JPH047506Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an improvement of a conveyor type kiln.

[Conventional technology and its technical issues]

Conveyor-type firing furnaces are commonly used as means for pre-firing and final firing of ceramic substrates for mounting electronic components and fine ceramics for engineering. This firing process requires high-temperature conditions of over 1000°C to meet the demands for high quality ceramics, and is performed under very clean conditions, i.e., with high purity gas in the furnace and an atmosphere with little dust and other fine particles. In order to obtain suitable temperature conditions, it is required that the objects to be processed be transported stably.

However, in conventional conveyor-type firing furnaces, a mesh belt made of heat-resistant metal is passed through a furnace core tube made of heat-resistant metal, and atmospheric gas is supplied at the inlet and outlet sides of the furnace core tube, allowing the natural flow to proceed. Because the structure allows the flow to flow through the openings in the cylinder and rear cylinder, the atmosphere inside the furnace cannot be maintained at a low oxygen concentration due to intrusion of outside air and stagnation in the case.Also, sliding contact between metals makes it impossible to maintain a low oxygen concentration inside the furnace. There was a problem with large amounts of trash being brought in.

In addition, since the belt slides directly on the bottom of the furnace core tube, and the furnace core tube is easily deformed due to thermal fatigue, conveyance resistance is large and belt meandering tends to occur over time. If the conveyance speed of the processed material to obtain the
There were problems such as damaging the objects to be processed and requiring complicated maintenance.

The present invention was devised to solve the above-mentioned problems, and its purpose is to be able to form a good atmosphere under high-temperature conditions, to generate less foreign matter and dust, and to reduce the amount of material to be treated. Our objective is to provide a conveyor-type kiln that allows for stable and smooth conveyance and is suitable for precise kiln under clean conditions.

[Means to solve the problem]

In order to achieve the above object, the present invention is a firing furnace in which a front cylinder and a rear cylinder are installed in front and behind a furnace body with a built-in furnace core tube, and a conveyor belt is passed between them. A mechanism is provided to blow atmospheric gas onto the workpiece from the floating ceiling and side surfaces, while suction pipes are inserted in the inlet and outlet areas of the furnace core tube to exhaust the atmosphere inside the furnace to the outside of the furnace. A rectifying atmosphere blowing mechanism is installed horizontally between the end opening and the furnace core tube opening to blow out the atmospheric gas toward the opening and downward, and a ceramic chain is installed at the inner bottom of the furnace core tube, front tube, and rear tube. It is equipped with ceramic rails that make contact with the belt rollers.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 6 show an embodiment of a conveyor type kiln according to the present invention. Reference numeral 1 denotes a tunnel-shaped furnace body made of a refractory material, and 2 a furnace core tube passing through the furnace body 1, which is made of a heat-resistant metal material such as stainless steel. 3 is the front cylinder (inlet cylinder), 4 is the rear cylinder (outlet cylinder)
and are connected to the front and rear of the furnace core tube 2 via flanges, respectively. Reference numeral 5 designates a heating element installed inside the furnace body 1, and reference numeral 6 designates a ceramic chain belt whose tension side extends from the front cylinder 3 to the rear cylinder 4.

As shown in FIGS. 3 to 5, the hearth tube 2 is supported by a hearth plate 20 made of a refractory such as SiC on the outside of the bottom, and a rail plate made of a refractory such as mullite on the inside of the bottom. A rail plate 21 is laid over the entire length, and a rail plate 22 made of ceramic such as quartz is laid on the front tube 3 and the rear tube 4 at the same level as the rail plate 21. Further, rail plates 23 made of the same material are installed below the furnace body 1, the front cylinder 3, and the rear cylinder 4. At least the rail material 21 is prevented from shifting in the furnace width direction by the protrusions 24, 24 on both sides, as shown in FIG. A plurality of rail portions 25 running in the longitudinal direction are provided at the top of each rail plate 21, 22, 23.

