JP2993094B2 - Muffle tube type heating furnace - Google Patents

Description

The present invention relates to a muffle tube type heating furnace.

[Conventional technology]

The muffle tube type heating furnace is configured by penetrating a muffle tube supported by a support into a hollow furnace body having a heating means therein.

[Problems to be solved by the invention]

In such a muffle tube type heating furnace, when the temperature of the muffle tube rises, the muffle tube tends to largely expand in the axial direction due to thermal expansion. In the case of extension of the muffle tube, the muffle tube receives a frictional resistance between a plurality of supports that support the muffle tube, so that the muffle tube cannot be straightly extended in the axial direction and is curved. Therefore,
If the temperature of the muffle tube rises and falls repeatedly due to repeated operations, the muffle tube will be repeatedly fatigued due to repeated bending, causing deformation and cracking within a short period of time, making it unusable. there were.

The present invention has been made to solve the above-mentioned problems (technical problems) of the prior art, and by applying a tensile force to a muffle tube, when the muffle tube is expanded, it is straightened in the axial direction thereof. It is an object of the present invention to provide a muffle tube type heating furnace capable of preventing fatigue due to repetition of bending as in the above-mentioned prior art and enabling a longer life.

[Means for solving the problem]

The muffle tube type heating furnace in the present invention,
In a muffle tube type heating furnace in which a muffle tube supported by a support is penetrated into a hollow furnace body having a heating means therein, a tension force is applied to the muffle tube in the axial direction thereof. Attaching a device, a temperature detector adapted to detect the temperature in the furnace, and a switching valve for tension device operation control for generating the tensile force by operating the tension device, comprising: When the temperature detected by the temperature detector is in the process of increasing the furnace temperature, the switching valve is controlled to operate the tension device to apply the tension to the muffle tube.

[Action]

The muffle tube is heated by the heating means to increase the temperature. The object to be processed is passed through the heated muffle tube and heated in the atmosphere gas in the muffle tube. When the muffle tube thermally expands in the axial direction due to a rise in temperature, the furnace temperature is detected by a temperature detector, and based on the detection, the tension device is operated, and the tension in the axial direction from the tension device applied to the muffle tube is increased. The force causes the muffle tube to extend straight in its axial direction.

〔Example〕

Hereinafter, drawings showing an embodiment of the present application will be described. In FIG. 1 showing a blackening furnace as an example of a heat treatment apparatus provided with a muffle tube, reference numeral 1 denotes a first heating furnace, 2 denotes an introduction portion provided on the front side thereof, and 3 denotes a rear side of the first heating furnace 1. The second heating furnace provided (the second heating furnace 3 is a heating furnace because its internal temperature is higher than room temperature, but in the case of a blackening furnace, the temperature is higher than the internal temperature of the first heating furnace 1. It is a cooling and holding furnace for heat treatment of the object to be processed.) 4 is a cooling device, and 5 is for transferring the object to be processed from the introduction section 2 through the first heating furnace 1, the second heating furnace 3, and the cooling device 4. Is shown.

The first heating furnace 1 will be described with reference to FIG.
Reference numeral 6 denotes a base frame, 7 denotes a hollow furnace body provided on the base frame, 8 denotes a heating means (heater) provided inside the furnace body 7, 9 denotes a muffle provided through the inside of the furnace body 7. In a tube, for example
It is supported by a large number of supports 10 arranged at intervals of about 1.5 m. The cross-sectional shape of the muffle tube 9 is, for example, rectangular, and its height is, for example, 250 mm and its width is 800 mm. The length of the muffle tube 9 is very long, for example, about 10 m. Reference numeral 9a denotes one end of the muffle tube 9 in the axial direction, which is fixed to the furnace body 7. Although not shown, an air supply means for supplying atmospheric gas into the muffle tube 9 is attached to the end 9a as is well known. 9b is the other end, which can be freely displaced in the axial direction with respect to the furnace body 7. Reference numeral 12 denotes a tensioning device attached to the muffle tube 9 for applying a tensile force to the muffle tube 9 in the axial direction. Reference numeral 13 denotes a cylinder of the apparatus, the main body of which is a mounting base fixed to the base frame 6.
Connected to 14. The piston rod 15 of the cylinder is connected to the end 9b through a support frame 18 and an introduction tube 19 described below. The cylinder 13 has a stroke corresponding to the expansion length of the muffle tube 9 (for example, 150 m).
Those larger than m) are used.

