JPS6242014A - Manufacture of measuring pipe for electromagnetic flow meter - Google Patents

Abstract

PURPOSE:To execute the simple and secure sealing between the electrode and the hole and to prevent the performance deterioration at the time of using the meter by burning the ceramic pipe after the electrode formed by treating the surface with the high melting point conductive metal to the spindle for the electrode is fitted and inserted to the hole of the unburnt ceramic pipe. CONSTITUTION:After an electrode 16 formed by treating the surface with the high melting point metal at a spindle 14 for the burned ceramic-made electrode is fitted and inserted to an electrode fitting hole 12 of an unburned ceramic pipe 13, burning is executed. In such a way, even when the metallic quantity used is small, the outer diameter of the electrode can be enlarged and the affinity to the hole 12 for fitting the ceramic pipe 13 is made satisfactory. Since burning is executed after the electrode 16 is fitted and inserted to the hole 12 for fitting the unburnt ceramic pipe 13, the shrinking allowance of the ceramic pipe is larger than the shrinking allowance of the electrode 16. Thus, the sealing between the electrode 16 and the hole 12 for fitting can be executed simply and without fail, and the bad influence to the performance at the time of using the meter can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a measuring tube for an electromagnetic flowmeter using a ceramic material.

[Conventional technology]

Conventionally, in the manufacturing method of this type of measuring tube for an electromagnetic flowmeter, as shown in FIG.
The one that inserts and fires is used.

[Problem that the invention seeks to solve]

However, in the case of using metal for the former, that is, the electrode 3, the metal must be durable against the firing temperature of the ceramic, and its coefficient of thermal expansion must be close to that of the ceramic. Therefore, there is a problem in that usable metals are limited to expensive metals such as platinum.

Therefore, in order to economically manufacture measuring tubes for electromagnetic flowmeters,
It is conceivable to reduce the outer diameter of the electrode 3, but in this case, the input impedance increases when viewed from the side of the electromagnetic flowmeter converter, which has the disadvantage of adversely affecting its performance.

On the other hand, in the latter case, that is, when a conductive ceramic is used for the electrode 3, although it differs somewhat depending on the composition, the conductivity is inferior to that of ordinary metal, so there is a performance problem similar to the above case.

[Means for solving problems]

The method for manufacturing a measuring tube for an electromagnetic flowmeter according to the present invention involves forming an electrode for an electromagnetic flowmeter by surface-treating eight ceramic rods for electrodes with a high-melting-point conductive metal, and then leaving the electrodes in an untreated state. The electrode and the ceramic tube are fired after being inserted into an electrode mounting hole drilled in a fired or semi-fired ceramic tube.

In addition, a method for manufacturing a measuring tube for an electromagnetic flowmeter according to another invention of the present invention includes forming electrodes for an electromagnetic flowmeter by subjecting eight ceramic rods for electrodes to surface treatment with a high-melting-point conductive metal. Next, this electrode is inserted into an electrode mounting hole drilled in an unfired or semi-fired ceramic tube, the electrode and the ceramic tube are fired, and a conductive head is attached to the fluid to be measured side of the electrode. .

The present invention was developed in view of the above circumstances, and it is possible to easily and reliably seal between an electrode and an electrode mounting hole, and also to reduce costs. The present invention provides a method for manufacturing a measuring tube for an electromagnetic flowmeter that does not adversely affect performance.

[For production]

In the present invention, since the electrodes are formed by subjecting eight ceramic rods for electrodes to surface treatment with a high melting point conductive metal, the electrode diameter can be increased even if the amount of metal used is small. In addition, since the electrode and the ceramic tube are fired after the electrode is inserted into the electrode mounting hole drilled in the unfired or semi-fired ceramic tube, the shrinkage of the ceramic tube is larger than that of the electrode. Become.

Furthermore, in another aspect of the present invention, since a conductive head is attached to the electrode on the side of the six flow objects to be measured, this conductive head is exposed inside the tube.

〔Example〕

FIG. 1 is a sectional view for explaining a method of manufacturing a measuring tube for an electromagnetic flowmeter according to the present invention. In the figure, reference numeral 11
1 is a measurement tube for an electromagnetic flowmeter, which includes an unfired or semi-fired ceramic tube 13 having an electrode attachment hole 12 in the center in the axial direction, and a tube inserted into the electrode attachment hole 12 of the ceramic tube 13. Outer peripheral surface 14a and insertion end surface 14b
and an electrode 16 formed of eight fired ceramic electrode rods 14 having a metal conductive part 15,
It is held under pressure by individual connecting pipes (not shown). A signal lead wire 17 is connected to a terminal on a terminal board (not shown), and is soldered to the side of the conductive portion 15 opposite to the fluid to be measured.

The metal used for the conductive portion 15 is preferably a high melting point metal such as platinum or platinum-iridium alloy, which has a melting point higher than the ceramic firing temperature (1000 to 1600° C.) used in manufacturing the measuring tube.

Next, a method for manufacturing the electromagnetic flowmeter measuring tube 11 configured as described above will be explained.

First, the outer peripheral surface 14 of the 8 rods 14 for electrodes of fired ceramics.
By applying platinum paste to a and the insertion end surface 14b and baking it at a heating temperature of 800 to 1600°C,
That is, the electrodes 16 are formed by subjecting the eight rods 14 for electrodes to surface treatment with a high melting point metal. Next, this electrode 16
is inserted into the electrode attachment hole 12 of the unfired or semi-fired ceramic tube 13, and then fired at a firing temperature of 1000 to 1600°C.

