JPH0425648B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a control system for an enamelled wire baking furnace, and particularly to this type of control system that prevents the quality from changing even when changing the furnace temperature setting when replacing the core wire bobbin. [Technical Background of the Invention] Conventionally, hot air circulation enamelled wire baking furnaces have been known for baking insulating paint onto core wires such as copper wires and aluminum wires to produce insulated wires for use in electric motors and the like. As shown in FIG. 1, in this baking furnace, a wire 4 runs from a wire entrance 2 to a wire exit 3 of a wire running path 1, and a baking varnish (for example, polyester (PEW),
Ester-based resins such as polyester imide (EIW), or polymarine-based resins such as polyvinyl formal (PVF) and polyurethane (UEW))
The solvent is heated to a high temperature using combustion gas supplied from a damper (switch) GAS-D, combusted by a catalyst 6, and the high-temperature air is circulated by a blower 7 in the direction of the arrow in the figure. In this furnace, in addition to the damper GAS-D that adjusts the amount of air 8 supplied (therefore, the amount of gas 9 (e.g., butane) supplied according to the amount of air), dampers are installed at various locations. It is provided. That is, the damper F-D installed at the top of the furnace body
is for adjusting the amount of air exhausted from the furnace body. PB-D is a damper that forms a pressure chamber and seals hot air from the furnace body. Together with damper D, C-D is a damper that sends hot air directly to the upper part of the evaporation zone EZ. Further, B-D is a damper that separates hot air into the hardening zone CZ and the evaporation zone EZ, which changes the air volume in the hardening zone and the evaporation zone, which affects the baking degree of the baking line. These dampers GAS-D, FD, PB-
By adjusting the opening degrees of D, CD, and BD, an optimum temperature distribution can be given to the evaporation zone EZ and the hardening zone CZ, and the degree of baking of the varnish applied to the electric wire can be determined. In order to measure such temperature distribution, temperature detection points are provided at various locations on the furnace body. That is, measurement point 16 before the hot air is divided into the hardening zone and the evaporation zone (its temperature is designated as B-T), and measurement point 1 at the confluence of the hot air blowing from the furnace body and the cold air from the damper PB-D.
7 (the temperature is PB-T), measurement point 18 in the middle of the hardening zone (the temperature is K-T), measurement point 19 in the upper part of the evaporation zone (the temperature is J ₁ -T), evaporation This is the measurement point 20 at the lower part of the zone (its temperature is _J2 -T). The core wire is fed out from the core wire bobbin 47 in the furnace where the temperature distribution as described above is formed, is wound a predetermined number of times between the pulleys 42 and 43 via the pulley 41, and then is wound up via the pulleys 44 and 45. It is wound onto a bobbin (not shown). Linear speed is controlled by pulley 44 by AC variable speed motor _M15 .
It is controlled by driving the motor and changing its rotation speed. Conventionally, when replacing the core wire bobbin 47, it has taken a considerable amount of time to pull out the core wire ends of the old and new bobbins, joint them, and then replace the new bobbin. However, in the high-temperature, high-speed machine of the hot air circulation type enamelled wire baking furnace as described above, it is troublesome to draw out the core wire, and there are many troubles in the joint work. For this reason, when replacing the core wire bobbin, it is necessary to reduce the wire speed and perform the jointing operation, but this has the disadvantage that the degree of baking exceeds the characteristic and the resulting product becomes scrap. [Object of the Invention] The present invention has been made to solve the above-mentioned conventional difficulties, and it provides an enameled wire that has a correlation between the furnace temperature and the wire speed when replacing the core wire bobbin, thereby stabilizing the quality characteristics. The purpose is to provide a control method for a baking furnace. In order to achieve this objective, the control method for the enameled wire baking furnace according to the present invention uses an enameled wire baking furnace that can control the furnace temperature to a predetermined temperature distribution with respect to the wire speed of the enameled wire, and coats the core wire with insulating coating. to produce an enamelled wire by baking in the baking furnace, lowering the furnace temperature when replacing the core wire bobbin,
Thereafter, the linear velocity is increased again, and the linear velocity is decreased or increased in accordance with the temperature change in the curing zone. Furthermore, in order to further improve the characteristics, this control method reduces the linear velocity earlier by a predetermined time when the furnace temperature falls, and increases the linear velocity after a predetermined time delay when the furnace temperature rises. It is something. [Preferred Embodiments of the Invention] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. First, control of the furnace temperature and its temperature distribution will be explained. Generally, one furnace burns various types of wires with wire diameters of about 0.4 to 2 mmφ, but the wire speed varies depending on the wire diameter, and the furnace is made up of a set of two wires, for example. As many as 70 sets of wires are being baked at the same time, but they are naturally affected by the heat from the neighboring furnace, and the steady supply of gas also varies depending on the diameter of the wires and the type of varnish. Under these circumstances, in order to control the temperature of the furnace, for example, the temperature at the measurement point 16 must be controlled by the damper 5.
