TWI509219B - Material testing machine - Google Patents

Description

Material testing device

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a material testing device for applying tensile stress or compressive stress to a test piece to test the mechanical properties of the material, and more particularly to a round tube protruding test device, which applies internal pressure to a circular tubular test piece and applies a shaft. Force to carry out the biaxial stress test.

In order to achieve high-accuracy press forming simulation, high-accuracy material property evaluation is required by multiaxial stress test. In particular, it is known that the evaluation of material properties in a large strain zone, the hydraulic bulging test is effective. Non-Patent Document 1 discloses an axial force-internal pressure type tubular tube projection test apparatus (hereinafter referred to as "circular tube projection" in which a hydraulic pressure projection test is performed by applying an internal pressure to a circular tubular test piece and applying an axial force. Test device"). In the round pipe projection test apparatus, the central portion of the test piece in the tube axis direction is expanded (expanded in the circumferential direction and the tube axis direction), and the longitudinal section forms a bell-shaped convex top portion. The stress in both the circumferential direction and the tube axis direction was obtained from the outer diameter, the thickness, the radius of curvature in the tube axis direction, and the test load (internal pressure and axial force) at the convex top of the test piece.

[Previous Technical Literature]

[Non-patent literature]

[Non-Patent Document 1] Sanghara Leehiko "High-precision material molding in a large strain zone using an axial force-internal pressure type round pipe projection test device" [Search on November 8, 2011], Internet <URL: http ://www.tuat.ac.jp/~seeds/jseeds/07seedstext/093-0185/parts/0185.pdf>

However, the test piece is not completely axisymmetric with respect to the tube axis, and the outer diameter or thickness is different depending on the direction (the orientation around the tube axis). Moreover, for this reason, the amount of deformation of the convex top also becomes asymmetrical with respect to the tube axis. In the past, the outer diameter of the test piece was measured in only one direction, so that the measured value of the outer diameter was dispersed, and the strain measurement accuracy of the test piece was lowered.

The present invention has been made in view of the above problems, and an object thereof is to provide a material testing device which can perform high-accuracy axial force-internal pressure type pipe convexity without using a strain gauge for measuring deformation behavior of a test piece. Test out.

According to an embodiment of the present invention, there is provided a material testing device which applies a stress in an internal pressure and a tube axis direction to a test piece having a circular tubular shape, and measures strain of the test piece. The material testing device according to the embodiment of the present invention includes a plurality of radial direction displacement detecting portions that detect a radial displacement of the outer peripheral surface of the effective length central portion in the tube axis direction of the test piece, and an axial direction displacement detecting portion. The displacement in the tube axis direction of the outer peripheral surface of the effective length central portion of the test piece is detected, and the calculation unit calculates the effective length of the test piece based on the detection results of the radial direction displacement detecting unit and the axial direction shift detecting unit. The central portion has a circumferential direction and a tube axis direction strain, and the plurality of radial direction displacement detecting portions are configured to detect displacements in different directions around the tube axis of the test piece.

According to this configuration, the dispersion of the measured value of the outer diameter of the test piece is suppressed to a low level, and the strain of the test piece can be measured with high accuracy.

Further, the plurality of radial direction displacement detecting portions may be configured to include first, second, and third radial direction displacement detecting portions disposed at intervals of 120 degrees around the tube axis of the test piece.

According to this configuration, since the diameter is measured by the displacement in the radial direction detected without deviation from the orientation around the tube axis of the test piece, a diameter measurement value with less error can be obtained.

Further, each of the plurality of radial direction displacement detecting portions includes a first shift meter that detects a radial displacement of the outer peripheral surface of the effective length central portion of the test piece, and at least a plurality of radial direction displacement detecting portions One is provided with a second shift meter that is arranged side by side in the tube axis direction with respect to the first shift meter, and detects a radial displacement of the outer peripheral surface of the test piece, and the arithmetic unit may be configured to move according to at least one radial direction. The detection results of the first and second shift meters of the position detecting unit calculate the radius of curvature in the tube axis direction of the outer peripheral surface of the effective length central portion of the test piece.

The first, second, and third shift meters are provided with a needle, and the distal end thereof is vertically protruded against the outer peripheral surface of the test piece, and is movable in the longitudinal direction according to the displacement of the outer peripheral surface of the test piece in the radial direction. It is also possible to detect that the displacement of the outer circumferential surface of the test piece in the radial direction is detected by the displacement of the detection needle.

According to this configuration, since the deformation of the test piece can be measured by merely infusing the needle protrusion against the outer peripheral surface of the test piece, it is not necessary to attach the strain amount to a complicated preparation work such as a test piece, and the measurement can be efficiently performed. Also, the shift amount of the needle can be easily measured with high accuracy by a commercially available shift meter.

The shift meter includes: a fixed frame; the movable frame is slidably disposed in a radial direction of the test piece with respect to the fixed frame; and a contact displacement sensor having a crotch portion; and a contact portion from the crotch portion One end is telescopically protruded in the radial direction of the test piece, and the crotch portion is attached to the movable frame, and the front end of the contact abuts against the contact sub-protrusion plate provided in the fixed frame, and the needle may be mounted on the movable frame to be long The direction is toward the radial direction of the test piece, and the structure is protruded from the end of the movable frame facing the test piece.

According to this configuration, it is possible to freely set the arrangement of the needles without being restricted by the size and shape of the commercially available contact type displacement sensor, and to realize a material testing device superior in assembly property and ease of use.

Further, according to an embodiment of the present invention, there is provided a material testing device for applying a stress in a specific direction to a test piece to measure a response of the test piece. The material testing device according to the embodiment of the present invention includes a frame, and the first movable portion includes a movable chuck, and is provided to be movable in a specific direction with respect to the frame to fix one end of the test piece, and a fixing portion. The utility model has a fixing chuck fixed to the frame and fixing the other end of the test piece, and a second movable part comprising: a central measuring device, between the first movable part and the fixed part, is arranged to be movable relative to the frame Moving in a specific direction, measuring a response in a central portion of a specific direction of the test piece when a load is applied to the test piece; an actuator is fixed to the frame to drive the first movable portion in a specific direction; and a link The mechanism, the connecting frame, the first movable portion and the second movable portion move the central portion measuring device to the center of the movable chuck and the fixed chuck corresponding to the movement of the first movable portion.

According to the above configuration, since the central portion measuring device moves to the central portion in the axial direction of the test piece in accordance with the expansion and contraction of the test piece, the central portion of the test piece can be often measured by the central portion measuring device.

Moreover, the track further extends in a specific direction, and the first movable portion may be provided with a first runner (scradder block) that meshes with the track, and the first slider is supported to be slidable in a specific direction. The second movable portion may also be provided with a second slider that meshes with the rail, and the second slider is supported to be freely slidable in a specific direction.

According to this configuration, since the first and second movable portions are respectively supported by the first and second sliders, the weight of the first and second movable portions causes an unnecessary bending stress or the like to be applied to the test piece, which does not occur. Further, since the first and second movable portions can be moved to a specific direction (axial force direction) with low resistance, the test load is applied to the test piece without being attenuated, and a highly accurate material test can be performed.

Further, the fixing portion further includes: a load-bearing sensor that measures a load applied in a specific direction of the test piece; and a third slider that is meshed with the rail to be freely movable to a specific direction, and the fixed chuck may be disposed in the third The slider is fixed to the frame structure via a load cell.

According to this configuration, since the weight of the fixing chuck is supported by the third slider, the weight of the third slider causes an unnecessary bending stress to be applied to the test piece, which does not occur. Further, since the fixed chuck can be moved to a specific direction (axial force direction) with low resistance, the test load is transmitted to the load cell without being attenuated, and a highly accurate material test can be performed.

Further, the connecting mechanism has: a first link, one end of which is connected to be rotatable via the first pin at the first movable portion; and the second connecting member, one end of which is connected to the second movable portion via the second pin Connected into a spin And a third connecting member, one end of which is coupled to be rotatable via a third pin disposed on an opposite side of the first pin with respect to the second pin, the other end of the first connecting member and the third connecting member The end is connected to be rotatable via a fourth pin, the other end of the second connector being coupled to the first or third connector via the fifth pin for rotation, the fourth pin being spaced from the first pin by a fourth The interval between the pin and the third pin may be equal to the interval between the fifth pin and the fifth pin, and the first and third pins are connected to the same connector as the fifth pin.

The first movable portion, the second movable portion and the fixed portion respectively have a bottom plate, and the first, second and third sliders are respectively mounted on the lower surface thereof, and the movable chuck, the central portion measuring device and the fixed chuck are respectively respectively Mounted on each of the bottom plates and disposed above the bottom plate, the connecting mechanism may be mounted under the respective bottom plates and disposed under the bottom plate.

