JPH08977A - Method for vacuum heat treatment and apparatus - Google Patents

Abstract

PURPOSE:To make the quality of an article const. and to shorten the heat treating time by a method wherein the temp. distribution in a room under high temp. and high pressure storing the article to be treated is made const. and, thereafter, while the room is made vacuum, the article is heated by using a heating means arranged to be close to the article. CONSTITUTION:A highly precise article 24 is arranged in a room 26 and heating means 28, 30, 31 and 44 provided on the periphery of the room 26 are actuated and, at the same time, inner pressure in the room is elevated. After the room temp. reaches a specified temp., while this temp. is kept at a const. temp. and the pressure in the room is kept at a high pressure atmosphere, a required heat treatment is performed while the article is kept at const. pressure and temp. After a specified time passes through, while the room temp. is kept const., the pressure in the room is decreased down to at most atmospheric pressure to perform degassing treatment. Then, the pressure in the room is elevated up to at least atmospheric pressure and while the room temp. is gradually lowered, aging treatment of the article 24 is performed. While the inside of the room is kept under a furthermore elevated pressure condition, the heating means is not actuated to quench the article 24 and the pressure in the room is decreased to atmospheric pressure and the article 24 is taken out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus for heat-treating surfaces of glass and epoxy resin plates, heat treatment of liquid crystal display elements, and heat treatment of high precision articles such as various electronic parts. The present invention relates to a heat treatment method and apparatus capable of subjecting an article to heat treatment such as vapor deposition or baking to obtain a desired uniform quality.

[0002]

2. Description of the Related Art Conventionally, in this type of processing operation, a vacuum heating apparatus 1 as generally shown in a front view (FIG. 3A) and a side view (FIG. 3B) of FIG. 3 has been widely used. . The apparatus 1 has a generally cylindrical chamber 2 in which various workpieces to be heat-treated (for example, liquid crystal display elements) are housed.
Is provided. A heating means 3 is arranged around the chamber 2. Further, in the back of the chamber 2, a partition plate 4 for adjusting the wind direction and a heating means 5 such as a fin heater are provided. Further, a heat exhaust duct 6 for quickly discharging the heat in the chamber 2, a vacuum pump 7 for bringing the inside of the chamber 2 to a vacuum state, and a vacuum exhaust duct for returning the vacuum state to the atmospheric pressure quickly. 8. A fan motor 9 and the like for circulating hot air in the chamber 2 are provided.

[0003] However, the vacuum heating operation using such a known apparatus 1 exhibited a behavior as shown in FIG. 2B.
That is, when the time is plotted on the horizontal axis and the temperature change of each part of the work in the room and the pressure change in the room are plotted on the vertical axis, the heating means 3, while maintaining the pressure in the chamber 2 at atmospheric pressure with the start of the work, 5, the temperature in the chamber 2 is increased by the fan motor 9 in the chamber 2, and the air in the chamber 2 is moved from the center portion of the chamber 2 to the back. 5, is directed radially outward, and further moves the chamber 2 toward the user,
When the airflow 10 is generated again toward the center portion of the chamber 2 toward the back, the temperature of each portion of the work stored in the chamber 2 sequentially increases. After t ₁ hour (for example, 1.5 hours), the temperature of each part of the work reaches the temperature T ₁ (for example, 200 ° C.) with some variation. in this case,
The temperature variation (v) of each part of the work is ± 5 ° C. to 15 ° C. even if a forced air circulation flow is performed in the chamber 2. In this state, the work is heated and held for about 2 to 3 hours, and at this time, firing,
Deposition and other desired heat treatment operations are performed.

After that, the pressure in the room is reduced from atmospheric pressure to about 1 Torr, and the room temperature is lowered while sequentially turning off the heating means power source, and the work is aged for a predetermined time (for example, about 0.5 hours). Thereafter, the pressure in the chamber 2 was returned to the atmospheric pressure, and the temperature in the chamber 2 was lowered to room temperature, thus completing the thermal processing of the workpiece.

