JP4441466B2 - Mechanical property test equipment - Google Patents

Description

  The present invention relates to a mechanical property testing apparatus for measuring mechanical properties such as tensile strength, compressive strength, bending strength or tensile fatigue strength of materials such as metals, ceramics, and resins in a high-pressure gas atmosphere. . More specifically, in a test device using a frame-type high-pressure vessel that is excellent in safety and can easily replace test pieces and jigs, the gas pressure load acting on the load rod of the test device is balanced. In particular, the present invention relates to a mechanical property test apparatus with improved load load measurement accuracy and workability for attaching / detaching a test piece.

  To grasp the mechanical properties such as tensile strength, compressive strength, bending strength and tensile fatigue strength of materials such as metals, ceramics and resins used under high-pressure gas atmosphere, use these materials under high-pressure gas atmosphere This is important for equipment design. Under such a special environment, a peculiar phenomenon of the material is expressed.

  Generally, the strength characteristics of materials such as metals, resins, and ceramics change under a high-pressure gas atmosphere. For example, it is known that the ductility of a metal increases under a high pressure of several hundred MPa, and in a specific gas atmosphere, for example, a high-pressure hydrogen gas atmosphere, a steel material absorbs hydrogen and becomes brittle. It is known.

  In particular, in recent years, research and development of fuel cells using hydrogen as fuel has been activated, and rapid progress from the prototype stage to the practical use stage has been recognized for its application, mainly in automobiles and household use. In particular, in automotive applications, the application to commercial vehicles is rapidly being developed in the form of boosting the global warming problem and rising fossil fuels, and filling cylinders with hydrogen compressed to a high pressure of 35 MPa or 70 MPa as fuel. Compressed hydrogen type to be used is preceded.

  Then, the pressure is reduced by a pressure reducing valve from such a high pressure state, and the material used for this valve is a steel-based material. This is very important, and it is an urgent task to accumulate experimental data on strength characteristics.

  On the other hand, since the test apparatus itself for measuring mechanical properties such as tensile strength in a high-pressure hydrogen gas atmosphere of several tens to several hundred MPa is also exposed to such an atmosphere, the structural material as well as the structural material is sufficient. The fact is that there is no simple measuring device.

  In order to measure mechanical properties such as tensile strength and compressive strength of a material, a load is applied to a test piece of a specific size and shape, and at the same time, both the load applied to the test piece and the amount of deformation are measured. There is a need. When such measurement is performed in a high-pressure gas atmosphere, the load is applied to the test piece from the outside of the high-pressure vessel by storing the test piece in the test piece support provided inside the high-pressure vessel forming the high-pressure gas atmosphere. Will be added separately.

One of the technical problems in this respect is to reduce the influence of an error in the load value due to the high pressure gas pressure acting on the load rod. In order to solve this problem, two conventional methods have been proposed.
Such a conventional mechanical property testing apparatus will be described below with reference to FIGS. 5 and 6 of the accompanying drawings.

  FIG. 6 shows a longitudinal sectional view of a conventional material testing atmosphere container (see Patent Document 1). According to this conventional example, the structure part combining the piston 45 and the pressure chamber 41 is provided between the load load shaft 40 and the test atmosphere chamber 42 in which the test piece 44 loaded with the test load is accommodated. The test atmosphere chamber 42 and the pressure chamber 41 are communicated with each other by a pipe 43, and the gas inside the high-pressure vessel 46 is introduced into the pressure chamber 41 in this portion to balance the load due to the gas pressure. In this method, a load due to pressure is not applied.

  However, according to the material test atmosphere container 47, in order to form the pressure chamber 41, the seal 48 attached to the load load shaft 40, the seal 49 attached to the piston 45, and the narrow portion of the piston 45 are attached. Three seals of the seal 50 are required.

  That is, when the load shaft is extracted from the high-pressure vessel into the atmosphere as it is, the load due to the gas pressure is applied as a load, but structurally only one seal portion is required, but three seals are required, and Since a portion with a large diameter is included, the area of the sliding portion is three times or more, and the resistance force due to the frictional force increases accordingly. Further, as the atmospheric pressure becomes higher, the frictional force generated in these portions becomes larger, and gas leakage is more likely to occur.

