JP2004354010A - Heat treatment oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment oven capable of suppressing the dispersion of temperature distribution of a heat treatment chamber while simplifying the structure of a door to suppress the increase in thickness or weight of the door to the utmost, and also preventing adhesion of a binder evaporated matter. <P>SOLUTION: In this oven, an atmospheric gas heated in the oven 1 is carried from the rear of the heat treatment chamber 6 within the oven to the front inlet/outlet door 2 with circulation to heat treat the matter to be treated placed in the heat treatment chamber 6 in the atmospheric gas. A plurality of straightening plates 13 parallel to the inner surface of the door 2 are mounted at intervals on the inside of the door 2. A filter 11 is set in the rear of the heat treatment chamber 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a batch-type oven that heat-treats an object in an atmosphere gas such as heated air.
[0002]
[Prior art]
There are various types of conventional batch-type heat treatment ovens. As a typical example, while circulating an atmosphere gas such as air heated in the oven, the heat treatment oven in the oven is arranged from behind the heat treatment chamber in the oven to the front. A so-called "front-blowing type" heat treatment oven is known, in which the above-mentioned atmosphere gas is caused to flow toward a door of an entrance and an object placed in a heat treatment chamber is heat-treated in the above-mentioned atmosphere gas. .
[0003]
Such a “front blowout type” heat treatment oven usually has a wind tunnel installed inside an entrance door in front of the heat treatment oven, and smoothly circulates the atmosphere gas in the heat treatment chamber through the wind tunnel, thereby disturbing the atmosphere gas in the heat treatment chamber. The flow is suppressed to prevent large variations in the temperature distribution.
[0004]
In the cassette transfer type continuous heat treatment equipment, a wind tunnel is installed inside the door, and a horizontal rectifier perpendicular to the inner surface of the door is installed at the bottom of the wind tunnel to heat-treat the workpiece in the upper cassette. It is also known that the heating atmosphere gas used in the above-mentioned rectifier is made into a parallel laminar flow in the horizontal direction through the above-mentioned wind tunnel and flows to the processing object of the lower cassette, so that the processing objects of the upper and lower cassettes can be simultaneously heat-treated. (For example, see Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei 10-232089 (Page 3, Page 7, FIG. 1)
[0006]
[Problems to be solved by the invention]
However, when the wind tunnel is installed inside the door as in the above-mentioned conventional "front blowout type" heat treatment oven, the thickness and weight of the door increase, and a flow rate adjusting plate for the atmospheric gas flowing through the wind tunnel is required. Therefore, there was a problem that the structure became complicated. Further, there is also a problem that the temperature of the sheet metal forming the wind tunnel is partially lowered, and the volatile matter generated from the object to be processed solidifies and adheres at a low temperature portion of the wind tunnel. It seems that these problems occur almost similarly in the continuous heat treatment apparatus of Patent Document 1 described above.
[0007]
Further, in the cassette transfer type continuous heat treatment apparatus of Patent Document 1, a horizontal rectifier perpendicular to the inner surface of the door is attached to the lower part of the wind tunnel inside the door. Even if the gas is installed inside the door of the above-mentioned “front blow-out type” heat treatment oven, where the gas flows from behind the heat treatment room toward the front door, the flow of the atmosphere gas in the heat treatment room is minimized and the temperature distribution is minimized. It is of no use to reduce the variation.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to address the above-described problems. An object of the present invention is to simplify the structure of a door, to suppress an increase in the thickness and weight of the door as much as possible, and to make the temperature distribution of the heat treatment chamber uneven. Another object of the present invention is to provide a front-blowing-type heat treatment oven that can suppress the occurrence of a binder and prevent the adhesion of volatile binder.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the heat treatment oven of the present invention, while circulating the atmosphere gas heated in the oven, flowing the atmosphere gas from the back of the heat treatment chamber in the oven toward the front door of the front entrance, the heat treatment chamber An oven for heat-treating an object to be processed placed in an atmosphere gas, wherein a plurality of rectifying plates parallel to the inner surface of the door are mounted on the inside of the door at intervals. is there.
[0010]
In this way, the heat treatment oven with multiple rectifying plates mounted on the inside of the door has a simpler door structure compared to a conventional heat treatment oven with a wind tunnel and a flow control plate installed inside the door, and the door has a simpler structure. Increases in thickness and weight can be significantly suppressed. In addition, the atmosphere gas in the heat treatment chamber flows toward the inflow end of the current plate, and is rectified and circulated when passing through the passages between the current plates, so that the turbulent flow of the atmosphere gas in the heat treatment chamber is suppressed. In addition, the temperature of the rectifying plate is not partially reduced, and the variation in the temperature distribution inside the heat treatment chamber is reduced, thereby improving the accuracy. In addition, since the temperature of the current plate does not decrease as described above, the volatile binder generated from the processing object does not solidify and adhere.
