JP3082211B2 - Vacuum furnace and temperature uniforming method in vacuum furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to quenching, tempering or sintering of various materials to be treated.
The present invention relates to a vacuum furnace used for performing heat treatment such as firing, and a method for uniforming temperature in the vacuum furnace.

2. Description of the Related Art In a furnace of this type, for example, a heater is provided on an upper surface side and a lower surface side of a space in which a material to be processed is placed in a vacuum vessel, and a temperature for detecting the temperature of the material to be processed. A detector is provided, and the heating value of the heater is controlled based on the detected value.

[Problems to be Solved by the Invention] In such a conventional vacuum furnace, since the material to be processed is only heated from the upper surface and the lower surface, the heating on the side surface is not sufficient, and the heat treatment on the upper surface and the lower surface is difficult. 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 provided also on the side surface side, and the heater on the side surface side is controlled based on a value detected by the temperature detector. Such a technique is preferable from the viewpoint of improving the uniformity of the entire temperature of the material to be processed. However, there is a problem that the control network for the temperature detector becomes extremely complicated as the number of temperature detectors increases.

The present invention has been made in order to solve the above-mentioned problems (technical problems) of the prior art, and has a method in which the heating values of a plurality of heaters are mutually deviated based on a detection value from one temperature detector. To provide a vacuum furnace and a temperature uniforming method in a vacuum furnace capable of performing heating in a state where uniformity of temperature distribution of a material to be processed is improved by a simple control network by controlling in a state. With the goal.

[Means for Solving the Problems] The vacuum furnace of the present invention is configured such that, in a vacuum vessel having a space in which a material to be treated is placed, a material to be treated that is placed in the space in which the material is placed is located around the space. In a vacuum furnace provided with a plurality of heaters for heating, a heating value controller is individually provided in a power supply path of each of the plurality of heaters, and the plurality of heating value controllers and a vacuum vessel are provided. In order to detect the temperature of the material to be processed in the vacuum chamber and to simultaneously control the plurality of heating value adjusters, the heat generation between the plurality of heaters is performed between the plurality of heaters and one temperature detector provided in the vacuum vessel. Each of the plurality of heating value adjusters is provided with a separate deviation setting device so that the amount can have a deviation.

[Operation] Heat is applied to the material to be processed from the heaters on the upper surface side, the lower surface side, and the side surface side, and the uniformity of the entire temperature distribution is improved. In the case of the heating, the temperature of the material to be processed is detected by the temperature detector, and the amounts of heat generated by the plurality of heaters are controlled based on the detected value. In the case of this control, the amounts of heat generated by the plurality of heaters are controlled in such a manner that a deviation set in advance by the deviation setting device is provided based on the detection value of one temperature detector. As a result, the material to be processed can be heated in a state where the entire temperature is made uniform.

[Embodiment] Drawings showing an embodiment of the present application will be described below. 1 and 2, reference numeral 1 denotes a vacuum furnace. Reference numeral 2 denotes a vacuum vessel, which comprises a main body 3 and a door 4 provided at the entrance 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 an entrance of the main body 6, and a space inside the main body 6 is a heat treatment chamber 8. Reference numeral 10 denotes a mounting table provided in the heat treatment section 8, and a space above the mounting table is a space 11 in which the material to be processed is located. Reference numerals 12a to 12f denote heaters disposed around the existing space 11, which are provided on the upper surface side, the lower surface side, and the left, right, front, and rear side surfaces of the existing space 11, respectively ( In the present specification, the side of the door is referred to as front, and the opposite side is referred to as rear, and the left and right refer to the left and right as viewed from the door side), each of which is attached to a heat insulating wall. In some cases, the heaters 12e and 12f on the front and rear sides are not provided. Reference numeral 13 denotes a temperature detector provided in the processing chamber 8, which is capable of detecting a high temperature. For example, a thermocouple is used. Next, reference numeral 15 denotes a well-known cooling mechanism for the material to be processed, which will be described below. 16 is cooler, 17
Is a cooling fan, which is driven by a fan motor 18. 19 is a motor cover for holding a vacuum. The ducts 20 and 21 each have a duct. The duct 20 has a gas flow port on its lower surface, and the duct 21 has a gas flow port on its upper surface.
Reference numerals 22, 23 denote dampers for switching between upstream and downstream. In such a cooling mechanism 15, the dampers 22, 23 operate the cooler 16 and the fan 17 in the state shown in the drawing,
Cooling gas circulates along the path shown by the solid arrow,
The workpiece placed at 11 is cooled. Dampers 22, 23
By switching the cooling gas, the material to be processed can be cooled by flowing the cooling gas from the bottom to the top in the storage space 11.