  In addition, when such a balance mechanism is incorporated into the upper lid or lower lid of the high-pressure vessel, the ease of replacement of these seal rings also becomes a problem, so the lid on the side where the balance mechanism is mounted has a rather complicated structure. . Furthermore, in order to generate this balance force, it is necessary to have a very complicated structure, such as a pipe for applying the same gas pressure as that in the pressure vessel to the pressure chamber. .

  Another method is a mechanical property test apparatus proposed by the inventors of the present invention. As shown in FIG. 7, a balance rod 54 having the same diameter as that of the pull rod 58 for overloading is used. In this method, the pull rod 58 is disposed so as to penetrate the high-pressure vessel 55 at a position facing the lid 56 through which the pull rod 58 penetrates.

  In the case of this method, compared to the above method, the contact area between the seal ring 53a and the pull rod 58 arranged at the seal portion of the pull rod 58 with the lid 56 can be reduced, so that the load error due to the frictional force can be reduced. Has the advantage.

  However, since a large load due to a high gas pressure of several tens to 100 MPa is applied to the support member 52 that couples the pull rod 58 and the balance rod 54 inside the high pressure vessel 55, in order to hold this Even when a high-strength material is used, it is necessary to ensure a sufficient cross-sectional area. The presence of the support member 52 has a problem that not only the mounting space of the test piece 51 is narrowed but also the replacement of the test piece 51 itself is very complicated.

Further, since the balance rod 54 has a structure that penetrates the lid 57 that opposes the lid 56 through which the pull rod 58 penetrates, the concentricity of the holes that penetrate these two lids 56 and 57 is very important, and this is shifted. If it exists, a bending load will generate | occur | produce in the pull rod 58, and a load measurement precision will fall.
Japanese Patent Publication No.54-10875 JP 2004-340920 A

  Summarizing the problems of the conventional example as described above, in the first conventional example, the resistance force due to the frictional force increases due to the increase in the sliding area due to the increase in the seal location, and gas leakage also occurs. Had the problem of being easy to do. In the second conventional example, the support member in the high-pressure vessel narrows the mounting space for the test piece and makes it difficult to replace the test piece, and the load measurement on the concentricity of the two holes through which the rod passes is performed. There was a problem that the accuracy was likely to decrease.

  Accordingly, an object of the present invention is to provide a high-accuracy mechanical property apparatus that does not increase the number of sealing points of the high-pressure vessel and that does not cause the support member to narrow the mounting space of the test piece.

In order to achieve the above object, the means employed by the mechanical property test apparatus according to claim 1 of the present invention penetrates the high-pressure vessel through a test piece mounted inside the high-pressure vessel under a high-pressure gas atmosphere. In a mechanical property test apparatus for measuring mechanical properties of the test piece by applying a test load by a load load actuator through a load load rod, the high pressure vessel is a high pressure cylindrical vessel, an upper lid and a lower lid. The high-pressure vessel has a lower lid fixedly supported by a high-pressure vessel gantry and is mounted on the load-loading rod of the load-loading actuator on an extension of the load-loading rod opposite to the test piece side. Te, with a fluid cylinder which is connected to the piston for balancing having substantially the same cross-sectional area and high-pressure gas receiving area of said load-bearing rod is disposed, The fluid cylinder is directly connected to the load rod of the load load actuator, this fluid cylinder is fixed to the high pressure vessel by a bracket, and a cylindrical connecting member is coupled to the load rod. The connecting member is coupled to a load-loading rod constituting the load-loading actuator via a load cell, while the cylindrical connecting member is formed with a window hole for avoiding interference with the bracket. It is characterized by being made.

Means according to claim 2 Mechanical properties testing device according to the adopted in the present invention, in the mechanical properties testing device according one of claims, wherein the load cell, characterized in that a strain gauge type load cell is there.