According to this configuration, when the movable chuck, the central portion measuring device, and the fixed chuck are operated, the connecting mechanism does not interfere with the operation, and the operation or maintenance of the central portion measuring device and the chuck can be easily performed.

Further, the frame may include a fixed plate having an upper surface of the horizontal surface, the rail being mounted on the upper surface of the frame, and a central portion of the side surface of the fixed plate forming a concave portion which is recessed in the horizontal direction and has a shape formed along the rail. At the bottom, the connection mechanism is disposed in the recess.

According to this configuration, since the connection mechanism is housed in the recessed portion of the fixed plate and does not protrude from the fixed plate to the side, the work such as attachment and detachment or maintenance of the test piece can be efficiently performed without being interfered by the connection mechanism. get on.

The present invention provides a material testing device which can perform high-accuracy material testing with a simple structure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The material testing device 1 according to the embodiment of the present invention is an axial force-internal pressure type for measuring the elastoplastic behavior of the test piece T at this time by applying an internal pressure and an axial force to the test piece T of a circular tubular shape. Tube projection test. The first and second figures are a front view and a top view, respectively, of the material testing device 1. The third drawing is an A-A arrow view of the second drawing, and only shows the frame 10 and the sensor unit moving mechanism 100 which will be described later. In the following description, the left-right direction in the first figure is taken as the X-axis direction (the right direction is taken as the positive X-axis direction), and the direction perpendicular to the paper is taken as the Y-axis direction (from the front side of the paper) The direction of the back side is the positive direction of the Y-axis, and the vertical direction is the Z-axis direction (the upper direction is the positive direction of the Z-axis). In the second diagram, the vertical direction (Y-axis direction) is referred to as "in-depth direction", and the upper side is referred to as "inside" side, and the lower side is referred to as "front side".

The material testing device 1 includes a frame 10, a hydraulic cylinder 20, a first movable portion 30, a second movable portion 40, a fixing portion 50, an inductor unit moving mechanism 100, a hydraulic source, a hydraulic source, and a control unit not shown. . Further, the hydraulic source is a device for supplying the hydraulic pressure for driving the hydraulic cylinder 20, and the hydraulic source is a device for supplying a pressurized liquid (for example, water in which the rust preventive is mixed) to the tube of the test piece T. The frame 10 is a bottom frame of each part of the support material testing device 1, and the parts of the material testing device 1 other than the hydraulic source, the hydraulic source, and the control device are mounted on the fixed plate 12, and the fixed plate 12 is placed on the upper surface of the frame 10. In the central portion of the fixed disk 12 in the X-axis direction, a substantially rectangular recess 12a is formed on the front side and the inner side, respectively, and the fixed disk 12 has a substantially H-shaped outer shape in a top view (second drawing). Further, the frame 10 includes a pair of inner side faces covering both side faces in the depth direction of the frame 10, and a pair of inner side walls 16 having a substantially U-shaped horizontal cross section, which is below the edge portion of each recessed portion 12a of the fixed plate 12. Each of the pair of horizontal bottom plates 18 respectively plugs the openings of the pair of internal spaces S formed by the inner wall side 16 and the outer wall side 14 respectively.

The fourth figure is a top view of the sensor unit moving mechanism 100. The sensor unit moving mechanism 100 moves the second movable portion 40 into the second movable portion 40 (directly, the sensor unit 200 to be described later) according to the movement of the first movable portion 30, and is often correctly disposed in the first movable portion. 30 is a mechanism with an intermediate point of the fixing portion 50. The sensor unit moving mechanism 100 is provided with two sets of linear guides 120 and a connecting mechanism 140. Each of the linear guide rails 120 includes: one rail 121; and three sliders 122, 123, and 124 that are engaged with the rails 121 to smoothly move along the rails 121. The rails 121 of the two sets of linear guides 120 are disposed between the pair of recesses 12a, respectively, and the recesses 12a are formed in the fixed plate 12.

In other words, the two rails 121 extending in the X-axis direction are arranged in parallel in a predetermined interval in the Y-axis direction, and are fixed to the upper surface of the fixed plate 12. The first movable portion 30 and the second movable portion 40 are respectively attached to the sliders 122 and 123 of each linear guide 120. The first movable portion 30 and the second movable portion 40 are configured to be smoothly slidable by the linear guide 120, respectively. The ground moves in the X-axis direction. A chuck 52 (described later) of a fixing portion is attached to each of the sliders 124. Further, the sliders 122, 123, and 124 are connected by the link mechanism 140, and even if the slider 122 moves, the slider 123 is configured to be accurately disposed in the middle of the sliders 122 and 124.

The details of the connection mechanism 140 will be described later. Further, a linear encoder not shown in the figure for detecting the position of the slider 122 is provided on the fixed plate 12. The linear encoder is connected to be communicable with the control unit. In the test, the position information of the first movable portion 30 detected by the linear encoder (ie, the position information of the chuck 32 described later) is sent to the control unit and recorded in the control unit. Memory device.

The hydraulic cylinder 20 is a hydraulic linear actuator that is linearly driven in the X-axis direction by a hydraulic pressure supplied from a hydraulic source not shown. The cylinder tube 21 of the hydraulic cylinder 20 is fixed to the end portion of the fixed plate 12 in the negative X-axis direction via a bracket 24. A piston rod 22 that moves in the X-axis direction protrudes from the positive X-axis end of the cylinder tube 21. At the front end of the piston rod 22, an attachment means 23 is provided, which is connected to the piston rod 22 and the collet 32.

The first movable portion 30 includes a base 31, a collet (movable chuck) 32, and a connecting member 33. A slider 122 of each linear guide 120 is attached to both ends of the lower surface of the base 31 in the depth direction. Further, a chuck 32 is attached to the upper surface of the base 31, and the chuck 32 holds one end of the test piece T. Therefore, the relatively large weight of the collet 32 is supported by the base 31 and the two sets of linear guides 120 so as to be freely slidable in the X-axis direction. Further, the back surface of the chuck 32 (on the left side surface of the first drawing) is fixed to the attachment 23 of the hydraulic cylinder 20 via the connecting member 33, and the chuck 32 is driven in the X-axis direction in accordance with the movement of the piston rod 22. As described above, by supporting the relatively large weight of the collet 32 with the linear guide 120 in a slidable configuration, the hydraulic cylinder 20 can be smoothly and correctly subjected to the X-axis direction without applying a bending moment to the hydraulic cylinder 20. Drive. Further, no unnecessary bending stress is applied to the test piece T, and a correct test can be performed.

The second movable portion 40 includes a base 41 and an inductor unit 200. Sliders 122 of the respective linear guides 120 are attached to both end portions of the lower surface of the base 41 in the depth direction. Moreover, the sensor unit 200 is attached to the upper surface of the base 41, and the sensor unit 200 measures the shape of the center part of the longitudinal direction (X-axis direction) of the test piece T. The details of the sensor unit 200 will be described later.

The fixing portion 50 includes a base 51 , a chuck (fixing chuck) 52 , a connecting member 53 , a load cell 54 , and a bracket 55 . On the upper surface of the base 51, a chuck 52 is mounted, and the chuck 52 holds the other end of the test piece T. A slider 124 of each linear guide 120 is attached to both ends of the lower surface of the base 51 in the depth direction. Therefore, the relatively large weight of the collet 52 is supported by the base 51 and the two sets of linear guides 120 so as to be freely slidable in the X-axis direction. Further, the back surface of the chuck 52 (on the right side surface of the first drawing) is attached to the mounting base of the load cell 54 via the connecting member 53.

From the load of the load cell 54 being seated (the plate on the right side of the first figure), the load receiving strip 54a is vertically protruded, the load receiving strip 54a is fixed to the bracket 55, and the bracket 55 is mounted on the fixed tray 12. With the force measuring device 54 thus configured, the test load (axial force) applied to the X-axis direction of the test piece T is detected. Further, as described above, by supporting the relatively large weight of the collet 52 with the linear guide 120 to be a freely slidable structure, a large bending moment is not applied to the dynamometer 54, and the dynamometer 54 can be correctly used. Axial force measurement.

Further, since the collet 52 can move on the linear guide 120 with low resistance in the X-axis direction, the axial force applied to the collet 52 is transmitted to the dynamometer 54 with almost no loss, and the dynamometer 54 is correct. Ground detection. Further, the load cell 54 is connected to the control unit, and the detection signal (resistance value of the strain gauge) of the load cell 54 is read by a well-known bridge circuit provided in the control unit, and converted into test load data. The test load information detected by the load cell 54 during the test corresponds to the position information of the first movable portion 30 that is simultaneously detected, and is recorded in the memory of the control unit.

