JPH03152390A - Method and device for temperature control of fusion furnace - Google Patents

Abstract

PURPOSE:To automatize working by evaluating supply power by evaluating means for raising a melt to target temperature based upon the required supply power and preset fusion time. CONSTITUTION:Required power for fusion of a fused material throw into a fusing furnace 1 is previously estimated by evaluation means 11 based upon the weight of the fused material and characteristic values of the same. On the basis of the evaluated power, power is supplied to a fusing furnace 1 and the material is completely fused. Temperature of a melt 4 is automatically measured by temperature measuring means 5, and the evaluation means 11 evaluates required supply power on the basis of temperature difference between the temperature of the melt 4 and target temperature and further evaluates supply power of raising to the target temperature from the preset fusion time. Hereby, monitoring of fusion by a worker is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a temperature control method for a melting furnace and an apparatus thereof, and particularly to a temperature control method for a melting furnace that automates temperature control during melting of melted material. and regarding equipment.

[Prior Art] In a melting furnace for melting metal materials, temperature control is performed to raise the temperature of the molten metal to a desired temperature, and the amount of electricity applied to the melting furnace is controlled based on the measurement result of the molten metal temperature. By controlling the temperature of the molten metal, the temperature of the molten metal reaches a predetermined temperature with high accuracy.

As prior art related to this, for example, JP-A-63-
108190 @ publication and Japanese Patent Publication No. 1-32916 are known. The former predicts the temperature of the molten metal at the time the set cycle time is reached based on the rate of temperature rise of the molten metal.
The input power is calculated by comparison with the temperature, and the molten metal temperature is made to reach the target temperature in a predetermined cycle time.

The latter calculates the time required to raise the molten metal by 1°C in response to the furnace input, measures the temperature of the molten metal after melting with a humidity sensor, and then adds 1°C for each of the above hours to reach the target temperature. I am trying to output a signal at that point.

[Problems to be Solved by the Invention] However, in the case of the devices disclosed in both of the above-mentioned publications, in order to measure the humidity of molten metal, it is necessary to determine whether or not the molten material has completely melted. In the latter case (Japanese Patent Publication No. 1-32916@publication), supervision by an operator was required during melting of the melted material. The former (Unexamined Japanese Patent Publication No. 1983-
108190), the molten state is determined based on whether the detected temperature T is higher than the molten metal temperature TO, which is the plus of the melting temperature, but it is extremely difficult to insert a temperature sensor into the furnace before melting. Since this is difficult and the accuracy of temperature measurement is low, in reality, a supervisor is required as in the former case.

In addition, in the latter case, there is no means to set the dissolution time within a predetermined time, and the dissolution time fluctuates due to fluctuations in each weighing condition.
It is unsuitable in cases where cycle time is restricted, such as in one-shot Merck.

Generally, in both cases, there is no switching of the input power until the melting is completed or after the melted material has completely turned into molten metal, so in the case of rapid melting in a short time, temperature control cannot be done in time. There is a risk that the melting furnace will become A-bajito.

The present invention has focused on the above-mentioned problems, and aims to provide a temperature control method and device for a melting furnace that does not require operator monitoring during melting of melted materials and can melt in accordance with the cycle time. shall be.

[Means for Solving the Problems] A temperature control method for a melting furnace according to the present invention that meets this objective is as follows:
In a temperature control method for a melting furnace that melts a melting material by supplying electric power, the amount of electricity required to completely melt the melting material input into the melting furnace is determined in advance from the weight and characteristic values of the melting material, The molten material is melted by supplying electric power based on the electric power, the temperature of the molten metal is automatically measured after the melting of the molten material is completed, and the temperature difference between the automatically measured molten metal temperature and the molten metal target temperature is required. The method consists of calculating the amount of power to be supplied to raise the temperature of the molten metal to a target temperature from the required power supply port and a preset melting time.

Further, the temperature control device for a melting furnace according to the present invention includes a temperature measuring means that automatically measures the temperature of the molten metal in the melting furnace, and a temperature measuring means that automatically measures the temperature of the molten metal in the melting furnace, and a temperature control device that automatically measures the temperature of the molten metal in the melting furnace. At the same time, the required power supply port is determined from the temperature difference between the temperature of the molten metal measured by the temperature measuring means and the target temperature of the molten metal. a calculation means for calculating the power to be supplied to bring the molten metal up to the target temperature from a set melting time; and a power control means for controlling energization m to the melting furnace based on a signal from the calculation means. It consists of a device equipped with the following.