The ceramic chain belt 6 consists of a plurality of rows, each of which is made up of a plurality of sets of ceramic link plates 60, 60, one on the left and one on the left, connected by a pin 62 of a ceramic roller 61. It is configured to be able to rotate around 62. The ceramic roller 61 is supported on its tight side by the rail portions 25 of the rail plates 21 and 22 so as to be freely in contact with each other, and its loose side is also supported in such a manner as to be freely in contact with the rail portion 25 of the rail plate 23. The ceramic chain belt 6 is meshed with a driven sprocket 63 provided on the inlet side, and meshed with a drive sprocket 65 rotated by a variable speed drive device 64 on the exit side.
Both sprockets 63 and 65 have a non-metallic construction with the ceramic chain belt 6, that is, they are entirely made of ceramic or have a heat-resistant metal surface coated with ceramic.

On the other hand, the furnace core tube 2 is provided with a mechanism for spraying atmospheric gas onto the workpiece W over its entire length. Specifically, several ceiling-side atmosphere introduction pipes 7 and 7' are inserted from the inlet and outlet sides to the central part in the furnace length direction. Several side atmosphere introduction pipes 8, 8', 9, and 9' are each inserted to reach the central portion in the longitudinal direction.

Each of these atmosphere introduction pipes 7, 7', 8, 8', 9,
9' is the U-bolt fitting 1, as shown in Figure 5.
0, and are supported by the furnace core tube 2 at regular intervals, the tip of each introduction tube is closed, and nozzle holes 70, 80, and 90 are arranged at fine pitches on the circumferential surface.
As shown in Fig. 5, the nozzle holes 70 of the ceiling-side atmosphere introduction pipes 7, 7' are opened diagonally downward, and the nozzle holes 89 of the side-side atmosphere introduction pipes 8, 8', 9, 9' are at the center of the furnace core tube. It is opened in the direction facing.

Large-diameter suction pipes 11, 11' are inserted into the inlet and outlet sides of the furnace core tube 2 in parallel with the ceiling-side atmosphere introduction pipes 7, 7'.
11', as shown in FIGS. 3 and 4, has a suction port 110 near its tip, and its rear end is led to an exhaust duct outside the furnace. Figures 3 to 5 as necessary
As shown by the imaginary lines in the figure, suction guide atmosphere conduits 12 and 12' are provided at the inlet and outlet of the furnace core tube 2 so as to cross the width direction near the ceiling area, and the nozzle holes arranged therein are provided. Atmospheric gas may be blown out from 120 in the direction of suction port 110 . The suction guide atmosphere introducing tubes 12, 12' are rotatably supported by the furnace core tube 2, and the blowing angle is made variable by adjusting means 13 such as a handle outside the furnace.

On the other hand, the front cylinder 3 has a tapered shape with a cross-sectional area that decreases toward the inlet as shown in FIG. In the ceiling area between this and the furnace core tube inlet, a rectifying atmosphere blow-off tube 14 is horizontally suspended in the furnace width direction. As shown in FIG. 3, nozzle holes 140 are arranged at a predetermined pitch in the rectifying atmosphere blowout pipe 14, and the blowout angle is diagonally downward toward the inlet.

The rear cylinder 4 is similar, that is, it has a tapered shape with a cross-sectional area that decreases toward the outlet as shown in FIG. A rectifying atmosphere blow-off pipe 14' is provided in the ceiling area between this and the furnace core tube so as to cross the width direction.
0' are arranged at a predetermined pitch. An air cooling mechanism 15 is provided on the outer periphery of the rear cylinder 4.

FIG. 7 shows another embodiment of the present invention using a front cylinder as a representative, and a pressure equalizing box 160 is provided around the front cylinder between the outside air inflow resistor 31 and the rectifying atmosphere blowout pipe 14. A gas curtain mechanism 16 is provided. Of course, the same structure can be adopted for the rear cylinder 4 as well.