Next, the connection mechanism 140 will be described with reference to the first, third, and fourth figures. Further, in the present embodiment, the two connection mechanisms 140 are vertically disposed in the internal space S of the frame 10. The structure of the two connection mechanisms 140 is only a mirror image relationship with each other, and only the structure of the connection mechanism 140 regarding the front side will be described in detail.

The connecting mechanism 140 has three long plate-like connecting members (movable connecting members) 141, 142, and 143 which are rotatably connected by pins, and a fixed connecting member 140a which is fixed to the upper surface of the fixed plate 12. At both ends of each movable connecting member, a connecting hole for passing the pin is opened, and at the fixed connecting member 140a, a connecting hole is opened at one end. Further, in the movable connecting member 143, a third connecting hole is opened in the middle of the connecting holes at both ends. Further, a bearing hole of one of the two connecting members that are connected is provided with a bearing that maintains the pin to be freely rotatable, whereby the respective connecting members are connected to each other so as to be smoothly rotatably rotated. The connecting member 141 and the connecting member 143 are the same length members having the same connecting member length (the interval at which the connecting holes are provided at both ends) 2L, and the connecting member 142 has half of the connecting member length.

As shown in the fourth figure, pins 145 and 146 are fixed to the both ends of the bases 31 and 41 in the depth direction by pin fixing members 145a and 146a, respectively. The pin 145 is inserted into the connection hole of one end of the connector 141, and the connector 141 is connected via the pin 145 so as to be freely rotatable at the base 31. Likewise, the connector 142 is coupled via the pin 146 to be free to rotate on the base 41. Further, one end of the connector 143 is connected via the pin 147 so as to be freely rotatable at one end of the fixed connector 140a. The other end of the connecting member 141 is connected to the other end of the connecting member 143, and is freely rotatable via the pin 148. Further, the other end of the connecting member 142 is connected to the central portion of the connecting member 143, and is freely rotatable via the pin 149.

As described above, since the connecting members 141 and the connecting members 143 are equal in length, the triangles in which the pins 145, 147, and 148 are apexes become an isosceles triangle (hereinafter referred to as "isosceles triangle 578"). Further, the length of the connecting piece of the connecting member 142 is half of the length of the connecting piece of the connecting piece 143, and since the connecting hole of the other end of the connecting piece 142 and the connecting hole of the center of the long direction of the connecting piece 143 are connected by the pin 149, The isosceles triangle (hereinafter referred to as "isosceles triangle 679") which becomes the connection pins 146, 147, and 149. The isosceles triangle 578 and the isosceles triangle 679, the similarity ratio becomes a similar figure of 2:1. Therefore, even if the first movable portion 30 (pin 145) moves, the pin 146 is often located at an intermediate point between the pin 145 and the pin 147. That is, when the first movable portion 30 driven by the hydraulic cylinder 20 moves in the X-axis direction, the connecting mechanism 140 connected to the first movable portion 30 by the pin 145 operates, and the pin 146 is connected to the connecting mechanism. The second movable portion 40 of the 140 moves to an intermediate point between the moved first movable portion 30 and the fixed portion 50. Further, the pins 145, 146, and 147 are attached to the reference positions in the X-axis direction of the first movable portion 30, the second movable portion 40, and the fixed portion 50 (specifically, the bases 31, 41, 51) (X-axis) Benchmark point). At the X-axis reference point of the first movable portion 30 and the fixed portion 50, when the test piece T is attached to the material testing device 1, the substantial end portion of the test piece T (the end portion of the deformable portion that is not clamped by the chuck) Is configured. Therefore, at the X-axis reference point of the second movable portion 40, an intermediate point of the span of the test piece T (an intermediate point of the effective length of the test piece T) is disposed. Further, the sensor unit 200 provided in the second movable portion 40 is configured to measure the shape of the test piece T at the X-axis reference point of the second movable portion 40. Therefore, even if the length of the test piece T changes due to the test load in the test, the shape of the central portion in the substantially long direction of the test piece T can be often measured by the sensor unit 200.

Next, an inductor unit 200 according to an embodiment of the present invention will be described. The sensor unit 200 is often disposed between the movable chuck 32 and the fixed chuck 52 by the above-described inductor unit moving mechanism 100 for measuring a test piece at the center of the span of the test piece T in the test. A component of the radial direction of the outer peripheral surface of T and the displacement in the longitudinal direction. The fifth figure is the second movable portion 40 in which the inductor unit 200 is mounted in the positive direction of the X-axis. Further, the sixth diagram is a view of the sensor unit 200 as seen in the positive direction of the Y-axis (i.e., from the front side of the material testing device 1). The sensor unit 200 includes a plate 201, a first radial direction displacement detecting unit 220, a second radial direction displacement detecting unit 240, a third radial direction displacement detecting unit 260, and an axial direction shift detecting unit 280. The plate 201 is a flat plate extending perpendicularly from the end portion of the susceptor 41 in the positive X-axis direction, and an opening 201a is formed in the center portion, and the opening 201a has an arcuate edge that passes through the test piece T. The opening 201a is opened at the upper portion on the front side (in the upper right portion of the fifth drawing), and the test piece T can be taken in and out into the opening 201a via the opening portion.

The first radial direction direction shift detecting unit 220, the second radial direction shift detecting unit 240, the third radial direction shift detecting unit 260, and the axial direction shift detecting unit 280 are attached to one side of the plate 201 (in the fifth The side of the paper sheet side of the figure). Further, the first radial direction displacement detecting unit 220, the second radial direction displacement detecting unit 240, and the third radial direction displacement detecting unit 260 are disposed at intervals of 120° around the axis of the test piece T. Further, the first radial direction displacement detecting unit 220 is disposed directly above the test piece T.

The seventh diagram is a view of the first radial direction displacement detecting unit 220 as seen from above. As shown in the sixth and seventh figures, the first radial direction displacement detecting unit 220 includes a plate 221, three contact type shift meters 230a to 230c, three pins 223a to 223, and sensor holders 224a to 224. Each of the pins 223a to 223c is fixed to the main bodies 231a to 232 of the contact type shift meters 230a to 230b, and the three linear guides 228 support the main bodies 231a to 232 and the needles 223a to 223c of the contact type shift meter with respect to the plate 221, respectively. Freely slides in the up and down direction (Z-axis direction).

Each of the contact type shift meters 230a to 230c includes a substantially columnar body 231a to 251 and a rod-shaped contact piece 232a to c. Circular holes are formed in the main bodies 231a to 231, and extend from the one end on the central axis, and the contact members 232a to 232 are accommodated in the circular holes so as to be slidable in the direction of the central axis. Further, the contact members 232a to 232 are pushed to the distal end portion side by the coil springs not shown in the main bodies 231a to 231 of the contact type shift meter, and the distal end portions of the contact members 232a to 232 are from the main body 231a to c. One end protrudes to the outside. The contact shift meters 230a to 230 detect the position or displacement of the central axis direction (measurement axis direction P) of the contact pieces 232a to 232 of the bodies 231a to 231.

The plate 221 is perpendicularly protruded from one surface (surface on the negative side in the X-axis direction) of the plate 201, and is disposed in parallel with the support plate of the test piece T. A rail 228m is fixed to one surface (surface on the negative side in the Y-axis direction) of the plate 221, and the rail 228m extends in the Z-axis direction of the three linear guide rails 228 arranged at equal intervals in the X-axis direction. On each of the rails 228m, a slider 228n is slidably engaged along the rail 228m. Plates 225a to 225 of the sensor holders 224a to 224 are attached to the mounting surfaces of the sliders 228n, respectively. Further, clamps 226a to 226 are attached to the surfaces on the opposite sides of the sliders 228n of the respective plates 225a to 225, and the clamps 226a to 242 are used to mount the main bodies 231a to 231 of the contact type shift meter. The main bodies 231a to 231 of the contact type shift meter are slidably supported in the measurement axis direction P with respect to the plate 221 (that is, the frame of the sensor unit 200) by the attachment clamps 226a to 242c.

From the lower ends of the plates 225a to 255, the arms 227a to 227 extend horizontally to the negative side of the Y-axis, respectively. Through-holes are formed in the distal end portions of the arms 227a to 227, and the through-holes extend in the Z-axis direction through which the needles 223a to 223 pass. The needles 223a to 223 are fixed to the arms 227a to 227 by fixing screws 229 in a state in which the distal end is accurately protruded from the lower surface of the arms 227a to 227 by a specific length. Thereby, the needles 223a-c are respectively fixed in parallel with respect to the main bodies 231a-c of the contact type shift meter, and the main bodies 231a-c of the contact type shift meter are slidably supported in the Z-axis direction (i. Direction P).

