JP4426155B2 - Heating device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heating device used as a reflow furnace, a curing furnace or the like.
[0002]
[Prior art]
In a conventional heating device such as a reflow furnace, the maximum power is simultaneously supplied to a plurality of heaters provided in the furnace at the time of startup, or the startup time of the device is set in advance as shown in Japanese Patent No. 2885047. It is measured by experiment, the current consumption of each heater decreases as the heater temperature rises, and the control unit stores a time such that the current is less than a certain value. There is a heater start-up method to start up.
[0003]
[Problems to be solved by the invention]
Among the heating devices, when a heating device that supplies maximum power to a plurality of heaters at the same time is used as production equipment, the current consumption at the start-up of the equipment exceeds the limit of the factory power equipment, which may cause power failure. is there.
[0004]
In addition, when each heater is started up in order for each time obtained in advance by experiment, it takes time to obtain the start-up time of each heater in advance by experiment, and the start-up depends on the set temperature of the heater. Since the time changes, the time interval stored in the control unit in advance must allow some margin, and the start-up time cannot be shortened for a plurality of temperature conditions.
[0005]
In addition, since the total current consumption of the heater is not monitored, depending on the condition setting, the start-up of the first heater is not completed, and power supply to the next heater is started while the current consumption is still large. There is a risk of causing a power failure.
[0006]
Furthermore, to reduce the total current consumption of the heating device, if the individual heater capacity is reduced, the total current at the start-up of the device will decrease, but the temperature control speed will be reduced, that is, at the time of temperature adjustment operation after the start-up of the device, It takes a long time to recover the decrease in the furnace temperature when heating the substrate carried into the furnace during production operation, and the productivity deteriorates and the temperature controllability decreases. There's a problem.
[0007]
The present invention has been made in view of the above points, and prevents power failure due to excessive current consumption when the apparatus is started up, and has an appropriate start-up time when starting up a plurality of heaters in order at regular intervals. An object of the present invention is to provide a heating apparatus that solves the difficulty of setting and ensures the recovery performance of the temperature drop in the furnace during the temperature control operation after starting up the apparatus.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a furnace body, a plurality of heaters for heating the workpiece positioned below the conveyor along the conveyor for conveying the workpiece in the furnace body, and the workpiece positioned above the conveyor for heating the workpiece. And a controller for controlling the power supplied to the plurality of heaters located below and above the conveyor . The controller is provided as a heater located below the conveyor among the plurality of heaters when the apparatus is started up. In addition to supplying the necessary power, the power supplied to at least one of the heaters located above the conveyor is limited so that the total power supplied to the plurality of heaters does not exceed a predetermined upper limit value. controls to as switching parameter temperature with increasing temperature, decreasing the power supplied to the heater which is positioned below the conveyor Its decrease a heating device so as to supply power, controller while controlling the total power consumption of each heater of the furnace body below a predetermined value, conveyor heater positioned above the conveyor to control the By effectively using the power consumption reduction in the heater located below the heater located above the conveyor , the device can be started up in a short time while keeping the maximum current consumption at the time of startup of the device below the upper limit. As a result, power failure due to excessive current consumption can be prevented, and the power supply equipment does not need to be changed to a large capacity, so that the equipment cost can be reduced. In particular, as the temperature rises, control is performed to reduce the power supplied to the heater located below the conveyor , and the reduced power is supplied to the heater located above the conveyor. Since the individual heaters start up in order so that the sum of the values does not exceed a certain upper limit value, it is difficult to set an appropriate start-up time as in the case of starting up a plurality of heaters in order at predetermined time intervals. Can solve sex. That is, since it is not necessary to store the apparatus start-up time in the apparatus in advance, it is not necessary to conduct an experiment for the determination, and it is possible to perform optimal start-up control even when the set temperature is changed or the apparatus state is changed. .
[0009]
請 Motomeko 2 invention described, the controller of the heating apparatus according to claim 1 Symbol placement is device start at temperature adjustment during operation after raising the upper limit value sum predetermined supply electric power to a plurality of heaters The power supplied to each heater is controlled individually so that the total power supplied to each heater does not exceed the upper limit even after the equipment is started up. Even after raising the temperature, power failure can be prevented, and power can be supplied to necessary heaters to quickly recover the decrease in furnace temperature.