Therefore, a technique has been devised and implemented in which the temperature at the measurement point 17 is controlled by the damper 11, and the temperature at the measurement point 20 is controlled by the damper 10 using a PI controller. However, in this technique, the measurement point 1
Although the temperatures at points 6 and 17 can be controlled to a desired constant value, point 1, which is an important control amount in this example,
8, 19, and 20 cannot be adjusted to a predetermined temperature distribution or gradient. This means that if you adjust one damper to control one of the measurement point temperatures to a desired value,
This is because even if the temperature at that point can be adjusted to the desired value, the temperatures at other points will also change. That is, a large number of controlled variables (in the case of this embodiment, point 1
Temperature PB-T, K at 7, 18, 19, 20
-T, J ₁ -T, J ₂ -T) (in this example, points 16, 17, 18, 19, 20
The temperatures at B-T, PB-T, K-T, J ₁ -T,
J ₂ -T) is a large number of manipulated variables (in the case of this example, dampers GAS-D, FD, PB-D, CD, B
- In control (multivariable control) where each variable changes when any one of the opening degree of D) is operated, each manipulated variable is adjusted so that each controlled variable becomes the desired value by measuring the measured amount. It is impossible to control both simultaneously and automatically using conventional PI control technology. Further, due to the correlation between the controlled variable and the manipulated variable of multiple variables, a control method based on each pair of controlled variable and manipulated variable has poor stability of the controlled variable and poor responsiveness. Therefore, in one embodiment of the present invention, when performing multivariable control of an enameled wire baking furnace, a detection element for a measured quantity including a controlled quantity such as the furnace temperature is used to
At the same time, manipulated variables such as damper opening are adjusted so that each controlled variable reaches the desired value (set target value).
And it is intended to be automatically controlled. Next, such multivariable control will be sequentially explained. First, in this example, each damper shown in FIG.
GAS-D, FD, PB-D, CD, and BD are stepping motors M5, M10, and M1, respectively.
The opening degree is adjusted by 1, M12, and M14,
In addition, thermocouples are installed at points 16, 17, 18, 19, and 20. Each stepping motor receives an input signal (shown as a solid line) and generates an output signal (shown as a dotted line). Furthermore, an output signal is generated from the motor M ₁₅ that regulates the linear velocity, and the linear velocity is indicated by the linear velocity meter 40 . Each thermocouple also produces an output signal. These signals are I/O
(A/D) A/D converted by controller 25
CPU26 (manufactured by Heuretsu Patscard Co., Ltd.)
HP1000M series), where it is calculated and
The controlled signal is sent to the controller 25 again.