FIG. 6 shows an atmosphere supply system, in which _N2 gas is used in this example. 170 is a dry N ₂ gas supply source, a main pipe 171 is connected to a wet device 172, the outlet side thereof is branched and inserted into a gas heater 173, and branch pipes 174a, 1
74b is the ceiling side atmosphere introduction pipe 7, 7', the branch pipes 174c, 174d are the inlet side side atmosphere introduction pipes 8, 9, and the branch pipes 174e, 174f are the outlet side side atmosphere introduction pipes 8', 9'. and are connected to each other to supply humidifying wet gas. In addition, the main pipe 171 is connected to the wet device 17.
A branch pipe 175 is branched from the upstream side of 2, and connected to the rectifying atmosphere blowing devices 14, 14' on the inlet and outlet sides through branch pipes 176a and 176b, thereby supplying dry gas.

[Effect of the embodiment]

The workpiece W is placed on the ceramic chain belt 6 at the entrance workbench. The ceramic chain belt 6 has a driven sprocket 63 on the inlet side and a drive sprocket 65 on the outlet side meshing with each other, and moves at a required speed by driving and rotating the drive sprocket 65.

At this time, each roller 61 of the ceramic chain belt 6 is connected to the ceramic rail plate 21 installed at the bottom of the front tube 32, the furnace core tube 2, and the rear tube 4.
Since the loose side also comes into rolling contact with the rail portion 25 of the rail plate 23 on the lower side of the furnace body, there is little running resistance. Also, link board 6
Since the rollers 61 between 0 and 60 run in a tight manner on the rail portion 25, and the rail plates 21 and 22 are also prevented from shifting by the protrusions 24 and 24, meandering does not occur. Moreover, although the hearth tube 2 is exposed to high temperatures exceeding 1000°C, the thickness direction of the bottom part is connected to the hearth plate 20.
Since it is sandwiched between the rail plate 21 and the rail plate 21, deformation or distortion due to heat is difficult to occur, and the shape of the passage is maintained well. These allow for extremely smooth conveyance and a precise heating temperature curve.
In addition to the fact that the conveyor belt is supported by rolling friction, both the belt and the support means are made of a ceramic material with good wear resistance, so there is very little dust generated during conveyance, and there is no risk of contamination in the furnace. It is possible to prevent quality deterioration due to adhesion to objects to be processed.

Due to the movement of the ceramic chain belt 6, the workpiece W enters the front cylinder 3 from the inlet shutter 30,
Next, the atmosphere is heated while moving through the furnace core tube 2, cooled while passing through the rear tube 4, and the inlet shutter 4 is heated.
0 to the exit workbench. During this time, over the entire length of the furnace core tube 2, the ceiling side atmosphere introduction tubes 7, 7', the side side atmosphere introduction tubes 8, 8', 9,
Wet gas is blown out from each of the nozzle holes 70, 80, and 90 at 9', and is finely sprayed from above and from the left and right sides of the object W to be processed. At the same time, in the inlet zone and outlet zone, suction air is working through large-diameter suction pipes 11 and 11' arranged on the ceiling, and volatile components (binder) contained in the processed material W are being sucked in.
The atmosphere polluted by such substances is collected here and discharged to the outside of the furnace.

The gas introduced into the furnace through the introduction tube increases in volume by being heated, and flows to the inlet and outlet sides of the furnace core tube 2. However, the flow is not necessarily uniform, and stagnation may occur throughout the furnace, or the flow distribution in the width direction of the furnace may be uneven. This allows the front cylinder 3
Outside air enters through the opening of the rear cylinder 4 and increases the oxygen concentration in the furnace. However, in the present invention, rectifying atmosphere blow-off pipes 14, 14' are provided in the ceiling areas of the front cylinder 3 and rear cylinder 4 at right angles to the furnace length direction, and a large number of nozzle holes 140, 140' arranged in these are provided. Dry gas is blown out from the opening side in a downward shower. Therefore, the outflow of gas from inside the furnace core tube 2 is promoted, and at the same time, the flow is rectified so that it becomes uniform in the width direction of the furnace, and the gas is pushed toward the bottom side, that is, directly facing the opening cross section. It flows. Furthermore, since the widths of the front cylinder 3 and the rear cylinder 4 become narrower toward the opening, the gas flow rate increases. Therefore, these synergistic effects reliably prevent outside air from entering the furnace, and the oxygen concentration inside the furnace can be maintained at an extremely low value even though it is a tunnel furnace.