In the mechanical property testing apparatus according to claim 1 of the present invention, the high-pressure vessel is constituted by a high-pressure cylindrical vessel, an upper lid and a lower lid, and the high-pressure vessel has a lower lid fixedly supported by a high-pressure vessel gantry, A load-bearing rod of the load-loading actuator has a cross-sectional area that is on the extension of the load-loading rod on the side opposite to the test piece side and has substantially the same cross-sectional area as the high-pressure gas pressure receiving area of the load-loading rod. A fluid cylinder having a piston connected thereto, and the fluid cylinder is directly connected to the load rod of the load actuator, the fluid cylinder being fixed to the high pressure vessel by a bracket, A cylindrical connecting member is coupled to the load rod, and this connecting member constitutes the load load actuator. While that is coupled via a load cell rod, wherein the cylindrical connecting member, since the window holes for avoiding interference with the bracket is formed, the sealing portion of the rod for load-bearing of the high-pressure vessel Since there is only one place and the balance rod is not present in the high-pressure vessel, a high-accuracy mechanical property new apparatus can be realized without narrowing the mounting space for the test piece. In addition, there is an effect that the load by the high-pressure gas does not act on the load cell at all.

Further, according to the mechanical property test apparatus according to claim 2 of the present invention, since the load cell is a strain gauge type load cell , a test load applied to the test piece by the load rod is applied to the load cell. Can be measured directly. As a result, when the test load value is converted from the hydraulic pressure, the error due to the frictional force of the seal ring acting on the load load rod can be eliminated, so that the test load value can be accurately grasped.

First, a mechanical property test apparatus according to Embodiment 1 of the present invention will be described below with reference to FIG. 1 which is a schematic longitudinal sectional view thereof.
In FIG. 1, a high-pressure vessel 2 of a mechanical property test apparatus 1 is composed of a high-pressure cylindrical vessel 3, an upper lid 4a, and a lower lid 4b. The high-pressure cylindrical container 3 and the upper lid 4a and the lower lid 4b are sealed by fixing seal rings 17a and 17b, respectively, and a high-pressure gas pipe 12a for forming a high-pressure gas atmosphere And is connected to the lower lid 4b.

  A lower lid 4b and a load-loading actuator (hydraulic cylinder) 6 are fixed to the high-pressure vessel pedestal 5, and a test piece 10 is fixed on the upper surface of the lower lid 4b, and a load-loading rod 7 is attached to the test piece 10. A support member 9 for receiving a test load loaded via the is fixed.

  The test piece 10 is fixed to the stay 14 and the load loading rod 7 of the support member 9 by fixing jigs 11a and 11b, respectively. The support member 9 is composed of two or four struts 13 structured to be screwed into the lower lid 4b and a stay 14 fixed to the upper ends of the struts 13, and the stay 14 is provided with the fixing jig 11a. Is installed.

  The test load is configured to be applied to the test piece 10 via the load load rod 7 by the actuator (hydraulic cylinder) 6. The actuator 6 for driving the load-loading rod 7 is composed of a piston 15a and a cylinder 15b, and applies the hydraulic pressure supplied from the hydraulic pipes 16a and 16b to the piston 15a, whereby the load-loading rod 7 is driven. It is.

  The load-loading rod 7 is introduced into the high-pressure vessel 2 through a sliding seal ring 18a interposed in the through hole of the lower lid 4b. Note that the test load acting on the test piece 10 is obtained by conversion from the hydraulic pressure supplied to the actuator 6.

  On the opposite side of the load rod 7 of the actuator 6 is a piston 8a, a cylinder 8b, which is the same diameter as the load rod 7 and integrated with the balance rod, and a sliding seal ring 18c for maintaining airtightness. The fluid cylinder 8 comprised by this is arrange | positioned. The high pressure gas pipe 12b introduces a high pressure gas having the same pressure as the gas pressure in the high pressure vessel into the fluid cylinder 8, thereby canceling the load due to the gas pressure acting on the test piece 10. .

  The cross-sectional area of the piston 8a is preferably the same as the pressure receiving area of the load-loading rod 7, but it is sufficient if it is sufficient to cancel the load due to the gas pressure. It does not need to be, and may be substantially the same.

  The actuator 6 for applying a test load to the load-loading rod 7 may be a mechanical type in which a ball screw and an electric motor are combined in addition to the hydraulic type as shown in FIG. In FIG. 1, the load-loading rod 7 is integrated with the piston 15a of the hydraulic cylinder 6 as an actuator. However, in order to facilitate disassembly and assembly, a load measuring load cell described later is mounted. Therefore, it is preferable that the load load rod 7 and the piston 15a be divided.

