Strength testing device

Abstract

Provided is a strength testing device with which it is possible to investigate strength on the basis of a crushing position on a test article. A strength testing device (1) performs a strength test by applying pressure to a test article (5) between a base (3) and a slide (4) of a press working machine (2). The strength testing device (1) comprises: a placement jig (6) for placing the test article (5) on the base (3); and a flat plate jig 7 that is attached to the slide (4) and has a contact surface (7a) that comes into contact with the test article (5) on the opposite side of the test article (5) from the placement jig (6). The strength testing device (1) also comprises: a load measurement unit (10) that is interposed between the slide (4) and the flat plate jig (7), and that measures the compression load P applied to the test article (5); a displacement measurement unit (20) that measures the position of the slide (4); and a data accumulation unit that outputs the compression 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).

Description

Strength Testing Equipment

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

[0002] Conventionally, a known die load measuring device has a plurality of load sensors (load cells) arranged in a grid pattern between the upper die and the lower surface of the slide of a die (see Patent Document 1, etc.). In such a device, the load sensors measure the load acting on the die during press working. This prevents damage to the die by determining whether a load exceeding a permissible value acts on the die.

[0003] Jikko No. 58-128797

[0004] In recent years, there has been a demand for destructive testing of large structures that cannot be contained in a compression testing machine to measure their load capacity, etc. However, conventional die load measuring devices measure the strength of dies used in press machines. Therefore, further improvements were needed to crush test pieces (workpieces) of various shapes, such as large structures, and to examine in detail whether the crushed parts have the required strength.

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

[0006] The strength testing apparatus of the present invention performs a strength test by applying pressure to a test piece between the base and slide of a press machine. The strength testing apparatus includes a mounting jig for mounting the test piece on the base, and a flat plate jig attached to the slide and having an abutment surface against which the test piece abuts on the opposite side of the mounting jig. The strength testing apparatus also includes a load measuring unit interposed between the slide and the flat plate jig for measuring the compressive load applied to the test piece. The strength testing apparatus also includes a displacement measuring unit for measuring the position of the slide, and a data accumulating unit for correlating the compressive load measured by the load measuring unit with the position of the slide measured by the displacement measuring unit.

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

[0008] FIG. 1 is a perspective view illustrating a basic configuration of a strength testing apparatus according to a first embodiment of the present invention. FIG. 2 is a side view illustrating the configuration of the strength testing apparatus according to the first embodiment, as viewed from the direction of the arrow II in FIG. 1. FIG. 3 is a top view illustrating the configuration of the strength testing apparatus according to the first embodiment, as viewed from the direction of the arrow III in FIG. 1. FIG. 4 is a side view illustrating the configuration of the strength testing apparatus according to the first embodiment, as viewed from the direction of the arrow IV in FIG. 1. FIG. 5 is a perspective view illustrating a test piece measured using the strength testing apparatus according to the first embodiment. FIG. 6 is an FS diagram illustrating the results of measuring the test piece shown in FIG. 5 using the strength testing apparatus according to the first embodiment. FIG. 7 is an FS diagram illustrating the results of measuring the test piece shown in FIG. 7 using the strength testing apparatus according to the second embodiment.

[0009] Hereinafter, a strength testing device 1 according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] As shown in Figure 1, the strength testing device 1 of the first embodiment performs a strength test by applying pressure to a test piece 5 using a press machine 2. The press machine 2 moves a slide 4 located above in a direction toward and away from a base 3 located below. When performing normal press working, the press machine is configured to sandwich raw material between dies attached to the base 3 and the slide 4 and compress the raw material in the vertical direction to perform press working.

[0011] The strength testing apparatus 1 of the first embodiment uses such a press machine 2 to perform a destructive test on a large structure (test piece 5) that would not fit into a typical compression testing machine, thereby measuring the withstand load, etc. For this reason, instead of a mold used in press working, the strength testing apparatus 1 is equipped with a mounting jig 6 for mounting the test piece 5 on the base 3, and a flat plate jig 7 attached to the slide 4 and having an abutment surface 7a against which the test piece 5 abuts on the opposite side of the mounting jig 6. Of these, the mounting jig 6 has a flat plate-like base body 6b that is placed on the base 3, and block-shaped stoppers 6a fixed to the four corners of the base body.