[0011]
In the heat treatment oven of the present invention, it is preferable to provide a filter for passing an atmospheric gas behind the heat treatment chamber. In this way, dust and contaminants are removed when the circulating atmosphere gas passes through the filter, and the purified atmosphere gas flows into the heat treatment chamber. Disappears. Therefore, such a heat treatment oven is suitable as a clean oven used for a wafer manufacturing process in a semiconductor factory.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 is a schematic sectional view showing an embodiment of the heat treatment oven of the present invention.
[0014]
This heat treatment oven 1 is formed in a box shape with a bottom wall 1a made of a heat insulating wall, front and rear left and right side walls 1b, and a top wall 1c, and a heat insulating wall 2a is attached to an entrance of a front side wall 1b inside. The door 2 is attached so that opening and closing are possible.
[0015]
Inside the heat treatment oven 1, a partition 5 is provided at substantially the same height as the upper edge of the door 2, and a lower side of the partition 5 is a heat treatment chamber 6. On the upper side of the partition wall 5, an upper passage 7 which is a part of a circulation passage through which an atmospheric gas (for example, clean air or the like) circulates is formed. A plurality of sheathed heaters 8 (elongated pipe-shaped heaters in which a resistance heating wire is inserted into a metal sheath tube and filled with an insulating material) are introduced into the upper passage 7 through the top wall 1c. The atmosphere gas flowing in the upper passage 7 can be heated to around 500 ° C. A fan 9 for sending the heated atmospheric gas is attached to the outlet of the upper passage 7, and is driven by a motor 10 installed on the top wall 1c.
[0016]
Behind the heat treatment chamber 6, two heat-resistant filters 11, 11 are mounted vertically one above the other, and between the heat-resistant filters 11, 11 and the rear side wall 1b, one of the circulation passages through which the atmospheric gas flows. A rear passage 12 serving as a part is formed. The heat-resistant filters 11 and 11 are heat-resistant filters each having a heat-resistant temperature of about 500 ° C., each including a filter element using a heat-resistant glass fiber and a filter frame made of a heat-resistant metal. It is integrated by sandwiching it with a metal net, fixed to a filter frame and sealed. As a heat-resistant material constituting the heat-resistant filter 11, glass fiber or SUS having a heat-resistant temperature of about 500 ° C. is used.
[0017]
On the heat insulating wall 2a inside the door 2, a plurality of straightening plates 13 parallel to the inner surface of the door 2 (the surface of the heat insulating wall 2a) are attached with a plurality of them at intervals. The rectifying plate 13 is made of a heat-resistant metal plate capable of withstanding high heat of 500 ° C. or more, and is attached by welding to upper and lower stays 14 projecting from the heat insulating wall 2 a of the door 2. . The innermost rectifying plate 13 has a slightly larger vertical dimension than the other rectifying plates 13, and when the door 2 is closed as shown in FIG. 1, the lower end (inflow end) of the innermost rectifying plate 13. An opening having an appropriate size is formed between the base and the bottom wall 1a. When the door 2 is closed, the upper end of the innermost rectifying plate 13 is close to the front end of the partition 5, and the atmospheric gas in the heat treatment chamber 6 does not substantially flow out to the upper passage 7 from this close portion. It is configured as follows.
[0018]
The number of the rectifying plates 13 and the interval between the rectifying plates 13 are not particularly limited, and may be set so as to ensure a necessary flow rate of the atmospheric gas. In general, the number of the rectifying plates 13 is in a range of 2 to 5 sheets. It is preferable that the distance be within the range of 1 to 5 cm. When a plurality of rectifying plates 13 are mounted on the inside of the door 2 in this manner, the structure of the door is simplified and the thickness of the door is simplified as compared with a conventional heat treatment oven in which a wind tunnel or a flow control plate is mounted on the inside of the door. And an increase in weight can be greatly suppressed.
[0019]
The circulation passage through which the atmospheric gas circulates in the oven is composed of a back passage 12, heat-resistant filters 11, 11, a heat treatment chamber 6, a passage between the flow straightening plates 13, and an upper passage 7. Atmospheric gas heated to a high temperature (for example, 450 ° C. or higher and lower than the heat resistant temperature of the filter 11) by the heater 8 is purified by passing through the heat resistant filters 11 and 11 while being circulated through the circulation passage by the fan 9 and is then heated. Flows from behind to the front door 2 of the entrance, and the object to be treated in the heat treatment chamber 6 is heat-treated in this clean high-temperature atmosphere.
