JPS62131187A - Soaking method in sintering furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sintering furnace for sintering ceramics, metal powders, etc. at high temperatures in atmospheric gas in a pressurized or depressurized pressure vessel. .

[Conventional technology and its problems] In a ceramic sintering furnace where ceramics are sintered at a high temperature of around 2000°C under reduced pressure or increased pressure in an inert gas atmosphere, the heated object is uniformly heated to about ±10°C. Very strict thermal uniformity may be required. However, in conventional sintering furnaces, it took a very long time to transfer heat to the inside of the object to be heated, so it was not easy to achieve such uniform temperature. For this reason, there was a problem in that soaking took time and productivity deteriorated. To solve this problem, it has been known to improve the situation by installing a fan inside the furnace to stir the atmospheric gas inside the furnace.
Even so, there was still a heating delay inside the object to be heated, and a sufficient effect was not achieved.

[Means for Solving the Problems] The present invention aims to provide a heat equalization method that solves the problems of the prior art described above. In a sintering furnace in which a processing chamber is formed, and an electric heater is further provided in the processing chamber so as to surround the object to be heated, and the object to be heated is sintered at high temperature in an atmospheric gas, there is a Open a ventilation hole.

Alternatively, the object to be heated is housed in a container having a vertically extending ventilation hole in the center thereof, and atmospheric gas is caused to convect through the ventilation hole.

[Example code] Next, one embodiment of the present invention will be described with reference to the drawings.

First, the outline of this sintering furnace will be explained with reference to FIG.

The pressure vessel 1 has a cylindrical body part 2 and a canopy part 3 connected to each other by flanges 4, 4, and a bottom cover part 5 and a flange part 6, 6 of the body part 2 by a removable tightening ring 7. It is tightened so that the inside can be sealed airtight. Reference numeral 8 denotes a communication port that communicates with the inside of the pressure vessel 1, and the communication port 8 is connected to a pressure pump or a pressure reduction pump that pumps the required atmospheric gas. 9.9 is an insertion port through which a temperature measuring thermocouple can be inserted airtight into the pressure vessel.

A processing chamber 11 is provided within the pressure vessel 1 and has a heat insulating wall formed in a cylindrical shape so that a ventilation gap 10 exists between the pressure vessel 1 and the inner surface thereof. The processing chamber II has a body 12 covered with a lid member 13, and the lid member 13 is suspended from an operating rod 15.15 of a cylinder 14.14 provided outside the ceiling of the pressure vessel I. Then, by operating the cylinders 14, 14 and lifting the lid member 13 as shown in FIG. 2, an opening 16 is formed in the upper outer periphery of the body 12. A bottom cover member 17 is fitted to the bottom of the processing chamber 11, and the container 20 is placed on a table 18 provided on the bottom cover member 17.
An object to be heated 19 is placed therein. Note that the bottom cover member 1
7 is supported by the bottom cover portion 5 of the pressure vessel 1. An opening 22 is provided at the center of the bottom cover member 17, into which a plug member 23 is fitted. This plug member 23 is fixed to the operating rod of a cylinder 21 provided on the bottom lid part 5, and the opening 22 is opened and closed by moving the plug member 23 forward and backward by the operation of this cylinder 21. Reference numeral 24 denotes a carbon electric heater provided in the processing chamber 11 to surround the object to be heated 19 . Further, 25 is a fan provided on the ceiling of the processing chamber 11, and a rotating shaft 26 of the fan passes through the lid member 13 and is supported by a bearing 27 provided on the canopy 3, and a portion of the rotating shaft 26 that protrudes above the lid. A permanent magnet 28 is fixed to the. Reference numeral 29 denotes an airtight cover made of a magnetically permeable material and fixed to the outer surface of the rotating shaft 26 so as to surround the permanent magnet. An annular permanent magnet 30 is provided on the outside of the cover 29 so as to surround it and is fixed to a rotating shaft 31, and the rotating shaft 31 is connected to a rotating shaft of a motor 32 and a transmission belt 33 wound between the pulleys. The permanent magnet 30 is rotated around the cover 29 by driving the motor 32. When the permanent magnet 30 rotates, the permanent magnet 28 inside the cover 29 is magnetically induced, the rotating shaft 26 rotates in the same direction, and the fan 25 rotates. Note that 34 is a cooler provided in the ventilation gap 10, and the cooler 5 is constructed so that cooling water flows through the heat transfer pipe.