[0012] The flat plate jig 7 is made of a flat plate member that is generally rectangular in plan view. As shown in Fig. 2, a flat contact surface 7a is formed on the lower surface of the flat plate jig 7. The upper end of the test piece 5 contacts the center of the contact surface 7a.

[0013] Furthermore, the strength testing apparatus 1 is equipped with a load measuring unit 10 that is interposed between the slide 4 and the flat plate jig 7 and measures the compressive load applied to the test piece 5, and a displacement measuring unit 20 that measures the position of the slide 4. The load measuring unit 10 of the strength testing 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 underside of the slide 4 and the upper surface of the flat plate jig 7. The mounting plate member 4a is detachably fixed to the underside of the slide 4 by bolting or the like.

[0014] As shown in Fig. 3, in the strength testing apparatus 1 of the first embodiment, four load cells 11 are arranged in a ring shape at equal intervals so as to surround the center of the contact surface 7a, and each load cell 11 is arranged in pairs at approximately equal distances from the test piece 5. As a result, when the press machine 2 with the slide 4 positioned above is opened, the flat plate jig 7 is suspended horizontally via the four load cells 11 below the mounting plate member 4a fixed to the slide 4. As a result, as shown in Fig. 4, a space is formed between the flat plate jig 7 attached to the slide 4 and the mounting jig 6 placed on the base 3, in which a large test piece 5 that cannot be contained in a general compression testing device can be placed.

[0015] Furthermore, the strength testing apparatus 1 of the first embodiment is provided with a displacement measuring unit 20 above the slide 4 that measures the vertical position of the slide 4 (see FIG. 1). The displacement measuring unit 20 of the first embodiment has a laser displacement meter 21. The laser displacement meter 21 can measure the vertical position of the slide 4 by irradiating the upper surface side of the slide 4 with laser light from above downward.

[0016] As shown in FIG. 2, the strength testing apparatus 1 is also equipped with a data collection unit 8. The data collection unit 8 is connected to a load measurement unit 10 and a displacement measurement unit 20. The data collection unit 8 of the first embodiment uses the load F measured by the load measurement unit 10 as the stress of the test piece 5 to create load-displacement data associated with the slide position S of the slide 4 measured by the displacement measurement unit 20. Here, the slide position S of the slide 4 is assumed to be equivalent to the strain dimension of the test piece 5. The data collection unit 8 is configured to output, from a monitor or printer, an FS diagram in which the vertical axis indicates the load F and the horizontal axis indicates the slide position (displacement) S, as shown in FIG. 6, for example, based on the created load-displacement data.

[0017] Next, the effects of using the strength testing apparatus 1 of the first embodiment to measure the strength of a test piece 5 having a complex shape as shown in Fig. 5 will be described. The test piece 5, whose strength is measured in the first embodiment, is integrally combined with a long portion 5b having a longitudinal direction in the up-down direction when placed on the upper surface of the mounting jig 6, and a short portion 5a having a shorter dimension in the up-down direction compared to the long portion 5b.

[0018] Furthermore, a flat plate material 5c having a generally rectangular shape in plan view is welded in advance to the lower end surfaces of the short portion 5a and the long portion 5b of the test specimen 5. The flat plate material 5c is detachably fixed by bolting or the like to the upper surface of the base body 6b of the mounting jig 6 installed on the base 3. In the first embodiment, the test specimen 5 to be subjected to a strength test is positioned in the front-rear and left-right directions so that the upper end of the long portion 5b of the test specimen 5 abuts the center of the abutment surface 7a provided on the flat plate jig 7. As a result, the test specimen 5 (see FIG. 1 ), which is stably placed on the upper surface of the mounting jig 6, is less likely to tip over in the front-rear and left-right directions even if crushing progresses.

[0019] In the strength testing apparatus 1 of the first embodiment, a space is formed between the flat plate jig 7 and the mounting jig 6 that allows a large test specimen 5 to be placed therein. A test specimen 5 having a complex shape, such as that shown in FIG. 5 , can be placed 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, the strength testing apparatus 1 allows a large space to be set for the test specimen 5. Therefore, the shape of the mounting jig 6 can be changed to align the test specimen 5 with the direction in which the compressive load P is applied. Therefore, it is possible to measure mechanical properties such as the withstand load of the compressive load P applied to the test specimen 5 from various directions while the test specimen 5 is stabilized on the mounting jig 6.