[0005]

In the vacuum heat treatment method for a work using such a known apparatus 1, each work of the work is heated in the portion A heated to the temperature T ₁ as shown in FIG. 2B. ± 5 ° to 15 ° at the part
A variation (v) in the temperature of C occurs, and in particular, the temperature is high in the portion near the heating means, that is, the outer portion of the work, and low in the portion distant from the heating means, that is, the inner portion of the work. Although such a temperature variation (v) tends to decrease somewhat due to the fact that the work is maintained at the constant temperature T ₁ in the chamber 2, at the start of the aging process when the work is under a high temperature vacuum. , The temperature variation of each part of the work tends to be further increased due to the temperature drop caused by the pressure reduction. Furthermore, in the cooling step after the aging process, in some cases, the temperature rapidly drops in the outer part of the work, but inside the work, the temperature drop is not so rapid, and in other cases, the opposite occurs. ,
Due to the latent heat of the outer wall of the chamber 2, the temperature of the outer part of the work is not lowered easily, and the temperature inside the work is rapidly decreased. Therefore, the molecular arrangement of the heat-treated work is not uniformly processed and its quality is often reduced. There was a problem that variation occurred in the.

Furthermore, in the conventional apparatus 1, since the heating means is located outside the work accommodating chamber 2, it takes a long time to heat the inside of the chamber to a predetermined temperature. In addition, it takes about 0.5 hours or more for the heat of the heating means to be dissipated in the entire apparatus and for the apparatus to return to room temperature due to heat dissipation after aging. There was also a problem that it took more than 5 hours.

[0007]

According to the present invention, in order to solve the above-mentioned problems, a heating means is provided outside a room, another heating means is further provided in the room, and the heating step is performed under atmospheric pressure. In particular, the process is performed under high pressure.In particular, the first heating step uses all the heating means inside and outside the room and simultaneously raises the indoor pressure.Furthermore, when the room is evacuated, the heating means inside the room preheats the work. The temperature of the workpiece is made uniform while the temperature is reduced, and the indoor pressure is further increased when the temperature drops. The temperature drop pattern can be freely controlled as much as possible, and rapid cooling can be performed by opening the gas exhaust valve while pressurizing the room when taking out the work.
This makes the quality of the work constant and further shortens the heat treatment processing time.

[0008]

The temperature distribution in the room under the high temperature and high pressure accommodating the article to be treated is kept constant, and then, while the chamber is kept in a vacuum state, the article is heated using the heating means arranged close to the article. Physicochemically uniform heat treatment of the article is performed by keeping the temperature.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. Vacuum heat treatment apparatus 20 of the present invention
1A is a schematic surface view thereof, and FIG.
FIG. 1C is a side view of a transfer gantry for transferring a workpiece to be processed into the apparatus, and FIG. 1C is a side view of the apparatus showing an internal structure.

The present apparatus 18 includes an apparatus main body 20 having a heating vacuum chamber 26, and a gantry 22 for supplying an article to be processed such as a liquid crystal display element, that is, a work 24 to the heating vacuum chamber 26.
It consists of and. A heating means 28 such as a coil heater or a panel heater having the same function as the heating means 3 of the known apparatus 1 shown in FIG. Further, another heating means 30 such as a coil heater or a panel heater is provided in a portion inside the chamber 26 and opposed to the work 24. Further, it is preferable that a similar heating means 31 is arranged on the inner wall surface of the chamber 26. In the chamber 26, a fan for flowing an airflow in a direction indicated by an arrow 32, a driving source 34 for driving the fan, and the chamber 2
A pressurized gas introduction valve 36 for increasing the pressure inside 6, a filter 38 through which the air flows, a HEPA filter 40, and a wind direction plate 42 are attached. Further, the work 2 of the gantry 22
The heating means 44 is also attached to the front side of 4. Further, a gas exhaust valve 35 for reducing the pressure in the chamber 26, and a vacuum pump 4 for creating a vacuum atmosphere in the chamber 26.
6 is provided.

