Strength testing device

Abstract

To enable the strength to be examined that corresponds to the crush position of a test piece.SOLUTION: A strength testing device 1 is designed to conduct a strength test by pressurizing a test piece 5 between a base 3 and a slide 4 of a stamping machine 2. The strength testing device 1 comprises a placement jig 6 for placing a test piece 5 on the base 3; and a flat plate jig 7 attached to the slide 4 and having a contact surface 7a which the test piece 5 comes into contact with on the opposite side to the placement jig 6. The strength testing device 1 further includes: a load measuring unit 10 for measuring a compressive load P applied to the test piece 5 and interposed between the slide 4 and the flat plate jig 7; a displacement measuring unit 20 for measuring the position of the slide 4; and a data accumulation unit for outputting the compressive load P measured by the load measuring unit 10 in association with the position of the slide 4 measured by the displacement measuring unit 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a strength testing device.

Background Art

[0002] Conventionally, as a mold load measuring device, a device in which a plurality of load sensors (load cells) are arranged in a lattice pattern between the upper mold and the lower surface of the slide of the mold is known (see Patent Document 1, etc.). In such a device, when performing press working, the load acting on the mold is measured by the load sensor. Thereby, it is measured whether a load exceeding the allowable value acts on the mold, and breakage of the mold is prevented.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, there are cases where it is required to perform a destructive test on a large structure that does not fit in a compression tester and measure the load-bearing capacity, etc. However, the conventional mold load measuring device measures the strength of the mold used in a press working machine. For this reason, in order to press and crush test pieces (workpieces) having various shapes such as large structures and examine in detail whether there is the required strength at the crushed position, further improvement has been required.

[0005] An object of the present invention is to provide a strength testing device capable of examining the strength according to the crushing position of a test piece.

Means for Solving the Problems

[0006] The strength testing device of the present invention performs a strength test by pressing a test piece between the base and the slide of a press working machine. The strength testing device includes a mounting jig for mounting the test piece on the base, a flat jig attached to the slide and having a contact surface where the test piece abuts on the opposite side of the mounting jig, and a load measuring unit that is interposed between the slide and the flat jig and measures the compressive load applied to the test piece. Further, the strength testing device includes a displacement measuring unit that measures the position of the slide, and a data integration unit that associates the compressive load measured by the load measuring unit with the position of the slide measured by the displacement measuring unit.

Effect of the Invention

[0007] According to the present invention, there is provided a strength testing device capable of examining the strength of a test piece.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0009] Hereinafter, the strength test apparatus 1 according to the embodiment of the present invention will be described with reference to the drawings as appropriate.

[0010] As shown in FIG. 1, the strength test apparatus 1 according to Embodiment 1 pressurizes a test piece 5 using a press machine 2 to perform a strength test. The press machine 2 slides a slide 4 located above in the proximity and separation direction with respect to a base 3 located below. When performing normal press working, in the case of performing normal press working, a raw material is sandwiched between dies attached to the base 3 and the slide 4, and the raw material is compressed in the vertical direction for press working.

[0011] The strength test apparatus 1 according to Embodiment 1 uses such a press machine 2 to perform a destructive test on a large structure (test piece 5) that does not fit in a general compression tester and measures the load-bearing capacity and the like. Therefore, the strength test apparatus 1 includes a placement jig 6 for placing the test piece 5 on the base 3 instead of the die used for press working, and a flat plate jig 7 attached to the slide 4 and having a contact surface 7a with which the test piece 5 abuts on the opposite side of the placement jig 6. Among these, the placement jig 6 has a base body 6b on a flat plate placed on the base 3, and block-shaped stoppers 6a respectively fixed to the four corners of the base body.

[0012] Further, the flat plate jig 7 is composed of a flat plate member that is substantially rectangular in plan view. As shown in FIG. 2, a flat contact surface 7a is formed on the lower surface side of the flat plate jig 7. The upper end portion of the test piece 5 abuts on the central portion of the contact surface 7a.