[Function] In the temperature control method of a melting furnace configured as described above and its method, first, the temperature required for the melting material charged into the melting furnace to be completely melted is calculated based on the weight and characteristic values of the melting material. The amount of electric power is determined in advance by the calculation means. Then, electric power is supplied to the melting furnace based on the determined electric power amount, and the melting material is completely melted. When the molten material is melted, the temperature of the molten metal is automatically measured by the temperature measuring means. The calculation means calculates the required amount of power to be supplied from the temperature difference between the automatically measured temperature of the molten metal and the target temperature of the molten metal, and roughly calculates the amount of power to be supplied to the molten metal to the target from this amount of power to be supplied and the preset melting time. The power supplied to change the temperature is calculated.

In this way, the temperature of the molten metal is measured by the humidity measuring means after the molten metal is completely melted based on the amount of power supplied by the extraction means.
There is no need for an operator to monitor the complete melting of the melt.

In addition, after the melting vi 11 is completely melted, the required supply rate is calculated from the temperature difference between the measured temperature of the molten metal and the target temperature of the molten metal, and this supply power amount and the preset value are determined. Since the electric current to be supplied is adjusted according to the melting time, it is possible to adjust the temperature according to the cycle time, and it also prevents the melting furnace from overshooting due to a sudden rise in temperature. .

[Embodiments] Below, preferred embodiments of the melting furnace temperature control method and device according to the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1 to 6 show a first embodiment of the present invention, of which FIG. 1 shows a temperature control installation of a melting furnace to which the present invention is applied.

In FIG. 1, 1 indicates a melting furnace, and a high-frequency heating coil 3 is arranged around the outer periphery of a furnace body 2 of the melting furnace 1;
has been done. Melting material is put into the furnace body 2,
The melted material is heated by the high frequency heating coil 3 through the IJ and melted.

Temperature measuring means 5 for measuring the temperature of molten metal 4 melted by high-frequency heating coil 3 is arranged above furnace body 2 . The temperature measuring means 5 is attached to the elevating means 6, and when measuring the temperature, the temperature measuring means 5 can be immersed in the molten metal by the lowering operation of the elevating means 6. In this embodiment, the temperature measuring means 5 is composed of a thermocouple immersed directly into the molten metal 4, but a non-contact type temperature measuring means such as the late tFJ thermometer may also be used. Therefore, when a non-contact type temperature measuring means is used, the elevating means 6 as in this embodiment is not necessary. The high frequency heating coil 3 and the temperature measuring means 5 are connected to a temperature υ control means. The temperature control means 7 is a CP of a microcomputer as @ calculation means.
It is composed of a UII, an AD converter 12, and a power control means 13.

The CPU II has a function of determining the electric power required for completely melting the melting material introduced into the melting furnace from the 1,000G of the melting material and the characteristic values. Also, c p u t
i calculates the required amount of power to be supplied from the temperature difference between the temperature of the molten metal 4 measured by the temperature measuring means 5 and the target temperature of the molten metal 4, and calculates the amount of power to be supplied from this amount of power and the preset melting time. It has a function to calculate the power to be supplied to bring the molten metal to the target temperature.

The temperature measuring means 5 is connected to the CPtJl via the AD converter 12.
connected to l. In other words, since the temperature measuring means 5 is composed of a thermal lightning pair, it is necessary to convert an analog signal into a digital signal, and the temperature information is sent to the CPU 11.
A digital signal is input to.

The high frequency heating coil 3 of the melting furnace 1 is controlled by the power υ control means 13
It is connected to the CPU 11 via. Electricity control means 1
3 has a function of controlling energization ω to the high frequency heating coil 3 based on a signal from the cpuil. Also, g
The elevating means 6 for lowering the degree measuring means 5 four times is the CPU 1
1, and the temperature measuring means 5 moves up and down based on output signals from the CPU 11h1 and others.

Note that the initial input power amount WH, the initial input time t1, the melting time tc, the target melting temperature Tc, and the heat-retaining power W are preset in the CPU 11.

The initial input power ωW H, can be determined theoretically from characteristic values such as the weight, material, shape, etc. of the melted material, or can be determined by statistically processing data on actual melting.