Each of the needles 223a to 223 is disposed at a central axis (X-axis) of the test piece T that is perpendicular to (parallel to the Z-axis), and is equally spaced at a certain interval (10 mm intervals in this embodiment) in the X-axis direction. Arranged. Further, the center needle 223b is accurately placed at the X-axis reference point of the second movable portion 40, and the tip end is brought into contact with the center of the span of the test piece T.

Further, from the vicinity of the lower end of one surface of the plate 221, the contact sub-protrusion plate 222 protrudes perpendicularly to the negative side of the Y-axis and parallel to the test piece T. The front ends of the contact pieces 232a to 232 of the contact type displacement meter abut against the upper surface of the contact sub-protrusion plate 222. As described above, since the contact springs 232a to 232 are pushed to the distal end side by the coil springs provided in the main bodies 231a to 231 of the touch type shift meter, the main bodies 231a to 232 and the needle 223a of the contact type shift meter are used. The -c moves upward, and the contact members 232a to 232 continue to abut against the contact sub-protrusion plate 222, and further protrude from the main bodies 231a to 232. Thereby, the amount of movement of the needles 223a to 127 in the Y-axis direction is detected by the contact type shift meters 230a to 230c.

Similarly, the second radial direction displacement detecting unit 240 includes a plate 241 (contact sub-protrusion plate 242), a contact shift meter 250, a needle 243, and an inductor holder 244 for fixing the needle 243 to the contact displacement. The body 251 of the meter 250; the linear guide 248, the body 251 supporting the contact shift meter, and the needle 243 are slidable relative to the plate 241 in the measurement direction Q of the contact shift meter 250. However, the second radial direction displacement detecting unit 240 includes only one set of the contact shift meter 250, the needle 243, the sensor holder 244, and the linear guide 248, and the plate 241 is disposed parallel to the plate 201. Further, the second radial direction displacement detecting unit 240 is provided with a spring mechanism 245 which presses the body 251 of the contact type shift meter against the gravity of the test piece T and pushes the tip end of the needle 243 frequently. Connected to the test piece T.

Further, the central axis of the needle 243 is accurately placed at the X-axis reference point of the second movable portion 40, and is configured to measure the radial displacement of the outer peripheral surface of the span portion of the test piece T. Further, in the second radial direction shift detecting portion 240, the configuration of the sensor holder 244 or the relative arrangement relationship between the plate 241, the needle 243, the inductor holder 244, the linear guide 248, and the contact shift meter 250 are The measurement axis direction of the contact shift meter 250 is different from the point of the sensor holders 224a to 224 in the first radial direction displacement detecting unit 220, the plate 221, the needles 223a to c, and the sensor. Since the arrangement relationship of the support members 224a to 224, the linear guide 228, and the contact type shift meters 230a to 230c is the same, detailed description of each portion of the second radial direction displacement detecting unit 240 will be omitted.

Further, since the configuration of the third radial direction shift detecting unit 260 is a mirror image of the configuration of the second radial direction shift detecting unit 240, a detailed description of the configuration of the third radial direction shift detecting unit 260 will be omitted.

In the axial force-internal pressure type tube projection test, the tubular test piece T was expanded in the circumferential direction at the center of the span by the internal pressure. That is, the longitudinal section of the test piece T is changed into a bell shape which has a apex at the center of the span. The strain in the circumferential direction of the test piece T is mainly based on the radial direction of the outer peripheral surface of the center portion of the span of the test piece T measured by the first, second, and third radial direction displacement detecting portions 220, 240, and 260. Shift to calculate. In addition, for example, the circumferential direction of the test piece T can be determined based on, for example, only the radial direction shift of the point on the outer peripheral surface of the center portion of the span of the test piece T measured by the third radial direction displacement detecting unit 260. strain. However, in the present embodiment, the first, second, and third radial direction displacement detecting units 220, 240, and 260 measure the outer peripheral surface of the test piece T at intervals of 120° around the central axis of the test piece T. The displacement in the radial direction makes it possible to more accurately measure the strain in the circumferential direction of the test piece T by using these three measured values. Further, as described above, the first radial direction displacement detecting unit 220 includes three shift meters which are arranged at equal intervals in the central axis direction of the test piece T. Thereby, the bell-shaped deformation curvature of the longitudinal section of the test piece T is determined, and the strain in the circumferential direction of the test piece T can be measured more accurately.

Next, the configuration of the axial direction shift detecting unit 280 will be described. The axial direction shift detecting unit 280 detects the amount of elongation in the central axis direction of the outer peripheral surface of the center portion of the span of the test piece T. The eighth diagram is a view in which the axial direction shift detecting unit 280 is viewed in the negative X-axis direction. Further, the Y' axis and the Z' axis of the eighth figure are coordinate axes for rotating the Y axis and the Z axis by 40° around the X axis as shown in the fifth figure. The ninth diagram is a view in which the axial direction shift detecting unit 280 is viewed in the positive direction of the Y' axis. Also, the tenth figure is a B-B arrow view in the ninth figure. In addition, the eighth to tenth views show the state in which the setting jig 370 is attached, and the setting jig 370 is used to set the axial direction shift detecting unit 280 to the initial state in order to mount the axial direction shift detecting unit 280 on the test piece T. Used. The test is performed in a state where the setting jig 370 is removed.

The axial direction shift detecting unit 280 includes a plate 281 that is vertically fixed to the plate 201, and a movable plate 282 that is disposed parallel to the plate 281. On the surface of the movable plate 282 facing the plate 281, a rail 283m extending in the Z'-axis direction is fixed. Further, a slider 283n is fixed to one surface of the plate 281, and the slider 283n is meshed with the rail 283m. In other words, the movable plate 282 is attached to one surface (the surface on the negative side in the Y'-axis direction) of the plate 281 via the linear guide 283 constituted by the rail 283m and the slider 283n, and becomes the Z' axis with respect to the plate 281. The direction is free to slide. With this, in the test, even if the expansion of the test piece T causes the outer peripheral surface to be displaced to the axial direction shift detecting portion 280 side (radial direction), the axial direction shift detecting portion 280 is also in the radius according to the displacement of the test piece T. Since the direction is smoothly moved, the unnecessary stress is applied to the axial direction shift detecting portion 280 and the test piece T, and the displacement measurement of the test piece T by the axial direction shift detecting portion 280 can be stabilized and continued. In the movable plate 282, the thumb screw 284 is rotatably mounted, and the thumb screw 284 is engaged with the female screw provided on the mounting surface of the rail 283m. Further, on the surface of the movable plate 282 facing the plate 281, a plurality of positioning pins 282a are provided, and the positioning pins 282a are engaged with the positioning shape (hole or groove) provided in the mounting surface of the rail 283m. The movable plate 282 can be mounted to be freely detachable with high positional accuracy with respect to the rail 283m by the positioning pin 282a and the thumb screw 284. When the test piece T is replaced, in order to secure the space required for the replacement of the test piece T, the hand screw 284 is released, and the movable plate 282 is detached from the rail 283.

Further, a bearing portion 310 (tenth diagram) is provided at a front end portion of the movable plate 282 in the negative Z' axis direction, and the main body portion 300 of the bearing portion 310 supporting the axial direction displacement detecting portion 280 is freely rockable around the Y' axis. . The main body portion 300 includes a shaft 320 , a plate 330 , a first sliding portion 340 , a second sliding portion 350 , and a contact shift meter 360 . The contact shift meter 360 is the same as the contact type shift meters 230a to 230c. One end of the shaft 320 extending in the Y'-axis direction is rotatably supported by a plurality of ball bearings 312 provided in the bearing portion 310. Further, at the other end of the shaft 320, a plate 330 is vertically fixed. That is, the plate 330 disposed parallel to the movable plate 282 is supported by the shaft 320 and the bearing portion 310 so as to be freely rockable around the Y' axis with respect to the movable plate 282. With this configuration, even in the case where, for example, the test piece T is largely deformed by warpage or the like in the test, since the main body portion 300 of the axial direction displacement detecting portion 280 is smoothly swayed according to the deformation of the test piece T, the shaft is prevented. The direction shift detecting unit 280 is damaged by the excessive load on the test piece T. In addition, when the test piece T is attached to the material testing device 1, the axial direction displacement detecting unit 280 does not hinder the movement of the test piece T, and even if the device has the axial direction shift detecting unit 280, the change is made. It is possible to install/detach the test piece T.

