JPS63118912A - Control method for baking temperature - Google Patents

Abstract

PURPOSE:To control a temperature difference at each part of a baking object less than a constant level, and to perform uniform baking, by performing temperature control at every stage of temperature increasing process, targeted temperature maintaining process, temperature decreasing process, and control stopping. CONSTITUTION:In a baking temperature control computer, a control program is started up periodically by an internal timer, and after temperature Ti are inputted from all of thermocouples 1-n, mean temperature TAVE, minimum temperature TMIN, and maximum temperature TMAX are found. And a process is judged as the temperature increasing process when the mean temperature is less than the lower limit value (T0-alpha2) of the allowable temperature width of targeted temperature, and as the targeted temperature maintaining process at a time when it arrives at the lower limit value (T0-alpha2) of the allowable temperature width of the targeted temperature, and as the temperature decreasing process at the time when temperature decreasing targeted temperature T1 to decrease the temperature of the baking object part is set. Also, in the temperature decreasing process, at the time when temperature arrives at TAVE<(T1+beta1) that is the upper limit of the allowable temperature width of the temperature decreasing targeted temperature, it is judged as the control stopping, and an OFF command is issued to all of the heater power source CTTn.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a baking control device that performs ON10FF control of a heater, and is particularly suitable for baking control when baking is performed within a target temperature range with a constant temperature difference. Regarding the method.

[Conventional technology]

Conventionally, baking temperature control is performed by controlling a heater 2 that heats a baking target 1, a thermocouple 3 installed near the heater, and a temperature measurement value from the thermocouple 3 based on a baking target temperature, as shown in FIG. Heater power supply CTT5 0N/
It is composed of a control computer 4 that performs OFF control. In the control method of such a conventional device, as shown in Fig. 3, a control program is periodically activated by an internal timer of the control computer, the temperature is read in from the thermocouple in block A, and the temperature is read in in block B as shown in Fig. 4. ○N/' of CTT as shown
In order to avoid unnecessary OFF operations, a permissible range is set, and if the intake temperature is above the upper limit (T o + T 1), CTT is applied.
OFF command value 9, CT if below lower limit value (To-Tt)
A TON command value of 10 is created, and the command is output to the CTT in block C.

Note that within the allowable range (T o −T x− to T o +
T t ), the current state of CTT is maintained.

In such a conventional method, there are parts where the temperature rises and falls quickly depending on the temperature characteristics of the heater and the part to be baked.
As shown in the figure, the temperature difference between the sensor that rose and fell quickly and the sensor that fell slowly became large, and thermal stress was generated. As described above, in the conventional method, consideration has not been given to temperature control that reduces individual temperature differences in each part to be baked during the process of raising the baking target temperature and the natural temperature cooling process when the control is stopped.

[Problem that the invention seeks to solve]

The above conventional technology does not take into account temperature control to reduce the temperature difference between each part of the baking target during the process of raising the temperature to the target temperature and the natural temperature cooling process after stopping the baking temperature control, and the individual temperature differences are large. Therefore, there was a problem that thermal stress was generated.

An object of the present invention is to use a baking temperature control system, in which temperature control is performed to raise the temperature to a target temperature in the temperature raising process, temperature control within the target temperature tolerance range is performed in the target temperature maintenance process, and temperature decreasing target is also used when lowering the temperature of the part to be baked. Setting the temperature, temperature control to lower the temperature to the target temperature is divided into temperature control steps, and temperature control stopping state below the target temperature is divided into temperature control stop steps, and at each control step, the temperature difference between each part to be baked is reduced, The object of the present invention is to provide a multi-stage baking control method for uniform baking.

[Means for solving problems]

The above purpose is to judge each stage of the temperature control method: temperature increase process, target temperature maintenance overpoint, temperature decrease process, and control stop, and in each process, perform temperature control to reduce the temperature difference of each part to be baked by /h. It is achieved by doing.

Here, the vertical allowable width in the temperature raising process and target temperature maintenance process is α1. α2. The vertical allowable width during the temperature cooling process is β1.
Let it be β2. There are two methods for determining the temperature control process: one uses the average temperature of all thermocouples, and the other uses the average, maximum, and minimum temperatures of all thermocouples. When the average temperature of all thermocouples is used as the judgment criterion for each stage, the average temperature is the lower limit of the allowable temperature range of the target temperature To shown in Fig. 6 (T o - α
13 is the temperature increasing process until reaching 2), and the allowable temperature Yamauchi (
T.

−α! ``TO+aO), 14 is the target temperature maintenance process, and the temperature reduction process is until it reaches the upper limit (T1+β1) of the allowable temperature range of the target temperature T1 after baking is completed, and if the upper limit of the allowable temperature range is reached, 15 is controlled. It will be stopped.

When the average temperature, minimum, and maximum temperature of all thermocouples are used as the criteria for each stage, the minimum temperature is the target temperature To shown in Figure 6.
1 until the lower limit of the allowable temperature range (T o - α2) is reached.
6 is the temperature rising process, and the average temperature of all thermocouples is within the allowable temperature range (T).

