JPH0317254Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an apparatus for determining whether a graphite crucible used in a gas-in-metal analyzer is good or bad.

This type of graphite crucible is normally subjected to sampling inspection immediately after manufacturing, but during subsequent packaging, transportation, and storage, cracks or chips may occur, or the quality may deteriorate due to moisture content, so it is difficult to dispose of these defective products. If this is used for analysis, accidents may occur, such as the current not flowing through the extraction furnace, or even if it does, the value is abnormal. There is a drawback that when the current value is abnormal, the reliability of the sample analysis value decreases.

In view of these conventional drawbacks, the present invention aims to accurately and quickly determine whether a graphite crucible is good or bad immediately before it is used for analysis.

Hereinafter, embodiments of the present invention will be described based on the drawings.

Fig. 1 shows an embodiment of the present invention, and in this figure, A and B represent a graphite crucible C (its size is, for example, 14 mm in diameter, 1.2 mm in wall thickness, and 20 mm in height).
An upper electrode and a lower electrode are sandwiched from above and below with a pressure of Kg/cm ² , and one of these electrodes is configured to be movable in the vertical direction. D is a current supply device (power supply) that supplies current to the electrodes A and B and the graphite crucible C;
It is configured to supply a considerably smaller current (for example, about 1 A) compared to the current flowing during analysis in the extraction furnace (usually about 1000 A). E is a voltmeter that measures the voltage between the electrodes A and B.

By the way, it is considered normal for graphite crucible C of the above size to have a resistance value in the range of 6 mΩ ± 1 to 1.5 mΩ. For example, if the resistance value is as large as 9 mΩ, a current of 1000 A is applied during analysis. When flowing, there is an inconvenience that the temperature rises too much and destroys the graphite crucible C, making it impossible to extract.On the other hand, if the resistance value is as small as 3mΩ, a current of 1000A may be applied during analysis. There is a disadvantage that when a current is applied, the temperature does not rise and the desired extraction cannot be performed.

Therefore, a graphite crucible C is placed between the electrodes A and B.
Clamp it with a pressure of about 50Kg/cm ² and connect it to the current supply device D.
When a current of 1A is supplied to the graphite crucible C, the reading on the voltmeter E at that time is 6mV±1~
1.5mV, that is, the resistance value is 6mΩ±
Those in the range of 1 to 1.5 mΩ are considered good, and those outside this range are considered defective, and only graphite crucibles C that are judged to be good are used for analysis in the extraction furnace. Incidentally, the output of the voltmeter E may be input to a microcomputer and the computer may determine whether the device is good or bad. Next, FIGS. 2 to 5 show a second embodiment of the present invention. In FIGS. 2 and 3, 1 is an air cylinder, and a lower block 3 is fixed to the upper end of a rod 2 of the air cylinder. A rotary actuator 4 is housed within the lower block 3, and a lower electrode 6 made of copper is fixedly connected to an output shaft 5 of the rotary actuator 4. In the rotary actuator 4, as shown in FIG. 4, for example, when air is introduced into one chamber 8 through the hole 7, the blades 9 and the output shaft 5 rotate about 45 degrees in the direction of arrow P. ,next,
When air is introduced into the other chamber 8' through the hole 7' by switching the air flow path, the blades 9 and the output shaft 5
A structure in which the rotation angle is rotated approximately 45 degrees in the direction of arrow Q is used. In addition, various structures such as those using gears and racks can be adopted. 10 is a bearing for absorbing the thrust load generated by the pressing force of the air cylinder 1. Next, reference numeral 11 denotes an upper block fixed to a support frame (not shown), and inside thereof, a vertical hole 12 and a horizontal hole 13 are provided.
A rod 15 having a recess in the center is inserted. 16 is a sample input port, 17 is a shutter for opening and closing the upper opening of the vertical hole 12, and 18 is a carrier gas inlet provided through the wall of the horizontal hole 13. Next, reference numeral 19 denotes an upper electrode made of copper that is fixedly connected to the upper block 11 and is connected to the lower opening 2 of the vertical hole 12.
It has a vertical hole 21 continuous to 0 and a stepped portion 22 provided in the middle thereof. This stepped portion 22 has a fifth
As shown in the figure, three grooves 23 are provided radially, and the diameter R of a virtual circle connecting the outer ends of these grooves 23 is larger than the outer diameter r of a graphite crucible 27, which will be described later. ing. 24 is an extraction gas flow path, 2
5 is an O-ring for sealing. Although not shown, the upper and lower electrodes 19 and 6 each have a cooling mechanism. Therefore, in order to perform gas analysis in a metal sample, first place the graphite crucible 27 on the upper end surface 26 of the lower electrode 6 as shown in FIG. The graphite crucible 27 is pressed between the lower surface of the stepped portion 22 of the upper electrode 19 and the upper end surface 26 of the lower electrode 6 at a pressure of, for example, about 20 kg/cm ² by moving one rod 2 forward. Next, terminal X,
A current is passed from a current supply section (not shown) through Y to the upper and lower electrodes 19, 6 and the graphite crucible 27 clamped between them, and a voltmeter E (see Fig. 3) is connected to the upper and lower electrodes 19, 6. The electric resistance value of the graphite crucible 27 is known by reading the instruction indicated by the medium phantom line, and if the value is within a predetermined range (the range shown in the first embodiment), the process moves to the next step. . (If the value is outside the specified range,
The lower electrode 6 is lowered and the defective graphite crucible is taken out and discarded. ) Note that it is preferable that the current value passed at this time is lower (for example, 1 ampere) than the current (for example, 1000 ampere) that is passed during gas extraction, which will be described later. Next, the rotary actuator 4 is operated to rotate the output shaft 5 lower electrode 6 about 45 degrees clockwise around the axis of the output shaft 15, that is, around the vertical axis, and then counterclockwise. Rotate approximately 45 degrees in the direction. Then, the graphite crucible 27 has upper and lower electrodes 19,
6 and the lower electrode 6 rotates, so the contact surfaces of the graphite crucible 27 and the upper and lower electrodes 19, 6 become familiar with each other and come into closer contact. That will happen.