The pedestal 22 for supplying the workpiece 24 to be processed into the chamber 26 or taking out the processed workpiece from the chamber 26 is preferably provided below the apparatus main body 20 in order to facilitate the approach of the workpiece into the chamber 26. It is desirable to be supported and guided by rollers or the like so as to be able to move on the extending rail. The gantry 22 has a work support 23 for holding the work 24 in a predetermined state. Further, the gantry 22 is provided with a shielding door 25 for shielding the heating vacuum chamber 26. A rising piece rising from the work support 23 is provided between the door 25 and the work 24, and a heating means 44 such as a coil heater or a panel heater is attached inside the rising piece. .

The device 20 according to the present invention is significantly different from the known device 1 in that additional heating means 30 and 31 are provided in a chamber 26 for heat-treating the work 24. It has a gantry 22 that facilitates taking in and out, the gantry 22 has an additional heating means 44, and a pressurized gas introduction valve 36 for adjusting the pressure in the room is provided. In other respects, it is substantially the same as the known device 1.

The behavior in the heat treatment of the work 24 by the apparatus 20 of the present invention will be described with reference to FIG. 2A. As in FIG. 2B, the time is plotted on the horizontal axis, and the temperature change at each point of the work 24 in the chamber 26 and the change in room pressure are plotted on the vertical axis. The process includes an initial processing area, a pressure and temperature adjustment area,
It is composed of a heat treatment step (firing step), a deaeration step, an aging step, a cooling step, and an opening step.

In the initial processing region, the pressurized gas introduction valve 36 is opened at the same time as the operation is started, and the pressure in the chamber 26 is rapidly increased to a pressure higher than the atmospheric pressure by supplying, for example, nitrogen gas into the chamber 26. . This pressure value varies depending on the characteristics, dimensions, applications and other conditions of the article to be treated, but is generally about 2.
About 5 to 3 atmospheres will be common. However, this pressure is merely an example, and the present invention is not limited thereto. The temperature of the chamber 26 along with this, by using a heating means 28,30,31,44, rapidly raised to the vicinity of T ₁ of the same as described above. At this time, an airflow in the direction of arrow 32 is generated in the chamber 26 by the fan motor 34. In the apparatus of the present invention, since the heating means is additionally arranged at a position closer to the periphery of the work as compared with the known apparatus, the temperature of each part of the work 24 stored in the chamber 26 is reduced. Can be raised quickly.

Next, in the pressure temperature adjustment region, the gas exhaust valve 35 is adjusted to lower the room pressure to some extent. The pressure at this time is not limited, but may be about 2 atm. However the temperature in the room, despite such degassing, the temperature by radiation heat or convection heat from the heating means, leading to T _1. This temperature T ₁ is generally about 200 ° C., though it varies depending on the desired characteristics of the article to be treated, dimensions, use and other conditions. However, this temperature is merely an example, and the present invention is not limited thereto. According to the present apparatus, the heating medium quickly and evenly spreads around the entire circumference of the work 24 due to the heating under the high pressure atmosphere, and as a result, the work 24 is shorter than the time t _{1 in} FIG. 2B by the time t ₁ . is able reach a predetermined temperature range in _a.

[0016] In the heat treatment area, after the workpiece 24 has reached a predetermined temperature range T _1, for example, while maintaining using only heaters 28 and the heater 31 to the temperature in the chamber 26 to the value, the article to be treated predetermined Heat treatment is, for example, about 2-3
Time is applied to achieve proper firing. In the apparatus of the present invention, since the work is performed under a high-pressure heat medium, it is almost impossible that temperature variation occurs on the work surface due to a positional difference between the inside and outside of the work 24 as the article to be processed. No, even if there is, the temperature difference w is ± 2
It has been found by the applicant's experiment that the angle is about 5 °. This value means that the variation is less than half that in the known device.

