JPH068782B2 - Cryogenic material testing equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a material testing device for performing a tensile test, a fatigue test, a fracture toughness test and the like in a cryogenic range using a cryogen such as liquid helium and hydrogen.

(Prior Art) In recent years, due to the development of superconducting technology and the like, research on materials used at cryogenic temperatures has been actively conducted, and accordingly, a test device for measuring material performance at cryogenic temperatures has been demanded. It is coming. For this reason, various cryogenic material testing devices have been proposed. For example, Japanese Utility Model Laid-Open No. 59-82839 proposes a cryogenic tensile testing device. In this test device, in order to reduce heat infiltration of the liquid cryogen into the storage chamber, a heat insulating plate is arranged in layers in the upper part of the storage chamber so as to surround a pull rod and the like.

(Problems to be Solved by the Invention) By the way, in a cryogenic container, how to prevent or reduce the heat invasion into the container is a big problem. An important issue is how to suppress heat invasion from the strength members necessary for material testing such as rods or columns. That is, in the case of the tensile tester as described above, the pull rod supporting a large load becomes thick, so that heat intrusion from the outside becomes very large and evaporation of the cryogen increases. If the measurement time is long, or if it is a large-scale device, it will not be possible to use it as it is if there is a large amount of evaporation.Therefore, it is necessary to lengthen the pull rod to reduce heat intrusion, or to use a special liquefaction refrigerator. To do. In the former case, the device is long, and in the latter case, the device is expensive and large-scale. Although a heat insulating plate is used as described above to solve such a problem, suppression of heat intrusion is insufficient only by these measures. Therefore, the present invention has been made for the purpose of providing an apparatus capable of suppressing evaporation of a freezing agent as much as possible and reducing restrictions in a test.

(Means for Solving the Problem) Therefore, in the present invention, an apparatus main body having an accommodation chamber for accommodating a liquid cryogen and maintaining a test piece at a predetermined temperature, an upper lid for sealing the apparatus main body, and the accommodation attached to the upper lid In a cryogenic material testing device having a column housed in a chamber and an operating rod slidable on the upper lid and inserted in the chamber, a radiation plate is provided between the column and the operating rod for evaporating gas. The object is achieved by arranging it in the accommodating chamber with a space through which it passes, extending around it to the upper lid and covering it with a radiation plate cover, and attaching an outlet for evaporative gas to the inside of the radiation plate cover of the upper lid. .

(Operations and Examples) Hereinafter, the details of the present invention will be described using examples. In FIGS. 1 and 2, reference numeral 1 is a cryostat in which liquid helium 13 is housed, an upper lid 2 is attached to the upper portion thereof, and a liquid helium liquid injection port 16 is provided in the upper lid 2. Each member for material test is housed and inserted in the cryostat 1. That is,
First, a plurality of columns 4 are attached to the lower surface of the upper lid 2, and a bottom plate 5 is attached to the lower ends of the columns 4. Further, a pull rod 3 which slides through the center of the upper lid 2 is inserted into the cryostat 1, and the lower end of the pull rod 3 has the hanging metal fitting 1
1, a bearing 9 having a hole through which evaporative gas can pass is attached to the column 4, and supports the pull rod 3. A test piece attachment means 10 is provided on the upper surface of the bottom plate 5, and a plurality of radiation plates 6 are arranged in layers on the upper part of the support column 4 with gaps between the support column 4 and the pull rod 3, respectively. A foam material 7 is inserted between the radiating plates 6 and extends around the radiating plate 6 to the lower surface of the upper lid 2 and is covered with a radiating plate cover 8. The evaporative gas outlet is provided inside the radiating plate cover 8 of the upper lid 2. 15 is attached. Liquid nitrogen 14 for cooling is contained inside the side wall of the cryostat 1. When a cryogenic tensile test is performed in the state shown in FIG. 1, heat invades from the outside, especially through the pull rod 3 and the support 4, and the liquid helium 13 evaporates. Of the vaporized gas, the gas that enters between the inner wall of the cryostat 1 and the radiation plate cover 8 cannot extend to the outside of the test apparatus because the radiation plate cover 8 extends to the upper lid 2. Therefore, when the evaporative gas goes out to the outside, it enters the inside of the radiation plate cover 8 through the hole provided in the bearing 9 or the gap between the pull rod 3 and the bearing 9, and further the gap between the radiation plate 6 and the pull rod 3 or the column 4. Passing through, it rises while exchanging heat with the pull rod 3 or the column 4, reaches the lower surface of the upper lid 2 inside the radiation plate cover 8, and goes out of the apparatus through the gas outlet 15. At that time, since the temperature of the rising gas is low, the evaporation of liquid helium can be suppressed by utilizing the sensible heat. Using this device (cryostat 1 inner diameter 280 mm, depth 770 mm), liquid helium 13 was stored and a crack growth rate measurement test of the test piece 12 was carried out to measure the evaporation amount of liquid helium. However, liquid helium of 5 or more was required for the test piece 12 to be completely immersed. In order to prove the effect in this embodiment, the same comparative test as above was carried out using a conventional tensile tester with the radiation plate cover 8 removed from the above tensile tester, and the evaporation amount of liquid helium was measured. The above measurement results are shown in Table 1. As can be seen from Table 1, when the test apparatus according to the present invention was used, the evaporation amount of liquid helium per unit was reduced to 40% as compared with the conventional one.

(Effect of the Invention) As is known from the above description, the cryogenic material testing apparatus according to the present invention has an effect of significantly reducing the evaporation amount of liquid helium as compared with the conventional one, and as a result, the following effects are obtained. Also occurs. First, the measurable time becomes long.
Secondly, the range that can be achieved without the refrigeration system in manufacturing a large-scale device is expanded. Thirdly, since it is not necessary to lengthen the pull rods and columns, the test equipment can be downsized,
The cost of the device can be reduced and the amount of liquid helium required can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of the cryogenic material testing apparatus according to the present invention taken along the line BB ′ in FIG. 2, and FIG. 2 is taken along the line A- in FIG.
It is an A'expansion sectional view. 1: Cryostat 2: Top cover 3: Pull rod 4: Support rod 6: Radiant plate 8: Radiant plate cover 15: Evaporated gas outlet

Claims (1)

[Claims] 1. An apparatus main body having an accommodating chamber for accommodating a liquid cryogen and maintaining a test piece at a predetermined temperature, an upper lid for sealing the apparatus main body, and a column mounted on the upper lid and accommodated in the accommodating chamber. In a cryogenic material testing device having an operation rod that is slidable on the upper lid and inserted into the accommodation chamber, the radiation plate is provided with a gap through which evaporative gas passes between the support column and the operation rod. A cryogenic material testing device, which is arranged in a room, is extended to the upper lid and is covered with a radiation plate cover, and an outlet for vaporized gas is attached to the inside of the radiation plate cover of the upper lid.