JPH0452215A - Vacuum furnace and temperature equalization method in vacuum furnace - Google Patents

Abstract

PURPOSE:To uniformize temp. distribution of the whole material to be treated by individually arranging calorific value adjustor to plural heaters for heating the material to be treated and individual deflection setter for giving the deflection to calorific value of the heater between the calorific value adjustor and temp. detector for the material to be treated. CONSTITUTION:By conducting electric power to the heaters 12a-12f after vacuum evacuating the vacuum vessel 2, the heat is generated with these and the material 3 to be treated is heated mainly with radiation and transfer of the heat from the heaters 12a-12f. Then, temp. of the material 31 to be treated is detected with the temp. detector 13 and based on these signals, current adjustor 26 is controlled through the temp. adjustor 28 and the deflection setter 29 to control output of each heater 12a-12f. Further, control of the outputs to these heaters 12a-12f is executed under condition of giving the deflection preset to the deflection setter 29. Therefore, the material 31 to be treated set in the setting space 11 is heated to almost uniform temp. at the every parts.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vacuum furnace used for subjecting various materials to heat treatment such as quenching, tempering, sintering, and firing, and a method for controlling the temperature in the vacuum furnace. Concerning a homogenization method.

[Prior Art] In this type of furnace, for example, heaters are provided on the upper surface side and the lower surface side of the space where the material to be treated is placed in a vacuum container, and a temperature sensor is installed to detect the temperature of the material to be treated. A detector is provided, and the amount of heat generated by the heater is controlled based on the detected value.

[Problems to be Solved by the Invention] In such conventional vacuum furnaces, the material to be processed is heated only from the top and bottom surfaces, so the side surfaces are not sufficiently heated, and there is a There was a problem that the temperature difference became large. Therefore, a technique has been devised in which a heater and a temperature detector are also provided on the side surface side, and the heater on the side surface side is controlled based on the detected value by the temperature sensor. Such technology is
This is preferable in terms of improving uniformity of the temperature of the entire material to be treated. However, there is a problem in that as the number of temperature detectors increases, the control network becomes extremely complex.

The present invention was made in order to solve the problem (technical plan B) of the prior art described above, and uses the detected value from one temperature sensor to create a deviation in the amount of heat generated by a plurality of heaters. To provide a vacuum furnace and a temperature uniformization method in a vacuum furnace, which can perform heating in a state in which the temperature distribution of a material to be treated is improved with a simple control network by controlling the material in a state in which the temperature is uniform. The purpose is to

[Means for Solving the Problems] In order to achieve the above object, the vacuum furnace of the present invention provides, in a vacuum container having a storage space for a material to be treated inside, the storage spaces around the storage space. In a vacuum furnace equipped with a plurality of heaters for heating the material to be processed, which is placed in the A separate deviation setting device is installed between the temperature detector installed in the vacuum container to detect the temperature of the material to be processed in the vacuum container so as to allow deviation in the amount of heat generated by the plurality of heaters. This is an intervention.

[Function] Heat is applied to the material to be treated from the heaters on the upper surface side, lower surface side, and side surface side, and the uniformity of the temperature distribution over the entire surface is improved. In the case of heating, the temperature of the material to be treated is detected by a temperature detector, and the amount of heat generated by the plurality of heaters is controlled based on the detected value.

In the case of the 'vI control, the amount of heat generated by the plurality of heaters is controlled with a deviation set in advance in a deviation setting device based on a value detected by one temperature detector.

As a result, the material to be processed can be heated with the entire temperature being made uniform.

"Example code" The drawings showing the embodiments of the present application will be described below.

In Figure 1.2, 1 indicates a vacuum furnace. Reference numeral 2 denotes a vacuum container, which is composed of a main body 3 and a door 4 provided at the entrance/exit of the main body 3. Reference numeral 5 denotes a heat insulating wall, which is composed of a main body 6 and a door 7 provided at the entrance/exit of the main body 6, and the space inside thereof serves as a heat treatment chamber 8.

Reference numeral 10 denotes a mounting table provided in the heat treatment chamber 8, and the space above it serves as a storage space 11 for the material to be treated.