-α2~T1+αl), 17 is the target temperature maintenance process, and the temperature reduction process is until the maximum temperature reaches the upper limit (T1+β1) of the allowable temperature range of the target temperature T1 after baking, and When the upper limit is reached, control is stopped at step 18. As for the control method in each temperature control process, as shown in FIG. 7, in the temperature raising process, the upper limit of the allowable temperature range (T)

An OFF command is output to the heater corresponding to the thermocouple 21 whose temperature has exceeded +α1), and an ON command is output to the heater corresponding to the thermocouple 22 whose temperature has fallen below the lower limit of the allowable temperature range (T o -α2). Further, each part to be baked has a part where the temperature rises quickly. Therefore, considering the temperature difference between the temperature of each thermocouple and the lowest temperature, we set the allowable temperature difference TLz (upper limit) and TL2 (lower limit) for monitoring the temperature difference, and the thermocouple when the allowable temperature difference TLI is reached is set. An OFF command is issued to the pair of heaters 19, and the difference between the lowest temperature and the allowable temperature difference TLz
At the time point 20 when the time point 20 is reached, an ON command is output. In other words, two types of control are performed: target temperature control and monitoring of the temperature difference between the lowest temperature and the lowest temperature.

The lower limit of the allowable temperature range (T
An ON command is output to the heater 24 whose temperature is below o-α2).

In the temperature decreasing process, the upper limit of the allowable temperature range (T1 + βl)
An OFF command is sent to the heater corresponding to the thermocouple that has exceeded the temperature limit.
Outputs an ON command to 5. In addition, considering the temperature difference between each part of the baking target, allowable temperatures TLa (upper limit) and Ti4 (lower limit) are set to monitor the temperature difference with respect to the maximum temperature, and the parts where the temperature decreases quickly are stopped when the control is stopped. If the heater 27 reaches the lower limit TLa of the allowable temperature difference before reaching the
The command is sent to the heater 26 whose temperature difference has reached the upper limit TLa.
Outputs N command. In the temperature decreasing process, as in the temperature increasing process, temperature difference control between the target temperature and the maximum temperature is performed. When the control is stopped, an OFF command is output to all heaters.

[Effect]

Baking temperature control according to the present invention involves inputting the temperature of each baking machine, the temperature of the part to be controlled, the temperature from the heater, the abnormality signal from the power supply, etc., and determining whether there is an input failure or overheating abnormality, and detecting the abnormality. It operates to output a CTT OFF command. This prevents malfunctions such as damage to thermocouples, heaters, and power supplies.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1, 8, 9, and 1.
This will be explained with reference to FIGS. 0 and 11.

As shown in FIG. 1, this embodiment includes heaters (1 to n) 2 that heat a baking object 1 and a thermocouple (1
This is an example applied to a plant comprising a baking temperature control computer 4 that performs 0NXOFF control 7 of the heater power supply CTT (contactors 1 to n) 5 based on the temperature measurement value 6 from the thermocouple 3 and the temperature measurement value 6 from the thermocouple 3.

In this example, when the temperature control process was evaluated using the average value of all thermocouples, the average value of all thermocouples was the highest.

It is shown by two cases when the lowest temperature is used.

The processing flow when the average value of all thermocouples is used to evaluate the temperature control process is shown in Section 8. The baking results are shown in FIG. 9, and FIG. 10 shows the baking results. In the baking temperature control calculator, as shown in FIG.

The control program is started periodically by an internal timer, and after inputting the input temperature Ti from all thermocouples (1 to n) in block A, the average temperature T AVE! is input in block C. ,
Find ^X for the minimum temperature TMIN and maximum temperature T.

In block D, as shown in FIG. 10, the average temperature TAVE is the lower limit of the allowable temperature range (T o - α
2) If it is below, it is a temperature increase process, and at the time 30 when the target temperature reaches the lower limit of the allowable temperature range (T o - α2), it is a target temperature maintenance process, and a temperature decrease target temperature T1 is set for decreasing the temperature of the baking target part. The temperature decreasing process is determined at 31°, that is, at the time when the target temperature is set lower than the previous time (To T1). In block E, as shown in FIG. 10, in the temperature decreasing process TAVE < (Ti + β) In other words, at the time point 32 when the target temperature for decreasing temperature reaches the upper limit of the allowable temperature, it is determined that the control is stopped.
Block E outputs an OFF command to all CTTs.

In block F, that is, in the temperature rising process, the current temperature data Ti from all thermocouples reaches the lower limit value (T o - α2) of the target temperature allowable temperature (Fig. 10, 33).
) and thereafter, if T i > (To+ a z), the CTT of the heater corresponding to Ti is turned OFF.

If Ti<(To-α2), ON output is performed. Also, the current temperature Ti is the lower limit (T) of the target temperature allowable temperatures.

−α2) or less, the temperature difference (T
A check 740 is performed to see if i-TMts) is within the allowable temperature difference. When the temperature difference (T i −TMrN) exceeds the upper limit Tt, z of the allowable temperature difference, the CTT of the heater corresponding to Ti is turned OFF, and when the temperature difference falls below the lower limit TLZ of the allowable temperature difference, the ON output is output. In other words, in the target temperature maintenance process, as shown in H block 05 in Figure 9, the target temperature tolerance range (To-α2
~To+α1), T i > (To+ct
If x>, the CTT of the heater corresponding to Ti is turned OFF, T
If i<(To+az), ON output is performed.