Next, the introduction unit 2 will be described. Reference numeral 17 denotes a base frame, which is integrally formed with the base frame 6 of the heating furnace 1. Reference numeral 18 denotes a support frame provided on the base frame 17, and the displacement of the muffle tube 9 in the axial direction with respect to the base frame 17 is free. 19 is a support frame
An introduction cylinder attached to 18 has one end connected to the end 9b of the muffle tube 9.

Next, the second heating furnace 3 has a configuration equivalent to that of the first heating furnace 1, wherein 21 is a base frame, 22 is a furnace body, 23 is heating means (heater), 24
Is a muffle tube, and 24a is an end of the muffle tube 24 fixed to the furnace body 22. As with the muffle tube 9, an air supply means for feeding atmospheric gas into the muffle tube 24 is provided. Reference numeral 24b denotes an end of the muffle tube 24 which is freely displaceable in the axial direction with respect to the furnace body 22, and reference numeral 25 denotes a support. 26 shown in FIG.
Is a pulling device attached to the muffle tube 24, which applies a pulling force in the axial direction to the muffle tube 24, and is configured equally to the pulling device 12. That is, 27 is a cylinder, 28 is a mounting base, and 29 is a piston rod. Reference numeral 30 denotes a connection frame connecting the piston rod 29 and the end portion 24b, a vertical frame 31 provided in a state parallel to the axial direction of the muffle tube 24, and an extension frame attached to one end thereof.
The other end of the vertical frame 31 is connected to the end 24b, and the end of the overhang frame 32 is connected to the piston rod 29.

Next, reference numeral 33 denotes an intermediate muffle connecting the end 9a of the muffle tube 9 and the end 24a of the muffle tube 24. The gas in the muffle tubes 9, 24 is blown into the muffle 34 by blowing a partitioning gas into the muffle 34. Atmosphere gas partitioning means 34 for partitioning the gases is provided.

Next, the cooling device 4 will be described. A muffle tube 35 is attached to the connection frame 30 and has one end connected to the end 24b of the muffle tube 24. In the vicinity of the muffle tube 35, there is provided a nozzle 37 for blowing the pressure-fed cooling air to the muffle tube 35.

Next, a mesh belt conveyor is used as the transfer device 5. 39a to 39f are guide or drive rolls, 40
Is a mesh belt shown as a conveying means, is hung on the above-mentioned many rolls 39a to 39f, and sequentially moves on each bottom surface of the introduction cylinder 19, the muffle tubes 9, 24, and the muffle tube 35,
It recirculates on the route returning to the introduction cylinder 19 again.

Next, FIG. 4 shows a control system of the tension device 12. Reference numeral 41 denotes a temperature detector for detecting the temperature inside the furnace 7, and for example, a thermocouple is used. 42 is a temperature controller, 43
Numerals indicate switching solenoid valves as switching valves for switching and controlling the supply of compressed air for operation to the cylinder 13.

In the heat treatment apparatus having the above configuration, the heaters 8 and 23 generate heat in the first and second heating furnaces 1 and 3, respectively, so that the muffle tubes 9 and 24 are heated, and the atmosphere gas is sent into each tube. And the cooling device 4
Cooling air is blown from 37, and the transport device 5 is operated.

In this state, an object to be processed, for example, a shadow mask of a cathode ray tube, is placed on the mesh belt 40 in the introduction section 2. The material to be processed is introduced into the introduction cylinder 19 as the belt 40 moves.
Through the muffle tube 9. The object to be processed in the muffle tube 9 is heated to a predetermined temperature, for example, 600 ° C. in the atmosphere gas in the tube 9. Next, the object to be processed reaches the inside of the muffle tube 24, where it is cooled to, for example, 500.degree.
Thereafter, the object reaches the inside of the muffle tube 35, where it is cooled to approximately room temperature. As described above, the object passes through the muffle tube 9, the muffle tube 24, and the muffle tube 35, so that the object is subjected to a predetermined process (for example, a blackening process).