[0020] In the strength test of the first embodiment, the slide 4 slides downward toward the base 3, and the central portion of the contact surface 7a of the plate jig 7 abuts against the upper end surface of the long portion 5b of the test piece 5, as shown in FIG. 2 or 4 . The compressive load P of the slide 4 is transmitted to the test piece 5 from the mounting plate member 4a via the load cells 11 and the plate jig 7, and presses the test piece 5 in the vertical direction between the slide 4 and the mounting jig 6 placed on the base 3. The compressive load P of the press 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 compressive load P that can be output using, for example, a 1,000-ton press machine. The load speed is set to a constant speed of, for example, approximately 10 mm / s while moving in the slide direction.

[0021] When a compressive load P is applied to the test specimen 5 and it is compressed between the base 3 and the slide 4, stress is generated. The stress is dispersed in all directions from the center of the flat plate jig 7, against which the upper end surface of the long portion 5b of the test specimen 5 abuts, and is transmitted almost evenly to each load cell 11 of the load measuring unit 10, where it is measured as a load F. In this case, in the strength testing apparatus 1 of embodiment 1, the upper end of the long portion 5b of the test specimen 5 abuts the center of the abutment surface 7a at the start of compression, suppressing movement in the front-rear and left-right directions. Therefore, even as the crushing progresses, there is little displacement, and the distance to each of the load cells 11 arranged in pairs on either side of the test specimen 5 remains almost constant.

[0022] Furthermore, the load speed is set to a constant speed, for example, about 10 mm / s, during movement in the sliding direction. Therefore, the upper end of the long portion 5b continues to abut against the abutment surface 7a, eliminating the risk of the test specimen 5 tipping over. Therefore, the load F transmitted via the flat plate jig 7 is evenly distributed and measured almost evenly by each of the load cells 11 arranged around it. The load F measured by the load measuring unit 10 is the stress of the test specimen 5 and indicates its strength. Therefore, the loads F measured by each load cell 11 are collected and added up in the data collecting unit 8, allowing the strength of the test specimen 5 to be measured.

[0023] Furthermore, the load cells 11 of the strength testing apparatus 1 of embodiment 1 are arranged at equal intervals in a ring shape. Therefore, when stress is applied to the flat plate jig 7 from the test piece 5, the flat plate jig 7 approaches the mounting plate member 4a fixed to the slide 4 evenly within its plane while remaining horizontal. This further homogenizes the load F measured by each load cell 11, improving measurement accuracy. The strength testing apparatus 1 then abuts the mounting plate member 4a of the slide 4 against the stopper 6a to stop the downward movement, thereby completing the measurement of the strength of the test piece 5.

[0024] 2, the displacement measurement unit 20 measures the vertical position of the slide 4 using a laser displacement meter 21 and sends the measurement data to the connected data collection unit 8. The data collection unit 8 regards the measured vertical slide position S of the slide 4 as the strain dimension due to deformation of the test specimen 5. The data collection unit 8 then outputs the load F measured by the load measurement unit 10 in relation to the slide position S based on the measurement data measured by the displacement measurement unit 20. This makes it possible to investigate the strength corresponding to the strain dimension in the crushing direction that indicates the crushing state of the test specimen 5.

[0025] More specifically, the data collection unit 8 of the first embodiment regards the load F measured by the load measurement unit 10 as the stress of the test piece 5, and creates load-displacement data that correlates the load F 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 collection unit 8 outputs an FS diagram, for example, as shown in FIG. 6, from a monitor or a printer.

[0026] The FS diagram shown in FIG. 6 shows the measurement results of a test specimen 5 having a complex shape as shown in FIG. 5 . The FS diagram reveals that the load F increases and decreases multiple times as the collapse progresses depending on the slide position S. This allows the strength of the test specimen 5 to be examined according to the collapse position. Furthermore, the FS diagram allows the mechanical properties to be analyzed based on the slope of the FS line, the area inside the FS line, and the like. In particular, by analyzing the measurement results of a test specimen 5 having a complex shape as in the first embodiment, mechanical properties such as load capacity depending on the progress of collapse can be obtained. In this way, the strength testing device 1 of the first embodiment can perform a destructive test on a large test specimen 5 that would not fit in a typical compression testing machine, measure the load capacity, and evaluate the strength of the test specimen 5.