The container 20 containing the object to be heated 19 is made of the same material as the object to be heated, that is, in this case, ceramics.
As shown enlarged in FIG.

A plurality of discs 36 each having a through hole 35 in the center, a small diameter cylinder 37 whose both ends fit into the through hole 36, and the disc 36.
A large diameter cylindrical body 38 is fitted to the outer peripheral edge of the cylindrical body 38. In the fitted state, the cylindrical bodies 37 and 38 are sandwiched between the discs 36 and piled up to form an annular chamber 39.
By accommodating the heated object 19 in 9, a ventilation hole 4 is formed in the center.
0 is formed in a vertical shape.

In this sintering furnace, as shown in FIG. 1, the lid member 13. The plug member 23 is closed to thermally shut off the processing chamber 11 by its heat insulating wall. Then, the object to be heated 19 in the container 2o is heated by the electric heater 24.

The fan 25 causes the atmospheric gas in the processing chamber 11 to undergo forced convection as indicated by the broken line arrow in the figure. That is, electric heater 2
4, the atmospheric gas in the processing chamber 11 is convected not only on the outside of the container 20 but also through the ventilation hole 40 that runs vertically through the center, heating the object to be heated 19 housed in the annular chamber 39 from both the outside and the inside. do. Then, the object to be heated 19 is uniformly heated to around 2000° C. and sintered. On the other hand, when cooling the heated object 19, the cylinders 14, 14.21 are operated to move the lid member 13 and plug member 23 to open the opening 16.22 as shown in FIG. Cooling water is then passed through the cooler 34 and the fan 25 is rotated to cause atmospheric gas to flow into the ventilation gap 10 as indicated by the broken line arrow in FIG. That is, since the atmospheric gas in the processing chamber 11 is guided through the opening 16 into the ventilation gap 1o, passed through the cooler 34 to be cooled, and then circulated to the processing chamber 11 through the opening 22, the heated object 19 transfers heat to the cooler 34 by convection. It is stolen and cooled down.

In addition, in a carbon container with a diameter of 300n+m,
A ventilation hole of 0 mra was provided, and the sample (
When the ceramics) were heated to 1600°C, there was a temperature difference of 30°C in the case without ventilation holes, but by providing ventilation holes, the temperature difference was reduced to 15°C.

Further, when the atmospheric gas was forced to be convected by a fan as in this example, the temperature difference was further reduced to 8° C., and heat uniformity was achieved extremely effectively.

Although this embodiment shows an example in which the object to be heated 19 is housed in the container 20 in which a ventilation hole 40 is formed, if such a container is not used, the object to be heated may be provided with a ventilation hole. Good too. In this case, the vent holes not only improve heat uniformity through convective heat transfer, but also facilitate the dissipation of gas generated during sintering to the outside, thereby preventing the formation of bubbles in the sintered product.

[Effect of the invention] The present invention is as described above with respect to the embodiments.

A vertical ventilation hole is provided in the center of the object to be heated or its container, and the atmospheric gas is convected through this vent, so that the object to be heated can be heated or cooled from the inside, speeding up the temperature uniformity. Improve temperature distribution. Therefore, it has a remarkable effect of improving the quality and productivity of sintered ceramic products and the like.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; Fig. 1 is a longitudinal cross-sectional view of a sintering furnace, Fig. 2 is a longitudinal cross-sectional view showing its operating state, and Fig. 3 is an enlarged view of a heated object container. The vertical sectional view, FIG. 4, is a sectional view taken along the line X--X in FIG. 3. 1...Pressure vessel, 11...Processing chamber, 19...
・Heated object. 20...Container, 40...Vent hole. Patent applicant: Daido Steel Co., Ltd.

Claims (1)

[Claims] A processing chamber surrounded by an insulating wall is formed in a pressure vessel whose atmospheric pressure can be controlled, and an electric heater is further provided in the processing chamber to surround the object to be heated, and the object to be heated is heated to high temperature in an atmospheric gas. In a sintering furnace for sintering, a ventilation hole that runs vertically through the center of the object to be heated is provided, or the object to be heated is housed in a container that has a ventilation hole that runs vertically through the center of the object,
1. A method for equalizing heat in a sintering furnace, characterized in that atmospheric gas is caused to flow through the vent hole.