[0013] Furthermore, the strength test apparatus 1 includes a load measurement unit 10 that measures the compressive load applied to the test piece 5 intervening between the slide 4 and the flat plate jig 7, and a displacement measurement unit 20 that measures the position of the slide 4. The load measurement unit 10 of the strength test apparatus 1 has four load cells 11. Each load cell 11 is disposed between the lower surface of a flat mounting plate member 4a attached to the lower surface side of the slide 4 and the upper surface of the flat jig 7. The mounting plate member 4a is detachably fixed to the lower surface side of the slide 4 by means such as bolt fastening.

[0014] As shown in FIG. 3, in the strength test apparatus 1 of Embodiment 1, four load cells 11 are arranged annularly at equal intervals so as to surround the central portion of the contact surface 7a, and each load cell 11 is arranged at a substantially equal distance from the test piece 5 and in pairs. Thereby, in a state where the press working machine 2 in which the slide 4 is located upward is open, below the mounting plate member 4a fixed to the slide 4, the flat jig 7 is horizontally suspended via the four load cells 11. Thereby, as shown in FIG. 4, a space is formed between the flat jig 7 attached to the slide 4 and the mounting jig 6 placed on the base 3, through which a large test piece 5 that does not fit in a general compression tester can be interposed.

[0015] Furthermore, the strength test apparatus 1 of Embodiment 1 is provided with a displacement measurement unit 20 for measuring the vertical position of the slide 4 at a position above the slide 4 (see FIG. 1). The displacement measurement unit 20 of Embodiment 1 has a laser displacement meter 21. The laser displacement meter 21 can irradiate laser light downward from the upper surface side of the slide 4 to measure the vertical position of the slide 4.

[0016] Also, as shown in FIG. 2, the strength test apparatus 1 is provided with a data integration unit 8. The data integration unit 8 is connected to the load measurement unit 10 and the displacement measurement unit 20, respectively. The data integration unit 8 of Embodiment 1 creates load-displacement data associated with the slide position S of the slide 4 measured by the displacement measurement unit 20 using the load F measured by the load measurement unit 10 as the stress of the test piece 5. Here, the slide position S of the slide 4 is made equivalent to the strain dimension of the test piece 5. Then, based on the created load-displacement data, the data integration unit 8 is configured to output, for example, an F-S diagram with the load F on the vertical axis and the slide position (displacement) S on the horizontal axis as shown in FIG. 6 from a monitor or a printer.

[0017] Next, the operational effects when measuring the strength of the test piece 5 with a complex shape as shown in FIG. 5 using the strength testing apparatus 1 of Embodiment 1 will be described. The test piece 5 whose strength is measured in Embodiment 1 has a long portion 5b having a longitudinal direction in the vertical direction while being placed on the upper surface of the mounting jig 6, and a short portion 5a having a shorter dimension in the vertical direction compared to the long portion 5b, which are integrally combined.

[0018] Also, on the lower end surfaces of the short portion 5a and the long portion 5b of the test piece 5, a flat plate member 5c that is substantially rectangular in plan view is welded in advance. The flat plate member 5c is detachably fixed to the upper surface of the base body 6b of the mounting jig 6 installed on the base 3 by bolt fastening or the like. In Embodiment 1, the test piece 5 for which a strength test is to be performed is positioned in the front-rear, left-right directions so that the upper end of the long portion 5b of the test piece 5 abuts against the central portion of the contact surface 7a provided on the flat plate jig 7. Thereby, the test piece 5 (see FIG. 1) placed stably on the upper surface of the mounting jig 6 is less likely to fall in the front-rear and left-right directions even as crushing progresses.

