JPS63213281A - Control of heat-treatment furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for controlling a heat treatment furnace that heat-treats a workpiece in the furnace by controlling the heater temperature in the furnace according to a predetermined heat pattern. Regarding.

[Prior Art] Conventionally, this type of control method simply controls the heater temperature according to a predetermined heat pattern. Therefore, regarding the temperature inside the furnace, only the heater temperature was detected and used as a feedback signal.

[Problems to be Solved by the Invention] Generally, the interior of the object to be processed has poor heat conduction, and the surface thereof has good heat conduction. Therefore, when soaking each part of the object to be treated, it is necessary to gradually raise the temperature while taking into consideration the temperature between the internal low temperature part and the high temperature part on the surface thereof.

However, as mentioned above, in the case of conventional control methods, the temperature of the object to be processed itself is ignored, and only the heater temperature is monitored, and the heater temperature is simply controlled according to a predetermined heat pattern. During actual operation, even if there was a large temperature difference between the inside and the surface of the object, the operation continued. Therefore, in such a case, there is a problem that the object to be treated cannot be subjected to soaking treatment.

This invention solves these problems.

[Means for Solving the Problems] The heat treatment furnace control method of the present invention is a heat treatment furnace that heat-treats a workpiece in the furnace by controlling the heater temperature in the furnace to generate heat according to a predetermined heat pattern. In the control method, the temperature of the high temperature part and the low temperature part of the workpiece is detected during heat treatment of the workpiece,
The temperature difference between them is determined, and when the heater is generating heat according to the heat pattern, the heat pattern is changed on the condition that the temperature difference exceeds a predetermined value, and the temperature difference of the workpiece is kept small. Features.

[Function] The heat treatment furnace control method of the present invention is based on the condition that when the heater is generating heat according to the heat pattern, the temperature difference between the high-temperature part and the low-temperature part of the workpiece exceeds a predetermined value. By changing the heat generation amount of the heater to a small value, the temperature difference between each part of the object to be processed is automatically suppressed to a small value, and the object to be processed is subjected to soaking treatment, thereby improving and uniformizing the quality of the product.

[Example] Hereinafter, one embodiment of the present invention will be described based on the drawings.

First, a configuration example of a control device for implementing the present invention will be outlined based on FIG. 5.

In the figure, 1 is a heat treatment furnace, and a plurality of heaters 2 provided therein heat the object W to be heat treated. Each of the heaters 2 is connected to a heater temperature control means 3, and the heater temperature control means 3 controls each heater 2 while feeding back a detection signal from a heater temperature sensor 4 attached to each heater 2. It is. The heater temperature control means 3
The control is heat generation control according to the heat pattern set by the heat pattern setting means 5.

The heat pattern setting means 5 first sets an initial heat pattern by being initialized by the initial setting means 6, and thereafter changes the setting of the heat pattern in response to a change command from the heat pattern changing means 7.

The heat pattern changing means 7 processes the temperature detection signal manually inputted from the product temperature detecting means 8 as will be described later.
An R change command is issued in accordance with the calculation result. A plurality of temperature sensors 9 attached to the high temperature part and the low temperature part of the workpiece W are connected to the product temperature detection means 8. The high temperature part of the object W to be processed is, for example, the surface part with good heat conduction, and the low temperature part is the inside part with poor heat conduction.

Next, an actual control method will be explained.

First, the heat pattern setting means 5 sets an initial heat pattern. Now, let's take a look at that initial heat pattern.
Pattern A in the figure is used. The heater temperature control means 3 controls the heater 2 to generate heat according to the heat pattern A, and heat-processes the object W to be processed.

During the heat treatment according to such heat pattern A, the product temperature detection means 8 detects the actual temperature of each part of the workpiece W. If the heat treatment progresses as initially planned, the high-temperature part of the workpiece W changes as shown by curve a in Figure 4, and the low-temperature part of the workpiece W changes as shown by the curved line in the figure. Change.

The heat pattern changing means 7 monitors the temperature of the workpiece W during heat treatment, and issues a heat pattern change command when the temperature exceeds an allowable range due to various factors. That is, the heat pattern changing means 7 has two types of functions, and the first function is to change the maximum value of the temperature of the workpiece W (MA
This is a function that calculates the difference between X ) and the minimum value (MIN) and issues a command to change the heat pattern according to the situation, on the condition that the difference exceeds a predetermined setting value.
Further, the second function is the maximum value (M
This is a function that monitors A x ) and issues a command to change the heat pattern according to the situation, on the condition that the maximum value becomes equal to or higher than a predetermined heating limit temperature of the object W to be processed.