12a to 12f are heaters disposed around the storage space 11, and are provided on the upper surface side, the lower surface side, and the left, right, front, and rear sides of the storage space 11, respectively. In this specification, the door side is referred to as the front, the opposite side is referred to as the rear, and left and right refer to the left and right as seen from the door side), and each is attached to a heat insulating wall. heaters 12e on the front side and rear side;
In some cases, 12f is not provided. Reference numeral 13 denotes a temperature detector provided in the processing chamber 8, which is capable of detecting high temperatures, and uses a thermocouple, for example. Next, reference numeral 15 indicates a well-known cooling mechanism for the material to be treated, which will be explained below. 1
6 is a cooler, and 17 is a cooling fan, which is driven by a fan motor 18. 19 is a motor cover for maintaining vacuum. Reference numerals 20 and 21 designate ducts, and the duct 20 and the duct 21 have gas flow ports on their lower and upper surfaces, respectively. 22 and 23 are dampers for upstream and downstream switching. In such a cooling mechanism 15, when the dampers 22 and 23 operate the cooler 16 and fan 17 in the state shown in the figure, the cooling gas is circulated along the path shown by the solid arrow, and is supplied to the storage space 11. The placed material to be treated is cooled. By switching the dampers 22 and 23, the material to be processed can also be cooled by flowing the cooling gas from the bottom to the top in the holding space 11.

Next, FIG. 3 showing the control system of the heaters 12a to 12f will be explained. In FIG. 3, lowercase letters a to f attached to the reference numbers indicate that each member indicated by the reference number corresponds to each of the heaters 12a to 12f, and in the following, Unless necessary, the explanation will be given using symbols omitting the lowercase letters a - r. A power terminal 25 is connected to a commercial power source. Reference numeral 26 denotes a heat generation amount regulator interposed in the power supply path to the heater, and for example, a current regulator is used. For example, a thyristor is used as such a current regulator. 27 is a transformer that lowers the voltage. By connecting the current regulator 26 and transformer 27 in the order shown in the figure, it is sufficient that the current gliff device 2G has a small current capacity. Reference numeral 28 denotes a well-known temperature controller which outputs a control signal based on the detected temperature value obtained from the temperature detector 13. Reference numeral 29 denotes a deviation setting device which receives a control signal from the temperature controller 28, adds a preset deviation value to the control signal, and provides a signal to which the deviation value has been added to the current controller 26. It's Nishide.

Next, heat treatment of a material to be treated using the vacuum furnace will be explained.

m4 and m7 are opened, and the material to be processed 31 is placed on the mounting table 10. The placed state is such that large objects 31 are left as they are, and small objects 31 are stacked on a shelf, for example. Next, the door 4.7 is closed, the inside of the vacuum container 2 is evacuated, and the heaters 12a to 12f are energized to generate heat.
The material to be treated 31 is heated mainly by radiation heat transfer from the heaters 12a to 12f.

In the case of the above heating, the temperature of the material to be treated 31 is measured by the temperature detector 13.
Based on the signal therefrom, the current regulator 26 is controlled via the temperature controller 28 and the deviation setting device 29, and the output of each heater 12a to 12f is controlled. The outputs of the heaters 12a to 12f are controlled with a deviation set in the deviation setting device 29 in advance. Therefore, all parts of the material 31 placed in the storage space 11 are heated to a substantially uniform temperature.

The deviation value to be set in each of the deviation setting units 292 to 29f described above is determined depending on the shape and size of the material to be processed 3I, the loading state in the storage space 11, etc. It is preferable to experimentally determine in advance various values that can make the temperature of the material 31 uniform, and to select and use one of these values that suits the actual situation.

Once the material to be processed 31 has been heated to a predetermined level as described above, the power supply to the heater is stopped, cooling gas is introduced into the vacuum container 2, and the cooler 16 and fan 17 are activated as described above. The processing target material 31 is cooled.

When the cooling is finished, the doors 4 and 7 are opened and the processed material 31 that has undergone heat treatment is taken out.