[0019] In the strength testing apparatus 1 of Embodiment 1, a space is formed between the flat plate jig 7 and the mounting jig 6 through which a large test piece 5 can be interposed. In the test piece 5 with a complex shape as shown in FIG. 5, it can be interposed between the base 3 and the slide 4 with the longitudinal direction of the long portion 5b aligned with the vertical direction in which the compressive load P is applied. In this way, in the strength testing device 1, the space where the test piece 5 is installed can be set large. Therefore, the shape of the mounting jig 6 can be changed to align the direction in which the test piece 5 is placed with the direction in which the compressive load P is applied. Therefore, it is possible to measure the mechanical properties such as the load-bearing capacity of the compressive load P applied to the test piece 5 from various directions while it is stabilized on the mounting jig 6.

[0020] In the strength test of Embodiment 1, the slide 4 slides downward toward the base 3, and the central portion of the contact surface 7a of the flat plate jig 7 is brought into contact with the upper end surface of the long portion 5b of the test piece 5 as shown in FIG. 2 or FIG. 4. The compressive load P of the slide 4 is transmitted from the mounting plate member 4a to the test piece 5 through each load cell 11 and the flat plate jig 7, and the test piece 5 is pressurized in the vertical direction between the mounting jig 6 placed on the base 3. The compressive load P of the press working machine 2 is preferably set to a value used in normal press working or a value smaller than the normal value within the range of the compressive load P that can be output using, for example, a thousand-ton press machine. Further, the load speed is set to be constant, for example, about 10 mm / s while moving in the slide direction.

[0021] When the compressive load P is applied to the test piece 5 and it is pressurized between the base 3 and the slide 4, stress is generated. The stress is dispersed from the central portion of the flat plate jig 7 that is in contact with the upper end surface of the long portion 5b of the test piece 5 in all directions and is transmitted to each load cell 11 of the load measurement unit 10 almost evenly and measured as the load F. At this time, in the strength testing device 1 of Embodiment 1, at the start of compression, the upper end of the long portion 5b of the test piece 5 comes into contact with the central portion of the contact surface 7a, and the movement in the front-rear, left-right directions is suppressed. Therefore, even if the crushing progresses, the displacement is small, and the distance to each load cell 11 arranged in pairs with the test piece 5 in between hardly changes.

[0022] Also, while the loading speed is moving in the sliding direction, it is set at a constant speed, for example, about 10 mm / s. Therefore, the upper end of the long portion 5b keeps contacting the contact surface 7a, and there is no risk of the test piece 5 falling over. Accordingly, the load F transmitted through the flat jig 7 is evenly distributed and measured almost equally by each load cell 11 arranged around it. The load F measured by the load measurement unit 10 is the stress of the test piece 5 and indicates the strength. Therefore, the load F measured by each load cell 11 can be collected in the data integration unit 8 and summed up to measure the strength of the test piece 5.

[0023] Furthermore, the load cells 11 of the strength test apparatus 1 of Embodiment 1 are arranged annularly at equal intervals. Therefore, when stress is applied from the test piece 5 to the flat jig 7, the flat jig 7 approaches evenly in the plane to the mounting plate member 4a fixed to the slide 4 while remaining in a horizontal state. Thus, the load F measured by each load cell 11 can be further homogenized to improve the measurement accuracy. Then, the strength test apparatus 1 abuts the mounting plate member 4a of the slide 4 against the stopper 6a to stop the downward movement and ends the measurement of the strength of the test piece 5.

[0024] As shown in FIG. 2, the displacement measurement unit 20 measures the vertical position of the slide 4 with a laser displacement meter 21 and sends it as measurement data to the data integration unit 8 to which it is connected. The data integration unit 8 uses the measured slide position S in the vertical direction of the slide 4 as the strain dimension due to the deformation of the test piece 5. Then, the data integration unit 8 associates and outputs the load F measured by the load measurement unit 10 with the slide position S based on the measurement data measured by the displacement measurement unit 20. Thereby, it is possible to examine the strength according to the strain dimension in the crushing direction indicating the crushing state of the test piece 5.

