JPH0719647B2 - Method for correcting outside temperature of induction heating temperature - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention uses a high frequency induction heating means to heat a member at 100 to 250 ° C.
More specifically, the present invention relates to a method for correcting an outside air temperature of an induction heating temperature suitable for baking a paint or solidifying a binder by raising a temperature to a low temperature of at least 300 ° C. or lower and then maintaining the temperature for a predetermined time.

(Prior Art) A high-frequency induction heating means is used to bake paint and solidify a binder, and the temperature is used to complete the process in a short time, and the required space is small. The use of this method tends to be widespread for reasons such as easy incorporation.

Conventionally, from experiments or experience, the optimum temperature rising temperature for the coating material used, baking of the binder, etc. was found, and the temperature of the member was raised to that temperature within a predetermined time.
The power output from the high-frequency power source is set to a predetermined value in relation to the mass of the member, the coil shape, the heating time, etc., and the initial setting power is changed unless the quality of the paint used, binder, etc. is changed. It never changed.

(Problems existing in the prior art) However, while paints, binders, etc. are relatively sensitive to temperature, on the other hand, there is a change in the outside air temperature of one day and a change in the outside air temperature of 30-40 ° C depending on the season. Therefore, the temperature difference in the low temperature region heating is 10 to 20%. Therefore, as shown in Fig. 2, when setting the power of the high-frequency power source in the experiment, the power needed to raise the temperature to Cn during the heating time "t0 to t2" without considering the ambient temperature condition. If there is, the applied heat energy to the paint used, which is transmitted from the member heated by the applied energy by the applied power, is displayed as a cross-hatched line between the time “t1 to t3” for maintaining the temperature Co or more and Cn or less. If the area corresponds to the area, if the optimum baking finish is set, if the heating is performed in an outside temperature state higher than the outside temperature at the time of the above-mentioned experiment, the input energy is constant, and therefore, in the elapsed time, t1
~ Α ~ t3 + β "is maintained above the temperature Co and the temperature higher than the reference temperature Cn is also Cn ', so the applied heat energy from the member to the paint, etc. This corresponds to the sum of the shaded area and the shaded area, resulting in excessive heat energy application. On the contrary, if the outside air temperature during the heating is lower than that during the experiment, the heat energy is insufficiently applied.

Further, when the heating is performed in two steps, that is, the heating by heating and the subsequent heating by keeping the power at a low level, the heating time becomes longer than that in the above example. The temperature difference will be further accumulated,
The excess and deficiency of the thermal energy applied to the paint used will increase.

Furthermore, when induction heating is performed on the members on the production line that flow continuously and the members are heated in the previous step and there is residual heat during the induction heating, for example, in consideration of the residual heat. Even if the thermal energy to be applied to the paint used is determined and the electric power is set by calculating the energy input to the components, the residual heat is dependent on the outside temperature, and the running speed of the line is always guaranteed to be constant. This is not always the case, and excess or deficiency of the heat energy applied to the paint used and the like occurs.

The excess or deficiency of the applied heat energy has a great influence on the peeling factor of the paint, the binder and the like and the bonding strength, and causes the variation of the finished quality, and therefore a countermeasure has been demanded.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems existing in the case of inductively heating a member to a low temperature, which is affected by changes in the outside temperature, and the outside temperature is automatically adjusted. By correcting the heating temperature of the member to be constant at all times, the excess and deficiency of the heat energy applied to the paint used, etc. can be eliminated, and a high quality finish and leveling of the induction heating temperature can be achieved. The purpose is to provide.

(Structure of the Invention) The structure of the present invention is (1) in the case of heating the member to a low temperature of 300 ° C. or lower by the high-frequency induction heating means or keeping the temperature for a predetermined time after (2) storage and calculation functions. The controller provided with (3) input energy determined in relation to the mass of the member required to raise the temperature of the member to a predetermined temperature or to heat the member for a predetermined time according to each stage of the ambient temperature (3) K
w) and the outside temperature correction chart, and (4) Multi-step input energy (Kw) and the adjustment value of the power setting device of the high-frequency power supply that is determined according to each input energy (Kw) within the specified energizing time. A high-frequency power supply power adjustment chart comparing the corresponding current signal is stored in advance, and (5) the controller is configured to output a current signal according to the adjustment value to the power setting device, and (6) above. The outside air temperature immediately before heating the member or the surface temperature of the member was measured and set so that it could be input to the above controller. (7) The controller controlled the set power of the high frequency power source based on the input measurement value. This is a method for correcting the outside air temperature of the induction heating temperature, which is characterized in that

(Operation of the Invention) In the present invention, in the low temperature heating of the member by the high frequency induction heating means, the heating is performed by the variable input energy which is automatically corrected according to the outside air temperature or the residual heat, and the heating temperature of the member is constantly maintained. It has a certain effect.

(Example) The present invention will be described in detail below with reference to the block diagram shown in FIG.

In the figure, 1 is a heating station, 2 is a high frequency power source for heating, 3 is a controller, and 4 is a probe for measuring temperature. The heating station 1 includes an induction heating coil connected to the high-frequency power source 2 and a member that is arranged to face the induction heating coil with a predetermined gap or moves while facing the induction heating coil. The high-frequency power source 2 is a known power source and includes a power setting device that can change the voltage input to the primary side. The controller 3 is a device for executing the method of the present invention, which has a memory / arithmetic function, a built-in temperature measuring device for receiving temperature information measured by the probe 4, and a power setting device of the high frequency power source 2. It is configured to be able to output a current signal that captures a predetermined adjustment value. The temperature measurement probe 4 is made of, for example, a Pt resistance temperature detector, and is arranged close to the member arrangement position of the heating station 1 so that the temperature inside the heating station 1 can be measured or a member is provided through a forward / backward mechanism. The surface temperature is set to be measurable by being configured to contact the surface for 2 to 3 seconds, for example.

