JPS6350651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a high-temperature tensile test device, and more particularly to a high-precision high-temperature tensile test device.

[Background of the invention]

In high-temperature tensile equipment, not only is it necessary to install the load application mechanism and pressure sealing mechanism for the test piece in the high-temperature chamber on the low-temperature side, but also there must be an axial connection between the mechanism and the high-temperature chamber. There are parts that cause temperature differences. In this case, when the high temperature portion is located below and the low temperature portion is located above, convection occurs in the fluid surrounding the temperature difference portion, and this convection thermally deforms the temperature difference portion over time. This thermal deformation has a negative effect on the stress added to the test piece and the elongation of the test piece, resulting in a reduction in test accuracy.

[Purpose of the invention]

In view of the above, it is an object of the present invention to prevent stress added to a test piece and temporal fluctuations in elongation of the test piece, and to improve test accuracy.

[Summary of the invention]

In order to achieve the above object, the present invention provides a high-temperature chamber in which an opening provided on the upper end surface or the lower end surface is closed by a lid having a test piece holder inside, and a water-cooling jacket attached to the outside of the lid. a confinement tube, which is inserted into the confinement tube and protrudes into the high-temperature chamber through the lid, holds a test piece at the protruding end, and is movable in the axial direction; , this pull rod and the sealing pressure mechanism attached to the opposite side of the high temperature tank of the sealing tube, and the section from the lower end of the water cooling jacket to the lid within the gap formed between the pull rod and the sealing tube (this section is There is a temperature difference in the axial direction.The upper part of the water-cooled jacket is in a low-temperature region and does not produce a temperature distribution.

In the following specification of the present application, the term "different material" basically refers to a third component (member) different from the pull rod and the sealing tube. In other words, this member (different material) has the ability to hydrodynamically reduce the movement of high-temperature water within the gap and does not impede the movement of the pull rod, and the material used in the present invention is typically stainless wool. It is a wool-like sintered member or a ring-like product. When a ring-shaped member is used, it must be able to move or deform freely in the axial and radial directions, and have heat insulating properties, and it is also necessary to form a gap between it and the pull rod.

In addition, a plurality of grooves are provided in the axial direction on the outer peripheral surface of the pull rod so that the temperature distribution in the axial and circumferential directions does not change due to external conditions, and the convection in the gap between the pull rod and the confining tube is It is preferable that the structure is such that it occurs constantly within the groove.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

In Fig. 1, 1 is a high-temperature tank made of SUS316 that is surrounded by an electric furnace 2 and has an opening 1a on the upper end surface, and 3 is a lid that closes the opening 1a of the high-temperature tank 1 via an O-ring 4. A protrusion 3a is provided on the inside of 3. 5 is a test piece attachment ring attached to the tip of the protrusion 3a, 6 is a test piece attachment tool attached to the test piece attachment ring 5 via a nut 7, and 8a and 8b are mother plates attached to the lid 3. Loop connection pipe, 9 is lid 3
A confining tube 11 is installed on the outer surface of the confining tube and has a water cooling jacket 10 on the top thereof, and a pull rod 11 is inserted into the confining tube 9 and protrudes into the high temperature bath 1 through the lid 3. This pull rod 11 is attached to the shaft It is provided so that it can be moved in the direction.

12 is a gap formed between the sealing tube 9 and the pull rod 11, and a foreign material 13 is inserted into a part of this gap 12, that is, the gap between the lower end of the water cooling jacket 10 and the lid 3. As this different material 13, for example, a stainless wool sintered member is used, but this sintered member 13 is made of 18-9 stainless steel.
It is made by sintering 10μφ fine wire at high temperature. Since the thin wires are made up of a structure in which they are locally joined to each other,
Thin wire is a material that is not only difficult to peel off, but also easy to cut. 14 is a test piece held between one end of the pull rod 11 (lower end in the figure) and the upper end of the test piece holder 6; 15 is a sealing material attached to the top of the confining tube 9; 16a to 16c are the pull rods 11 and These O-rings are respectively provided between the sealing material 15, between the sealing tube 9 and the sealing material 15, and between the pull rod 11 and the sealing tube 9.