  When exchanging the test piece 10 mounted in the high-pressure vessel 2, the upper lid 4a and the high-pressure vessel cylinder 3 are integrally lifted upward using a hydraulic or mechanical lifting mechanism (not shown), The operation is performed with the support member 9 and the like fixed to the lid 4b exposed.

  Needless to say, when the mechanical characteristics are tested by the mechanical characteristics test apparatus 1 according to Embodiment 1 of the present invention shown in FIG. 1, the lower lid 4b and the actuator 6 are attached to the high-pressure vessel gantry 5. The support member 9 and the high-pressure cylindrical container 3 are fixed to the lower lid 4b, and the fluid cylinder 8 is fixed to the actuator 6 integrally as shown in FIG. It is important that The fixing means may be general fixing means such as bolts and nuts.

Next, a mechanical characteristic test apparatus according to Embodiment 2 of the present invention will be described below with reference to FIG. 2 which is a schematic longitudinal sectional view thereof and FIG. 3 which is a circuit diagram showing a circuit configuration of a strain gauge. .
It should be noted that the second embodiment of the present invention differs from the first embodiment in that there is a difference in the method of grasping the test load acting on the test piece, and the rest is exactly the same as the first embodiment. The same reference numerals are attached to the same components, and the differences are described below.

  That is, in FIG. 1 according to the first embodiment of the present invention, the test load acting on the test piece 10 is shown as an example converted from the hydraulic pressure of the hydraulic cylinder 6, but the lower lid 4b of the load load rod 7 is shown. Friction forces generated at the through holes, the piston portion 15a of the hydraulic cylinder 6 and the sliding seal rings 18a, 18b and 18c of the fluid cylinder 8 are included as errors in order to inhibit the test load due to the hydraulic pressure. .

  In particular, in the case of a fatigue test in which a test load is applied by reciprocating motion, the frictional force acts in the opposite direction when the load-loading rod 7 moves upward and downward, so that the hydraulic pressure of the hydraulic cylinder 6 is increased. Becomes to draw a hysteresis with respect to the position of the load rod 7, and it becomes difficult to accurately measure and control the test load acting on the test piece 10.

  Therefore, in the second embodiment of the present invention, as shown in FIG. 2, the strain gauge type load cell 30 is interposed between the support member 9 and the fixing jig 11 a and fixed to the test piece 10. The applied test load is directly measured by the load cell 30. The mounting position of the load cell 30 may be interposed between the load loading rod 7 and the fixing jig 11b.

  FIG. 3 is a circuit diagram showing a circuit configuration of a strain gauge for measuring a test load attached to the load cell 30 and applied to the test piece 10 with the strain gauge. Reference numerals 21a, 21b, 21c, and 21d in the figure are strain gauges, and the Wheatstone bridge circuit 20 is formed by these strain gauges.

  Of these strain gauges, two of the active gauges 21a and 21b are attached in the direction of load application at positions opposite to the outer periphery of the load cell 30 by 180 degrees as shown by reference numeral 21 (21a and 21b) in FIG. The two dummy gauges 21 (21c, 21d) are attached in the circumferential direction of the outer periphery of the load cell 30 that is perpendicular to the active gauge.

  In FIG. 3, a voltage is applied to the Wheatstone bridge circuit 20 by the voltage application power source 22, the voltage measured by the voltmeter 23 is read, and the test load acting on the test piece 10 is detected. It is configured.

  By adopting such a circuit configuration, it is possible to eliminate the influence of disturbance uniformly applied to the four strain gauges 21a to 21d, for example, the influence of disturbance due to temperature change or hydrostatic pressure, and the distortion component at the time of attachment. Can be eliminated.

Next, a mechanical property test apparatus according to Embodiment 3 of the present invention will be described below with reference to FIG. 4 which is a schematic longitudinal sectional view thereof.
The third embodiment of the present invention differs from the first embodiment in that the load cell for detecting the test load acting on the test piece is provided not only in the high pressure vessel but also outside the high pressure vessel. Since there is a difference in the points, and the others are exactly the same, the same reference numerals are given to the same components as those in the first embodiment, and the differences will be described below.