Measuring tube 1 for electromagnetic flowmeter equipped with electrode 16 in this way
1 can be manufactured reliably.

Note that when manufacturing the measuring tube 11 for the electromagnetic flowmeter described above, an example was shown in which eight electrode rods 14 made of fired ceramic were used as the electrodes 16, but if one with a relatively small shrinkage margin is selected, half-fired 8 rods for ceramic electrodes may also be used. That is, it is sufficient to use a combination of eight ceramic electrode rods whose semi-firing temperature is higher than that of the ceramic tube 13.

As described above, according to the method for manufacturing a measuring tube for an electromagnetic flowmeter according to this embodiment, the electrode 16 is formed by surface-treating the ceramic electrode 8-piece 14 with a high-melting-point conductive metal. The outer diameter of the electrode can be increased even if the amount of metal is small, and the electrode mounting hole 1 of the ceramic tube 13 can be
The affinity of electrode 16 for 2 becomes better. In addition, after inserting the electrode 16 formed of eight fired ceramic electrode rods 14 into the electrode mounting hole 12 drilled in the unfired or semi-fired ceramic tube 13, the electrode 16 and the ceramic tube 1 are inserted.
3, the shrinkage margin of the ceramic tube 13 becomes larger than that of the electrode 16.

In addition, in another invention of the present invention, FIGS.
As shown in the figure, a conductive tip 20.21 made of platinum or a platinum-iridium alloy is attached to the fluid to be measured side of the electrode 18.19 by brazing.
Both parts 20.21 will be exposed within the tube. Here, instead of the conductive tip 20.21, a conductive cap 22.23 may be used as shown in FIGS. 4 and 5.
In this case, the conductive caps 22 and 23 are each brazed,
The electrodes 24 and 25 are attached to the fluid to be measured side by caulking. Incidentally, if a material such as cream solder or bond film is used for the brazing operation in FIG. 4, the workability will be improved.

Furthermore, since the eight ceramic rods for electrodes in the present invention can be subjected to various treatments, for example, as shown in FIG. The shapes of the electrode 26, the electrode 27 having a stepped portion 27a for electrode positioning as shown in FIG. 7, etc. can be modified as appropriate.

Furthermore, in the present embodiment, an example was shown in which the No. 13 lead wire 17 was simply connected to the conductive part 15 of the electrode 16, but the present invention provides an example in which the No. 13 lead wire 17 is inserted through the attachment hole 29 provided in the electrode 28 as shown in FIG. After that, the signal lead wire 31 is connected to the conductive part 30, and the locking part 33 provided on the electrode 32 is connected as shown in FIG.
A signal lead (not shown) may also be connected to the mount, thereby ensuring its attachment.

〔Effect of the invention〕

As explained above, according to the present invention, the electrodes are formed by surface-treating eight ceramic rods for electrodes with a high-melting-point conductive metal, so even if the amount of metal used is small, the electrode diameter can be increased. be able to. Therefore, the cost can be reduced, and the performance of the meter is not adversely affected when it is used, unlike the conventional method. In addition, since the electrode and the ceramic tube are fired after the electrode is inserted into the electrode mounting hole drilled in the unfired or semi-fired ceramic tube, the shrinkage of the ceramic tube is larger than that of the electrode. In addition, the metal surface treatment improves the affinity between the electrode and the electrode mounting hole, making it possible to securely fix the electrode to the ceramic tube and easily and reliably seal between the electrode and the electrode mounting hole. Furthermore, since the coefficient of thermal expansion of the ceramic tube and the coefficient of thermal expansion of the electrode are approximately the same, the sealing performance will not deteriorate even if there is a temperature change.

Further, in another aspect of the present invention, since a conductive head is attached to the fluid to be measured side of the electrode, this conductive head is exposed inside the tube, and the wear resistance of the electrode can be improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view for explaining the method of manufacturing a measuring tube for an electromagnetic flowmeter according to the present invention, FIGS. 2 to 5 are sectional views showing electrodes in other embodiments, and FIGS. The figure is a cross-sectional view showing a modified example of the electrode shape in another embodiment, Figures 8 and 9 are cross-sectional views for explaining the connection state of the signal lead wire to the electrode, and Figure 10 is a conventional electromagnetic flow rate. FIG. 3 is a cross-sectional view for explaining a method of manufacturing a measurement tube. 12... Electrode mounting hole, 13... Ceramic tube, 14... 8 rods for electrode, 15... Conductive part, 16
····electrode.

Claims (2)

[Claims] (1) Electrode installation in which an electrode for an electromagnetic flowmeter is formed by surface-treating a ceramic electrode core rod with a high-melting-point conductive metal, and then this electrode is drilled into an unfired or semi-fired ceramic tube. A method for manufacturing a measuring tube for an electromagnetic flowmeter, which comprises firing an electrode and a ceramic tube after fitting the tube into a hole. (2) Electrode installation in which an electrode for an electromagnetic flowmeter is formed by surface-treating a ceramic electrode core rod with a high-melting-point conductive metal, and then this electrode is drilled into an unfired or semi-fired ceramic tube. 1. A method of manufacturing a measuring tube for an electromagnetic flowmeter, comprising: firing the electrode and the ceramic tube after inserting the tube into a hole; and attaching a conductive head to the fluid to be measured side of the electrode.