The plate 330, the first sliding portion 340, and the second sliding portion 350 are disposed substantially in parallel with each other, and a part of the plate 330 is sandwiched between the first sliding portion 340 and the second sliding portion 350. The first sliding portion 340 and the second sliding portion 350 are attached to the plate 330 via the linear guides 332 and 334, respectively, and are slidable in a specific direction (in the X-axis direction of the eighth to ninth views) with respect to the plate 330. Specifically, on both sides of the plate 330, a rail 332m of the linear guide 332 and a rail 334m of the linear guide 334 are mounted, respectively. Further, the slider 332n of the linear guide 332 is attached to the first sliding portion 340, and the slider 334n of the linear guide 334 is attached to the second sliding portion 350.

At one end of the first sliding portion 340 and the second sliding portion 350 (ends in the negative Z-axis direction of the eighth to tenth views), jaws 344 and 354 are provided, respectively, and the clips 334 and 354 are It abuts against the side of the test piece T. Further, at the other end portion of the first sliding portion 340, a clamp 342 is provided, and the clamp 342 fixes the body 361 of the contact shift meter 360. The contact shift meter 360 is configured such that the measurement axis (the axial direction of the contact sub-362) is parallel to the movable direction of the linear guides 332 and 334. At the other end of the second sliding portion 350, a contact sub-protrusion plate 352 perpendicular to the contact 362 is provided. When the clip 344 and the clip 354 are relatively moved in the measurement axis direction (the X-axis direction in the eighth to tenth drawings), the body 361 of the contact type shift meter fixed to the first sliding portion 340 is The contact sub-protrusion plate 352 of the two sliding portions 350 moves in the measurement axis direction. The contact 362 of the contact type shift meter is pushed against the protruding direction (X-axis negative direction) by a coil spring (not shown) provided in the main body 361, so that the contact end is abutted at the contact end. The state of the plate 352 is prevented, and the movement of the contact sub-bump 352 follows the movement in the X-axis direction. Thereby, the relative displacement of the clip 344 and the clip 354 is detected by the contact shift meter 360.

Further, hook plates 336 are attached to both ends of the plate 330 in the measurement axis direction. Hooks 336h are formed at both ends of the hook plate 336 in the Y'-axis direction. At the time of the test, as shown in the eighth figure, in a state where the leading ends of the clips 334, 354 abut against the test piece T, the rubber ring B is hung on the two hooks 336, and the rubber ring B is displaced in the axial direction. The test piece T is sandwiched between the body portions 300 of the portion. Thereby, the clips 334 and 354 are pushed against the side surface of the test piece T by the elastic force of the rubber ring B, so that the clips 334 and 354 do not slide on the side surface of the test piece T, and follow the axial displacement of the test piece T. To move, the shift in the direction of the axis is correctly detected.

Further, since the main body portion 300 of the axial direction displacement detecting portion 280 is configured to be swingable around the shaft 320, the test piece T is not unevenly uneven with respect to the center of the span in the case where the test piece T is warped or tested. In the deformation, even if the distance between the tip end of each of the clips 334 and 354 and the test piece T is different, the distance difference is released by the rotation of the main body 300, and the two clips 334 and 354 are surely protruded. On the side of the test piece T, it becomes possible to perform measurement of the correct axial direction shift frequently.

Further, as shown in the tenth diagram, positioning pins 346 and 356 are provided on the surfaces of the first sliding portion 340 and the second sliding portion 350 facing the setting jig 370, respectively. Further, a female screw 322 that meshes with the thumb screw 322 is formed on the central axis of the surface of the shaft 320 facing the setting jig 370. On the other hand, in the setting jig 370, a through hole 378 is formed, and the through hole 378 is passed through the holes 372 and 374 that engage the positioning pins 346 and 356 and the thumb screw 322. The positioning pins 346 and 356 are inserted into the holes 372 and 372 of the setting fixture 370, and the setting screw 370 is set to move in the axial direction by passing the thumb screw 322 through the through hole 378 of the setting jig 370 and screwing it into the female thread 322. The body portion 300 of the bit detecting unit 280. At this time, the shaft 320, the plate 330 integrally fixed to the shaft 320, the first sliding portion 340, the second sliding portion 350, and the setting jig 370 are fixed in a specific arrangement relationship. Further, at this time, the interval between the central axis of the shaft 320 in the X-axis direction and the tip end of the clip 344, and the interval between the central axis of the shaft 320 and the tip end of the clip 354 are set to a common specific value (in this embodiment). The form is 10mm). Further, the central axis of the shaft 320 is disposed directly above the center line of the susceptor 41 in the X-axis direction.

That is, the shaft 320 is located in the X-axis direction between the movable chuck 32 and the fixed chuck 52. Therefore, in a state in which the jig 370 is attached, the clips 344 and 354 are disposed at positions spaced apart from the central portion of the span of the test piece T in the positive X-axis direction and the negative direction at equal intervals. When the axial direction shift detecting unit 280 is placed on the test piece T in the state where the setting fixture 370 is set, the clips 344 and 354 are protruded from the test piece T at a predetermined interval in the center portion of the span of the test piece T. The outer peripheral surface can be fixed.

Next, the chucks 32 and 52 will be described in detail. In the eleventh and twelfth drawings, top and longitudinal cross-sectional views of the chucks 32 and 52 are shown, respectively. Further, in the eleventh and twelfth drawings, the chuck 52 on the right side indicates the state of the gripping state, and the chuck 32 on the left side indicates the non-clamping state. The chuck 32 includes a support block 610, a flange portion 620, a core portion 630, a collet 640, a sleeve 650, a slider 660, and two hydraulic cylinders 670 (the eleventh diagram). Further, the slider 660 is provided with four rods 662 and a connecting plate 664. In the support block 610, a flange portion 620 is attached to the side surface on the negative side in the X-axis direction, and a core portion 630 is attached to the side surface on the positive side in the X-axis direction. Further, four through holes 612 extending in the X-axis direction are formed in the support block 610. Each of the through holes 612 has an inner diameter slightly larger than the outer diameter of the rod 662, and the through holes 612 are slidably inserted by the rod 662. Further, one end of the four rods 662 on the negative side in the X-axis direction is fixed to the connection plate 664, respectively. The hydraulic cylinder 670 is configured to push the test piece T against the connecting plate 664 to the negative direction of the Y-axis. Further, the flange portion 620 is a structural portion for attaching the connecting member 33, and a flange mounting surface 622 is provided at one end of the flange portion 620, and the flange mounting surface 622 forms a screw hole (not shown). At the front end portion of the core portion 630, a cylindrical portion 632 having a diameter slightly smaller than the inner diameter of the test piece T is provided. Further, a tapered portion 634 is formed, and the tapered portion 634 is formed to be adjacent to the front end of the cylindrical portion 632, and the outer peripheral surface is tapered to the front end side. An annular groove 636 in which an O-ring of the device is formed is formed on the outer peripheral surface of the distal end side of the cylindrical portion 632. The collet 640 is an annular member, and four notches, not shown in the figure extending radially from the central axis, are formed. The collet 640 is divided into four by four recesses except for the inner peripheral side end portion on the side of the support block 610, and each of the divided pieces is movable in the radial direction. The inner circumferential surface of the collet 640 is a cylindrical surface slightly larger than the outer diameter of the test piece T, and covers the cylindrical portion 632 of the core portion 630. At the time of the test, the test piece T was sandwiched between the inner circumferential surface of the collet 640 and the cylindrical portion 632 of the core portion 630. Moreover, the outer peripheral surface of the collet 640 becomes a conical surface (conical surface) which becomes thinner toward the front end side. The inner circumferential surface of the sleeve 650 is also a conical surface that becomes the same taper angle as the outer circumferential surface of the collet 640, and the sleeve 650 covers the collet 640. Further, on the side of the support block 610 of the sleeve 650, a flange portion 652 that protrudes outward in the radial direction is formed.

The chuck 52 is provided with a support block 510, a core portion 530, a collet 540, a sleeve 550, a slider 560, and two hydraulic cylinders 570 (the eleventh diagram). Further, the collet 540, the sleeve 550, the slider 560, and the hydraulic cylinder 570 are members similar to the collet 640, the sleeve 650, the slider 660, and the hydraulic cylinder 670 of the chuck 32, respectively. Further, the core portion 530 has the same configuration as the core portion 630 of the chuck 32 except for the shape of the fixing portion of the support block 510 or the detailed structure of the pipe 514 to be described later. A flange mounting surface 522 is provided on the side surface of the support block 510 on the positive X-axis side, and the flange mounting surface 522 is formed with a screw hole for fixing the connecting member 53. A core portion 530 is attached to a side surface of the support block 510 on the negative side in the X-axis direction. Further, in the support block 510, four through holes 512 extending in the X-axis direction are formed, and each of the through holes 512 is slidably inserted into the rod 562 of the slider 560.

