JP2006118878A - Vacuum mass measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To compensate the fluctuation of performance of a weighing means by making calibration of the weighing means possible while weighing process. <P>SOLUTION: After the lid 3 of the vacuum vessel 1 is opened, and the sample vessel 2 storing the measuring object M is mounted on the weighing dish 18, the vacuum vessel 1 is evacuated then the measurement is started. The weight of the object M is detected by the electronic balance 10 and its numeric value is displayed on the control display part 11. The electronic balance 10 must be calibrated frequently during the weighing process because of its inevitable influence of temperature of the measuring object M of high temperature. For the calibration the measurement is temporary stopped, and by remotely moving the cam 22 by the motor 21 the cylinder part 14 is raised by moving the lever 20 for supporting the weighing dish 18 by the flange 15 of the upper end of the cylinder part 14. By the elevation of the weighing dish 18, the weight transition rod 17 is separated into upper part 17a and lower part 17b in that condition the zero point adjustment can be performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vacuum mass measuring apparatus capable of performing mass measurement in a vacuum state and performing calibration in a weighing process.

  It is extremely difficult to accurately measure minute load changes under adverse environmental conditions.

  For example, the amount of gas released from a hot molten metal in a vacuum may have to be measured as a change in mass using an electronic balance in time units. However, the characteristics of the electronic balance change due to thermal effects, etc., and it is often difficult to measure with high accuracy.

  In addition, frequent calibration is required for this purpose, but calibration is required in a vacuum, which is difficult.

  An object of the present invention is to provide a vacuum mass measuring apparatus that eliminates the above-mentioned problems, enables calibration of the weighing means during the weighing process, and can compensate for changes in the characteristics of the weighing means.

  In order to achieve the above object, a vacuum mass measuring apparatus according to the present invention is provided with weighing means in a vacuum vessel, and the weighing means supports a weighing pan placed in the vacuum vessel via a load transmission rod, In the process, means for remotely separating the weighing pan from the weighing means is provided.

  According to the vacuum mass measuring apparatus of the present invention, the weighing means can be arbitrarily calibrated during the weighing process, so that the accuracy of the weighing means can be maintained.

The present invention will be described in detail based on the illustrated embodiments.
FIG. 1 is a block diagram, and an openable and closable lid 3 is provided at the top of the vacuum vessel 1 for taking in and out an object M put in a sample vessel 2. Pipes 4 and 5 connected to cylinders or suction pumps for injecting gas or sucking gas are provided, and on-off valves 6 and 7 are provided in the middle of the pipes.

  A heat shielding box 8 fitted with a heat insulating material is arranged at the lower part of the vacuum vessel 1, and a partition plate 9 is provided horizontally in the middle of the heat shielding box 8. The precision electronic balance 10 is arranged in this space. The output of the electronic balance 10 is connected to a control display unit 11 disposed outside the vacuum vessel 1 via an electric wire 12.

  A circular opening 13 is provided in the upper part of the heat shielding box 8, and a cylindrical tube portion 14 is inserted into the opening 13 so as to be slidable up and down. A flange 15 is provided at the upper end of the cylindrical portion 14, and the cylindrical portion 14 is suspended from the upper edge of the opening 13 via the flange 15.

  On the other hand, a load transmission rod 17 made of a non-magnetic material is provided upward from the top of the electronic balance 10, and this load transmission rod 17 contacts the hole 16 and the cylinder portion 14 provided in the partition plate 9. The weighing pan 18 is attached to the upper end of the load transmission rod 17.

  The load transmission rod 17 is separable into an upper portion 17a and a lower portion 17b by an abutting structure at an intermediate portion. One end of a lever 20 that is rotatable about a fulcrum 19 is attached to a part of the cylindrical portion 14, and a cam 22 that is driven by a motor 21 is attached to the other end of the lever 20. The fulcrum 19 and the motor 21 are fixed to a frame (not shown) in the heat shielding box 8 and are operated by a command from the control display unit 11.

  As shown in FIG. 2, an annular magnetic force generator 23 is provided around the hole 16, and the inner space of the hole 16 is substantially in communication with the hole 16. In the magnetic force generator 23, an annular permanent magnet 25 is covered with a magnetic body 24, and an annular non-magnetic body 26 is attached to the inner surface so that the permanent magnet 25 is not exposed on the inner surface. The space in the non-magnetic material 26 is filled with a magnetic fluid 27, and the magnetic fluid 27 is attracted and held in the space by the magnetic action of the magnetic flux in the magnetic circuit formed by the permanent magnet 25 and the magnetic material 24. Has been.