  That is, in FIG. 1 according to the first embodiment of the present invention, the test load acting on the test piece 10 is shown as an example converted from the hydraulic pressure of the hydraulic cylinder 6, but in the third embodiment of the present invention. 4, a strain gauge type load cell 30 is provided at a predetermined position in the high-pressure vessel 2, and a load cell 31 other than the load cell 30 is connected to the load-loading rod 7 outside the high-pressure vessel 2 and the load load. Also provided between the actuators 6 for use.

  When performing a mechanical characteristic test not only in a high-pressure gas atmosphere but also under an atmospheric pressure, a load cell 31 is provided between the load-loading rod 7 and the actuator 6 in the same manner as in a normal testing machine. The machine shown in FIG. 4 according to the third embodiment of the present invention can be conveniently used, and the operation of verifying the load of the load cell 30 installed in the high-pressure vessel 2 can be easily performed. This is an advantage of the mechanical characteristic test apparatus 1.

  In this case, when operated in a high-pressure gas atmosphere, a load due to the high-pressure gas pressure also acts on the load cell 31 provided outside the high-pressure vessel 2. Therefore, as the maximum load of the load cell 31, a capacity obtained by adding a load due to the gas pressure determined by the product of the high pressure gas pressure and the cross-sectional area of the load load rod 7 to the test load applied to the test piece 10 is required. The net test load acting on the piece 10 needs to be corrected by the gas pressure.

Next, a mechanical property test apparatus according to Embodiment 4 of the present invention will be described below with reference to FIG. 5 which is a schematic longitudinal sectional view thereof.
The fourth embodiment of the present invention differs from the first embodiment in that a load cell is provided outside the high-pressure vessel with a configuration different from that of the third embodiment of the present invention. Since the configuration is exactly the same, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be described below.

  That is, in FIG. 1 according to the first embodiment of the present invention, the test load acting on the test piece 10 is shown as an example converted from the hydraulic pressure of the hydraulic cylinder 6, but in the fourth embodiment of the present invention. As shown in FIG. 5, a fluid cylinder 8 including a piston 8 a serving as a balance rod is directly connected to a load-loading rod 7, and the fluid cylinder 8 is physically fixed to a high-pressure vessel mount 5 by a bracket 32. Yes.

  A cylindrical connecting member 33 is coupled to the load-loading rod 7, and the connecting member 33 is connected to a load-loading rod 7 a constituting an actuator 6 for applying a test load via a load cell 31. Are combined.

  The cylindrical connecting member 33 is formed with a window hole 33a for avoiding interference with the high-pressure gas pipe 12a and the bracket 32. The actuator 6 is fixed to the container mount 5 or the bracket 32 by a frame (not shown). Such a structure according to the fourth embodiment of the present invention is more complicated than the above-described embodiment, but has an effect that the load by the high-pressure gas does not act on the external load cell 31 at all.

  As described above, in FIGS. 4 and 5 according to Embodiments 3 and 4 of the present invention, the illustration of the strain gauge attached to the load cells 30 and 31 is omitted, but FIG. 2 and FIG. 3 are used. Needless to say, a Wheatstone bridge circuit is formed by a strain gauge so that a test load can be detected in the same manner as described above.

  In the above, the mechanical property test equipment used at room temperature is the target. However, when changing the test temperature or conducting the mechanical property test at high or low temperature, it depends on the test temperature. It is necessary to heat or cool the test piece. Even in such a case, the present invention is very useful.

  That is, when the test temperature range is in the range of −150 ° C. to 200 ° C., the entire high-pressure vessel 2 is housed in a thermostatic chamber surrounded by a heat insulating material, and a gas at a predetermined temperature is injected and stirred. It is recommended to adopt the method. In particular, when the atmosphere inside the high-pressure vessel is a flammable gas such as hydrogen, the use of nitrogen as the gas circulating in the thermostatic chamber ensures safety when hydrogen leaks outside the high-pressure vessel. Securement becomes easy.

  Also, when testing at a low temperature of −150 ° C., a cooling structure using latent heat when liquid nitrogen is vaporized can be easily adopted, which is preferable. On the other hand, when a high temperature exceeding 200 ° C. is required, the above-described structure of the thermostatic bath can be adopted up to about 300 ° C., but when a higher temperature is required, the outside of the high-pressure cylindrical container 3 can be used. A structure in which a jacket for circulating the heat medium is attached to the inner part is preferable.