Therefore, the first function of the heat pattern changing means 7 is
The second function will be explained with reference to FIG. 2 and FIG. 3, and the second function will be explained with reference to FIG.

Figure 1 shows heater 2 according to initial heat pattern A.
is heating up (t,), the temperature difference (MAX
-MIN) becomes the set value 01 or more, that is, (M
This is an example of changing the twist turn when AX-MIN)≧01. In this case, the heat pattern changing means 7 issues a command to change to heat pattern B in the figure. This heat pattern B is a control pattern that keeps the temperature of the heater 2 constant for a predetermined period of time, and by following this control pattern, the temperature difference between the high temperature part and the low temperature part of the workpiece W is reduced. Then, when the temperature difference is sufficiently reduced, the original heat pattern A is restored.

Figure 2 shows heater 2 according to initial heat pattern A.
When the temperature of the workpiece W is kept constant (t,), if the temperature difference (MAX-MIN) of the workpiece W exceeds the set value C7, that is, (MAX-MIN)≧02. This is an example of changing the pattern. In this case, the heat pattern changing means 7 issues a command to change to heat pattern C in the figure. This heat pattern C is a control pattern that lowers the heater 2 by a predetermined temperature, and by following this control pattern, the temperature difference between the high temperature part and the low temperature part of the workpiece W is reduced. When the temperature difference is sufficiently reduced, the original heat pattern A is restored.

Figure 3 shows heater 2 according to initial heat pattern A.
A pattern when the maximum value (MAX) of the temperature of the workpiece W becomes equal to or higher than the set value 03 during temperature control (t,), that is, when (MAX)≧C8. This is an example of a change. The set value c3 is the heating limit temperature of the object W to be processed. In this case, the heat pattern changing means 7 issues a command to change to the heat pattern D in the figure. This heat pattern D is a control pattern that lowers the heater 2 by a predetermined temperature, and by following this control pattern, the high temperature portion of the workpiece W is lowered below the set value c3. Then, when the temperature of the high-temperature part has dropped sufficiently, the original heat pattern A is restored. -, the heat pattern changing means 7 monitors the actual temperature of the workpiece W during the heat treatment of the workpiece W, and by the first and second functions of the heat pattern changing means 7, Issues a command to change the heat pattern according to the situation.

Thereafter, when it is determined that the heat treatment has been sufficiently completed, the heater 2 stops generating heat, enters a cooling process, and ends the heat treatment.

The above operations are summarized in FIG. 6.

[Effects of the Invention] As explained above, the heat treatment furnace control method of the present invention allows the temperature difference between the high-temperature part and the low-temperature part of the workpiece to reach a predetermined value when the heater is generating heat according to the heat pattern. Since the heat pattern is changed on the condition that the temperature exceeds the limit, and the heat generation amount of the heater is kept small, the temperature difference between each part of the object to be processed can be automatically suppressed to a small value, and the object to be processed can be soaked. Therefore, it is possible to improve the quality and uniformity of products.

[Brief explanation of the drawing]

Figures 1 to 6 are diagrams for explaining one embodiment of the present invention, Figures 1 to 3 are diagrams for explaining examples of changes in heat patterns, and Figure 4 is diagrams for explaining initial heat patterns. 5 is a block diagram of the control device, and FIG. 6 is a flowchart explaining the control operation. 1... Heat treatment furnace, 2... Heater, 3...
...Heater temperature control means, 4...Temperature sensor for heater, 5...
Heat pattern setting means, 6... Initial setting means, 7... Heat pattern changing means, 8...
・Product temperature detection means, 9...Temperature sensor, W...Product to be processed. Applicant: Ishikawajima-Harima Heavy Industries Co., Ltd. Sumitomo Precision Industries Co., Ltd. Figure 2 Sa i“2 Figure 4 ○ Ginmon Figure 6

Claims (1)

[Scope of Claim] A method for controlling a heat treatment furnace for heat treating a workpiece in the furnace by controlling the temperature of a heater in the furnace to generate heat according to a predetermined heat pattern. Detects the temperature of the high temperature and low temperature parts of the workpiece,
The temperature difference between them is determined, and when the heater is generating heat according to the heat pattern, the heat pattern is changed on the condition that the temperature difference exceeds a predetermined value, and the temperature difference of the object to be processed is kept small. Characteristic control method of heat treatment furnace.