Next, FIG. 3 showing a control system of the heaters 12a to 12f will be described. In FIG. 3, lowercase letters a to f attached to reference numerals indicate that the members indicated by the reference numerals are members corresponding to the heaters 12a to 12f, respectively. Unless necessary, the description will be made with reference numerals in which lowercase letters a to f are omitted. Reference numeral 25 denotes a power supply terminal, which is connected to a commercial power supply. 26 is a calorific value controller interposed in the power supply path to the heater, and a current regulator is used as an example. As such a current regulator, for example, a thyristor is used. 27 is a transformer for reducing the voltage. By connecting the current regulator 26 and the transformer 27 in the order shown in the figure, the current regulator 26 having a small current capacity is sufficient. 28 is a well-known temperature controller,
A control signal is output based on a temperature detection value obtained from the temperature detector 13. Numeral 29 denotes a deviation setting device which receives a control signal from the temperature controller 28, adds a deviation value preset for itself to the control signal, and gives a signal to which the deviation value is added to the current controller 26. It is.

Next, the heat treatment of the material to be processed using the vacuum furnace will be described. The doors 4 and 7 are opened, and the workpiece 31 is placed on the mounting table 10. In the mounting state, the large workpiece 31 remains as it is,
Small ones are, for example, stacked on shelves. Then doors 4,7
Is closed, the inside of the vacuum vessel 2 is evacuated, and the heater 12a is closed.
To 12f, they generate heat, and the material to be treated 31 is mainly generated by radiant heat transfer from the heaters 12a to 12f.
Is heated.

In the case of the above-mentioned heating, the temperature of the processing target material 31 is detected by the temperature detector 13, and based on the signal from the temperature detector 13, the temperature controller 2
8. The current adjuster 26 is controlled via the deviation setter 29, and the output of each heater 12a to 12f is controlled. Those heaters 12a-1
Control of the output of 2f is performed in a state having a deviation set in the deviation setting unit 29 in advance. Therefore, the material to be processed 31 placed in the existing space 11 is heated to a substantially uniform temperature in any part thereof.

The deviation value to be set in each of the deviation setting units 29a to 29f is
Depending on the shape, size, loading state, etc. of the material 31 to be processed, various values that can make the temperature of the material 31 in each part of the existing space 11 uniform can be previously tested. It is better to select a value suitable for the actual situation from these values and use it.

When the target material 31 is subjected to the predetermined heating as described above, the power supply to the heater is stopped, the cooling gas is introduced into the vacuum vessel 2, and the cooler 16 and the fan 17 are operated as described above. , The material to be treated 31 is cooled.

Then, when the cooling is completed, the doors 4 and 7 are opened, and the material 31 subjected to the heat treatment is taken out.

Next, the heat treatment in the case where the type of the material to be processed, for example, the size, shape, material, etc., is changed will be described. As an example, in the case of heat treatment when the material to be processed is changed to a large material, for example, the setting value of the deviation setting unit 29b is changed so that the heat generation amount of the heater 12b is increased, and The same operation as described above is performed. As a result, the heat treatment can be performed in a uniform temperature distribution state even with the changed material to be processed.