  Further, when the temperature is higher than that, it is preferable that an electric heating type heater is arranged around the test piece 10 in the high-pressure vessel 2 and a heat insulating structure is arranged on the outer periphery thereof. In such a case, since the mechanical property test apparatus according to the present invention has no structure other than the support member 9 around the test piece 10, it is easy to mount a heater or a heat insulating structure.

  As described above, the mechanical property test apparatus according to the present invention measures the test load with high accuracy in the tensile test of metal, ceramics, resin, etc. and the measurement test of mechanical properties such as fatigue strength in a high-pressure gas atmosphere. In addition, it greatly contributes to the contribution of material mechanical technology by collecting test data, such as enabling control and simplifying the work of exchanging test pieces.

  In particular, it is possible to carry out the measurement of strength properties of metallic materials, etc. under a predetermined high-pressure hydrogen atmosphere, for which early establishment of material strength standards is desired, with high accuracy and efficiency, It greatly contributes to the safety design of equipment such as fuel cells and hydrogen engines that use hydrogen as a fuel, which is expected as an effective measure against global warming.

It is a longitudinal cross-sectional view which shows the mechanical characteristic test apparatus which concerns on Embodiment 1 of this invention. It is a longitudinal cross-sectional view which shows the mechanical property test apparatus which concerns on Embodiment 2 of this invention. It is a circuit diagram which shows the circuit structure of the strain gauge which concerns on this invention. It is a longitudinal cross-sectional view which shows the mechanical property test apparatus which concerns on Embodiment 3 of this invention. It is a longitudinal cross-sectional view which shows the mechanical characteristic test apparatus which concerns on Embodiment 4 of this invention. It is a longitudinal cross-sectional view which shows the conventional atmosphere container for material tests. It is a longitudinal cross-sectional view which shows the conventional mechanical property test apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mechanical property test apparatus, 2 ... High pressure vessel, 3 ... High pressure cylindrical vessel,
4a ... upper lid, 4b ... lower lid,
5 ... High-pressure vessel mount, 6 ... Hydraulic actuator, 7 ... Load load rod,
8 ... Fluid cylinder, 8a ... Balance rod (piston), 8b ... Cylinder 9 ... Support member, 10 ... Test piece,
11a, 11b ... Fixing jig, 12a, 12b ... High pressure gas piping,
13 ... post, 14 ... stay, 15a ... piston, 15b ... cylinder,
16a, 16b ... hydraulic piping, 17a, 17b ... fixing seal ring,
18a, 18b, 18c ... sliding seal ring,
20 ... Wheatstone bridge circuit, 21a, 21b, 21c, 21d ... Strain gauge, 22 ... Voltage application power source, 23 ... Voltmeter,
30, 31 ... load cell, 32 ... bracket,
33 ... Connecting member, 33a ... Window hole

Claims (2)

Under a high-pressure gas atmosphere, a test load is applied to a test piece mounted inside the high-pressure vessel through a load-loading rod that penetrates the high-pressure vessel, and thereby a mechanical load of the test piece is obtained. In a mechanical property testing device for measuring properties,
The high-pressure vessel is composed of a high-pressure cylindrical vessel, an upper lid and a lower lid, and the high-pressure vessel has a lower lid fixedly supported by a high-pressure vessel gantry,
The load load rod of the load load actuator is on an extension of the load load rod opposite to the test piece side and has a cross-sectional area substantially the same as the high pressure gas pressure receiving area of the load load rod. A fluid cylinder connected to a balancing piston is arranged ,
The fluid cylinder is directly connected to the load rod of the load actuator, and the fluid cylinder is fixed to the high pressure vessel by a bracket,
A cylindrical connecting member is connected to the load-loading rod, and the connecting member is connected to a load-loading rod constituting the load-loading actuator via a load cell,
A mechanical property testing apparatus, wherein the cylindrical connecting member is formed with a window hole for avoiding interference with the bracket . The load cell, the mechanical properties testing device according to claim 1, characterized in that the strain gauge type load cell.

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