  The load transmission rod 17 penetrates through the magnetic fluid 27 without contacting the non-magnetic body 26. The diameter of the load transmission rod 17 is, for example, 5 to 10 mm, and the distance from the inner diameter of the non-magnetic body 26 is 0. About 5 mm. As described above, the environmental atmosphere in the heat shielding box 8 separated by the partition plate 9 from above and below is hermetically isolated by the magnetic fluid 27 even if the hole 16 is provided in the partition plate 9.

  During the measurement, the cylindrical portion 14 is suspended from the opening 13 of the heat shielding box 8 by the flange 15, and the weighing pan 18 is supported by the load transmission rod 17. A weighing object M made of high-temperature molten metal placed in a heat-resistant sample container 2 is placed on the weighing pan 18 by way of, for example, a thermal insulating ceramic 27, so that the weighing is performed in a vacuum by the electronic balance 10. The amount of gas released from the object M can be measured by weighing.

  That is, when the measurement is started after the on-off valves 6 and 7 are operated and the gas in the vacuum container 1 is discharged, the weight of the object M is detected by the electronic balance 10 and the numerical value is displayed on the control display unit 11. Is done.

  At this time, since the gas is released from the object to be weighed in the vacuum, the measured value of the object to be weighed M gradually decreases, and the weight of the released gas can be measured. However, in this measurement, the accuracy and sensitivity of the electronic balance 10 are required to be particularly high. Although the electronic balance 10 is housed in the heat shielding box 8, the temperature due to the high-temperature weighing object M in the vacuum vessel 1 is measured. Changes in the characteristics of measured values due to effects are inevitable. Therefore, it is necessary to frequently calibrate the electronic balance 10, that is, to adjust the zero point even in the weighing process.

  In the calibration in the weighing process, the measurement is temporarily stopped, the load is set to zero, and the zero point is adjusted. That is, as shown in FIG. 3, the cam 22 is rotated by the motor 21 remotely via the control display unit 11, thereby moving the lever 20 and raising the cylinder part 14, and the flange 15 at the upper end of the cylinder part 14. Thus, the weighing pan 18 is raised and supported. As the weighing pan 18 rises, the load transmission rod 17 is separated into an upper portion 17a and a lower portion 17b at the intermediate portion, and the upper load including the weighing pan 18 is not transmitted to the electronic balance 10, so that the control display portion is in that state. 11 enables calibration by zero point adjustment.

  Since this calibration can be frequently performed in the weighing process, even if the zero point fluctuates due to a temperature change or the like during the measurement, the zero point fluctuation is compensated and accurate measurement can be performed.

  Further, by using the magnetic fluid 27 for hermetically closing the hole 16 of the partition plate 9, the measurement can be performed in a state where the environmental conditions of the electronic balance 10 and the object to be weighed M are separated. In particular, since the space where the electronic balance 10 is arranged is not evacuated, the time required for evacuating the vacuum container 1 and the amount of gas when filled with gas can be reduced.

  Since the load transmission rod 17 is a non-magnetic material, the load transmission rod 17 itself is not affected by the magnetic force. However, strictly speaking, the surface tension exerted by the magnetic fluid 27 on the load transmitting rod 17 affects the measurement accuracy. However, if the holding conditions for the magnetic fluid 27 are set so that the surface tension is sufficiently smaller than the resolution of the load to be measured, the required accuracy can be ensured.

It is a block diagram of an Example. It is a block diagram of the airtight means by a magnetic fluid. It is explanatory drawing at the time of calibration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum container 8 Heat shielding box 9 Partition plate 10 Electronic balance 11 Control display part 13 Opening 14 Cylinder part 15 Flange 16 Hole part 17 Load transmission rod 18 Weighing pan 19 Supporting point 20 Lever 21 Motor 22 Cam 27 Magnetic fluid

Claims (5)

  Weighing means is provided in the vacuum container, the weighing means supports a weighing dish arranged in the vacuum container via a load transmission rod, and means for remotely separating the weighing dish from the weighing means in the weighing process. A vacuum mass measuring device provided.   2. The vacuum mass measuring apparatus according to claim 1, wherein the weighing means is calibrated in a state where the weighing pan is separated from the weighing means.   The vacuum mass measuring apparatus according to claim 2, wherein the separating means comprises the load transmission rod made of two members, and both members are separated vertically.   4. The vacuum mass measuring apparatus according to claim 3, wherein an upper portion of the load transmitting rod to which the weighing pan is fixed is lifted by a mechanical means and separated from the weighing means.   The vacuum mass measuring device according to claim 1, wherein the space portion in which the weighing means is arranged is hermetically isolated from the space portion in which the weighing pan is arranged by a magnetic fluid.

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