The thirteenth picture is a C-C arrow view in the twelfth figure. In the flange portion 552 of the sleeve 550, four through holes 554 extending in the X-axis direction are formed. The through hole 554 has an insertion portion 554a that can be inserted through the head 562h of the rod 562, and a narrow gap portion 554b that extends from the insertion portion 554a in the circumferential direction (counterclockwise direction of the thirteenth diagram). Further, on the surface of the flange portion 552 facing the chuck 32, a winding portion 554c is formed around the narrow groove portion 554b. When the rod 562 is passed through the through hole 554 of the flange portion 552 to rotate the sleeve 550 in the clockwise direction, the head 562h of the rod 562 is engaged with the winding portion 554c of the flange portion 552 even if the rod 562 is positive on the X-axis. Driven in the direction, it does not fall off from the flange portion 552.

Further, in the support block 610 of the collet 32, the core portion 630, and the support block 510 and the core portion 530 of the collet 52, conduits 616, 636 and conduits 516, 536 are formed, respectively, which are supplied for application. A hydraulic fluid pressed against the test piece T. Further, water or hydraulic oil in which a rust preventive agent is mixed is used in the hydraulic fluid. One end of the line 516 of the support block 510 (the nozzle 516a) is connected to a hydraulic source not shown, and the other end is connected to one end of the line 532 formed at the core portion 530. A hydraulic gauge 590 is provided in the middle of the line 516. Further, the other end of the conduit 532 of the core portion 530 is opened on the outer peripheral surface of the tapered portion 534, and hydraulic fluid is injected into the tube of the test piece T from this opening. Further, a pipe 616 formed in the support block 610 of the chuck 32 is connected at one end to the valve 680 for deflation, and at the other end to the end of the pipe 636 of the core portion 630. Further, the outlet of the valve 680 is connected to a hydraulic fluid reservoir not shown. The other end of the pipe 636 of the core portion 630 is opened on the outer peripheral surface of the tapered portion 634, from which the hydraulic oil in the pipe of the test piece T is opened to flow into the pipes 636 and 616.

When the test piece T is sandwiched by the chuck 52, one end of the test piece T is inserted into the cylindrical portion 532 of the core portion 530, the cylindrical clip 540 is provided on the outer periphery thereof, and the sleeve 550 is further disposed on the outer periphery of the collet 540. When the sleeve 550 is installed, the rod 562 passes through the through hole 554 (the thirteenth diagram) of the flange portion 552, and the sleeve 550 is rotated in the clockwise direction, so that the head 562h of the rod 562 and the winding portion 554c of the flange portion 552 Engage. Similarly, the other end of the test piece T is placed on the chuck 32. Further, by inserting both ends of the test piece T into the cylindrical portion 532 of the core portion 530 and the cylindrical portion 632 of the core portion 630, the O-rings 536 and 636 are in close contact with the cylindrical portions 532 and 632, so that even the supply is provided. The hydraulic fluid hydraulic fluid also does not leak from the gap between the test piece T and the core portions 530, 630. Next, when the valve 680 is opened and the hydraulic fluid is sent from the hydraulic source at a low pressure, the hydraulic fluid is sent to the hydraulic oil reservoir via the lines 516, 536, the test piece T, the lines 636, 616, and the valve 680. At this time, the air in the test piece T and the pipes 516, 536, 636, and 616 is also discharged to the hydraulic oil reservoir with the hydraulic fluid, and the test piece and the pipes 516, 536, 636, and 616 are filled with the hydraulic oil. Next, when the valve 680 is closed and a specific initial hydraulic pressure is supplied by the hydraulic source, the hydraulic cylinder 570 (670) operates, and when the connecting plate 564 (664) is driven in the positive direction (negative direction) of the X-axis, it is fixed via At the rod 562 (662) of the connecting plate 564 (664), the sleeve 550 (650) is also strongly pressed into the positive X-axis direction (negative direction). With the tapered surface of the sleeve 550 (650), the collet 540 (640) is strongly pressed into the inner side, between the cylindrical portion 532 (632) of the core portion 530 (630) and the collet 540 (640), One end (the other end) of the piece T is firmly clamped. Further, when the pressure of the hydraulic fluid is removed after the test, the clamping of the collet 540 (640) is released by the rod 532 (662) and the sleeve 550 (650), so that it is in a non-clamped state. Further, in the support block 510 (610), a female screw 518 (618) for engaging the non-clamping bolt 566 (666) is provided, and the connecting plate 564 (664) is provided with a non-clamping bolt 566 (666). Through hole 564a (664a). The sleeve 550 (650), the collet 540 (640), and the test piece T are fixed so as not to be caught, and the non-clamping bolt 566 (666) is passed through the through hole 564a (664a) and screwed into the female thread 518. (618), by pressing the connecting plate 564 (664) into the supporting block 510 (610), the fixing of the collet 540 (640) is released, and the non-clamping state can be achieved.

Next, a method of calculating the strain and stress of the test piece T by the control unit (not shown) based on the detection result of the displacement of the test piece by the sensor unit 200 will be described. In the round pipe projection test, stress and strain changes in the circumferential direction (θ) of the circular tubular test piece T and the tube axis direction (φ) were measured. The circumferential direction stress σ _{φ of the} test piece T and the tube axis direction stress σ _θ are calculated by the equations (1) and (2), respectively. Further, the circumferential strain ε _{φ of the} test piece and the tube axis direction strain ε _θ are calculated by the equations (3) and (4), respectively. Further, the thickness t of the test piece T is calculated by the formula (5).

t = t ₀ ‧exp(ε _Φ -ε _θ ) ... (5)

L = L ₀ + e ₆ ... (6)

but,

P: internal pressure (hydraulic)

D: outer diameter of test piece T (D ₀ : initial value)

t: thickness of test piece T (t ₀ : initial value)

T: load in the tube axis direction

R _φ : radius of curvature in the tube axis direction

L: distance between punctuation points (L ₀ : initial value)

e ₆ : displacement in the axial direction of the outer peripheral surface of the center portion of the span of the test piece T (detected value of the axial direction shift detecting unit 280 )

Further, the internal pressure P is detected by a hydraulic gauge provided on a hydraulic source (not shown). Further, the tube axis direction stress T is detected by the load cell 54. Further, the outer diameter D of the test piece T and the radius of curvature R _{φ in the} tube axis direction were obtained by the method described below.

[Method of Obtaining Outer Diameter D]

The outer diameter D is detected by the first radial direction displacement detecting unit 220 (contact displacement meter 230b), the second radial direction displacement detecting unit 240, and the third radial direction displacement detecting unit 260, respectively, in the test piece T. The displacements e ₁ , e _{2 ,} and e ₃ in the radial direction of the outer peripheral surface of the span center (X-axis reference point) are calculated. Specifically, the outer diameter D of the test piece T is an amount by which the average value of the three displacement measurement values e ₁ , e _{2 ,} and e ₃ is the radius of the test piece T, and is calculated by the following formula (7).

Since the test piece T does not have complete axial symmetry, the deformation of the test piece T also becomes asymmetrical with respect to the tube axis. Therefore, when the change in the outer diameter of the test piece T is measured in only one direction, the error of the outer diameter D becomes relatively large, and the test accuracy (i.e., the finally obtained circumferential direction stress σ _φ and the tube axis direction stress σ _θ are accurate). Degree) will be low. In the present embodiment, the outer diameter D is calculated from the average of the radial displacement of the outer peripheral surface measured at three positions in the circumferential direction at the center of the span of the test piece T, and the measurement accuracy of the outer diameter D of the test piece T is measured. It will increase, and the circumferential direction stress σ _φ and the tube axis direction stress σ _θ become high precision. In addition, since the first radial direction displacement detecting unit 220, the second radial direction shift detecting unit 240, and the third radial direction shift detecting unit 260 are arranged at equal intervals around the tube axis of the test piece T, this is The average value of the displacement measurement values e ₁ , e _{2 ,} and e ₃ obtained by the three radial direction shift detecting sections becomes a value close to the average value of the entire circumference shift of the test piece T. That is, according to the configuration of the present embodiment, the measurement error can be effectively reduced by a small number of radial direction shift detecting portions.