The pull rod 11 is moved up and down by a stress applying mechanism (not shown) to apply stress to the test piece 14. This stress and the amount of displacement (elongation) of the test piece 14 are determined by a load cell (not shown) installed between the stress applying mechanism and the pull rod and a differential transformer (not shown) installed at the top of the pull rod 11. It is configured to be measurable.

Using the above-mentioned embodiment (in which the foreign material 13 is not inserted into the gap 12), a pure air of 85 kg f/cm ² is introduced into the high temperature tank 1 from the mother loop (not shown) through the connecting pipe 8a. Water was introduced, and the high temperature bath 1 was maintained at 250°C using an electric furnace 2. Next, the pull rod 11 was moved upward by a certain amount, and a load of 500 kg·f was applied to the test piece 14, and its change over time was measured. The results are shown in Figure 2, which shows that the measured load and elongation change randomly over time, and the maximum amount of change is 50%.
It was Kg・f.

In order to understand the reason for the above-mentioned random changes, as shown in FIG.
A thermocouple 17 is attached to the surface of the thermocouple 17, and this thermocouple 17 is connected to a temperature recorder 18 via a lead wire 19.
The temperature of the sealing tube 9 was measured.

The measurement results are shown in FIG. 4, where _t0 to _t3 are temperature distribution curves in the longitudinal direction of the confinement tube 9 at 0, 5, 12, and 17 minutes, respectively. It can be seen from FIG. 4 that the temperature within the confining tube 9 changes in a complicated manner with time. From the fluctuation period and the relationship between the measured load and the measured elongation, the confining tube 9
This is thought to be due to the intense convection phenomenon occurring within the gap 12 between the pull rod 11 and the pull rod 11. The pull rod 11 or sealing tube 9 due to thermal fluctuations
It is understood that the thermal deformation of is reflected in the above phenomenon.

Therefore, in this embodiment, in order to prevent the above phenomenon, a foreign material, that is, a stainless wool sintered member 13, is inserted into a part of the gap 12 between the sealing tube 9 and the pull rod 11 as described above, and the pull rod 11 and A gap of 0.08 mm was formed between the sintered member 13 and the sliding resistance was about 1 kg·f even if the two 11 and 13 were to come into contact with each other.

As a result, the temperature distribution on the outer surface of the sealing tube 9 is
As shown by the curve t ₀ in the figure, the curve was gentle, and no change over time was observed at all. The load change measured in the same manner was less than 2 kg·f, and the amount of elongation change of the test piece 14 was less than the measurement limit. Therefore, according to this example, the accuracy of the tensile test can be improved, so that it can be applied to SSRT tests and fatigue tests at high temperatures.

In the first embodiment described above, a stainless wool sintered member was used as the foreign material 13, but instead of this, a ring with high heat insulation properties that is movable or deformable in the axial and radial directions, such as SUS304 stainless steel or Teflon, can be used. A ring may also be used. This ring is formed with a plate thickness of 0.2 or 0.8 mm, and
The gap between the ring and the pull rod is 0.4 or 0.1
8 of these rings were provided in the axial direction, and the change in load over time was measured in the same manner as in the first example.

As a result, in all cases, by providing a ring in the gap, the load fluctuation was less than 2 kg·f, and an excellent effect was obtained. In particular, the best effect was obtained when a Teflon ring with a thickness of 0.8 mm was used and the gap between the ring and the pull rod was 0.1 mm.

On the other hand, when a stainless steel ring with a plate thickness of 0.2 mm was used and when the gap between the ring and the pull rod was set to 0.4 mm, a tendency for load fluctuation to increase was observed.

From the above results, according to this example, (i) convection is prevented from occurring in the gap between the ring and the pull rod, and (ii) convection is prevented from occurring in the gap between the ring and the sealing tube. It has also been found that (iii) the generation of convection can be prevented by making it difficult for the heat change to be transmitted to the pull rod, and (iii) by reducing the gaps between the ring, the confining tube, and the pull rod.