[0027] Furthermore, the laser displacement meter 21 of the first embodiment can measure the position of the slide 4 without coming into contact with the slide 4. Because no external force is applied to the slide 4, the load F to be measured is not affected. Therefore, the strength testing device 1 can more accurately measure the load F according to the crushing position of the test piece 5. Furthermore, the laser displacement meter 21 of the embodiment can measure the vertical position from above the slide 4, as shown in FIG. 1. Therefore, even if part of the test piece 5 is scattered by crushing, the scattered part is 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] 4, the strength testing apparatus 1 of the first embodiment is equipped with a screen 30 having a transparent plate material attached to one or more outer surfaces of the press machine 2. The screen 30 isolates the area between the base 3 and the slide 4 from the outside. As a result, even if part of the test piece 5 is crushed and scattered, the screen 30 prevents the scattered part from reaching surrounding measuring equipment, etc., thereby preventing damage to the measuring equipment, etc.

[0029] 7 shows the configuration of a strength testing apparatus 101 of embodiment 2. Note that parts that are the same as or equivalent to those of the strength testing apparatus 1 of embodiment 1 are assigned the same reference numerals, and the following description will focus on the differences. In embodiment 2, the bending strength of a rod-shaped test piece 25 is measured. The test piece 25 of embodiment 2 has a linear main shaft portion 25a, with one end 25b and the other end 25c of a generally T-shape integrally connected to both ends thereof. Therefore, 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 includes a first mounting jig 26a that supports one end 25b of the test specimen 25 from below, and a second installation jig 26b that supports the other end 25c of the test specimen 25 from below. The mounting jig 26 also includes a flat jig base plate 26c. The jig base plate 26c secures the first mounting jig 26a and the second installation jig 26b together while spaced apart by a fixed distance. The jig base plate 26c is then secured to the base 3 by bolts or the like.

[0031] As a result, when a strength test is performed, when the test piece 25 is placed on the mounting jig 26, one end 25b is supported by the first mounting jig 26a and the other end 25c is supported by the second installation jig 26b. A space of a desired size to allow bending deformation is formed below the main shaft portion 25a connecting the one end 25b and the other end 25c. In this state, the test piece 25 placed on the mounting jig 26 is supported at two points, the one end 25b and the other end 25c, and is placed stably on the base 3.

[0032] Furthermore, a pressing portion 27 projects from the center position on the underside of the flat plate jig 7 attached to the slide 4, with its lower end abutting against the main shaft portion 25a of the test piece 25 placed on the mounting jig 26 and pressing downward. The lower end 27a of the pressing portion 27 in the second embodiment is configured to abut against the upper surface of the longitudinal intermediate portion 25d of the main shaft portion 25a and apply a load from above downward.

[0033] In the strength test of embodiment 2, when the slide 4 is slid downward, the lower end of the pressing portion 27 protruding downward from the flat plate jig 7 abuts against the middle portion of the main shaft portion 25a of the test piece 25 and begins to press downward. When pressure is applied to the test piece 25 between the base 3 and the slide 4, the main shaft portion 25a of the test piece 25 is deformed downward and bent into a dogleg shape, as shown by the imaginary line in Figure 7. The stress of the test piece 25 is transmitted evenly to each load cell 11 of the load measuring unit 10 via the flat plate jig 7 and measured as a load F.

[0034] The displacement measuring unit 20 also measures the vertical position of the slide 4. The data accumulating unit 8 then outputs the load F measured by the load measuring unit 10 in association with the slide position S of the slide 4 measured by the displacement measuring unit 20. This makes it possible to investigate the relationship between the load and displacement of the test piece 5.

[0035] The FS diagram shown in FIG. 8 shows the bending strength measurement results of a rod-shaped test specimen 25 as shown in FIG. 7 . The FS diagram shows that the load F increases and then decreases as the collapse progresses depending on the slide position S. When analyzing the measurement results of test specimens 5 of various shapes and sizes, mechanical properties such as load capacity can be obtained according to the progress of deformation and collapse. Other configurations and effects are the same as those of the first embodiment, and therefore will not be described here. Thus, the strength testing apparatus 1, 101 of the embodiment can exhibit practically beneficial effects, such as the ability to perform destructive testing on large structures that cannot be contained in a typical compression testing machine and measure mechanical properties such as load capacity.