Next, the shutter 17 is opened and the input port 16 is opened.
The metal sample is dropped into the recessed part 14, and then the rod 15 is rotated 180 degrees to remove the metal sample from the recessed part 1.
The sample in 4 is passed through the vertical hole 21 into the graphite crucible 27.
Put it inside.

Then, while supplying carrier gas from the inlet 18, current is caused to flow from the current supply section (not shown) through the terminals X and Y to the upper and lower electrodes 19, 6 and the graphite crucible 27 sandwiched between these 19, 6. , the sample is dissolved in the graphite crucible 27 by the Joule heat generated in the graphite crucible 27, and from the sample, for example,
Hydrogen, oxygen, nitrogen, etc. are extracted as corresponding gas components and flowed out along with the carrier gas through the extracted gas flow path 24 as shown by arrow S in FIG. 3, and sent to a gas analyzer (not shown). The concentration is measured.

In the embodiment described above, only the lower electrode 6 is rotated, but the upper electrode 19 may also be rotated. In this case, it is desirable to rotate the upper and lower electrodes in opposite directions.

As mentioned above, this invention measures the electrical resistance of a graphite crucible before it is used for gas analysis to determine whether the graphite crucible is good or bad. It is possible to prevent the occurrence of an abnormal value of the current caused by the abnormal value and analysis errors caused by the abnormal value. Furthermore, since the electrical resistance value of the graphite crucible can be known in advance, it is also possible to control the current flowing in the extraction furnace during analysis according to the electrical resistance value of the graphite crucible. Analysis errors can be prevented. In addition, in the present invention, as shown in the first embodiment, upper and lower electrodes for determining pass/fail may be provided separately from the extraction furnace, or as shown in the second embodiment, the extraction furnace The upper and lower electrodes may be used as they are to form a pass/fail determination device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention, FIGS. 2 to 5 show a second embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of the extraction furnace before crucible clamping. FIG. 3 is a longitudinal sectional view of the extraction furnace when the crucible is clamped, FIG. 4 is a schematic diagram of the rotary actuator, and FIG. 5 is a bottom view of the essential parts of the extraction furnace. A, 19... Upper electrode, B, 6... Lower electrode,
C, 27...Graphite crucible, D...Current supply section, E
……voltmeter.

Claims (1)

[Scope of utility model registration request] An upper electrode and a lower electrode that press the graphite crucible from above and below, a current supply section that supplies current to the upper and lower electrodes and the graphite crucible, and a means that is connected to the upper and lower electrodes and measures the electrical resistance of the graphite crucible. A device for determining whether graphite crucibles are good or bad.