contact extensometer described in paragraph 1 or 2 may further comprise a moving member to which the camera is fixed, a position adjustment screw that moves the moving member in a direction toward or away from the test piece, and a position fixing screw that fixes the position of the moving member.

[0057] According to the video type non-contact extensometer described in paragraph 3, the position of the camera can be adjusted with a simple configuration, and the distance between the test piece and the camera can be set with high precision.

[0058] (Section 4) In the video type non-contact extensometer according to any one of paragraphs 1 to 3, the distance meter may be a laser distance meter.

[0059] According to the video-type non-contact extensometer described in paragraph 4, the laser distance meter has a small spot diameter of the laser light, so it is easy to identify which surface of the test piece is being measured. Therefore, compared to when it is not possible to identify the surface, it is possible to measure the elongation of test pieces of various shapes with high accuracy.

[0060] (Section 5) One embodiment of a materials testing machine is a materials testing machine comprising: a testing machine main body that applies a test load to a test specimen; a camera that photographs the test specimen, which has markings at predetermined intervals, and a video non-contact extensometer that measures the elongation of the test specimen from the displacement of the markings based on the photographic data captured by the camera when the camera is positioned so that the distance to the test specimen is a predetermined distance; and the video non-contact extensometer may also comprise a distance meter that is integral with the camera and measures the distance to the test specimen non-contact.

[0061] According to the material testing machine described in paragraph 5, a rangefinder is integrally provided on the camera, making it easy for any operator to easily and accurately adjust the camera position so that the distance between the camera and the test piece is the specified distance. [Explanation of symbols]

[0062] 1. Material testing machine 10 Testing machine body 30 Extensometer (video type non-contact extensometer) 42 Moving stage (moving member) 43 Position adjustment screw 44 Position fixing screw 51, 52 Camera 53 Rangefinder (laser rangefinder) 57 Display section D0 predetermined distance D1 Distance to test specimen M1, M2 marked line T test specimen

Claims

1. A video-type non-contact extensometer is provided with a camera that photographs a test specimen having marked lines at predetermined intervals, and measures the elongation of the test specimen from the displacement of the marked lines based on photographic data taken by the camera while the camera is positioned so that the distance to the test specimen is a predetermined distance, a support bar having a longitudinal shape extending in a direction approaching and separating from the test body; a movement mechanism supported by the support bar, the movement mechanism including a movement member supported so as to be movable in a longitudinal direction of the support bar; the camera fixed to the moving member; a range finder that is provided integrally with the camera and that measures the distance to the test piece in a non-contact manner; a display unit that is provided integrally with the camera and that displays the measured distance, the moving mechanism includes a position adjustment screw that moves the moving member toward and away from the test piece relative to the support bar. Video type non-contact extensometer.

2. A pole extending in the vertical direction; the horizontally extending support bar supported by the pole; the moving mechanism supported on a first end side of the support bar in the longitudinal direction; a weight supported on a second end side of the support bar in the longitudinal direction to shift the center of gravity of the weight applied to the support bar toward the pole; 10. The video non-contact extensometer of claim 1, comprising:

3. The display unit digitally displays the distance.

3. The video type non-contact extensometer according to claim 1 or 2.

4. A position fixing screw is provided to fix the position of the moving member.

4. The video type non-contact extensometer according to claim 1.

5. The rangefinder is a laser rangefinder.

5. The video type non-contact extensometer according to claim 1.

6. a testing machine main body that applies a test load to a test specimen; A material testing machine comprising: a camera that photographs the test specimen having marked lines at predetermined intervals; and a video non-contact extensometer that measures the elongation of the test specimen from the displacement of the marked lines based on photographic data taken by the camera while the camera is positioned so that the distance to the test specimen is a predetermined distance; a support bar having a longitudinal shape extending in a direction approaching and separating from the test body; a movement mechanism supported by the support bar, the movement mechanism including a movement member supported so as to be movable in a longitudinal direction of the support bar; the camera fixed to the moving member; a range finder that is provided integrally with the camera and that measures the distance to the test piece in a non-contact manner; The video non-contact extensometer includes a display unit that is integrated with the camera and displays the measured distance, the moving mechanism includes a position adjustment screw that moves the moving member toward and away from the test piece relative to the support bar. Material testing machine.

7. A pole extending in the vertical direction; the horizontally extending support bar supported by the pole; the moving mechanism supported on a first end side of the support bar in the longitudinal direction; The video type non-contact extensometer includes a weight supported on a second end side of the support bar in the longitudinal direction to shift the center of gravity of the weight applied to the support bar toward the pole.

7. A material testing machine according to claim 6.

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