JPH0114282B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flowing air electric furnace used for heat treatment of metals, for example, and is capable of achieving temperature uniformity in a low temperature range and a high temperature range.

Normally, in this type of electric furnace, especially those that require strict temperature uniformity or those that have a large processing zone that accommodates the materials to be heat-treated, a fan installed in the furnace body is used. It is necessary to increase the air velocity. However, when the flow rate is increased, the temperature rises due to the flow agitation energy, and in some cases it may rise up to approximately 100℃.
Although there is no problem in the low temperature range (90℃ to 200℃±2.5℃,
(artificial aging, etc.), temperature control is poor. Therefore, in conventional flow-air electric furnaces, especially those where temperature uniformity is strictly required, it has been common to provide separate furnaces for high-temperature ranges and low-temperature ranges.

However, providing separate furnaces not only costs money but also requires a large installation space.

The present invention has been made in view of the above circumstances, and its purpose is to enable a single furnace to use a low temperature range and a high temperature range, and to provide temperature uniformity in both these ranges. The goal is to provide the following.

In order to achieve the above object, the present invention provides an exhaust port on the discharge side of the fan provided in the furnace body and on the front side of the heater zone, and also provides an exhaust port on the suction side of the fan at a position away from the processing zone. It is characterized by having a mouth.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view of the entire cut-away furnace body, FIG. 2 is an enlarged vertical cross-sectional view of the furnace body, and FIG. 3 is an enlarged cross-sectional view of the furnace body. Reference numeral 1 in the figure is a pedestal, and a furnace body 2 is installed on the top of the pedestal. As shown in detail in FIG. 2, the furnace body 2 includes a steel plate 3a.
The inside is lined with a heat insulating material 3b to form a box shape, and the bottom 2a is double-opening.
A pine full case 5 for blocking radiant heat is installed in the furnace body 2 in a floating state. In the space between the inner surface of the heat insulating material 3b constituting the side wall of the furnace body 2 and the outer surface of the pine full case 5 opposing this, appropriate intervals are provided in the vertical and circumferential directions along the inner surface of the heat insulating material 3b. A plurality of electric heaters 4 are arranged at a distance from each other, and a portion where these electric heaters 4 are arranged forms a heater zone 6.

The upper part of the pine full case 5 is tapered into a roughly truncated pyramid shape, and a roughly cylindrical opening 5a is provided in the center of the upper part, and a flow fan 7 can be rotated within the opening 5a. is equipped with. Further, the bottom of the pine full case 5 is open. Further, inside the pine full case 5, a cage 8 for accommodating the object to be heat-treated is installed in a floating state by a cage lifting chain 14. The cage 8 is made of a wire mesh, and when the bottom 2a of the furnace body 2 is opened by a lifting device (not shown) installed on the pedestal 1, the cage 8 passes from the bottom of the pine full case 5 through the bottom 2a of the furnace body 2. Water tank 9 installed below the furnace body 2
It is configured to be lowered inside. Note that when the bottom 2a of the furnace body 2 is closed and the cage 8 is housed inside the pine full case 5,
The inside of the cage 8 becomes the processing zone 10 of the furnace body 2.

The configuration described above is approximately the same as a normal electric furnace. Next, an example of the exhaust port and the inlet port, which are the characteristic parts of the present invention, will be explained.

A plurality of exhaust ducts 11 (in FIG. 3
10 are shown. ) are placed. The exhaust ports 11a of these exhaust ducts 11 are located immediately after the airflow fan 7 where the airflow pressure is high, that is, the airflow fan 7 has a high airflow pressure.
It is the discharge side 7a of the heater zone 6, and is opened on the near side of the heater zone 6. Further, the exhaust duct 11 is provided with a damper 12, and the exhaust amount is controlled by adjusting the opening degree of the damper 12.

Further, a cage lifting chain 14 that connects the cage 8 to the lifting device (not shown) is inserted through the pine full case support pipe 13 that supports the pine full case 5 in a floating state in the furnace body 2. In addition to this, it also serves as a pipe for introducing outside air. That is, the upper end of the pine full case support pipe 13 opens outside the furnace body 2, and the lower end opens inside the upper part of the pine full case 5. The opening at the lower end of this pine full case support pipe 13 serves as an inlet 13a. The introduction port 13a is
The place where the flow pressure is lowest and is past the processing zone 10, in other words, the suction side 7 of the flow air fan 7
b, and is located at a location away from the processing zone 10 (a location where the temperature of the processing zone will not be directly lowered even if outside air is introduced).