Next, as another example, the first example (Fig. 1)
The cross-sectional shape of the pull rod 11 from the lower part of the water cooling jacket 10 to the lower surface of the high temperature tank lid 3 was formed as shown in FIG. That is, four grooves 20 each having a width of 4 mm and a depth of 2 mm were provided in the pull rod 11 in the axial direction, and a windbreak wall (not shown) was provided on the outside of the confining tube 9. The other structures are the same as those in the first embodiment, so drawings and explanations will be omitted.

In such an embodiment, the water temperature is 20±0.2℃.
The flow rate of water adjusted to 300± into the water cooling jacket
When a test was conducted in the same manner as in the first example with a supply of 2 ml/min, the load fluctuation was 2 to 4 kg·f. In this case, the temperature at the outer periphery of the confining pressure tube changes gently in the axial direction as shown by the curve _t0 in Figure 4, but in the circumferential direction it changes with maximum and minimum values every 90°C. . From this, convection phenomenon occurs in the gap, but by providing the groove in the pull rod as described above, it is expected that steady convection occurs, and there is no time dependence on the thermal deformation of the pull rod. I understand.

The first embodiment is configured such that the pull rod 11 holding the test piece 14 passes through the lid 3 that closes the opening 1a provided on the upper end surface of the high temperature bath 1 and is positioned above the high temperature bath 1. However, on the contrary, the pull rod may be configured to pass through a lid that closes an opening provided on the lower end face of the high temperature tank and be located below the high temperature tank.

Using this example configured in this way, tests were conducted in the same manner as in the first example, and as a result, the load fluctuation was
It was less than 0.5Kg・f. Furthermore, in the first embodiment, when the load repetition rate is 3Hz, the load fluctuation is 0.8
Kg・f, but in this example it is still
It was 0.5Kg・f. This is because by installing the high temperature tank in an upper position, not only is it theoretically difficult for convection to occur, but also it is possible to prevent the fluid from moving as the pull rod moves.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent stress added to a test piece and time fluctuations in the elongation of the test piece, thereby improving test accuracy.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the high temperature tensile test device of the present invention, Fig. 2 is a view showing the load and elongation during temperature measurement on the outer circumferential surface of the confining tube, and Fig. 3 is a diagram showing the temperature on the outer circumferential surface of the confining tube. FIG. 4 is a diagram showing the measurement method, FIG. 4 is a diagram showing the temperature measurement results on the outer peripheral surface of the confining tube, and FIG. 5 is a sectional view of a pull rod according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... High temperature tank, 1a... Opening, 3... Lid, 6... Test piece fixture, 9... Sealing tube, 10... Water cooling jacket, 11... Pull rod, 12... Gap, 13... Dissimilar material, 14... Test piece, 15... Seal material, 20...groove.

Claims (1)

[Scope of Claims] 1. A high-temperature bath whose opening provided on the upper end surface or the lower end surface is closed by a lid having a test specimen fixture inside, and a sealing tube attached to the outside of the lid and equipped with a water-cooling jacket. a pull rod inserted into the confining tube, protruding through the lid into the high temperature chamber, holding the test piece at the protruding end, and movable in the axial direction; It consists of a sealing mechanism attached to the opposite side of the sealing tube to the high temperature tank, and a member inserted into the section from the lower surface of the water cooling jacket to the lid within the gap formed between the pull rod and the sealing tube. , and a wool-like sintered member is used as the member. 2. A high-temperature bath whose opening provided on the upper end surface or lower end surface is closed by a lid having a test specimen fixture on the inside, a confining tube attached to the outside of the lid and equipped with a water cooling jacket, and a confining tube equipped with a water cooling jacket. a pull rod that is inserted into the tube and protrudes into the high temperature chamber through the lid, holds the test piece at the protruding end, and is movable in the axial direction; A sealing mechanism attached to the tank side and a gap formed between the pull rod and the sealing tube, which is movable or deformable in the axial and radial directions within the section from the lower surface of the water cooling jacket to the lid. A high-temperature tensile testing apparatus characterized in that a ring having heat insulating properties is inserted such that a gap is formed between the ring and the pull rod.