JPH0336072Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to an improvement of a water-cooled terminal that supplies power to a heating element of a resistance heating electric furnace (hereinafter referred to as a high-temperature electric furnace) used for sintering powdered metals or ceramics. It is something.

(Prior Art) Generally, graphite is often used in the heating element of the above-mentioned high-temperature furnace, and the power supply part is a copper water-cooled terminal to absorb conductive heat from the heating element.

Figure 3 shows a power supply section in which a graphite heating element is directly connected to a water cooling terminal. 9 is a heating element, which in the figure is made of graphite and has a rod shape, and 8 is a holder that collects the heating elements. It is made of graphite, the same material as the heating element. 6
is a conductor also made of graphite that connects the holder 8 and the water-cooled terminal 4. The water cooling terminal 4 is hollow inside and has a water cooling jacket 4a, and a power supply line 7 is connected to the outer end of the terminal 4 to receive power from a power source (not shown). By the way, in the figure, 1 is a heat insulating material constituting the furnace, 2 is a mounting hole, and 3 is a heat-resistant insulator that electrically insulates a live part and a heat insulating part.

FIG. 4 also shows the power supply section, but a high melting point, highly conductive connecting terminal 5 is interposed between the water cooling terminal 4 and the conductor 6 in FIG. This makes it possible to heat to higher temperatures with less conductive heat loss.

Figure 5. FIG. 6 shows a specific example of the connection between the water cooling terminal 4 and the conductor 6 or connection terminal 5, and FIG.
The connecting ends are overlapped and secured with bolts and nuts, and FIG. 6 shows an example in which the connecting ends are threaded and screwed together.

In the figure, reference numeral 4b indicates a cooling water introduction pipe, which is inserted into the jacket 4a from one end of the water cooling terminal 4, and the arrow indicates the direction in which the cooling water flows.

(Problems to be solved by the invention) In either connection method, when used for a long time, Γ reduction of cooling effect due to scale adhesion within the water cooling jacket 4a, Γ thermal expansion. Loosening due to repeated contraction, loosening due to Γ electromagnetic vibration, etc., may cause abnormal overheating of the connecting portion or poor contact of the overlapping portion 10a or the threaded portion 10b, and local heating due to increased contact resistance progresses, eventually causing the water-cooled terminal to fail. The overlapped or screwed portions on the 4 sides end up being melted and damaged, and arc discharge occurs at the localized melted locations, further progressing the melting damage. During this time, the current passing through the water cooling terminal 4 is
Since a discharge resistor is inserted in series in the electrical circuit, and the arc discharge is reduced compared to before it occurs, overcurrent relays, etc. cannot detect the occurrence of melting damage, and the melting damage may occur in the water cooling jacket. Eventually, water leakage will occur.

If a water leak occurs in this type of electric furnace, there is a risk that the water will rapidly evaporate and expand due to the high temperature inside the furnace, and at the same time, the sample and insulation material will be damaged.

The purpose of the present invention is to detect an overheating condition that causes water cooling terminal melting and to immediately cut off the power supply, thereby preventing water cooling terminal melting accidents that may lead to water leakage.

(Means for solving the problem) The structure of the present invention to achieve the above purpose is as follows:
To explain using FIGS. 1 and 2 corresponding to the embodiment, the present invention provides a conductor or connection from one end of the water cooling terminal 4 to a part of the water cooling terminal 4 that supplies power to the heating element 9 of the high temperature electric furnace. The present invention is characterized in that a loading section 14 is provided that reaches a connection section with a terminal, and a thermocouple 13 is loaded into this loading section 14.

(Embodiments) Preferred embodiments of the present invention will be described below based on the drawings.

Example 1 Fig. 1 is a schematic cross-sectional view showing one of the embodiments of the water-cooled terminal for a high-temperature electric furnace according to the present invention. is not shown. In Figure 1, water cooling terminal 4
and the graphite conductor 6 are fitted and screwed together with a screw. A part of the water cooling terminal 4 is provided with a loading part 14 in the form of a small diameter hole extending from the cooling water supply/drainage side to the threaded part 10b with the conductor 6, and the thermocouple 13 is inserted into this loading part 14 and screwed. This measures the temperature of the water cooling terminal near the joint. The thermocouple 13 is connected to a thermometer or the like with an alarm contact, and when the temperature rises abnormally, an alarm is issued and at the same time appropriate safety measures are taken, such as turning off the heating power source and displaying the information. The temperature near the threaded part 10b of the water cooling terminal 4 is approximately 200°C under normal conditions, and reaches over 800°C when melted.
By measuring the temperature of this part, it is relatively easy to detect the presence or absence of an abnormality.

In addition, in the figure, 11 is a drain port, and 12 is a water supply port.

Embodiment 2 FIG. 2 is a schematic sectional view of another embodiment. Second
In the figure, a hole 16 into which a small-diameter copper tube 15 is inserted is formed in the center of the threaded portion 10b of the water-cooling terminal 4, and the cooling water introduction tube 4b is inserted into the hole 16 from the outer end of the water-cooling terminal 4.
A small-diameter copper tube 15 passing through the interior is inserted and joined to form a loading section 14, and a thermocouple 1 is inserted into this loading section 14.
3 and measure the temperature at the center of the threaded part. According to this embodiment, there is no need to process a small-diameter long hole, and not only can a thermocouple be inserted relatively easily, but also the temperature of the threaded portion can be measured uniformly.

Note that a thermometer or the like with an alarm contact is connected to the end of the thermocouple 13, as in the first embodiment, so that when the temperature rises abnormally, an alarm is issued, the heating power supply is interrupted, the display is displayed, etc. Appropriate safety measures can be taken.

By the way, in the above-mentioned Examples 1 and 2, the case where the water-cooled terminal was screwed onto the conductor 6 was explained, but the invention is not limited to this. It is also possible to connect them together, or by overlapping them as shown in FIG.

(Effect of the invention) According to the present invention, a thermocouple is mounted in a part of the water-cooled terminal so that the tip of the thermocouple is located at the connection part with the conductor or the connection terminal, so the temperature of the connection part of the water-cooled terminal can be controlled. It has practical advantages such as being able to prevent melting of water cooling terminals that could lead to water leaks by measuring and detecting an abnormal rise in temperature in this area and cutting off the power supply. .

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of Embodiment 1 of a water-cooled terminal for a high temperature electric furnace according to the present invention, Fig. 2 is a schematic sectional view of Embodiment 2, and Figs. 3 and 4 show a conventional power supply device. The sectional view, FIG. 5, and FIG. 6 are explanatory diagrams showing the connection portion between the water cooling terminal and the conductor or connection terminal, respectively. 1 is a heat insulating material, 2 is a mounting hole, 3 is an insulator, 4 is a water cooling terminal, 4a is a water cooling jacket, 4b is a cooling water introduction pipe, 5 is a connection terminal, 6 is a conductor, 7 is a power supply line, 8
is a holder, 9 is a heating element, 10a is a polymerization part, 10
b is a threaded part, 11 is a drain port, 12 is a water supply port, 13
1 is a thermocouple, 14 is a loading section, 15 is a copper tube, and 16 is a hole.

Claims (1)

[Scope of utility model registration request] A high-temperature electric furnace characterized in that a thermocouple is loaded in a part of a water-cooled terminal that supplies power to a heating element of a high-temperature electric furnace, such that the tip of the thermocouple is located at the connection between the water-cooled terminal and the conductor or connection terminal. Water cooling terminal for furnace.