[Method of Obtaining Curvature Radius R _φ in Tube Axis Direction]

The tube axis direction curvature radius R _φ is a displacement e ₄ , e ₁ , e ₅ of the needles 223a to 223c detected by the three contact type shift meters 230a to 230c of the first radial direction displacement detecting unit 220. (8), (9) to calculate. Further, the sign of the shifts e ₁ to e ₅ is defined as a positive shift in the direction in which the radius of the test piece T is increased.

but,

S: arrangement interval of the needles 223a to 223 of the first radial direction displacement detecting unit 220

The above is an illustration of an exemplary embodiment of the present invention. The configuration of the embodiment of the present invention is not limited to the above description, and can be arbitrarily changed within the scope of the technical idea expressed by the description of the patent scope. That is, other embodiments of the present invention do not need to have all of the features described above, or may have other additional or alternative features.

In the above embodiment, the other end of the connecting member 142 whose one end is connected to the second movable portion 40 is connected at the central portion of the connecting member 143, but the other end of the connecting member 142 may be connected at the central portion of the connecting member 141. Further, the connecting member 142 is provided with two, and the other end of one of the connecting members 142 may be connected at the connecting member 141, and the other end of the other connecting member 142 is connected at the connecting member 143. In this case, since the second movable portion 40 becomes driven by the two connecting members 142, even if a heavy measuring unit is used, the measuring unit can be smoothly and correctly moved.

Further, in the above-described embodiment, the strain in the central portion of the test piece T is measured. However, the present invention can be applied to measurement other than the shape of the central portion of the test piece T. Measurements other than the shape of the present invention can be applied, and examples thereof include electrical characteristics (for example, resistance of test piece T) or optical characteristics (for example, light reflectance).

Further, in the above embodiment, the length of the connector of the connector 142 is set to 1/2 of the length of the connector of the connector 143, and the second movable portion 40 is configured to be often located in the middle of the first movable portion 30 and the fixed portion 50. Point, but it is also possible to arbitrarily set the connector length ratio of the connector 142 to the connector 143 (i.e., the similar magnification of the isosceles triangle 578 to the isosceles triangle 679).

In the above embodiment, the hydraulic actuator driven and controlled by the servo valve is used as the actuator, but other types of actuators (for example, driven by a servo motor) may be used. Electric hydraulic actuators or electric actuators driven by various motors).

In the conventional method of measuring the cross-sectional shape in the center in the longitudinal direction of the test piece and measuring it with a CCD camera or an inductor array, only the measurement accuracy lower than the arrangement interval of the light-receiving elements is obtained, and a small change cannot be detected. Further, even if the projection angle is diverged or diffracted, the measurement accuracy is low, and in the case of using a large test piece, since the projection distance becomes long, it cannot be measured with sufficient accuracy. According to the material testing device according to the embodiment of the present invention described above, by using the contact type shift meter, it is possible to perform measurement with much higher accuracy and accuracy than the conventional level, even if a large test piece T is used. The condition of the test can also be measured with sufficient accuracy. Further, a shift meter (for example, a laser light reflection type non-contact shift meter) other than the contact type shift meter can be used, and the shift meter of the other type can measure the locality with high accuracy and high precision. Shift.

Further, the above-described sensor unit moving mechanism is not limited to the round pipe projection test, and may be various other types of measurements for mechanical tests such as general tensile test, compression test, and torsion test.

1. . . Material testing device

10. . . frame

12. . . Fixed plate

12a. . . Concave

14. . . Outer wall side

16. . . Inner wall side

18. . . Horizontal bottom plate

20. . . Hydraulic cylinder

twenty one. . . Cylinder tube

twenty two. . . Piston rod

twenty three. . . Accessory device

24, 55. . . bracket

30. . . First movable part

31, 41, 51. . . Pedestal

33, 53. . . Connecting part

40. . . Second movable part

50. . . Fixed part

32, 52. . . Chuck

54. . . Force measurer

54a. . . Weight acceptance strip

100. . . Sensor unit moving mechanism

120, 283. . . Linear guide

122, 123, 124, 228n, 283n, 332n, 334n. . . Slider

140. . . Connection mechanism

140a. . . Fixed connector

141, 142, 143. . . Movable connector

145, 146, 147, 148. . . pin

145a, 146a. . . Pin fixture

200. . . Sensor unit

201a. . . Opening

220. . . First radial direction shift detecting unit

222, 242, 352. . . Contact sub-plate

223a～223c, 243. . . needle

224a～224c, 244. . . Sensor support

201, 221, 225a ~ 225c, 241, 281, 330. . . board

226a～226c,342. . . clamp

227a～227c. . . arm

228, 248, 332, 334. . . Linear guide

121, 228m, 283m, 332m, 334m. . . track

230a～230c, 250, 360. . . Contact shift meter

231a～231c, 251. . . Ontology

232a～232c,362. . . Contactor

240. . . Second radial direction shift detecting unit

260. . . Third radial direction shift detecting unit

280. . . Axis direction shift detecting unit

282. . . Movable plate

282a, 346, 356. . . Locating pin

284, 322. . . Hand screw

300. . . Body part

310. . . Bearing department

312. . . Jack joint

320. . . axis

322, 518, 618. . . Female thread

344, 354. . . Clips

336. . . Hook plate

336h. . . hook

340. . . First sliding portion

350. . . Second sliding portion

370. . . Set fixture

372, 374. . . hole

378, 512, 554, 564a, 612, 664a. . . Through hole

578, 679. . . Isosceles triangle

510, 610. . . Support block

516, 532, 536, 616, 636. . . Pipeline

516a. . . take over

522, 622. . . Flange mounting surface

530, 630. . . Nuclear department

534,634. . . Tapered part

536, 636. . . Annular groove

540, 640. . . Collet

550, 650. . . Sleeve

554a. . . Insertion

554b. . . Fine gap

554c. . . Sitting section

560, 660. . . Slider

562, 662. . . Rod

562h. . . head

566, 666. . . bolt

570, 670. . . Hydraulic cylinder

590. . . Oil pressure gauge

620, 652. . . Flange

632. . . Cylindrical part

664. . . Connection plate

680. . . valve

B. . . Rubber ring

T. . . Test piece

First Fig.: A front view of a material testing device according to an embodiment of the present invention.

Second Fig.: A top view of a material testing device according to an embodiment of the present invention.

Third picture: A-A arrow view in the second picture.

Figure 4: Top view of the sensor unit moving mechanism.

Figure 5: Side view of the sensor unit.

Figure 6: Front view of the sensor unit.

Figure 7: Top view of the first radial direction shift detector.

Figure 8: Side view of the axial direction shift detector.

Figure 9: A diagram of the axial direction shift detector as seen in the positive direction of the Y' axis.

Figure 10: B-B arrow view in the ninth figure.

Figure 11: Top view of the fixed collet and the movable collet.

Figure 12: Longitudinal section of the fixed collet and the movable collet.

Thirteenth figure: C-C arrow view in the twelfth figure.

1‧‧‧Material testing device

10‧‧‧ box

12‧‧ ‧ fixing

14‧‧‧ outer wall side

16‧‧‧ inner wall side

18‧‧‧ horizontal floor

20‧‧‧Hydraulic cylinder

21‧‧‧Cylinder tube

22‧‧‧ piston rod

23‧‧‧Affiliated devices

24‧‧‧ bracket

30‧‧‧First movable department

31, 41, 51‧‧‧ Pedestal

33, 53‧‧‧ Connecting parts

40‧‧‧Second movable department

50‧‧‧ Fixed Department

32, 52‧‧‧ chucks

54‧‧‧ dynamometer

54a‧‧‧Load-receiving strip

100‧‧‧ sensor unit moving mechanism

120‧‧‧linear guide

121‧‧‧ Track

122, 123, 124‧‧‧ slider

140‧‧‧Connecting institutions

141, 142, 143‧‧‧ movable joints

145, 146, 147, 148‧ ‧ sales

T‧‧‧ test piece

Claims (10)