[0025] Specifically, the data integration unit 8 of Embodiment 1 regards the load F measured by the load measurement unit 10 as the stress of the test piece 5 and creates load-displacement data associated with the slide position S of the slide 4 measured by the displacement measurement unit 20. Based on the created load-displacement data, the data integration unit 8 outputs, for example, an F-S diagram as shown in FIG. 6 from a monitor or a printer.

[0026] In the F-S diagram shown in FIG. 6, the measurement results of the test piece 5 having a complex shape as shown in FIG. 5 are shown. In the F-S diagram, it can be seen that the load F increases and decreases multiple times as the crushing progresses according to the slide position S. Therefore, the strength corresponding to the crushing position of the test piece 5 can be examined. And in the F-S diagram, the mechanical properties can be analyzed by the slope of the F-S line, the inner area surrounded by the F-S line, etc. In particular, by analyzing the measurement results of the test piece 5 having a complex shape as in Embodiment 1, mechanical properties such as the load-bearing capacity according to the progress of crushing can be obtained. Thus, in the strength testing apparatus 1 of Embodiment 1, a destructive test can be performed on a large test piece 5 or the like that does not fit in a general compression tester to measure the load-bearing capacity and the like, and the strength of the test piece 5 can be evaluated.

[0027] Also, the laser displacement meter 21 of Embodiment 1 can measure the position of the slide 4 without contacting the slide 4. Since no external force is applied to the slide 4, it does not affect the measured load F. Therefore, the strength testing apparatus 1 can measure the load F corresponding to the crushing position of the test piece 5 more accurately. Furthermore, the laser displacement meter 21 of the embodiment can measure the vertical position from above the slide 4 as shown in FIG. 1. For this reason, even if a part of the test piece 5 scatters due to crushing, it is not blocked by the slide 4 and does not reach the laser displacement meter 21. Therefore, damage to the laser displacement meter 21 can be prevented.

[0028] Further, as shown in FIG. 4, the strength testing apparatus 1 of Embodiment 1 is equipped with a screen 30 having a transparent plate material on one or a plurality of outer surfaces of the press working machine 2. The screen 30 blocks the area between the base 3 and the slide 4 from the external area. Thereby, even if a part of the test piece 5 scatters due to crushing, it does not reach the surrounding measuring instruments or the like due to the screen 30, and damage to the measuring instruments or the like is prevented.

[0029] FIG. 7 shows the configuration of the strength testing apparatus 101 of Embodiment 2. Regarding parts that are the same as or equivalent to the strength testing apparatus 1 of Embodiment 1, the same reference numerals are given, and the description will focus on the different parts. In Embodiment 2, the bending strength of the rod-shaped test piece 25 is measured. The test piece 25 of Embodiment 2 has a substantially T-shaped one end portion 25b and the other end portion 25c integrally connected to both ends of the linear main shaft portion 25a, respectively. For this reason, the strength testing apparatus 101 is provided with a mounting jig 26 for stably mounting the test piece 25 on the base 3.

[0030] The mounting jig 26 mainly has a first mounting jig 26a that supports one end portion 25b of the test piece 25 from below, and a second mounting jig 26b that supports the other end portion 25c of the test piece 25 from below. Further, the mounting jig 26 has a flat jig substrate 26c. The jig substrate 26c fixes the first mounting jig 26a and the second mounting jig 26b in an integrated state while being separated by a certain distance. And the jig substrate 26c is fixed on the base 3 by bolt fastening or the like.

[0031] Thereby, when the test piece 25 is placed on the mounting jig 26 when performing the strength test, one end portion 25b is supported by the first mounting jig 26a and the other end portion 25c is supported by the second mounting jig 26b, respectively. And a space portion of a desired size that allows bending deformation is formed below the main shaft portion 25a that connects between the one end portion 25b and the other end portion 25c. In this state, the test piece 25 placed on the mounting jig 26 is supported at two points, the one end portion 25b and the other end portion 25c, and is placed on the base 3 in a stable state.

