JPS5815132A - Preparation of thermocouple - Google Patents

Abstract

PURPOSE:To improve the sensitivity and response property, by bringing the tip of a supporting tube of a thermocouple into contact with and pushing said tip into a protective tube softened by heating and embedding the warm contact point in a sealing part or bringing said contact point into contact with said part. CONSTITUTION:One end of a quartz straight tube 1 used for a protective tube is softened by heating and is sealed and thermocouple wires 4, 5 inserted and held in a quartz tube 3 used as a supporting tube insertable to the tube 1 placing a hot contact point 6 at the tip, are inserted quickly into the tube 1 together with the tube 3 in a state of room temperature and the tip end are brought into contact with the inner face of a sealing part 2 in a softened state of the tube 1 and moreover, is pushed into the part 2 before reducing to a temperature lower than the softening temperature. Accordingly, the sensitivity and response property are improved because the contact 6 is embedded in the part 2 of the tube 1 or is in contact with the inner face.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a thermocouple, that is, a thermocouple for measuring temperature of molten metal and solidification temperature. The idea is to easily form thermocouples.

Conventionally, in order to achieve this purpose, a thermocouple hot junction, which is usually placed in the air inside a protection tube made of quartz, etc., was buried in the tip of the protection tube to transfer heat from the object to be measured, such as molten steel, to the hot junction. Conduction was conducted directly from the protective tube to the hot junction without involving heat conduction in the air (for example,
-8684, Utility Model Application Publication No. 58-147187). However, in all of these prior art techniques, the thermocouple wire is inserted into the protective tube in advance, the tip of the protective tube is heated and melted, and then each hot junction is crushed using pliers or the like. Since the contacts are buried within the tip of the protection tube, the hot junctions are also heated at the same time as the protection tube is heated.If the protection tube is made of quartz, its softening point is approximately 1650℃, and the thermocouple wire In the case of pt-Pt-Rh 1896, the melting point of Pt is 1769° C., and the heating temperature must be limited to a range above the softening point of quartz and below the melting point of Pt, but this is technically extremely difficult. Even if it were possible to control this heating temperature, the thermocouple wire used in disposable thermocouple thermometers is generally 10,07-40.
, 15 WM, so there was a drawback that the accuracy decreased significantly due to being kept under high temperature conditions close to the melting point for a long time, and as a result, the sensitivity and responsiveness decreased.

The present invention was developed in view of the above conventional drawbacks, and will be described in detail below. One end of a straight quartz tube (1) serving as a protective tube is heated and softened using an oxygen-propane flame or other means and sealed. This sealing part (2) has a thickness of about 0.5 to 1.0 mm.
t, the thermocouple wire (4) is inserted and held in the quartz thin tube (3) as a support tube that can be inserted into the quartz straight tube (1) with the hot junction (6) located at the tip. (5) is rapidly inserted into the straight quartz tube (1) together with the quartz thin tube (3) at room temperature, and the tip is brought into contact with the inner surface of the softened sealed part (2) of the straight quartz tube (1) to further soften it. Push it in before the temperature drops below temperature. After pushing it in, it stops heating and allows it to cool down naturally.

The thermocouple manufactured through this procedure has its hot junction (6) embedded in the sealing part (2) at the tip of the quartz straight tube (1) or in contact with the inner surface of the sealing part. It becomes.

According to the present invention as described above, the hot junction (6) of the manufactured thermocouple is embedded in the tip sealing part (2) of the quartz straight tube (1) or is in contact with the inner surface. Therefore, heat is conducted from the object to be measured to the hot junction without going through the air in the quartz straight tube (1), improving sensitivity and responsiveness, and there is no influence from air convection. Of course, the thermocouple itself has the effect of stabilizing the measured waveform, but in the manufacturing process of this thermocouple, the hot junction (6) was connected to a straight quartz tube (1
) When buried in or in contact with the sealed part (2) of the quartz straight tube (1), only the quartz straight tube (1) is heated to form a hot junction (6) and a thermocouple wire (
4) Since (5) is to push the quartz straight tube (1) into the sealed part (2) which is in a softened state at room temperature without heating, the heating temperature of the quartz straight tube (1) is determined by adjusting the softening point of the quartz and the thermocouple. The difficult work of controlling the melting point of the wire is completely unnecessary, and the thermocouple wire (4) (5).

Since the hot junction (6) is not exposed to high-temperature heating conditions for a long period of time, there is no risk of deterioration in accuracy.

Furthermore, by using a quartz tube when pushing the hot junction (6) into the sealing part (2), the work can be done quickly and reliably.

[Brief explanation of drawings]

The accompanying drawings show embodiments of the present invention; FIG. 1 is a cross-sectional view of the hot junction embedded in the sealing part, and FIG. 2 is a cross-sectional view of the hot junction in contact with the inner surface of the sealing part. 1: Quartz straight tube, 2: Sealing part, 3: Quartz thin tube, 4.5: Thermocouple wire, 6: Hot junction patent applicant Yamazato Electronite Co., Ltd. Figure 1
″jS2 diagram

Claims (1)

[Claims] (1) The thermocouple wire supported by the support tube is supported at room temperature by placing a hot junction at the tip of the protective tube under the condition of being heated and softened by heating the seal formed at one end. Insert the support tube together with the support tube, bring the tip of the support tube into contact with the softened sealing part, and push it in to bury the hot junction in the sealing part or contact the inner surface of the sealing part, and then stop heating the protective tube. Next is the method for manufacturing thermocouples that are made by natural cooling.