JPS6026280A - Rotary hearth type electric 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 The present invention relates to a rotary hearth type electric furnace, and particularly to a rotary hearth type electric furnace used for calcination and firing of ceramics and the like.

In general, a rotary hearth type electric furnace used for firing and firing ceramics rotates a circular B-shaped hearth tube that penetrates the furnace body at low speed, while surrounding the hearth tube within the furnace body. The inside of the furnace core tube is heated by metal heaters such as nichrome wires or counter wires arranged concentrically around the furnace core tube, or by heaters with a large number of silicon carbide rod-shaped heating elements arranged in parallel grids around the furnace core tube. 11. J construction is adopted.

However, in this type of electric furnace, heat is supplied to the object to be fired inside the furnace core tube; 1. The heat dissipated to the outside through the furnace wall (11.
In order to maintain the temperature at 400°C, it is necessary to use a large number of heaters to supply a large amount of heat, which increases power consumption and requires multiple heater control circuits, making the control device expensive. There was a problem. However, these factors are reflected in the cost of ceramic products and are also a contributing factor to the rise in their prices.

The purpose of the present invention is to reduce the power consumption of a rotary hearth type electric furnace and to lower the cost of its control device, thereby reducing the cost of ceramic products. a furnace core tube supported by a rotating furnace core tube, a main body that surrounds and insulates the furnace core tube, a heating heater disposed within the furnace core tube along its axis, A rotary hearth type electric furnace is characterized by comprising a drive source that rotationally drives a core tube through rollers.

That is, the present invention provides a cover piece that moves inside the furnace core tube, compared to the conventional one. Yo, 0 furnace 81. D Tube Iyasuke 6. Ka. Instead, a heater is installed in the center of the furnace core tube to heat the furnace directly by radiation and convection, while the furnace body is made of a heat insulating material so that heat is transmitted from the tube wall of the furnace core tube through the wall of the furnace body. This prevents heat from dissipating to the outside, thereby reducing heat loss and the number of heaters, and simplifying the control device.

Hereinafter, the present invention will be specifically described with reference to the accompanying drawings.

The figure shows an embodiment of the present invention, in which reference numeral 1 denotes a furnace core tube, which is rotatably supported by a rotating roller 2 and is rotationally driven, the rotational speed of which is usually 0. It is set to r5~5rpm. The furnace core tube 1 is surrounded by a furnace body 3 supported on a pedestal 4, and is inclined so that the end A on the supply port side of the object to be fired is slightly higher than the end E on the discharge port side. An automatic quantitative feeder (for example, an electromagnetic feeder) 6 is disposed adjacent to the end A on the feed port side. This automatic quantitative feeding device 6 automatically feeds the object to be fired from the hopper 5 to the furnace core tube 1 at a constant rate. A chute 7 is disposed adjacent to the discharge 1'' side end E of the furnace core tube 1, and a container 8 for storing a calcined or fired ceramic product is disposed on the chute 7. The furnace body 3 is made of a heat insulating material such as a heat insulating material or ceramic wool, and is designed to prevent heat loss from the furnace core tube 1. Inside the furnace core tube 1, a rod-shaped heater 9 is disposed coaxially with the axis thereof, and both ends of the heater 9 are connected to a power source (not shown) through heater terminals 10, respectively. This rod-shaped heater has a firing temperature of 1.000
Nichrome or Kanthal metal wire is used as the heating element material when the temperature is around 1000°C, and silicon carbide is used when the temperature exceeds 1000°C. Note that the shapes of the furnace core tube and heater can be arbitrarily changed as necessary.

When using the rotary hearth type electric furnace having the above structure, the hopper 5
An object to be fired, such as a ceramic molded product, is placed in a
The inside of the furnace core tube 1 is fed into the furnace core tube 1 at a predetermined rate by an automatic quantitative feeder 6 and rotated at low speed by a rotary roller 2 driven by an electric motor or other drive source, and is discharged from the supply port side end A. Move toward the exit side end E. In the furnace core tube 1, the object to be fired is first heated to the firing temperature in a preheating zone B, fired for a predetermined time in a soaking zone maintained at the firing temperature, and then slowly cooled to a predetermined temperature in a cooling zone. The product is discharged into the container 8 from the discharge port side end E. In general, the soaking zone is 1/2 to v3 of the heat generation length of the heater.

Therefore, in the process of moving the object to be fired in the furnace core tube, radiation from the heat generating part of the heater 9 disposed in the furnace core tube 1,
Direct heating and firing is performed by convection inside the furnace core tube, and heat radiation from the furnace core tube 1 to the outside is suppressed by the furnace body, so heat loss is significantly lower than in conventional equipment. Firing can be performed using electricity. Also,
At least one heater is disposed along the axis of the furnace core tube (compared to conventional ones, control is easier and the control device can be manufactured at a lower cost). Incidentally, in the electric furnace having the structure shown in the figure, the furnace core tube 1 serving as the rotary hearth is made of alumina, and its outer diameter is 160mm and the inner diameter is 140mm.
m, the length is 1500 mm, and the outer diameter is 3 along the axis.
0 body, the length of the heat generating part made of silicon carbide is 1000 mm, and the total length including the cotton electric parts connected to both ends of the heat generating part is 1600 rMn.
The heater 9 was installed, the furnace body was made of ceramic wool, and the temperature of the soaking chamber 11 was set at 1400°C to fire the ceramic. In comparison, the firing cost including power consumption can be reduced to 115%, the manufacturing cost of the control device can be reduced to 1/3, and the cost of ceramic products can be reduced by 10 to 20%.
I was able to reduce it.

As explained above, in the present invention, a heater is arranged in the center along the axis of the Z7 main furnace core tube, and the object to be fired is directly heated by radiant heat and convection to perform calcination or firing. Therefore, the firing cost can be significantly reduced, and the cost reduction of ceramic products can be achieved.

[Brief explanation of drawings]

The figure is an abbreviated front view of a rotary hearth type electric furnace according to the present invention. 1...Furnace core tube, 2...Rotating roller, 3...Furnace body,
9... Heater. Patent applicant Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] (1) A furnace core tube rotatably supported by rotating rollers, a furnace body that surrounds and insulates the furnace core tube, a heating heater disposed within the furnace core tube along its axis, and the rotation of the furnace core tube. A rotary hearth type electric furnace comprising a drive source that rotationally drives a furnace core tube through a roller.