Next, in the degassing region, the gas exhaust valve 3
5, the chamber 26 is degassed, and the vacuum pump 46
The pressure in the chamber 26 is reduced from about 2 atm to about 1 torr by operating the. At this time, the heat in the room is extracted together with the gas. Therefore, the work 24
The indoor heaters 30, 31, and 44, which are located close to the room, are turned on to keep the temperature of the room constant. As shown in FIG. 2A, the temperature of each part of the work varies due to a temporary drop in room temperature when the pressure is reduced, and the variation is immediately compensated by the action of the heater. In this way, the occurrence of temperature variation of each part of the work 24 during pressure reduction is prevented. In this regard, in the case of the known apparatus shown in FIG. 2B, since the heating means does not exist in the portion close to the work 24, it is not possible to quickly respond to the temperature drop generated at the time of decompression. For this reason, it was not possible to prevent an increase in variation in the temperature of each part of the work due to the temperature drop in the room caused by the decompression (see the portion B in FIG. 2B). The device of the present invention completely eliminates such drawbacks. By this process,
The deaeration process from the work surface is completed.

After the lapse of a predetermined time, the pressure in the chamber 26 is again raised to, for example, about 2 atm, and the aging process for aging the work 24 for a predetermined time (for example, about 0.5 hours), that is, for annealing is started. At this time, the temperature dispersion in each part of the work 24 is remarkably small, and it is found by the experiment of the applicant that it is about ± 1 to 4 °.

Thereafter, in the cooling step, the pressure in the chamber 26 is increased to, for example, about 2.5 to 3 atm. Preferably, the pressurized gas introduction valve 36 is opened and the gas exhaust valve 35 is appropriately opened and adjusted. The temperature inside the chamber 26 is rapidly lowered to room temperature by sequentially turning off the indoor heaters 30 while replacing the entire gas in the room while maintaining the room pressure constant.

Finally, in the open area, the inside of the chamber is opened to bring the pressure in the chamber to the atmospheric pressure, the work is allowed to cool, and then the work is taken out.

The apparatus of the present invention has heating means 30 and 31 such as a panel heater in the chamber 26. The heating means disposed directly opposite the work 24 is preferably made of a material having a small heat capacity, such as aluminum, which is easily heated and cooled as much as possible. This is because the heating time at the time of starting the work 24 and the cooling time at the time of heat radiation are shortened. Actually, in the apparatus of the present invention, the processing time t _{b of the} work is shortened by 1 hour or more as compared with the conventional apparatuses. In addition, since the amount of energy of radiant heat from the heating means is inversely proportional to the square of the distance from the heating means, the heat from the heating means is utilized by disposing the heating means at a position close to the work as in the apparatus of the present invention. Is significantly improved.

[0022]

According to the present invention, the temperature of the work rises very quickly, and the temperature distribution of each part of the work according to the arrangement position of the work hardly differs due to the heating of the work in a high-pressure atmosphere. A distribution is obtained. Further, in the aging or annealing step, the room temperature is maintained so as not to drop by the room heating means, so that a substantially uniform annealing process is performed on the whole work, so that the whole work processed by this apparatus is physicochemically homogeneous. Quality can be obtained. Therefore, the yield is extremely good. Further, according to the apparatus of the present invention, the predetermined heat treatment time can be shortened by 1 to 2 hours as compared with the conventional case, and the working time and energy consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a view showing an apparatus of the present invention, FIG. 1A is a front view of the apparatus, FIG. 1B is a side view showing a gantry for transferring a work to the apparatus, and FIG. 1C is a side view of the apparatus. .

FIG. 2 is a graph showing a pressure in a work processing chamber and a temperature state of each part of a work in the work processing chamber in relation to time, FIG. 2A is a graph showing a case in the present apparatus, and FIG. 2B is a graph. It is a graph which shows the case in a known device.

FIG. 3 is a view showing a known device of the same kind, FIG. 1A is a front view of the known device, and FIG. 1B is a side view of the known device.