[Effect of idea]

According to the present invention explained above, it is possible to carry out stable and smooth transport of the workpiece under high-temperature conditions, reduce the generation of dust during transport, and improve the flow of atmospheric gas inside the furnace. The atmosphere can be maintained at a high level of purity, and a clean and precise firing process can therefore be achieved. Furthermore, the furnace core tube is less deformed and the belt is less likely to be damaged due to rolling friction, resulting in excellent durability and easy maintenance.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional side view showing an embodiment of the conveyor type continuous firing furnace according to the present invention, Fig. 2 is a partially cutaway plan view of the same, Fig. 3 is an enlarged view of the first half of Fig. 1, and Fig. 4 is an enlarged view of the latter half of FIG. 1, FIG. 5 is a sectional view taken along line V-V in FIG. 1, FIG. 6 is a system diagram of atmospheric gas in the present invention, and FIG. 7 is another implementation of the present invention Give an example. 1...Furnace body, 2...Furnace core tube, 3...Front cylinder, 4...
... Rear cylinder, 5 ... Heating element, 6 ... Ceramic chain belt, 7, 7' ... Ceiling side atmosphere introduction pipe, 8,
8', 9, 9'...Side side atmosphere introduction pipe, 11, 1
1'... Suction pipe, 14, 14'... Rectifying atmosphere introduction pipe, 20... Hearth plate, 21, 22, 23... Rail plate, 25... Rail part, 31, 41... Outside air inflow resistor .

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a firing furnace of the type in which a front cylinder and a rear cylinder are connected in front and behind a furnace body with a built-in furnace core tube, and a conveyor belt is passed between them, A mechanism is installed to blow atmospheric gas onto the workpiece from the ceiling and sides, while suction pipes are installed in the inlet and outlet areas of the furnace core tube to exhaust the atmosphere inside the furnace to the outside of the furnace. A rectifying atmosphere blowing mechanism is installed horizontally between the opening at the end and the opening of the furnace core tube to blow out the atmospheric gas toward the opening and downward, and the inner bottoms of the furnace core tube, front cylinder, and rear cylinder are made of ceramic. A conveyor-type kiln characterized by a ceramic rail that connects the rollers of a chain belt. (2) The mechanism that blows atmospheric gas onto the workpiece from the ceiling and sides over the entire length of the furnace core tube consists of an atmosphere introduction tube that has many nozzle holes and is arranged along the ceiling of the furnace core tube, and a large number of It consists of an atmosphere introduction pipe that has nozzle holes and is arranged along both sides of the furnace core tube, and the rectifying atmosphere blowing mechanism consists of a tube that runs horizontally through the ceiling area of the front and rear cylinders in the width direction of the furnace. A conveyor-type kiln according to claim 1, wherein the pipe is provided with a large number of nozzle holes, and the cross-sectional area of the front cylinder and the rear cylinder decreases toward the opening. (3) The conveyor type kiln according to claim 1, wherein the ceramic rail is made of a plate, and the bottom of the hearth tube is sandwiched between the ceramic rail and the hearth plate. (4) The conveyor-type kiln according to claim 1, wherein the ceramic chain belt is meshed and driven by a drive sprocket on the outlet side, and the loose side makes rolling contact with the ceramic rail. (5) The conveyor type according to claim 1 of the utility model registration, which has several sets of link plates in the width direction and a rotatable roller between them, and the rotatable roller is supported by a protrusion of a ceramic rail. Firing furnace.