[0010]
In the invention described in claim 3 , the controller in the heating device according to claim 2 controls the pulse of the heater, and the number of heaters to be energized at the same time in the temperature control operation after starting up the device is limited to the upper limit. It has a calculation function that limits the number obtained by dividing the current divided by the maximum current consumption to the total number of heaters to the number obtained by rounding down the decimal part. By limiting the number of simultaneously energized heaters, a sufficient current can be supplied to a heater with a large temperature drop, and a quick temperature recovery is possible even with a large temperature drop. That is, in the normal operation state of the device after starting up the device, a heater full of the heater output can be supplied to the heater where the temperature has dropped significantly due to the passage of the substrate, etc. The recovery is fast and the maximum current consumption is reduced by configuring the heating device with a small output heater, or the maximum current consumption is reduced by limiting the current to the same ratio for all heaters. It can prevent that the temperature controllability of a heater deteriorates.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0012]
FIG. 1A shows an example of a reflow furnace as a heating device, that is, a heating furnace for reflow soldering, and a printed wiring board (hereinafter referred to as “this”) in which electronic components are mounted in a furnace body 11 via solder paste. A conveyor 12 that conveys the electronic component mounting board (referred to as “work W”) is provided.
[0013]
A preheater 13 and a reflow heater 14 (hereinafter referred to as “lower heaters 13, 14”) positioned below the conveyor 12 in the furnace body 11 along the conveyor 12, and a preheater 15 positioned above the conveyor 12. Reflow heaters 16 (hereinafter referred to as “upper heaters 15 and 16”) are arranged.
[0014]
The preheaters 13 and 15 preheat the workpiece W so as to gradually raise the temperature, and the reflow heaters 14 and 16 heat the solder paste applied to the workpiece W to a temperature at which the solder paste can be reflowed (melted).
[0015]
The lower heaters 13 and 14 and the upper heaters 15 and 16 are respectively provided with fans 17 and 18 facing each other. By the lower heaters 13 and 14 and the fan 17, the upper heaters 15, 16 and The fans 18 constitute hot air generating means.
[0016]
The hot air generated by these hot air generating means raises the atmospheric temperature in the furnace body 11 when starting the reflow soldering operation. During the reflow soldering operation, the atmospheric temperature in the furnace body 11 is set to a predetermined value. It works to keep it at preheat temperature or reflow temperature.
[0017]
The lower heaters 13 and 14 and the upper heaters 15 and 16 are connected to a controller 19 that controls the power supplied to the heaters 13 to 16 so that the total power consumption of the heaters 13 to 16 is not more than a certain value. ing.
[0018]
The controller 19 controls the heaters 13 to 16 as a pulse width modulation method (hereinafter referred to as “PWM method”), a switching frequency modulation method (PFM method), an instantaneous value control method, or a phase control method. Etc.
[0019]
As shown in FIG. 2, the controller 19 controls the power supplied from the power source 21 to the plurality of heaters 13 to 16 by the control method as described above, thereby controlling the temperatures of the heaters 13 to 16 or the surroundings of the heaters. A heater control unit 22 for individually controlling the atmospheric temperature is provided.
[0020]
Further, the controller 19 sets a temperature setting unit 23 for setting the temperature of each heater 13 to 16 or the ambient temperature around the heater to the heater control unit 22, and power or current supplied to each heater 13 to 16. The current detection unit 24 serving as a detection unit that directly or indirectly detects the current and the total current supplied to the heaters 13 to 16 detected by the current detection unit 24 does not exceed a predetermined value. The total current monitoring unit 25 outputs a command to the heater control unit 22 so that the total current supplied to the heaters 13 to 16 for temperature adjustment is limited to a predetermined value and redistributed. Are connected to each other.
[0021]
The current detection unit 24 may directly detect the current value supplied to each of the heaters 13 to 16, but when the heater control unit 22 adopts the PWM method, the heater on-duty ratio (= on) of the heater control unit 22 It is also possible to calculate the current supplied to each of the heaters 13 to 16 from the time / switching period) and other control values.
[0022]
The heater control unit 22 is connected to an alarm unit 26 that issues an alarm when the total current monitoring unit 25 senses an abnormality that prevents the maximum current consumption condition from being met.