[Explanation of symbols]

18: vacuum heat treatment apparatus 20: apparatus main body 22: gantry 23: work support base 24: work 25: shielding door 26: chamber 28, 30, 3
1: Heating means 34: Fan and drive source 35: Gas exhaust valve 36: Pressurized gas introduction valve 44: Heating means 46: Vacuum pump

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location F27B 5/05 8926-4K 5/16 8926-4K 5/18 8926-4K F27D 7/06 C 8926-4K

Claims (10)

[Claims] 1. A high-precision article 24 in a predetermined chamber 26
In a vacuum heat treatment method for subjecting a chamber to a vacuum heat treatment, arranging an article to be treated in a chamber 26, operating a heating means provided around the chamber 26, and simultaneously increasing an internal pressure in the chamber, After the temperature reaches a predetermined temperature, the room temperature is maintained at a constant temperature and the article is kept at a constant pressure and a constant temperature while the room pressure is maintained in a high pressure atmosphere, and a desired heat treatment is performed. Depressurize the room pressure to below atmospheric pressure while keeping the room temperature constant, and increase the room pressure to above atmospheric pressure and gradually lower the room temperature to age the article to be processed. Performing treatment, quenching the article to be treated by disabling the heating means while maintaining the chamber in a further elevated pressure state, reducing the pressure in the chamber to atmospheric pressure, and vacuum heating from the chamber 26 Retrieving the physical already an article to be treated, the vacuum heat treatment method of high precision article 24 to a vacuum heat treatment by the steps of. 2. A high precision article 24 in a predetermined chamber 26.
In a vacuum heat treatment method of subjecting a chamber to a vacuum heat treatment, arranging an article to be treated in a chamber 26, activating heating means arranged on the outer and inner circumferences of the chamber 26, Pressure at least 2
After the room temperature reaches a predetermined temperature, the room temperature is maintained at a constant temperature mainly by the outer periphery heating means of the room, and the room pressure is maintained at about 2 atm. Heating and holding the article, reducing the indoor pressure to about 1 Torr after a predetermined time has elapsed, maintaining the indoor temperature at the predetermined temperature by means of the inner circumference of the chamber, and reducing the indoor pressure to at least 2 atm. Aging treatment of articles to be processed while gradually lowering the room temperature by raising the pressure to the above pressure and disabling the inner circumference heating means, heating while maintaining the room pressure at a further increased pressure state Disabling means and pressurized gas introduction valve 36 and gas exhaust valve 3
5, the object to be treated is rapidly cooled by opening the step 5; the pressure in the room is reduced to the atmospheric pressure; and the object to be treated after vacuum heating is taken out of the chamber 26. A vacuum heat treatment method for performing vacuum heat treatment. 3. The vacuum heat treatment method according to claim 1 or 2, wherein the heat treatment is vapor deposition or baking treatment. 4. A high precision article 24 in a predetermined chamber 26.
In a vacuum heat treatment apparatus for performing vacuum heat treatment on a chamber, a chamber 26 accommodating a high-precision article 24, a heating means 28 provided outside the chamber 26, and at least one additional heating means provided inside the chamber 26. (30, 31, 44), a pressurized gas introduction valve 36 that can adjust the chamber 26 to a pressurized state, a gas exhaust valve 35 that can adjust the chamber 26 to a depressurized state, and the chamber The pump means 46 capable of adjusting 26 to a vacuum state, the heating means 28, and 30 and / or 31 and / or 44, the pressurized gas introduction valve 36, the gas exhaust valve 35, and the pump means 46 are independent. A vacuum heat treatment apparatus for heat-treating the high-precision article 24 in a chamber 26 by vacuum heat treatment, which comprises: 5. A gantry 22 on which a high-precision article 24 is placed is provided, and the gantry 22 is movable in and out of a chamber 26 of the vacuum heat treatment apparatus 20. Item 4. The vacuum heat treatment apparatus according to item 4. 6. The vacuum heat treatment apparatus according to claim 5, wherein a heating means 44 is attached to the gantry 22. 7. The vacuum heat treatment apparatus according to claim 1, wherein the heating means is a coil heater. 8. The vacuum heat treatment apparatus according to claim 1, wherein the heating means is a panel heater. 9. The vacuum heat treatment apparatus according to claim 1, wherein the high-precision article to be treated 24 is a liquid crystal display element. 10. The vacuum heat treatment apparatus according to claim 4, wherein the heat treatment is vapor deposition or baking treatment.