Therefore, when operating the furnace in the low temperature range,
By adjusting the opening degree of the damper 12 provided in each exhaust duct 11 and rotating the flow air fan 7, a portion of the air in the furnace body 2 sent from the discharge side 7a of the flow air fan 7 to the heater zone 6 can be adjusted. is discharged from the exhaust port 11a through the exhaust duct 11 before the heater zone 6. The remaining air passes through the heater zone 6 and is temperature-controlled by the electric heater 4 in the heater zone 6, and then flows into the cage 8 inside the Matsuful case 5 from the opening at the bottom of the Matsuful case 5. ,
The material to be heat-treated in the cage 8 is heated and flows to the suction side 7b of the flow fan 7, where the inlet 13a
Air that is lower in temperature than the air inside the furnace body 2 that has flowed into the furnace body 2 from the furnace body 2 is mixed with the air, and is drawn into the flow air fan 7 together with the air. That is, a portion of the air within the furnace body 2 is replaced with lower temperature air outside the furnace body 2. By repeating this, the influence of temperature rise due to the energy of flowing air agitation is removed.

In addition, when operating the furnace in a high temperature range (the high temperature range is 450°C to 600°C, which is quite far from the low temperature range of 90°C to 200°C), fully close the damper 12 of each exhaust duct 11, The air flow fan 7 is rotated to circulate the air in the furnace body 2 to the heater zone 6 and the processing zone 10.

Note that 16 in the figure is a motor that rotationally drives the air flow fan 7, and 17 in the figure is a motor that rotationally drives the airflow fan 7.
This is a temperature detector that has multiple units installed in it. The electric heaters 4 are individually controlled by signals from the temperature detector 17. In this way, each electric heater 4 disposed in the heater zone 6 is individually controlled, although there is almost no temperature difference in the vertical direction of the furnace body 2 due to the air stirring effect by the flow air fan 7. This is because this effect is not sufficiently produced in the front and rear and left and right directions of the furnace body 2, and a slight temperature difference occurs.

In the above embodiment, the damper 12 may be provided with a motor that is driven according to the temperature within the furnace body 2, and the opening degree of the damper 12 may be automatically adjusted by the motor to control the temperature. Further, the pipe for introducing outside air may be provided separately, but if it is used in combination with the pine full case support pipe 13 as in the embodiment, the structure will be simplified.

As explained above, according to the present invention, the exhaust port is provided on the discharge side of the flow air fan of the furnace body and on the side near the heater zone, and the exhaust port is provided on the suction side of the flow air fan and away from the processing zone. Since an inlet is provided in the furnace, when the furnace is operated in a low temperature range, using the same exhaust port and the same inlet, part of the air inside the furnace body can be replaced with outside air whose temperature is lower than that of the air. When exchanging this air, since the inlet is on the suction side of the flow air fan and is located away from the processing zone, the air flowing in from the inlet is immediately flushed with the air flow inside the furnace body. Air is sucked into the air fan and does not directly flow into the processing zone and lower the temperature of the processing zone, and the exhaust port is on the discharge side of the air fan and in front of the heater zone. This prevents the air flowing in from the mouth from being discharged as is without mixing with the air inside the furnace body, ensuring that the air inside the furnace body can be exchanged, and eliminating the inconvenience of directly dissipating the heat in the heater zone. Does not occur.

That is, when the flow rate inside the furnace body is increased and the furnace moves in a low temperature range, the influence of temperature increase due to flow agitation energy can be removed without any problem, and the temperature can be easily controlled.

Therefore, according to the present invention, one furnace can be used in both the low temperature range and the high temperature range, and excellent temperature uniformity can be obtained in both these ranges. Separate furnaces were set up for each purpose.
Problems such as high costs and large installation space can be solved.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a front view of the entire cut-away furnace body, FIG. 2 is an enlarged vertical cross-sectional view of the furnace body, and FIG. 3 is an enlarged cross-sectional view of the furnace body. It is a diagram. 2...furnace body, 3b...insulation material, 4...electric heater, 6...heater zone, 5...pine full case, 7...flow air fan, 7a...discharge side, 7b...
...suction side, 8...cage, 10...processing zone,
11...Exhaust duct, 11a...Exhaust port, 13a
...Introduction port, 16...Motor.

Claims (1)

[Claims] 1 A flow air type in which a flow air fan is installed in the furnace body, and the flow air fan circulates the gas heated in the heater zone by passing it through the processing zone where the object to be processed is stored and then sending it back to the heater zone. In the electric furnace, an exhaust port is provided on the discharge side of the flow air fan of the furnace body and on the side near the heater zone, and an exhaust port is provided on the suction side of the flow air fan at a position away from the processing zone. A flowing air electric furnace with a mouth.