[0020]
Above the upper passage 7 which is a part of the circulation passage, a cooling bypass passage 15 for cooling the atmospheric gas is formed, and the bypass passage 15 is provided with a water-cooled cooler having a large number of cooling fins. 16 are installed. A water supply pipe 16a for supplying cold water to the cooler 16 and a drain pipe 16b for discharging heat-exchanged water are connected to the cooler 16 through the top wall 1c of the oven.
[0021]
On the lower side of the cooler 16, as a passage switching means for switching between the upper passage 7 of the circulation passage and the bypass passage 15 and flowing the atmospheric gas, a first switching plate 17a having a substantially T-shape and a second switching plate having a flat plate shape are provided. 17b is attached rotatably by 90 °. As shown in FIG. 1, when these switching plates 17 a and 17 b are at the upper passage opening position, the first gate 7 a and the second gate 7 b of the upper passage 7 are opened, and are located forward of the cooler 16 of the bypass passage 15. The side (inlet side) is closed by the first switching plate 17a, and the junction (outlet side) of the bypass passage 15 is also closed by the second switching plate 17b, so that the atmospheric gas flows through the bypass passage 15 for cooling. Instead, it flows through the upper passage 7 of the circulation passage. When these switching plates 17a and 17b are rotated by 90 ° as indicated by a virtual line (dashed line), the first gate 7a and the second gate 7b of the upper passage 7 of the circulation passage are connected to the first switching plate 17a and the second gate 7b. The bypass plate 15 is closed by the second switching plate 17b, the inlet side and the outlet side of the bypass passage 15 are also opened, and the bypass passage 15 is opened. Therefore, the circulating atmospheric gas passes through the cooler 16 of the bypass passage 15 and joins the upper passage 7. Will do.
[0022]
A cooling air jacket 19 is provided on the inner side of the three side walls 1 b (left and right side walls and rear side wall) except for the front side wall of the oven 1. The back passage 12 and the like are partitioned. An air supply port 19a for supplying air for cooling to the air jacket 19 is provided on the top wall 1c of the oven, and an exhaust port 19b for discharging air from the air jacket 19 is provided below the bottom wall 1a of the oven 1. Have been. The cooling air jacket 19 is a planar ventilation layer in which the inner surface of the side wall 1b of the oven 1 is recessed, supplies cooling air to the jacket 19 from an air supply port 19a, and absorbs heat from an exhaust port 19b. By discharging the air and flowing the air through the air jacket 19, the high-temperature atmosphere gas is cooled relatively slowly. In order to increase the cooling efficiency of the air jacket 19, it is preferable to provide a large number of heat absorbing fins 19c projecting from the air jacket 19 to the back passage 12 of the circulation passage, as indicated by phantom lines in FIG.
[0023]
In FIG. 1, reference numeral 20 denotes a supply / exhaust pipe for supplying / exhausting atmospheric gas into / from the oven 1.
[0024]
Next, the operation of the heat treatment oven 1 will be described.
[0025]
An object to be processed (not shown) is set in the heat treatment chamber 6 of the oven 1, and the air in the oven 1 is replaced with an atmosphere gas (for example, clean air or the like) supplied from the supply / exhaust pipe 20. When the fan 9 is turned by the motor 10 while the sheath heater 8 is generating heat while the 17a and the second switching plate 17b are in the upper passage opening position shown in FIG. 1, the atmospheric gas sent out by the fan 9 becomes a circulation passage, that is, It circulates through the back passage 12, the heat-resistant filters 11, 11, the heat treatment chamber 6, the passage between the flow straightening plates 13, and the upper passage 7, and is heated by the sheath heater 8 when passing through the upper passage 7 to a predetermined heat treatment temperature. (For example, 450 ° C. or higher and lower than the heat resistant temperature of the filter 11). Then, when passing through the heat resistant filters 11, 11, dust and contaminants are removed to purify the atmospheric gas, and the purified atmospheric gas flows from behind the heat treatment chamber 6 toward the door 2 of the entrance and exit. The object to be processed set in the heat treatment chamber 6 is subjected to heat treatment in an appropriate atmosphere gas without being adversely affected by dust and contaminants.