The above-mentioned initial input power IWH is set within a range where the following relationship holds, taking as an example the power ff1WHH required to completely melt the melting material and the total input power ff1WHH until reaching the target melting temperature. Ru.

WHH+α<WHl<WHT xk Here, α is a margin coefficient for variations in melting efficiency and for complete melting, and k is a margin coefficient for variations in melting efficiency and for preventing overheating beyond the target melting temperature. Further, the total supplied power ffiWH■ is obtained in the same manner as WH)f.

In this example, the melting weight, the material and shape of the melting material are determined using a one-shot melter, etc., and the weight of the melting material is
Melting is performed after measuring and adjusting the melted abrasive material to a predetermined melted weight. However, a setting device (not shown) is provided in the temperature control means 7 to preset the weight of the melted material and other initial values. , QptJll via the setter every cycle.
[It is also possible to adopt a method of inputting initial values.

Next, a method of controlling the temperature of the melting furnace in this embodiment will be explained.

2 to 5 show characteristic diagrams showing the principle of the temperature control method in this embodiment. Of these, FIG. 5 shows the relationship between the melting time and the amount of supplied power.
W +−1, is supplied to the melting furnace. Figure 4 is a diagram showing the relationship between the electric power supplied to the melting furnace and time, and the time O
It is shown that the supplied power between t and t is Wo = WH,/l.

As a result of this electric power Wo being supplied to the melting furnace, the relationship between the temperature of the melted material and time becomes as shown in FIG. here,
Curve a represents an average example, curve b represents an example of the lowest dissolution efficiency within the range of variation, and curve C represents an example of the highest efficiency. As a result of supplying the initial supply power ff1WH, the molten metal temperature IT at time t is t a and T , respectively.
t b , Tt c becomes.

As is clear here, the initial supply power is 1ttWH.

Even in the least efficient case, the molten metal temperature T,b at the time of completion of supply = time t is T,b with respect to the melting completion temperature Tut.
It is set within the range of =T)l +Tα (TC is a margin coefficient). In addition, even in the most efficient case, the initial supplied power IWH, is the molten metal temperature T, c at time t, relative to the target melting temperature Tc: Tt C = TC - TB (TB is inertia and is margin coefficient).

In curves a, b, and c in Fig. 2, the molten metal temperatures at time t are T, a, T, b, T, and c, respectively.
The temperature difference from the target melting temperature TC is ΔTa = TC
−T,a,ΔTb=TC−T,b.

ΔTc=TCT,C, and if the temperature difference is increased by the time difference Δt=tc−t from the predetermined melting time tc, the target melting temperature TC can be reached in the predetermined melting time tc. Here, the amount of power required to increase the molten metal temperature by the temperature difference ΔT is expressed by the following equation.

ΔWH= η ×ρXMX△T+ΔWH (η: Furnace efficiency ρ: Specific heat of molten metal M: Melt weight ΔWH = Heat insulation
However, the required input power W in this case is W=ΔWH/Δt=η 8ρXMXΔT+Δt ΔW 1−1K =axΔT+W and Δt (a: coefficient WK: heat insulation power). Figure 3 shows the relationship between the temperature difference ΔK and the required power supply W. For the temperature differences ΔTa, ΔTb, and ΔTc corresponding to curves a, b, and c in Figure 2, the supplied power is W, respectively.
It can be seen that a, Wb, and WC.

In FIG. 4, the level of power supplied after time t is lowered because in the case of rapid melting, the rate of temperature rise is too fast and overheating is likely to occur due to delay in the control system. In other words, the drop in the supplied power after time t is:
This is a means for reducing the temperature increase rate and achieving the target melting temperature with high accuracy, and is essential in the case of rapid melting, and is also effective for improving accuracy in the case of normal melting. This method of lowering the level of supplied power does not require any special equipment; in the case of rapid melting, the initial input power amount WH, can be increased within the allowable range, and the time t, can be set as small as possible. It becomes possible. In addition, in normal melting, the initial supply power WH
, is the same, but since the rate of temperature increase is not very fast to begin with, the time t.

It is more economical to set the value to a larger value because the initial power supply becomes smaller.

FIG. 6 shows the procedure of information processing in CPtJll as operator Q.