[0023]
Furthermore, in the surface of each preheater 13-16 in the furnace body 11 or in the atmosphere heated by each preheater 13-16, temperature sensors 27, 28 such as thermocouples for measuring the heater temperature or furnace atmosphere temperature. , 29 and 30 are arranged, and these temperature sensors 27 to 30 are connected to the heater control unit 22, and the temperature information detected by each temperature sensor 27 to 30 is taken into the heater control unit 22. It is.
[0024]
As shown by a solid line in FIG. 1B, the controller 19 first supplies power to the lower heaters 13 and 14 among the plurality of heaters 13 to 16 when the apparatus is started up. The power supplied to 15 and 16 is limited so that the total power consumption does not exceed a predetermined upper limit value, that is, the sequential startup maximum power (i2). Since control is performed so that the power supplied to the lower heaters 13 and 14 that are not restricted is reduced, a control function is provided to supply the reduced power to the upper heaters 15 and 16 that are restricted in power. Yes.
[0025]
In FIG. 1 (b), the dotted lines indicate the time-dependent changes in power consumption and furnace atmosphere temperature in the conventional synchro start-up method in which the lower heaters 13 and 14 and the upper heaters 15 and 16 are energized simultaneously. Although the synchro start-up completion time (Т1) during which the ambient temperature rises to the set temperature is short, the maximum power (i1) for start-up sync is high, and there is a risk of causing a power failure exceeding the limit of factory power equipment.
[0026]
On the other hand, in FIG. 1B, the solid line is controlled so that the lower heaters 13 and 14 are first energized and the power consumption decreases as the temperature of the heaters 13 and 14 increases. FIG. 4 shows changes with time in power consumption and furnace atmosphere temperature in the sequential start-up method according to the present invention in which substantially reduced electric power is supplied to the upper heaters 15 and 16 from the sync start-up completion time (Т1).
[0027]
In this sequential start-up method, the sequential start-up completion time (Т2) during which the furnace interior temperature rises to the set temperature is longer than the synchro start-up completion time (Т1), but all heaters 13 to 16 are started up with low power. The system can be started up in a shorter time than the case, and the sequential startup maximum power (i2) is low, so that it is within the limits of the factory power facility, and power failure can be reliably prevented.
[0028]
Next, the function and effect of the illustrated embodiment will be described.
[0029]
At the time of starting up the heating device, the total power consumption (hereinafter, the voltage is constant and the power is referred to as “current”) in a predetermined order among all the heaters 13 to 16 provided in the heating device. The required electric power is supplied to the heaters 13 and 14 positioned below the conveyor 12, for example, within a range that does not exceed the upper limit value), that is, within a range that does not exceed the upper limit current. To do.
[0030]
At this time, the total current is constantly monitored by the total current monitoring unit 25. When an abnormality occurs, power supply to the lower heaters 13 and 14 is stopped, and the power exceeding the limit of the factory power facility Prevent obstacles.
[0031]
As the temperature of the lower heaters 13 and 14 rises and approaches the set target temperature, the heater control unit 22 supplies current to the one or more lower heaters 13 and 14 that have started to start up. Control to decrease.
[0032]
Then, in addition to energizing the heaters 13 and 14 positioned below, with reaching the set temperature as a switching parameter, one or more heaters 15 and 16 positioned above the conveyor 12, for example, As long as the total current consumption does not exceed the upper limit, supply of the reduced current starts.
[0033]
In addition, the upper limit value of the total current consumption is given a certain margin, and when the lower heaters 13 and 14 that have started starting up have reached the set temperature, the next upper heaters 15 and 16 are turned on. It may be controlled to start up.
[0034]
At this time, reaching the set temperature of the lower heaters 13 and 14 is determined by directly monitoring the heater current with the current detection unit 24 and the total current monitoring unit 25 and detecting that the current value has decreased. good.
[0035]
Further, the heater control unit 22 that has acquired the temperature information from the temperature sensors 27 and 28 may directly detect the arrival of the set temperature and determine whether the lower heaters 13 and 14 have reached the set temperature.