In block H, that is, in the temperature decreasing process, in block 05 shown in FIG.
is the upper limit of the allowable temperature range (Tz
+β1) After time 34, Ti>(Tz+β2)
Then, turn off the CTT of the heater corresponding to Ti, and set T
If i < (Tz-β2), outputs ON. The current temperature Ti is the upper limit of the allowable temperature range of the target cooling temperature (T I + β1
) or above, the current temperature data Ti and the maximum temperature T MAX
Monitor the temperature difference between the Temperature difference (T M^x-Ti)
exceeds the upper limit TLA of allowable temperature difference ((THAX-
T i ) > Ti8) C of heater corresponding to eTi
TT is turned ON, and when the allowable temperature difference becomes less than the lower limit TL4 ((THAX-Ti)<TL4), outputs TEOFFF. Next, an example will be shown in which the temperature control process is evaluated using the average value, maximum, and minimum temperatures of all thermocouples.

In this example, in comparison with the case where the average value of all thermocouples is used, block D shown in FIG. The temperature difference control method within each stage is the same except that the judgment of the control process of block E is different.For the explanation of this embodiment, only the judgment process of the control process of blocks D and H shown in FIG. 8 will be shown. , the baking results of this example are shown in FIG. 11. As shown in FIG. 11, if the lowest temperature Txx is below the lower limit (To-α2) of the allowable temperature range of the target temperature, the temperature rise process is performed. At a time point 35 when the lowest temperature T[N reaches the lower limit (To-α2) of the allowable temperature range of the target temperature.

During the process of maintaining the target temperature, when lowering the temperature of the part to be baked,
At the time point 36 when the temperature reduction target temperature is set, the temperature reduction process begins. In block E of Fig. 8, the temperature decreasing process (TAVF!<
(Tt + β1)), the time point 37 when the maximum temperature T MAX reaches the upper limit of the allowable temperature difference (Tz + β1) of the target cooling temperature
It is determined that control is stopped at block 5, and an OFF command is output to all CTTs at block 5.

In addition, the target temperature 'ro, Tz allowable temperature range (
t 1 + (X Z + β11 β allowable temperature difference T
t, z, Tpz.

TLJITL4 can be input from outside the computer, or can be held inside the computer.

According to this example, when the average value of all thermocouples is used, compared to the case where the average value, minimum, and maximum of all thermocouples are used,
The time required for all the electrocouple temperatures to reach the target temperature can be shortened. In other words, the time to reach the target temperature maintenance process and control stop is faster. On the other hand, when the average, minimum, and maximum values of the current thermocouple are used, the temperature rise process and temperature decrease are faster than when the average value of all thermocouples is used. In the process, the temperature rising process slope lllA in Fig. 10
38, that is, the thermocouple with a low temperature, will not enter the target temperature maintenance process with a large temperature difference from the target temperature, and the part of the diagonal line 39, that is, the thermocouple with a high temperature, will not enter the target temperature maintenance process with a large temperature difference from the target temperature. This eliminates the possibility of entering a controlled stop with a large temperature difference.

In either case, uniform baking can be achieved with no thermal stress caused by temperature differences compared to the conventional method.

〔Effect of the invention〕

According to the present invention, a temperature increase process and a target temperature maintenance process.

By controlling the temperature at each stage of the temperature-lowering process and the control stop, the temperature difference between the parts to be baked can be controlled to below a certain level, and there is an effect that uniform baking can be performed at the target temperature without generating thermal stress.

[Brief explanation of the drawing]

Fig. 1 is a baking temperature control configuration diagram of an embodiment of the present invention, Fig. 2 is a conventional baking temperature control configuration diagram, Fig. 3 is a review diagram of baking temperature control according to the prior art, and Fig. 4 is a baking temperature control diagram of the conventional technology. Explanatory diagrams showing control results, Figures 5 to 7 are baking temperature control study diagrams of the present invention, 8th and 9th
Figure 1 is a baking temperature control flowchart according to an embodiment of the present invention.
Figure 0. FIG. 11 is an explanatory diagram of baking control results according to an embodiment of the present invention. 1... Baking object, 2... Heater, 3... Temperature measuring device (thermocouple), 4... Baking temperature control calculator, Figure 1, Port 2, No. 30, $1L Oral pronunciation: Average quantity & standard E(ra-1〉n-row),,
, □1,7 佽, 佽1. Reiten, 2 cheering bells C
Divided into one streetcar (1L) No. 10 (b)

Claims (1)

[Claims] 1. In a baking control device consisting of a plurality of heaters, a sensor that inputs the temperature of the baking target installed near the heater, and a control device that controls ON/OFF of the heater based on the temperature input from the sensor. ,
The temperature control process is divided into a temperature increase process, a target temperature maintenance process, a decrease process, and a control stop process, and the temperature difference between each part to be baked is minimized at each stage to reduce the occurrence of thermal stress. Baking temperature control method.