[0032] Also, on the lower surface side of the flat jig 7 attached to the slide 4, a pressing portion 27 that abuts the lower end against the main shaft portion 25a of the test piece 25 placed on the placing jig 26 and presses downward is protruding. The lower end 27a of the pressing portion 27 of the second embodiment is configured to abut against the upper surface of the intermediate portion 25d in the longitudinal direction of the main shaft portion 25a and apply a load from above to below.

[0033] In the strength test of the second embodiment, when the slide 4 is slid downward, the lower end of the pressing portion 27 protruding downward from the flat jig 7 abuts against the intermediate portion of the main shaft portion 25a of the test piece 25 and starts pressing downward. When the test piece 25 is pressurized between the base 3 and the slide 4, the test piece 25 deforms the main shaft portion 25a downward as shown by the phantom line in FIG. 7 and bends into a U shape. The stress of the test piece 25 is evenly transmitted to each load cell 11 of the load measuring portion 10 via the flat jig 7 and measured as the load F.

[0034] Also, in the displacement measuring portion 20, the vertical position of the slide 4 is being measured. And in the data integration portion 8, the load F measured by the load measuring portion 10 is associated with the slide position S of the slide 4 measured by the displacement measuring portion 20 and output. Thereby, the relationship between the load and displacement of the test piece 5 can be examined.

[0035] In the F - S diagram shown in FIG. 8, the measurement results of the bending strength of the bar - shaped test piece 25 as shown in FIG. 7 are shown. In the F - S diagram, it can be seen that the load F first increases and then decreases as the crushing progresses according to the slide position S. And when analyzing the measurement results of the test pieces 5 of such various shapes and sizes, mechanical properties such as load - bearing capacity according to the progress of deformation and crushing can be obtained. Regarding other configurations and operational effects, since they are the same as those in the first embodiment, the description is omitted. Thus, the strength testing apparatus 1, 101 of the embodiment can exhibit practically useful effects such as being able to perform a destructive test on a large structure that does not fit in a general compression tester and measure mechanical properties such as load-bearing capacity.

[0036] As described above, the strength testing apparatus 1 of the embodiment pressurizes the test piece 5 between the base 3 and the slide 4 of the press machine 2 to perform a strength test. The strength testing apparatus 1 includes a placement jig 6 for placing the test piece 5 on the base 3, and a flat jig 7 attached to the slide 4 and having a contact surface 7a against which the test piece 5 abuts on the opposite side of the placement jig 6. Further, the strength testing apparatus 1 includes a load measurement unit 10 for measuring the compressive load P applied to the test piece 5 intervening between the slide 4 and the flat jig 7, and a displacement measurement unit 20 for measuring the position of the slide 4. And the strength testing apparatus 1 includes a data integration unit 8 that outputs the compressive load P measured by the load measurement unit 10 in association with the position of the slide 4 measured by the displacement measurement unit 20.

[0037] The strength testing apparatus 1, 101 of the embodiment configured as described above can examine the strength according to the crushing position of the test piece 5. Specifically, the test piece 5 is placed on the base 3 in a stable state by the placement jig 6. When the test piece 5 is pressurized with the compressive load P between the base 3 and the slide 4, the stress of the test piece 5 is evenly transmitted through the flat jig 7 and measured as the load F by the load measurement unit 10. Also, the displacement measurement unit 20 measures the slide position of the slide 4. And in the data integration unit 8, the load F measured by the load measurement unit 10 is associated with the position of the slide 4 measured by the displacement measurement unit 20 and output. Thereby, the strength according to the crushing position of the test piece 5 can be examined.

[0038] Furthermore, the load measurement unit 10 has a plurality of load cells 11 arranged between the slide 4 and the flat jig 7. The plurality of load cells 11 can measure the load F transmitted through the flat jig 7 in a well-balanced and dispersed manner. Therefore, in the data integration unit 8, by collecting the loads F measured by the respective load cells 11, the mechanical properties such as the strength of the test piece 5 can be measured more accurately.