As shown in step 30, the process starts when the preparation for melting is completed, and in step 31, the initial supply power Wo is changed to 1, 11.
The material is output to the melting furnace 1 side via the control means 13, and the melted material in the melting furnace is heated by the high-frequency heating coil. In step 32, the timer starts operating, and in step 33, it is determined whether the operating interval has reached t, and this operation is repeated until the result is t≧main. In other words,
Determine whether the melted material is completely melted by time. If ↑≧↑ in step 33, the process proceeds to step 34, where a descending command is output to the lifting/lowering means 6 of the humidity measuring means 5, and the temperature measuring means 5 is immersed into the molten metal 4.

Then, the molten metal temperature T is changed to CPtJ via the A/D converter 6.
Read by ll. In step 37, CPU1
1, the temperature difference ΔT=Tc−T from the target melting temperature TC is calculated, and in step 38, the input power W=a・ΔT +W
is calculated. In step 39, the result is output to the power control means 13, and the amount of current applied to the high frequency heating coil 3 is switched.

If the immersion time of the temperature measurement means 5 into the molten metal 4 and the stabilization time until the start of temperature measurement are too long due to rapid melting, etc., the timer is set to two stages and the timer is set to 2 steps for the above-mentioned time. It is best to use a timer that times up quickly to output a command to lower the temperature sensor 4, or to reduce the level to the heat-retaining power WK.

After switching the energization m, the process proceeds to step 40, where the humidity of the molten metal 4 is monitored. When the temperature of the molten metal 4 reaches the target melting humidity Tc, the process proceeds to step 42, where a melting completion signal is output, the power supply is set to the heat retention type fJWK, the energization m of the high frequency heating coil 3 is switched, and the process ends. .

Second Embodiment FIGS. 7 to 9 show a second embodiment of the present invention. This example differs from the first example in the relationship between the melting time and the temperature of the melted material, and the relationship between the melting time and the supplied power. By assigning the same reference numerals as in the first embodiment, explanations of corresponding parts will be omitted.

FIG. 7 shows the relationship between time and the temperature of the melted material, and FIG. 8 shows the relationship between time and input power. In this example, L-
tc is divided into n sections, and the molten metal temperature T is set for each section amount.
By measuring the temperature of i and calculating the supplied power Wi from the temperature difference between the result and the target melting temperature - "C", △Ti = Tc - T, the temperature difference between the temperature and the target melting temperature - "C" is calculated. Modifications will be made to ensure that.

In FIG. 7, the temperature of the molten metal is T at time t, so the temperature difference is T, = Tc T1, and the time difference Δt, =
The power supply W supplied to the melting furnace from tc tl is 1q
It will be done. At the next temperature measurement timing t2, the same process as at t3 is performed, and this process is repeated until ti=t−c.

FIG. 9 shows a flowchart of information processing in the CPU II of this embodiment. The difference from the first embodiment is that
After reading the molten metal temperature T1 in step 34, Ti is compared with the target melting temperature Tc in step 35, and when Ti≦TC, the process proceeds to step 36, and the time ti and the predetermined melting time t are determined.
When ti≦tc, the same processing as steps 37 to 39 in the first embodiment is performed in steps 37' to 39.
39' and return to step 34. The reason why ti>tc in step 36 is that the predetermined dissolution time te
In this case, the process immediately returns to step 34 and the same process is repeated until l'-1-Tc is reached. The supplied power at this time is t, >
The power Wi is fixed to the power Wi immediately before reaching tc.

When Ti = TC in step 35, the process proceeds to step 42, where the warming power WK is outputted via the power control means 13, and the process ends.

In addition, in FIGS. 7 and 8, in order to make the explanation easier to understand, the display is divided into certain time units, but the CPU 11
It is sufficient to perform the processing in each processing cycle from steps 34 to 39, and the processing flow in FIG. 9 is expressed in the latter manner.

Third Embodiment FIGS. 10 and 11 show a third embodiment of the present invention. This embodiment is an example that can be applied to prevent the central part of the molten metal from rising due to excessively supplied power, causing the molten metal to splash out of the furnace, and thereby limiting the power supply from safety and other reasons.

The method for setting the initial input power ffi W Hl is the same as in the first embodiment, but as shown in the figure, the supplied power is changed before and after the start of melting, and after the start of melting, a relatively small power is used. to prevent the danger of rapid melting.