Then, from the calculation or experiment in advance, for example, 0 ℃, 5 ℃, 1
It is possible to obtain the input energy (Kw) required to raise the temperature of the member to the specified temperature within the specified energizing time for each of the multiple temperatures such as 0 ℃, ...... 40 ℃. The controller 3 stores the outside air temperature correction power chart shown in Table 1 in comparison with the input energy (Kw). In this case, input energy (K
Of course, w) is determined according to the mass of the member to be heated.

Further, the power setter normally adjusts the set power within the output range of 0 to 100% by the current signal selected in the range of 4 to 20 mA. Therefore, in order to adjust the power setting device corresponding to each input energy (Kw) of the outside temperature correction power chart, as shown in Table 2, for adjusting each input energy (Kw) and the set power of the power setting device. The high-frequency power supply power adjustment chart is made by comparing the current signal (mA) with the current signal (mA) and stored in the controller 3.

However, in practice, the output% is within a predetermined range (for example, 70 to 10
0%), and the current signal is allocated within that range, but in order to simplify the explanation, the high frequency power supply power adjustment chart in Case Table 2 is set to 100% range.

Further, in the present embodiment, the output% is inversely related to the magnitude of the number of the current signal (mA).

Further, the controller 3 is a program that enables interpolation from the vertical input energy (Kw) set value sandwiching the input measured value when the measured value input from the temperature measurement probe 4 indicates an intermediate value of the set temperature step. Is incorporated.

A case of inductively heating a member using the apparatus of the embodiment configured and set as described above will be described below with reference to Tables 1 and 2.

When a member coated with paint or the like is carried into the heating station 1, the outside temperature information is immediately input from the temperature measuring probe 4 to the controller 3. If the input measured value is, for example, 25 ° C., the controller 3 selects the input energy P25 (Kw) corresponding to the temperature by the stored outside air temperature correction power chart, and then stores the stored high frequency power supply power adjustment. The input energy P2 by the chart
The current signal 14 (mA) corresponding to 5 (Kw) is selected, and the current signal 14 (mA) is output to the power setting device. As described above, since the power setting device is configured to be adjusted to a predetermined power according to the input current signal, the high frequency power supply 2 uses the heating coil in the heating station 1 to generate the high frequency current according to the set power of the power setting device. Will be energized for a predetermined time.

By the energization, the member is heated to a predetermined temperature within a predetermined time, and a predetermined amount of thermal energy is applied to the paint or the like from the member thus heated, and the paint or the like is placed under ideal conditions by appropriate applied heat energy. It is baked or solidified.

(Other Embodiments) In the above description, an example in which the outside air temperature is set to 25 ° C. has been described. However, for example, when it indicates 23 ° C., interpolation operation is executed by calculation, and the current signal 13 is sent to the power setting device. Will be output.

When the temperature measurement probe 4 is set to contact the member surface, the member surface temperature at the start of heating and the member surface temperature raised to a predetermined time sufficiently shorter than the energization time are measured. The temperature difference may be calculated, and if the temperature difference is within a predetermined allowable range, energization may be continued, and if it exceeds the predetermined allowable range, energization may be stopped. With this configuration, since the power-time product is calculated, it becomes possible to monitor whether or not the high-frequency power supply is normally operating at the set power.

When performing two-stage heating, different input energies obtained by calculation are selected for heating at heating and heating for keeping warm, and a predetermined current signal is output from the controller 3 to the power setting device with a time lag. The sequence will be assembled as described above.

(Effects of the Invention) By carrying out the present invention, low temperature heating of a member using an induction heating means is not affected by changes in outside air temperature and is not affected by residual heat, and the heating temperature is always constant. Therefore, there is no excess or deficiency in the heat energy applied to the paint used, the binder, etc., and the baked or solidified finish maintains high quality and is leveled, which is praised for its remarkable effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram for explaining the method of the present invention, and FIG. 2 is an elapsed time-heating temperature relationship diagram for explaining the problems of the conventional method. 2 ... High frequency power supply 3 ... Controller

Claims (3)

[Claims] 1. When a member is heated to a low temperature of 300.degree. C. or lower by a high-frequency induction heating means or is kept warm for a predetermined time, a controller having a memory / arithmetic function is provided with a plurality of stages of outside air temperature and Input energy (Kw) determined in relation to the mass of the member required to raise the temperature of the member to a prescribed temperature or to keep it warm for a prescribed time depending on the stage
And an outside air temperature correction chart comparing with and a current signal corresponding to the adjustment value of the power setting device of the high frequency power supply that is determined according to each of the input energy (Kw) in multiple stages and each input energy (Kw) within the predetermined energizing time Is stored in advance, and the controller is configured to output a current signal corresponding to the adjustment value to the power setting device, and the outside temperature immediately before heating the member or the temperature of the member. A method for correcting the outside air temperature of the induction heating temperature, characterized in that the surface temperature is set to be measured and input to the controller, and the controller controls the set power of the high frequency power source based on the input measurement value. . 2. When the measured input value to the controller indicates the intermediate value of each stage of the outside air temperature, the input energy (Kw) corresponding to the upper and lower stages sandwiching the intermediate value is used to interpolate. A method for correcting the outside air temperature of the induction heating temperature according to the item. 3. The method according to claim 1, wherein the case where the surface temperature of the member is measured includes the case where the member has residual heat in the previous step.
A method for correcting the outside air temperature of the induction heating temperature according to the item.