A material testing device which applies a stress in an internal pressure and a tube axis direction to a test piece of a circular tubular shape, and measures strain of the test piece, and is characterized in that: a plurality of radial direction displacement detecting portions are provided, and the test piece is detected in the test piece a displacement in the radial direction of the outer peripheral surface of the effective length central portion in the tube axis direction; the axial direction shift detecting portion detects a displacement in the tube axis direction of the outer peripheral surface of the effective length central portion of the test piece; and a calculation unit Calculating the circumferential direction and the tube axis direction strain in the central portion of the effective length of the test piece according to the detection results of the radial direction displacement detecting unit and the axial direction shift detecting unit, wherein the plurality of radial direction shift detecting units are Each of the plurality of radial direction displacement detecting portions includes a first shift meter that detects the effective long center of the test piece, and is configured to detect displacements in different directions around the tube axis of the test piece. Displacement in the radial direction of the outer peripheral surface of the portion, at least one of the plurality of radial direction displacement detecting portions, including: a second shift meter, relative to the first shift In the radial direction of the tube axis, the displacement of the outer peripheral surface of the test piece in the radial direction is detected, and the first and second shift meters each include a needle, and the tip end is vertically protruded from the test piece. The outer peripheral surface is freely movable in the radial direction according to the displacement of the outer peripheral surface of the test piece in the radial direction; the fixed frame; The movable frame is slidably slidable in a radial direction of the test piece with respect to the fixed frame; and the displacement sensor includes: a crotch portion mounted on the movable frame; and a contact portion from one end of the crotch portion Stretching in the radial direction of the test piece, the front end of the contact of the displacement sensor abuts against the contact protrusion protruding plate provided in the fixing frame, and the needle is attached to the movable frame In the radial direction of the test piece, the longitudinal direction of the test piece is protruded from the one end of the test piece, and the displacement of the outer peripheral surface of the test piece is detected by detecting the amount of movement of the needle. The curvature radius in the tube axis direction of the outer peripheral surface of the effective length central portion of the test piece is calculated based on the detection results of the first and second shift meters of the at least one radial direction displacement detecting portion. The material testing device according to claim 1, wherein the plurality of radial direction displacement detecting portions include: first, second, and third radial direction displacement detecting portions, which are disposed at intervals of 120° Around the tube axis of the test piece. The material testing device according to claim 1 or 2, further comprising: a sensor unit moving mechanism that sets the plurality of radial direction displacement detecting portions and the axial direction shift detecting portion The sensor unit is moved in the tube axis direction of the test piece with respect to the device frame of the material testing device, and the sensor unit moving mechanism includes: The first movable portion includes a movable chuck that is movable in a tube axis direction of the test piece to fix the one end of the test piece, and the fixed portion includes a fixed chuck. And fixing the other end of the test piece to the device frame; the second movable portion is disposed between the first movable portion and the fixed portion, and the sensor unit is moved to the test piece with respect to the device frame Moving in the tube axis direction; an actuator fixed to the device frame to drive the first movable portion in the specific direction; and a connecting mechanism connecting the device frame, the first movable portion, and the second movable portion And moving the central portion measuring device to an intermediate point between the movable chuck and the fixed chuck corresponding to the movement of the first movable portion. A material testing device for applying a stress in a specific direction to a test piece to measure a response of the test piece, comprising: a device frame; and a first movable portion having: a movable chuck (chuck) opposite to the device frame And being fixed to move in the specific direction to fix one end of the test piece; the fixing portion includes: a fixing chuck fixed to the device frame to fix the other end of the test piece; and the second movable portion having: a central portion The part measuring device is configured to be movable in the specific direction with respect to the apparatus frame between the first movable portion and the fixing portion, and to measure the specificity of the test piece when a load is applied to the test piece. Response to the central direction; An actuator is fixed to the device frame to drive the first movable portion in the specific direction; and a connection mechanism that connects the device frame, the first movable portion, and the second movable portion, by corresponding to the foregoing a movement of the movable portion moves the central portion measuring device to the center of the movable chuck and the fixed chuck, so that the central portion measuring device is often located at a central portion of the test piece in the specific direction; and extends in the specific direction a first movable portion having a first slider that is engaged with the rail, and the rail and the first slider are supported to be slidable in the specific direction, and the second movable portion is provided A second slider that meshes with the aforementioned rail is supported by the rail and the second slider to be freely slidable in the specific direction. The material testing device according to claim 4, wherein the fixing portion further includes: a load sensor that measures a load applied in the specific direction of the test piece; and a third slider that engages with the track The fixing chuck is freely movable to the specific direction, and the fixing chuck is disposed on the third slider and is fixed to the device frame via the load sensor. The material testing device according to claim 4, wherein the connecting mechanism has: a first connecting member, one end of which is connected to be rotatable via the first pin at the first movable portion; the second connection a second end of the second movable portion via a second pin Connected to be rotatable; and a third connector, one end of which is coupled to be rotatable via a third pin disposed on an opposite side of the first pin relative to the second pin, the first connector The other end of the third connecting member is connected to be rotatable via a fourth pin, and the other end of the second connecting member is coupled to the first or the third connecting member via the fifth pin to be rotatable, The interval between the fourth pin and the first pin is equal to the interval between the fourth pin and the third pin, and the interval between the fifth pin and the second pin is equal to the fifth pin, and the first and the foregoing The third pin is connected to the same connector as the aforementioned fifth pin. The material testing device according to claim 6, wherein the first movable portion, the second movable portion, and the fixed portion respectively have a bottom plate, and the first, second, and third sliders are respectively mounted on In the lower surface, the movable chuck, the central portion measuring device, and the fixing chuck are respectively mounted on the bottom plate and disposed above the bottom plate, and the connecting mechanism is mounted under each of the bottom plates, and is disposed on the bottom plate. Below the bottom plate. The material testing device according to claim 7, wherein the device frame is provided with: a fixed plate having an upper surface, the track being mounted on the upper surface of the device frame, On one side of the side surface of the fixed plate, a central portion is formed with a recessed portion, the recessed portion is recessed, has a bottom portion extending in parallel to the track, and is recessed in a horizontal direction, and the first to third connecting members are respectively disposed in the concave portion Inside. A material testing device which applies a stress in an internal pressure and a tube axis direction to a test piece of a circular tubular shape, and measures strain of the test piece, and is characterized in that: a plurality of radial direction displacement detecting portions are provided, and the test piece is detected in the test piece a displacement in the radial direction of the outer peripheral surface of the effective length central portion in the tube axis direction; the axial direction shift detecting portion detects a displacement in the tube axis direction of the outer peripheral surface of the effective length central portion of the test piece; and a calculation unit Calculating the circumferential direction and the tube axis direction strain in the central portion of the effective length of the test piece according to the detection results of the radial direction displacement detecting unit and the axial direction shift detecting unit, wherein the plurality of radial direction shift detecting units are Each of the axial direction shift detecting portions includes a fixed plate, and the movable plate is provided in the Z-axis direction with respect to the fixed plate, respectively, in order to detect displacements in different directions around the tube axis of the test piece. Freely sliding; and the main body portion is provided to be freely rockable around the Y-axis at a front end portion of the movable plate in the Z-axis direction, and the main body portion is provided with a plate and is mounted The movable plate can swing freely; a first sliding portion having a first clip that is protruded from a side surface of the test piece, the first sliding portion being slidably slidable in the X-axis direction with respect to the plate; and the second sliding portion having a protrusion a second clip on the side of the test piece, the second sliding portion is slidably slidable relative to the plate in the X-axis direction; and a contact shift meter detects the first clip and the second clip on the X-axis Relative displacement of direction. A material testing device for applying a stress in a specific direction to a test piece to measure a response of the test piece, comprising: a device frame; and a first movable portion having: a movable chuck (chuck) opposite to the device frame And being fixed to move in the specific direction to fix one end of the test piece; the fixing portion includes: a fixing chuck fixed to the device frame to fix the other end of the test piece; and the second movable portion having: a central portion The part measuring device is configured to be movable in the specific direction with respect to the apparatus frame between the first movable portion and the fixing portion, and to measure the specificity of the test piece when a load is applied to the test piece. a response of the central portion of the direction; an actuator fixed to the device frame to drive the first movable portion in the specific direction; and a connection mechanism connecting the device frame, the first movable portion, and the second movable portion a portion that moves the central portion measuring device to the center of the movable chuck and the fixed chuck by corresponding movement of the first movable portion It is frequently located in the central portion of the measurement test a central portion of the sheet in the specific direction, the connecting mechanism having: a first connecting member, one end of which is connected to be rotatable via the first pin at the first movable portion; and the second connecting member, one end of which is via the second pin The second movable portion is coupled to be rotatable; and the third connecting member has one end connected to the third pin on the opposite side of the first pin with respect to the second pin, and the device frame is connected to be rotatable, the aforementioned The other end of the first connecting member and the other end of the aforementioned third connecting member are connected to be rotatable via a fourth pin, and the other end of the second connecting member is connected to the first or the aforementioned third connecting member via a fifth pin Rotating, the interval between the fourth pin and the first pin is equal to the interval between the fourth pin and the third pin, and the interval between the fifth pin and the second pin is equal to the fifth pin, and The first and the third pins are spaced apart from each other by the same connector as the fifth pin.