The signal is converted into A and applied to the stepping motor of each damper. Next, such a control system will be explained in detail based on FIG. 2. In this method, a plurality of control variables such as temperature (temperature PB- at points 17, 18, 19, 20
T, K-T, J ₁ -T, J ₂ -T) Y=Y ₁ Y ₂ Y ₃ Y ₄ (points 16, 17, 18, 1
Temperature B-T, PB-T, K-T at 9,20,
J ₁ -T, J ₂ -T Y ₁ Y ₂ Y ₃ Y ₄ Y ₅ is multiple manipulated variable such as damper opening (damper GAS-D, FD, PB-D, C-D, B -D
The _control variable is adjusted to its _target value Y _R = Y _{R1 Y R2 Y R3} Y _R4 when U = U 1 U 2 _{U 3} U ₄ U ₅ . The purpose is to control the amount of operation. The controlled quantities Y ₁ to _{Y 4} are drawn out from the extraction point 31 and connected to the subtraction points 32 of the target values YR ₁ to YR ₄ , respectively, and the difference between the controlled quantities and the target values Y ₁ −Y _R1 〓 〓 Y ₄ − Y _R4 = ε ₁ 〓 ε ₄ is obtained. These differences ε ₁ ...ε ₄ are applied to the calculation element C. Element C is a matrix written as C ₁₁ ...C ₁₄ 〓 〓 C ₅₁ ...C ₅₄ , where C ₁₁ ...C ₁₄ 〓 〓 C ₅₁ ...C ₅₄ ε ₁ 〓 ε ₄ = U′c ₁ 〓 U′c ₅ The manipulated variables U'c ₁ ... U'c ₅ are given by linear processing. These manipulated variables are each integrator I ₁
~ I ₅ is applied, an integral action is performed and the quantity Uc ₁ ~
It is applied as _Uc5 to each manipulated variable _U1 to _U5 . This quantity Uc is expressed as follows as a result of performing an integral function. Uc(t)＝Uc(t-1)＋C ₁₁ …C ₁₄ 〓 〓 C ₅₁ …C ₅₄ ε ₁ 〓 ε _4This integral operation includes not only the linear integral function by the integrator, but also the integral function. Or it includes operations similar to this. Further, the integral operation may include dynamic compensation. In addition, each element of calculation element C, C ₁₁ ...C ₁₄ 〓 〓 〓 C ₅₁ ...C ₅₄ , is optimized in advance using the control object as a model before automatically controlling the enameled wire baking furnace 30 as the control object. Control theory and target values YR ₁ to _{YR 4}
Manipulated variables U′c ₁ ~ U′C ₅ and manipulated variables
U ₁ to U ₅ and a simulation of the behavior of the controlled variables Y ₁ to _{Y 4} , and is determined most appropriately (“Control System Design for Furnace by
Using CAD”by K.Furuta et al at the IFAC
Symposium on the Theory and Application
of Digital Control, Delhi, Sessin 20, 1982). Further, the extraction point 31 is the feedback element F
It is connected to the subtraction point 33 via. As a result, a feedback operation is performed on the measured quantities Y ₁ to _{Y 5} including the controlled quantities Y ₁ to _{Y 4} through linear processing, and the manipulated quantities
It is applied subtractively to U ₁ to _{U 5} . This feedback operation may include dynamic compensation. The feedback output U _F is U _F = U _F1 〓 U _F5 = F ₁₁ ...F ₁₅ 〓 〓 F ₅₁ ... F ₅₅ Y ₁ 〓 Y ₅ . Note that each element of F ₁₁ ...F ₁₅ 〓 〓 〓 F ₅₁ ...F ₅₅ is also determined in advance by the aforementioned optimal control theory and simulation. Furthermore, the extraction point 34 is connected to the summing point 33 via a feed forward element N. As a result, a feedforward operation, that is, a proportional operation is performed on the target values Y _R1 to Y _R4 by linear processing, and is applied additively to the manipulated variables U ₁ to _{U 5} . This feed forward operation may include dynamic compensation. Feedforward output U _N
is, U _N = U _N1 〓 U _N5 = N ₁₁ …N ₁₄ 〓 〓 N ₅₁ … N ₅₄ Y _R1 〓 Y _R4 . In this case, each element of N ₁₁ ...N ₁₄ 〓 〓 N ₅₁ ...N ₅₄ is also determined in advance by the optimal control theory and simulation as described above. In this way, as a result of three types of operation inputs being supplied to the manipulated variable U, the manipulated variable U finally becomes as follows. U = Uc - U _F + U _N A limiter L is interposed in each operating line to stop the integral operation when the sum output Uc - U _F + U _N supplied to the manipulated variable exceeds a predetermined range. (Figure 2). In FIG. 2, the part surrounded by a dotted line represents the CPU, and the input interface for target values Y _R1 to Y _R4 includes an input/output device I/O-1 for A/D conversion,
The output interface for the manipulated variables U ₁ to U ₅ has D/
Input/output device I/O-2 for A conversion, control amount
An input/output device I/O-3 for A/D conversion is interposed at the input interface to the backward path of the measured quantities Y ₁ to Y ₅ including Y ₁ to _{Y 4} (FIG. 1). The multivariable automatic control system configured as described above operates as follows. First, the baking furnace 30 is operated to control the control amount Y ₁ to Y ₄
The initial value of the integral operation is set according to the measured quantities Y ₁ to _{Y 5} including (FIG. 3). Next, the CPU is set to the target value
YR ₁ to _{YR 4} , measured quantities Y ₁ to Y ₅ including controlled quantities Y ₁ to Y ₄
Read the data. The calculation element C, the feedback element F, and the feedback element N of the CPU each perform their calculations according to the values expressed by the above-mentioned determinant, and U′c=U′c ₁ 〓 U′c ₅ =C ₁₁ …C ₁₄ 〓 〓 C ₅₁ …C ₅₄ ε ₁ 〓 ε ₄ U _F ＝U _F1 〓 U _F5 ＝F ₁₁ …F ₁₅ 〓 〓 F ₅₁ …F ₅₅ Y ₁ 〓 Y ₄ U _N ＝U _N1 〓 U _N5 ＝N ₁₁ ...N ₁₄ 〓 〓 N ₅₁ ...N ₅₄ Y _R1 〓 Calculate Y _R4 . This manipulated variable output needs to be controlled and maintained within a predetermined range. Therefore, it is determined whether each manipulated variable output value is within the range, and if it is within the range, an integral operation is performed, and if it exceeds the range, it is output via limiter L. (Figure 3). In this way, the integrators I ₁ ... I ₅ act on _each manipulated variable U′c ₁ . yields an integral output of ′c ₅ . If such a function is introduced, even though the damper opening degree as the manipulated variable is 0 to 100% as in this embodiment, if the integral operation is performed from the start of the operation, the manipulated variable will initially be and the target value ε ₁ … ε ₄