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

Next, control of the heaters 12a to 12f in the furnace is performed by dividing the heaters 12a to 12f into two sets (for example, heaters 12a to 12c and heaters 12d to 12f) as shown by a two-dot chain line in FIG. In each group, the same control as in the above embodiment may be performed by one temperature detector 13 '(13 ") and one temperature controller 28'(28"). The shape of the heat insulating wall 5 is the second
The cross section may have a cylindrical shape other than a square shape as shown in the drawing.

[Effects of the Invention] As described above, in the present invention, when the material to be processed 31 is heated, heat is given to the material to be processed 31 from a plurality of surrounding heaters. Of course, in the case of the above-mentioned heating, the temperature of the material 31 to be processed is detected by the temperature detector 13, and the plurality of the plurality of Since the calorific values of the heaters are controlled at the same time, there is an effect that the material to be processed 31 can be heated in accordance with the temperature condition.

In addition, in the case of the above control, since the temperature detection by the temperature detector 13 controls one heater and controls a plurality of heaters, there is an effect that the control network can be simplified, and therefore, the cost related to the equipment is reduced. This has the utility of reducing power consumption and simplifying maintenance during operation. Further, since there is an advantage that the amounts of heat generated by the plurality of heaters can be simultaneously controlled in a state where they have a mutual deviation as desired, there is no hunting between the heaters, and the material to be processed 31 has the plurality of heaters respectively. There is a feature that the temperature control over the entire area can be performed more uniformly than when individual control is performed.

Furthermore, in the method of the present invention, even when the type of the workpiece 31 changes, the set value of the deviation is changed according to the change. Thus, there is an effect that heating can be performed in a state where the temperature distribution is made uniform.

[Brief description of the drawings]

1 is a longitudinal sectional view of a vacuum furnace, FIG. 2 is a sectional view taken along the line II-II in FIG. 1 to show the arrangement of heaters, and FIG. FIG. 2 is a circuit diagram showing a control system of FIG. 2. Vacuum container, 11 Space, 12a to 12f Heater, 13 Temperature detector, 26 Heat generation amount controller, 29 Deviation setter.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-17901 (JP, A) JP-A-3-110382 (JP, A) JP-A-62-112726 (JP, A) 63700 (JP, U) Jiko 1-43836 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C21D 1/773 B22F 3/10 F27D 11/02 H05B 3/00 350

Claims (2)

(57) [Claims] In a vacuum vessel having a space in which a material to be treated is placed, a plurality of heaters are provided around the space to heat the material to be placed in the space. In the vacuum furnace, a heating value controller is individually provided in each of the power supply paths of the plurality of heaters, and the plurality of heating value controllers and the temperature of the material to be processed in the vacuum vessel are detected. In order to simultaneously control the plurality of heating value adjusters, a plurality of the plurality of heaters may be provided with a deviation between the plurality of heaters and a single temperature detector provided in the vacuum vessel. A vacuum furnace, wherein an individual deviation setting device is provided for each of the calorific value controllers. 2. A vacuum vessel having a space in which a material to be treated is placed inside, and a plurality of heaters for heating the material to be treated placed in the space in which the material is placed are provided around the space. In the vacuum furnace, a heating value controller is individually provided in each of the power supply paths of the plurality of heaters, and the plurality of heating value controllers and the temperature of the material to be processed in the vacuum vessel are detected. In order to simultaneously control the plurality of heating value adjusters, a plurality of the plurality of heaters may be provided with a deviation between the plurality of heaters and a single temperature detector provided in the vacuum vessel. For each of the calorific value controllers, an individual deviation setting device is interposed, and when the material to be treated is kept in the existing space and heated, depending on the type of the material to be kept. By adjusting the setting value of each deviation setting device, By changing the heat value of the heater mutual temperature leveling method in a vacuum furnace, characterized in that to equalize the overall temperature of the processed material which is of stripping above of stripping space.