JPH0453927B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to the structure of a vacuum furnace.

In a vacuum furnace, objects to be heated are heated to a high temperature of 1,200 to 1,600°C mostly due to radiant heat transfer from the heater, and almost never due to convective heat transfer or heat conduction. When heating an object to a high temperature in this way, the inner surface of the heater or insulation material is at a high temperature, so the temperature can be raised in a short time using only radiant heat, but tempering, annealing, etc. When trying to heat an object to a relatively low temperature, a vacuum furnace has the drawback that it takes much longer than other atmospheric furnaces because there is almost no convective heat transfer. Therefore, if necessary, introduce atmospheric gas such as argon gas or chitsuso gas into the vacuum furnace to increase the furnace internal pressure to 100~100℃.
It is possible to accelerate heating by convection heat transfer at 760 Torr, but vacuum furnaces are generally not equipped with a stirring fan and only natural convection occurs, which may lead to inconveniences such as uneven temperature distribution within the furnace. Ta.
Therefore, for example, the application filed by the present inventors
As described in Publication No. 68948, it is conceivable to install a stirring fan inside the furnace to stir the atmospheric gas, but it is quite difficult to manufacture a stirring fan that can withstand high temperatures of 1200 to 1600°C. Even if it were made of fine ceramics or the like with high heat resistance, it would be expensive.

The present invention aims to eliminate the above-mentioned drawbacks and provide a vacuum furnace suitable not only for high-temperature heating but also for low-temperature heating. In a vacuum furnace in which a heating section is formed by enclosing a wall and an electric heater is provided inside the insulating wall, a window and a cover plate for closing the window are provided in a part of the insulating wall, and a motor that rotates a stirring fan is provided. is provided to move forward and backward outside the window in the heat-resistant airtight chamber, and by moving the motor forward, the stirring fan advances from the window into the heating section and faces the object to be heated. The invention is characterized in that the agitating fan is retracted from the heating section by moving backward, and the window can be closed from the cover plate.

Next, one embodiment of the present invention will be described with reference to the drawings.
In this vacuum furnace, a pressure-resistant airtight chamber 1 and a cooling chamber 2 are connected in series, an intermediate door 3 is provided between the two chambers, and an opening/closing door 4 for charging and extracting heat materials is provided in the cooling chamber 2. ing. Reference numeral 5 denotes a fork-shaped lift for carrying the heated object a, which enters the cooling chamber 2 and the pressure-resistant airtight chamber 1 along the lift rail 6 provided on the ceiling and carries the heated object a into the room. Loading and unloading.
Reference numeral 7 indicates a cooling atmosphere gas circulation fan provided in the cooling chamber 2. 3 is a cylinder whose operating shaft end is connected to the intermediate door 3, and when the intermediate door 3 is opened, by operating the cylinder, the intermediate door 3 is evacuated into the storage section 9 and the heated object a is placed under pressure. It is made so that it does not get in the way of charging and extracting into the airtight chamber 1. Inside the pressure-resistant airtight chamber 1 is a fixed stand 1 on which the heated object a is placed.
In addition, a heat insulating wall 11 made of graphite with excellent heat resistance is provided to surround the heated object a to form a heating section 12, and an electric heater 13 is arranged inside the heat insulating wall 11. do. Reference numeral 14 indicates that when the heated object a carried in on the lift 5 is lowered onto the fixed table 10 and when the heated object a on the fixed table 10 is placed on the lift 5 again, the heated object a is temporarily removed. A lifting rod 15 provided on the fixed base 10 to support the
indicates the cylinder that operates the lifting rod. Thus, the heating section 12 surrounded by the heat insulating wall 11
A window 16 is opened in the inner part of the
A stirring fan 17 is provided so as to face the stirring fan 1.
A motor 18 for rotating the motor 7 is supported by a cart 20 slidably disposed on a rail 19.
The operating shaft end of a cylinder 21 is connected to the back of the cylinder 21, and the motor 18 is moved to the rail 19 by the operation of the cylinder
The stirring fan 17 is configured to be able to advance or retreat from the window 16 into the heating section 12 by sliding along the window 16 . Note that 22 is a disc made of a heat insulating material fixed to the front surface of the motor 18 in order to close the window 16 when the stirring fan 17 is aligned with the window 16;
This is a stopper provided on the outer periphery of 8. 24 is a cover plate made of a heat insulating material that closes the window 16 when the stirring fan 17 is moved backward, as shown in FIG. The cylinder 2 is connected to the end of the operating shaft.
5 opens and closes the window 16.

In the vacuum furnace configured in this way, when heating at a low temperature, atmospheric gas is charged into the pressure-resistant airtight chamber 1, and the stirring fan 17 is advanced into the heating section 12 through the window 16 as shown in FIG. By rotating the stirring fan 17 and stirring the atmospheric gas in the heating section 12 around the object a, convective heat transfer is promoted and the object a is uniformly heated in a short time. On the other hand, when heating at a high temperature, the inside of the pressure-resistant airtight chamber 1 is evacuated, and the stirring fan 17 is moved back as shown in FIG. 2, and the lid plate 24 is closed. In this way, the stirring fan 17 will not receive radiant heat from the heating section 12 and can be prevented from overheating. Note that the stirring fan 17 does not require special heat resistance for this purpose and can be used as an existing stirring fan, but it is desirable to use one whose rotational speed can be adjusted in order to balance temperature distribution and heating capacity.

As described above in the embodiments, the vacuum furnace of the present invention is provided with a window and a cover plate for closing the window in a part of the heat insulating wall, and the motor for rotating the stirring fan is operated outside the window in the pressure-resistant airtight chamber. Since it is provided to move forward and backward, when heating at low temperatures, atmospheric gas is charged and the stirring fan is advanced into the heating section through the window to stir the atmospheric gas and promote convection heat transfer, thereby shortening the temperature of the object to be heated. Allows for uniform heating over time. Also,
During high-temperature heating, the stirring fan is removed from the heating section and the window is closed with a cover plate, which eliminates the risk of the stirring fan being exposed to the high temperature inside the heating section and overheating, which improves the heat resistance and durability of the stirring fan. The problem will go away.
Therefore, the present invention has the advantageous effect of providing a vacuum furnace that can realize efficient heating both during high-temperature heating and low-temperature heating.

[Brief explanation of drawings]

The drawings show an embodiment of the vacuum furnace according to the present invention. FIG. 1 is a partially sectional side view of the vacuum furnace, FIG. 2 is an enlarged longitudinal sectional view showing the operating state of the main parts, and FIG. FIG. 2 is a sectional view taken along line X-X in FIG. 2; a... Heated object, 1... Pressure-resistant airtight chamber, 11...
heat insulating wall, 12... heating section, 13... electric heater,
16...window, 17...stirring fan, 18...motor,
24...Lid plate.

Claims (1)

[Claims] 1. In a vacuum furnace in which a heating part is formed by surrounding an object to be heated in a pressure-resistant airtight chamber that can be charged with a vacuum or an atmospheric gas, and an electric heater is provided inside the insulating wall, the insulating wall A window and a cover plate for closing the window are provided in a part of the chamber, and a motor for rotating a stirring fan is provided to move forward and backward outside the window in the heat-resistant airtight chamber, and by moving the motor forward and backward, The stirring fan advances into the heating section through the window and faces the object to be heated, and by moving the motor backward, the stirring fan retreats from the heating section and the window can be closed from the cover plate. A vacuum furnace characterized by the following configurations.