[Effects of the Invention] As explained above, when the melting furnace humidity control method and device according to the present invention are used, the melting material I+ charged into the melting furnace is completely melted based on the weight and characteristic values of the melting material. The amount of power required for the molten material is determined in advance by a calculation means, and the molten material is melted by supplying power based on this power source. The required power supply is determined from the temperature difference between the automatically measured humidity of the molten metal and the target temperature of the molten metal, and the molten metal is heated to the target humidity based on the required amount of power supply and the preset melting time. Since the power to be supplied for increasing the power consumption is calculated by the calculation means, the following effects can be obtained.

K) There is no need for an operator to monitor the completion of melting of the melted material, and melting work can be automated and unmanned.

I With the conventional method of measuring the temperature from the time the melted material is introduced, it is unclear whether it is measuring the temperature of the melted material or the ambient temperature between the materials, and if melting has started partially, Although measurement errors are likely to occur, in the present invention, temperature measurement is started after complete melting, so such measurement errors can be reliably prevented.

Q) Since there is no delay in temperature control, there is no limit to the power supply and it can handle rapid melting.

■ Since the power supply is determined based on the humidity difference between the g degree at the time when the initial power supply port is turned on and the target melting temperature, as well as the time difference between the predetermined melting time, melting is completed accurately within the predetermined melting time, and the cycle time is fixed. If the temperature is too high, you can prevent the energy loss of keeping warm for the rest of the time. In addition, there is no longer a problem of not being able to meet the cycle time, and a decrease in productivity caused by this can be prevented.

(E) Since the initial power supply port and the completion timing can be adjusted so that the power supply level after the initial supply power is completed is low, the initial power supply port and the completion timing can be adjusted to quickly heat and melt with high power until the melting is completed.
After that, a sufficient heating rate can be achieved even by controlling the molten metal humidity, making it possible to control with high precision.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an apparatus used in the melting furnace temperature control method according to the first embodiment of the present invention, and FIG. 2 is a characteristic showing the relationship between the temperature of melted material and time in the apparatus of FIG. 1. Figure 3 is a characteristic diagram showing the relationship between the calculated temperature difference and required input power in the device shown in Figure 1, and Figure 4 is a characteristic diagram showing the relationship between supplied power and time in the device shown in Figure 1. , FIG. 5 is a characteristic diagram showing the relationship between melting time and amount of supplied power in the device shown in FIG. 1, FIG. 6 is a flowchart showing the procedure of information processing in the calculation means of the device shown in FIG. 1, and FIG. 8 is a characteristic diagram showing the relationship between the melting time and the temperature of the melted material in the melting furnace temperature control method according to the second embodiment of the present invention, and FIG. FIG. 9 is a flowchart showing the procedure of information processing in the calculation means when the characteristics of FIGS. 7 and 8 are used; FIG. 10 is a characteristic diagram showing the relationship between FIG. 11 is a characteristic diagram showing the relationship between the melting time and the temperature of the melted material in the melting furnace temperature control method; FIG. 11 is a characteristic diagram showing the relationship between the melting time and the supplied power based on the characteristics of FIG. 10. 1... Melting furnace 3... High frequency heating coil 4... Molten metal 5... Temperature measuring means 6... Lifting means 11... ...Performance means 13...Power control means Patent applicant Toyota Motor Corporation Fig. 1 Fig. 6 Fig. 9 Time (t)

Claims (1)

[Claims] 1. In a temperature control method for a melting furnace in which melting material is melted by supplying electric power, it is determined that the melting material charged into the melting furnace is completely melted based on the weight and characteristic values of the melting material. The required amount of electricity is determined in advance, the molten material is melted by supplying electricity based on the amount of electricity, the temperature of the molten metal is automatically measured after the melting of the molten material is completed, and the automatically measured temperature of the molten metal and the temperature of the molten metal are The required power supply amount is determined from the temperature difference with the target temperature, and the power supply for raising the molten metal to the target temperature is calculated from the required power supply amount and a preset melting time. Features: Melting furnace temperature control method. 2. Temperature measuring means for automatically measuring the temperature of the molten metal in the melting furnace, and determining the amount of electricity required to completely melt the melting material introduced into the melting furnace from the weight and characteristic values of the melting material. , the required amount of power to be supplied is determined from the temperature difference between the temperature of the molten metal measured by the temperature measuring means and the target temperature of the molten metal, and the amount of power to be supplied to the molten metal is determined based on the amount of supplied power and the preset melting time. A melting furnace comprising: a calculation means for calculating the power supplied to raise the temperature; and a power control means for controlling the amount of electricity supplied to the melting furnace based on a signal from the calculation means. Temperature control device.