[0039] Further, the load cells 11 are arranged in a ring shape. Therefore, the load F transmitted from the test piece 5 to the flat plate jig 7 is measured evenly by the load cells 11 arranged in a ring shape. Accordingly, the stress of the test piece can be measured more accurately.

[0040] Furthermore, the displacement measurement unit 20 is a laser displacement meter 21 that irradiates the slide 4 with a laser beam to measure the slide position S of the slide 4. Therefore, the laser displacement meter 21 can measure the slide position S of the slide 4 without contacting the slide 4. For this reason, it does not affect the load F measured by the load measurement unit 10. Accordingly, the strength testing device 1 can measure the stress corresponding to the crushing position of the test piece 5 more accurately. Furthermore, the laser displacement meter 21 of the embodiment can measure the vertical slide position S from above the slide 4 as shown in FIG. 1. For this reason, even if a part of the test piece 5 scatters due to crushing, it is not blocked by the slide 4 and does not reach the laser displacement meter 21. Accordingly, a practically useful effect such as preventing damage to the laser displacement meter 21 is exhibited.

[0041] The present invention is not limited to the above-described embodiments, and various modifications are possible. The above-described embodiments are exemplified for easy understanding and explanation of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, a part of the configuration of each embodiment can be deleted, or other configurations can be added or replaced. Possible modifications to the above embodiments are, for example, as follows.

[0042] In Embodiment 1.2, in order to examine the strength according to the displacement along the load input direction of the test pieces 5 and 25 with different shapes, the press machine 2 with a constant load speed during the movement in the slide direction is used, but it is not particularly limited to this. For example, the slide movement speed may change, such as being low in the first stage of the slide movement. That is, for the test piece 5 sized to fit between the base 3 and the slide 4 of the press machine 2, destructive tests can be performed on various test pieces to measure mechanical properties such as load-bearing capacity. Therefore, the slide speed, output, etc. of the press machine 2 are not particularly limited.

[0043] Also, the quantity of the load cells 11 used in the load measurement unit 10 and the pattern arranged in a circular shape are not particularly limited. For example, three load cells 11 may be arranged at the vertices of an equilateral triangle, or a plurality of five or more load cells 11 may be arranged in a pattern with a certain interval. Furthermore, any type of sensor or the like may be used as long as it measures the compressive load applied to the test piece 5 intervening between the slide 4 and the flat plate jig 7. That is, the quantity, type, and arrangement pattern, etc. of the load cells 11 and the like used in the load measurement unit 10 and the like are not particularly limited.

Explanation of Reference Numerals

[0044] 1 Strength testing device 2 Press machine 3 Base 4 Slide 5 Test piece 6 Mounting jig 7 Flat plate jig 7a Contact surface 8 Data integration unit 10 Load measurement unit 20 Displacement measurement unit

Claims

1. A strength testing device for performing a strength test by pressing a test piece between a base and a slide of a press working machine, a placement jig for placing the test piece on the base, a flat plate jig attached to the slide and having a contact surface against which the test piece abuts on the opposite side of the placement jig, a load measurement unit interposed between the slide and the flat plate jig for measuring a compressive load applied to the test piece, a displacement measurement unit for measuring the position of the slide, and a data integration unit for associating and outputting the compressive load measured by the load measurement unit with the position of the slide measured by the displacement measurement unit. A strength testing device characterized by comprising the above.

2. The strength testing device according to claim 1, wherein the load measurement unit has a plurality of load cells disposed between the slide and the flat plate jig.

3. The strength testing device according to claim 2, wherein the load cells are arranged in a ring shape.

4. The strength testing device according to claim 1, wherein the displacement measurement unit is a laser displacement meter that irradiates the slide with laser light to measure the position of the slide.

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