[0036] As described above, the strength testing apparatus 1 of this embodiment performs a strength test by applying pressure to the test piece 5 between the base 3 and slide 4 of the press machine 2. The strength testing apparatus 1 includes a mounting jig 6 for mounting the test piece 5 on the base 3, and a flat plate jig 7 attached to the slide 4 and having a contact surface 7a against which the test piece 5 contacts on the opposite side of the mounting jig 6. The strength testing apparatus 1 also includes a load measuring unit 10 interposed between the slide 4 and the flat plate jig 7 for measuring the compressive load P applied to the test piece 5, and a displacement measuring unit 20 for measuring the position of the slide 4. The strength testing apparatus 1 also includes a data accumulating unit 8 that correlates the compressive load P measured by the load measuring unit 10 with the position of the slide 4 measured by the displacement measuring unit 20 and outputs the result.

[0037] The strength testing apparatus 1, 101 of the embodiment configured as described above can examine the strength according to the crush position of the test specimen 5. More specifically, the test specimen 5 is stably placed on the base 3 by the mounting jig 6. When the test specimen 5 is pressed with a compressive load P between the base 3 and the slide 4, the stress of the test specimen 5 is transmitted evenly via the flat plate jig 7 and measured as a load F by the load measuring unit 10. The displacement measuring unit 20 also measures the sliding position of the slide 4. The data collecting unit 8 then outputs the load F measured by the load measuring unit 10 in association with the position of the slide 4 measured by the displacement measuring unit 20. This makes it possible to examine the strength according to the crush position of the test specimen 5.

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

[0039] The load cells 11 are arranged in a ring shape. Therefore, the load F transmitted from the test piece 5 to the plate jig 7 is measured evenly by the ring-shaped load cells 11. This allows the stress of the test piece to 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 coming into contact with the slide 4. This does not affect the load F measured by the load measurement unit 10. Therefore, the strength testing apparatus 1 can more accurately measure the stress corresponding to the crushing position of the test specimen 5. Furthermore, the laser displacement meter 21 of the embodiment can measure the slide position S in the vertical direction from above the slide 4, as shown in FIG. 1. Therefore, even if part of the test specimen 5 is crushed and scattered, the scattered part is blocked by the slide 4 and does not reach the laser displacement meter 21. This provides a practically beneficial effect, such as preventing damage to the laser displacement meter 21.

[0041] The present invention is not limited to the above-described embodiments, and various modifications are possible. The above-described embodiments are provided as examples to facilitate understanding of the present invention, and are not necessarily limited to those including all of the configurations described. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to delete part of the configuration of each embodiment, or to add or replace other configurations. Possible modifications of the above-described embodiments include, for example, the following.

[0042] In the first and second embodiments, a press machine 2 is used in which the load speed is constant throughout the slide movement in order to examine the strength of test pieces 5, 25 of different shapes in response to displacement along the load input direction. However, this is not particularly limited. For example, the slide movement speed may vary, such as being slower in the early stages of slide movement. In other words, as long as the test piece 5 is small enough to fit between the base 3 and slide 4 of the press machine 2, destructive testing can be performed on various test pieces to measure their mechanical properties, such as load resistance. Therefore, the slide speed, output, etc., of the press machine 2 are not particularly limited.

[0043] Furthermore, the number of load cells 11 used in the load measuring unit 10 and the circular arrangement pattern are not particularly limited. For example, three load cells 11 may be arranged at each vertex of an equilateral triangle, or five or more load cells 11 may be arranged in a pattern with regular intervals. Furthermore, any type of sensor may be used as long as it is interposed between the slide 4 and the flat plate jig 7 and measures the compressive load applied to the test piece 5. In other words, the number, type, arrangement pattern, etc. of the load cells 11 used in the load measuring unit 10, etc. are not particularly limited.

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

Claims

1. A strength testing apparatus for performing a strength test by applying pressure to a test piece between a base and a slide of a press processing machine, comprising: a mounting jig for mounting a test piece on the base; a flat plate jig attached to the slide and having a contact surface against which the test piece contacts on the opposite side of the mounting jig; a load measuring unit interposed between the slide and the flat plate jig for measuring the compressive load applied to the test piece; a displacement measuring unit for measuring the position of the slide; and a data accumulation unit for outputting the compressive load measured by the load measuring unit in relation to the position of the slide measured by the displacement measuring unit.

2. A strength testing device according to claim 1, wherein said load measuring section has a plurality of load cells disposed between said slide and said flat plate jig.

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

4. A strength testing device according to claim 1, characterized in that the displacement measuring section is a laser displacement meter which measures the position of the slide by irradiating the slide with laser light.

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