In the operation described above, the tension device 12 is operated as follows. First, at the start of the operation, in a state where the heating of the heater 8 has just started and the muffle tube 9 is in the process of increasing the temperature, the muffle tube 9 expands with the increase in temperature due to its thermal expansion. In this case, the temperature in the process of raising the temperature in the furnace, which is detected by the temperature detector 41, has not yet reached the operating temperature (the set temperature of the controller 42). Accordingly, the switching solenoid valve 43 is brought into a state as shown in FIG. 4 by the temperature controller 42. For this reason, the cylinder 13 generates an extension force,
The tensile force is applied to the muffle tube 9 by the force. The magnitude of the pulling force is set to the same level as that of the frictional resistance between the plurality of supports 10 and the muffle tube 9 but slightly larger. As a result of such a tensile force being applied, the muffle tube 9 is straightened in the axial direction.

When the temperature inside the furnace body 7 rises and reaches the operating temperature, the thermal expansion of the muffle tube 9 has been completed. Therefore, in that case, that is, when the temperature inside the furnace detected by the detector 41 reaches the temperature set in the controller 42, the switching solenoid valve 43 is switched from the illustrated state by the controller 42, and the cylinder 13 Becomes free. In this state, no tensile force is applied to the muffle tube 9.

On the other hand, when the operation of the furnace is terminated, the heater 8
Is stopped, the temperature of the muffle tube 9 decreases and contracts. In this process, the switching electromagnetic valve 43 is kept switched to the same state as in the case of the operating temperature, and the cylinder 13 is kept free. Therefore, the muffle tube 9 contracts in a well-known manner due to its own contraction force as the temperature falls.

In the second heating furnace 3 as well, the tension device 26 is similarly controlled, and the muffle tube 24 extends straight in the axial direction by the tensile force in the axial direction when the temperature rises, and the inside of the furnace reaches a predetermined temperature and the muffle tube When the elongation of the muffle tube 24 is completed, the above-described tensile force is removed, and when the temperature of the muffle tube 24 is lowered, the muffle tube 24 contracts as is well known by its own contraction force.

〔The invention's effect〕

As described above, according to the present invention, when the object to be processed is heated, the muffle tube 9 is heated by the heater 8 to raise the temperature, and the object to be processed is passed through the muffle tube 9. Can be heated in the atmosphere gas in the muffle tube 9, and if the muffle tube 9 is thermally expanded by raising the temperature as described above, the temperature in the furnace is detected by a temperature detector, Based on the detection, the pulling device is operated, and by applying a pulling force to the muffle tube 9, there is a feature that the muffle tube 9 can be stretched straight in the axial direction when the temperature is raised.

This means that the muffle tube can be prevented from bending during the thermal expansion of the muffle tube. Therefore, even if the muffle tube 9 repeatedly expands and contracts due to the repetition of heating and cooling of the muffle tube 9, the temperature in the furnace is kept constant every time. Since the detection is performed by the detector and the response is performed as described above, there is a utility that the fatigue due to the repetition of the bending as in the related art can be prevented and a long life can be used.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a schematic longitudinal sectional view of a heat treatment apparatus, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 shows a tension device in a second heating furnace. FIG. 4 is a plan view, and FIG. 4 is a diagram showing a control system of a tension device in a first heating furnace. 7 ... furnace body, 9 ... muffle tube, 10 ... support,
12 ... Tensioning device.

Claims (1)

(57) [Claims] 1. A hollow furnace having a heating means therein,
In a muffle tube type heating furnace in which a muffle tube supported by a support is penetrated, the muffle tube is provided with a tension device for applying a tensile force in the axial direction thereof, and the temperature in the furnace body is reduced. A temperature detector configured to detect the temperature, and a switching valve for controlling the operation of the tensioning device for generating the tensile force by operating the tensioning device, and the temperature detected by the temperature detector is detected in the furnace. A muffle tube type heating furnace wherein the switching valve is controlled to operate the tension device to apply the tension to the muffle tube when the temperature is in the process of increasing the temperature.