Since this is large, it is avoided that the damper opening degree effectively generates an undesirable manipulated variable signal of 200 or 300%. In this way, the integrator repeats the integration operation until the difference between the controlled variable and the target value ε=Y _R1 〓 Y _R4 −Y ₁ 〓 Y ₄ becomes zero, so that the controlled variable approaches the target value as much as possible. It forms a control loop. Thus, the manipulated variable U U=Uc-U _F + _UN is calculated and output to the controlled object 30. In this case, the feedback output U _F of the feedback element F has the function of stabilizing the inherent characteristics of the control system. On the other hand, the output U _N of the feedforward element N is
It accelerates the rise of the controlled variable Y so that it quickly approaches the target value _YR , and has a particularly great effect at the start of furnace operation. This element N further improves the responsiveness of the control system. In this way, when the manipulated variable U is output to the controlled object 30, it is delayed for a predetermined time until the next sampling,
The following operation is repeated again. In the above embodiment, there are four controlled variables and target values,
Although the case where there are five manipulated variables, manipulated quantities, and measured quantities has been described, the present invention is equally applicable to cases where there are l and m pieces, respectively (l and m are positive integers, and m≧l). It is. <Specific Example> The following experiment was conducted using a hot air circulation baking furnace as shown in FIG. Polyester varnish (polyester resin TVE manufactured by Toshiba Chemical Co., Ltd.) is placed at the bottom of the above furnace.
5326F, wire diameter 1.0 in applicator 48 containing 40% resin and 60% solvent (cresol, naphtha).
mm copper wire was passed through and varnish was applied to its outer periphery. The wire thus obtained is run through the furnace, the solvent for the varnish applied to the outer periphery of the wire is heated to high temperature with pure butane gas supplied from the damper GAS-D, and is combusted by the honeycomb type platinum catalyst 6 and then by the blower 7. circulated hot air. The temperatures at measurement points 17, 18, 19, and 20 were set to their respective steady-state temperature target values. Damper GAS-D, FD, PB-D, C-D, BD
The temperature at measurement points 17 to 20 including measurement point 16 is adjusted by controlling the opening degree of the
-T, K-T, J ₁ -T, and J ₂ -T were measured. The results are shown in FIG. In this figure, the same reference numbers as in FIG. 1 represent the same parts. As is clear from FIG. 4, the multivariable control starts at point X, and in the Y band, the temperatures PB-T, K-T, J ₁ -
T and _J2 -T were each adjusted independently to the target value. Furthermore, the temperature target values for measurement points 18 and 19 were set at points P and Q, respectively, with a 10°C increase. As is clear from the figure, the temperatures as control variables at the obtained measurement points 18 and 19 could be independently adjusted to each target value. Next, control of the enameling wire speed in relation to the above-mentioned furnace temperature and its temperature distribution will be explained. Temperature change d(K-T)/dt of hardening zone CZ of baking furnace
is read into the CPU 26 via the I/O controller 25. The CPU sends a signal obtained by calculating the linear velocity change dv/dt of the linear velocity V corresponding to this temperature change to I/
This signal is output to the EC motor _M15 via the O controller 25, and via the pulley 44, the linear speed of the enameled wire 4 is decreased or increased. Note that the correspondence between the temperature change and the linear velocity change is substantially a proportional operation, but it includes not only a linear proportional function but also an operation that includes a proportional function or is similar to this. Next, the correlation between furnace temperature and linear speed is
An example will be described in which the core wire of 1 is used under the same conditions as the above-mentioned specific example. In Fig. 5 a to c, the steady state is maintained for 30 minutes from the start of the measurement, and dampers C-D, B-D,
PB-D, GAS-D, FD and furnace temperature B-T, K-
T, J ₁ -T, J ₂ -T, and PB-T are controlled to predetermined opening degrees, furnace temperatures, and temperature distributions by the multivariable control described above. At 30 minutes, input to replace the core wire bobbin is given. That is, the target furnace temperature values Y _R1 to _{Y R4} (FIG. 2) are lowered for the joint work and bobbin replacement work. The damper opening degree is controlled by this low temperature target value, and the furnace temperature is lowered. Corresponding to the temperature change of the temperature K-T of the hardening zone CZ among the furnace temperatures, the rotational speed of the motor _M15 is lowered and the linear speed is also lowered.