Next, heat treatment when the type of the material to be treated, such as size, shape, material, etc., is changed will be explained. - For example, in the case of heat treatment when the material to be treated is changed to a larger material, the setting value of the deviation setting device 29b is changed so that the emitted heat amount of the Evaporator heater 12b becomes larger,
In this state, the same operations as in the above case are performed. As a result, even the changed material can be heat-treated with a uniform temperature distribution.

Next, in the control system shown in FIG. 3, when heat generation control is performed for all heaters without using the deviation setting device 29 as described above,
When the temperature distribution width in the furnace was actually measured in the case where the heat generation of all the heaters was controlled using the deviation setting device 29 as described above, improvements as shown in Table 1 below were observed.

Table 1 Next, the control of the heaters 12a to 12f in the furnace is controlled by the third
As shown by the two-dot chain line in the figure, the heaters 12a to 12f
two sets (for example, heaters 12a to 12c and heaters 12d to
12f), and each set has a temperature sensor 1.
3', 13'' and temperature controllers 28', 2B' may be used to perform the same control as in the above embodiment.Also, the shape of the heat insulating wall 5 may be cylindrical, in addition to the square cross-sectional shape as shown in FIG. It may be in the form of

[Effects of the Invention] As described above, in the present invention, when the material to be treated 31 is heated, heat is applied to the material to be treated 31 from a plurality of surrounding heaters, so that the entire material to be treated 31 is heated. Of course, this has the effect of heating the material 31 with improved uniformity of temperature distribution, and in the case of the above heating, the temperature detection S13
Since the temperature of the material 31 to be treated is detected and the amount of heat generated by the heater is controlled based on the detected value, there is an effect that heating can be performed in accordance with the temperature condition of the material 31 to be treated.

Moreover, in the case of the above control, even if the temperature is detected by the temperature detector 13 at one location, the amount of p+ generated by the plurality of heaters can be controlled with a mutual deviation. , it has the advantage of being able to control the temperature over the entire area in the same way as when each of the plurality of heaters is individually controlled. This has the usefulness of making it possible to simplify the control network for uniformizing the temperature of the material to be treated.

Furthermore, in the method of the present invention, even when the type of the material to be treated 31 changes, the set value of the deviation is changed in accordance with the change, so the above-mentioned method also applies to the changed material to be treated. There is an effect that heating can be performed in a state where the uniformity of temperature distribution is improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present application, and FIG. 1 is a vertical sectional view of a vacuum furnace, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1 to show the arrangement of the heater, and FIG. FIG. 3 is a circuit diagram showing a control system. 2... Vacuum container, 11... Storage space, 12a-12
f... Heater, 13... Temperature detector, 26... Calorific value regulator, 29... Deviation setting device. π Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] 1. In a vacuum container having a storage space for a material to be processed inside, a plurality of heaters are arranged around the storage space to respectively heat the material to be processed that is placed in the storage space. In the vacuum furnace equipped with the above-mentioned vacuum furnace, a calorific value regulator is individually installed in the power supply path of each of the heaters, and the vacuum vessel is connected to the vacuum vessel in order to detect the temperature of these calorific value regulators and the material to be processed in the vacuum vessel. A vacuum furnace characterized in that an individual deviation setting device is interposed between each of the plurality of heaters and a temperature detector provided therein so as to provide a deviation in the amount of heat generated by each of the plurality of heaters. 2. In a vacuum container having a space for holding the material to be processed inside, a vacuum furnace is provided with a plurality of heaters around the space for heating the material to be processed, respectively, which are placed in the space. , A heat generation amount regulator is individually installed in the power supply path of each of the above heaters, and a temperature control device provided in the vacuum container is installed to detect the temperature of the heat generation amount regulator and the material to be processed in the vacuum container. An individual deviation setting device is interposed between the heater and the detector so that the heat generation amount of the plurality of heaters can be varied, and when the material to be treated is placed in the holding space and heated. is characterized in that the temperature of the entire material to be treated left in the storage space is made uniform by adjusting the setting values of each of the deviation setting devices according to the type of the material to be treated that is left in the storage space. A method for equalizing temperature in a vacuum furnace.