JPS584977B2 - How to install a thermocouple - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermocouple mounting method for mounting a thermocouple within the wall of a pipe to be measured.

A sheath heater is a heater in which a cylindrical sheath is filled with an insulating agent such as magnesium oxide, and a heat generating wire such as a nichrome wire that generates heat is housed, and heats by passing electricity through the heat generating wire.

By the way, it is necessary to know the temperature of the sheath when heating it with a heater or cooling it by cutting off electricity.

Furthermore, it is required to know the temperature of the sheath at various positions.

Therefore, if a thermocouple is attached to the outer surface of the sheath for temperature measurement, it will show approximately the temperature of the sheath in a steady state, but in a transient state it will quickly cool down or overheat and will not show the true temperature of the sheath.

Furthermore, when a fluid such as gas or water flows around the sheath, the thermocouple's attached portion acts as a resistance that obstructs the flow of the fluid.

Therefore, attempts have been made to attach the thermocouple to the sheath within the sheath wall, but none of the conventional methods has been able to securely hold the thermocouple in the sheath without impeding the flow of fluid.

Therefore, this invention is an attempt to rationally solve the problems in view of the above circumstances.

This invention involves carving an axial groove in the outer wall of the tube to be measured, inserting the thermocouple into the groove, caulking the outer peripheral side of the groove side wall, attaching the thermocouple to the outer wall of the tube to be measured, and then attaching the thermocouple to the outer wall of the tube to be measured. This is a thermocouple installation method in which the measuring tube is narrowed to reduce its diameter and the thermocouple is attached to the tube to be measured.

This invention will be described in detail below based on one embodiment of the accompanying drawings.

Reference numeral 1 denotes a tube to be measured such as a sheath, and the inside thereof is filled with an insulating material 2 such as magnesium oxide and houses a heating wire (not shown) such as a nichrome wire that generates heat.

In order to measure the temperature inside the wall of the pipe to be measured,
Grooves 3 for embedding thermocouples are carved in the outer wall in the axial direction in a number corresponding to the measurement locations.

To attach the thermocouple 4 to the tube to be measured 1, first, the thermocouple 4 is inserted into the groove 3 with the measurement contact of the thermocouple 4 disposed at the upper end.

To give an example of this, the outer diameter of the tube to be measured 1 is 10.8 mm,
The thermocouple 4 has a diameter slightly smaller than 0.5 mm with a wall thickness of 1 mm, a groove width of 0.5 mm, and a groove depth of 0.5 mm.

Next, the caulking tool 5 is brought into contact with the groove 4 in which the thermocouple 4 of the tube to be measured 1 is attached, and the outer peripheral side of the side wall of the groove 4 is caulked as shown in FIG. hold.

This time, pressure is applied in the radial direction over the entire length of the tube 1 to be measured, and then the tube is passed through a rear die to reduce the tube diameter.

On the upper side, the outer diameter of 10.8 mm is reduced to 10.7 mm.

Since pressure is applied in the radial direction before this drawing process, the thermocouple 4 does not move in the axial direction during the drawing process.

Alternatively, only the measurement contact portion of the thermocouple 4 may be brazed with Ni, and after brazing, the outer surface is finished into a circular shape.

In this invention, in order to embed a thermocouple in the tube wall to measure the temperature inside the measuring tube rod, an axial groove is carved in the outer wall of the tube to be measured, the thermocouple is inserted into the groove, and the thermocouple is inserted into the groove. After caulking the outer periphery of the side wall, the tube to be measured is narrowed and reduced in diameter, so simply abutting with the caulking tool is sufficient to hold the thermocouple to the tube to be measured by applying pressure in the radial direction. However, since the holding force was not applied in the circumferential direction, it was insufficient, but since the drawing process was performed in the radial direction, the holding force in the circumferential direction was also sufficient, and the thermocouple was completely held.

In addition, the outer periphery of the tube to be measured may be narrowed, so there is nothing that acts as a resistance to the fluid flowing around it.

Furthermore, the thermocouple can be mounted within the measuring tube wall by simply crimping and squeezing, which is simpler than conventional mounting methods.

[Brief explanation of drawings]

FIG. 1 is a front view of the tube to be measured according to the present invention, and FIG.
3 to 5 show an embodiment of the thermocouple mounting method of the present invention. Figure 4 is a cross-sectional view showing the state in which the groove into which the thermocouple is inserted is caulked with a caulking tool;
FIG. 5 is a cross-sectional view showing a state in which the tube to be measured is constricted and reduced in diameter. 1...Pipe to be measured, 3...Groove, 4...
···thermocouple.

Claims (1)

[Claims] 1. Cut an axial groove in the outer wall of the tube to be measured, insert the thermocouple into the groove, swage the outer peripheral side of the groove side wall, and attach the thermocouple to the outer wall of the tube to be measured. Thermocouple attachment method 3, characterized in that the thermocouple is attached to the tube to be measured by narrowing the diameter.