When the furnace temperature falls, the linear velocity is lowered earlier by a predetermined time _t1 . This is the enamelled wire pulley 42-43
This is because the wire is wound 5 to 10 times in between, and there is a thermal time lag between the beginning and end of the winding. For 60 to 80 minutes, the furnace temperature remains low,
Linear speed is also maintained at a low speed, and joint work and bobbin replacement are performed during this time. Again, at 80 minutes, to return the furnace temperature to the original temperature,
The target values Y _R1 to _{Y R4} are set to the first high temperature.
The damper opening degree is controlled, and the furnace temperature and its temperature distribution are returned to their original state in 95 minutes. The line speed is also increased correspondingly to the temperature increase of the temperature K-T in the hardening zone of the furnace. Furthermore, when the furnace temperature rises, the linear velocity changes over the aforementioned time t ₁
For the same reason mentioned for a given time t ₂
It will be raised later. Note that t ₂ is substantially equal to t ₁ . Figure 6 shows the vertical line 1 for the sampling position time for confirming quality characteristics when the furnace temperature changes in Figure 5a.
It is shown in ~10. The table below shows quality characteristic comparison data for each sampling number of position times 1 to 10. As is clear from the table, as a result of creating a predetermined correlation between the furnace temperature and linear speed when changing the furnace temperature setting when replacing the bobbin,
The quality of the hue value was unchanged from that in the steady state, and a good quality enameled wire was obtained. In addition, the above examples are examples of enamelled wire with PEW0.5mmφ, but PVF, _U EW, EIW
The same excellent effect was obtained for lines such as .

【table】

【table】

〔Effect of the invention〕

As is clear from the above embodiments, according to the enameled wire baking furnace control of the present invention, a predetermined correlation is given to the furnace temperature and wire speed when changing the furnace temperature setting when replacing the core wire bobbin. As a result, the same quality characteristics as in the steady state of the furnace can be obtained.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a hot air circulation enamelled wire baking furnace as a controlled object, Fig. 2 is a block diagram of an automatic control system in which the present invention is applied to the controlled object, and Fig. 3 is an operational flowchart of the system. Fourth
The figure is a graph showing the control result values of the controlled variable (temperature) and the manipulated variable (damper opening) by this method. Figure 5 a, b, and c are graphs of furnace temperature, damper opening, and linear velocity. Figure 6 5 is a diagram showing sampling position times for confirming quality characteristics in FIG. 5a; FIG. 30...Enameled wire baking furnace, 47...Core wire bobbin, K-T...Temperature in hardening zone, Fig. 5c...Line speed.

Claims (1)

[Claims] 1. In manufacturing an enameled wire by using an enameled wire baking furnace in which the furnace temperature can be controlled to a predetermined temperature distribution with respect to the linear speed of the enameled wire, and baking an insulating paint on the core wire in the baking furnace. , when replacing the core wire bobbin,
A control method for an enameled wire baking furnace, characterized in that the furnace temperature is lowered and then raised again, and the wire speed is lowered or raised in accordance with temperature changes in the hardening zone. 2. The enameled wire baking furnace according to claim 1, wherein when the furnace temperature falls, the linear speed is lowered earlier by a predetermined time, and when the furnace temperature rises, the wire speed is increased after a predetermined time delay. control method.