[0026]
When the object to be processed placed in the heat treatment chamber 6 is heat-treated while circulating the atmosphere gas as described above, the atmosphere gas flowing into the heat treatment chamber 6 from the heat-resistant filters 11 and 11 flows into the lower end (inflow end) of the current plate 13. The gas flows toward the opening between the gas flow path and the bottom wall 1a, is rectified when passing through the passages between the flow straightening plates 13, and returns to the upper passage 7, so that the turbulence of the atmosphere gas in the heat treatment chamber 6 occurs. The flow is suppressed, and the temperature of the flow straightening plate 13 is not partially reduced, so that the variation in the temperature distribution inside the heat treatment chamber 6 is reduced and the accuracy is improved. Incidentally, when heat treatment is performed at a high temperature of about 500 ° C., the conventional oven having a wind tunnel inside the door has a temperature distribution variation of about ± 5 ° C. In the oven 1, the variation in the temperature distribution is smaller than this, and is about ± 4 ° C. or less.
[0027]
Further, when the partial temperature drop of the current plate 13 is eliminated as described above, the concern that the volatile matter generated from the object to be processed solidifies and adheres to the surface of the low temperature portion of the current plate 13 is also eliminated. The operation of removing the deposits becomes unnecessary, and the maintenance becomes easy.
[0028]
During this heat treatment, the bypass passage 15 is closed by the first switching plate 17a and the second switching plate 17b of the passage switching means, and the atmospheric gas does not pass through the cooler 16 of the bypass passage 15, so that heat loss by the cooler 16 is eliminated. Power consumption of the sheathed heater 8 can be greatly reduced.
[0029]
The cooling after the heat treatment is performed in a high temperature range (a temperature range of about 280 ° C. to about 500 ° C.) in which quenching is likely to cause welding cracks and cracks in the sheet metal of the heat treatment chamber and the lining plate of the oven. The process is performed in two stages by dividing into a low-temperature region (a temperature region lower than around 280 ° C.) where it is difficult to generate. That is, the cooling in the high temperature region immediately after the heat treatment is performed by setting the first switching plate 17a and the second switching plate 17b to the upper passage opening position as shown in FIG. While the atmosphere gas is circulated with the 15 closed, heat is taken from the atmosphere gas and the heat treatment chamber by flowing cooling air through the cooling air jacket 19, so that the temperature is relatively slow until the temperature drops to about 280 ° C. To do.
[0030]
When the temperature drops to around 280 ° C., the first switching plate 17a and the second switching plate 17b are rotated by 90 ° as indicated by the phantom line in FIG. 15 is opened, and the ambient gas is circulated through a water-cooled cooler 16 in the bypass passage 15, thereby rapidly cooling the ambient gas to a temperature at which the ambient gas can be safely discharged. At the time of cooling in this low temperature range, the cooling by the air jacket 19 may be stopped or may be continued.
[0031]
As described above, if a cooling method in which relatively slow cooling by the air jacket 19 and rapid cooling by the cooler 16 are employed in two stages is adopted, rapid heat seen when cooling rapidly in a high temperature region of about 280 ° C. or higher is obtained. Since welding cracks, cracks, and the like of the sheet metal welding portion due to shrinkage can be prevented, the durability of the oven 1 is improved, and a longer life can be achieved. Although cooling by the air jacket 19 requires a relatively long time, rapid cooling by the water-cooled cooler 16 is performed in a short time, so that the total cooling time is not so different from that of the conventional cooling method. In particular, when cooling in the low temperature region is performed by using the cooler 16 and the air jacket 19 together, the cooling time can be further reduced.
[0032]
【The invention's effect】
As is clear from the above description, the heat treatment oven of the present invention can simplify the structure of the door, suppress the increase in the thickness and weight of the door as much as possible, and reduce the variation in the temperature distribution in the heat treatment chamber, so that the heat treatment oven can be uniformly treated. And excellent effects such as easy maintenance because there is no adhesion of binder volatiles to the current plate and the like.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing one embodiment of a heat treatment oven of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 heat treatment oven 2 door 6 heat treatment room 7 upper passage 8 sheathed heater 9 fan 11 heat-resistant filter 12 back passage 13 rectifying plate 15 cooling bypass passage 16 cooler 17 a first switching plate 17 b second switching plate 19 cooling air jacket 19 c heat absorption fin

Claims (2)

An oven that circulates the atmosphere gas heated in the oven, flows the atmosphere gas from behind the heat treatment chamber in the oven toward the front door, and heat-treats the workpiece placed in the heat treatment chamber in the atmosphere gas. 3. The heat treatment oven according to claim 1, wherein a plurality of rectifying plates parallel to the inner surface of the door are mounted on the inside of the door at intervals. 2. The heat treatment oven according to claim 1, wherein a filter for passing an atmospheric gas is provided behind the heat treatment chamber.

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