[0036]
Alternatively, the heater control unit 22 may monitor the on-duty ratio in the case of adopting the PWM method, detect the decrease, and determine whether the heaters 13 and 14 below reach the set temperature.
[0037]
In this way, by repeating the control of sequentially starting up the plurality of heaters using the temperature as a switching parameter, the heating device can be started up while keeping the current consumption below a certain value.
[0038]
Next, after starting up all the heaters 13 to 16, the temperature of each heater 13 to 16 or the ambient temperature around the heater reaches the set value set in the heater control unit 22 from the temperature setting unit 23, That is, even during the temperature adjustment operation after the start-up of the apparatus, the current detection unit 24 and the total current monitoring unit 25 monitor the current, and the furnace temperature decreases due to, for example, external substrate loading. Even when a large current flows, the currents to the heaters 13 to 16 are individually adjusted so that the total consumption current supplied to all the heaters 13 to 16 does not exceed a predetermined upper limit value, that is, the upper limit current.
[0039]
At this time, if the total current monitoring unit 25 and the heater control unit 22 perform separate operations, the temperature adjustment of the heaters 13 to 16 will not operate normally, so the total current monitoring unit 25 and the heater control unit 22 The operation of the heaters 13 to 16 is coordinated.
[0040]
That is, after starting up the apparatus, only the electric power necessary and sufficient for stabilizing the furnace temperature during the production operation is supplied to the heaters 13 to 16 without changing the power distribution to the heaters 13 to 16.
[0041]
Further, when the temperature is adjusted using a current PWM method in which the current supplied to the heaters 13 to 16 is pulse-controlled, even if the upper limit of the on-duty ratio of each heater 13 to 16 is limited, all the heaters 13 Since ~ 16 may be turned on, the total heater driving current may instantaneously exceed the upper limit current.
[0042]
For this reason, in the heater control unit 22 used in the present invention, the number of heaters that are energized at the same time during the temperature adjustment operation after the start-up of the apparatus is the total that each of the heaters 13 to 16 can consume at the maximum capacity. The arithmetic function of limiting the number obtained by multiplying the number divided by the maximum current consumption by the total number of heaters to the number obtained by rounding down the decimal part.
[0043]
In this way, a sufficient current can be supplied to the heater with a large temperature drop, and a quick temperature recovery can be achieved even with a large temperature drop.
[0044]
If there is a situation where the maximum current consumption condition cannot be satisfied in order to maintain the furnace temperature during production operation, the heater control unit 22 calls the heater overload or overcurrent request through the alarm unit 26. A warning like this is issued to notify the operator of the abnormality.
[0045]
Next, FIG. 3 shows actually measured data. The dotted line indicates the time-dependent changes in current consumption and power consumption in the conventional sync start-up method in which all the heaters 13 to 16 are energized simultaneously, and the solid line indicates First, when the lower heaters 13 and 14 are energized, and the detected temperatures detected by the temperature sensors 27 and 28 reach the set temperature, the upper heaters 15 and 16 are also energized. The time-dependent changes in current consumption and power consumption in the sequential startup method are shown. In this sequential startup method, when the current consumption and power consumption in the lower heaters 13 and 14 are reduced to predetermined values, the upper heater 15 , 16 shows a control state for supplying almost the reduced current and power.
[0046]
That is, in FIG. 3, the lower heaters 13 and 14 are energized for 27 minutes from the start of energization, and when the current consumption and power consumption of these heaters 13 and 14 are reduced to predetermined values, the upper heaters 15 and 14 are energized. By supplying almost the current and power for the decrease to 16, all the heaters 13 to 16 are started up with a small current and a small power, so that the apparatus start-up completion time is shortened.
[0047]
As described above, the device can be started up in a short time while keeping the maximum current consumption at the time of starting the device below the upper limit, thereby preventing power failure exceeding the limit of the factory power facility, Since the equipment does not have to be changed to a large capacity, the equipment cost can be reduced.
[0048]
In addition, since it is not necessary to store the device start-up time in advance in the device, no experiment is required for the determination, and optimal start-up control is performed even when the set temperature is changed or the device state is changed. be able to.
[0049]
Also, with this configuration, since the heater output is supplied individually to the heaters where the temperature has dropped significantly due to the passage of the substrate, etc. in the normal operation state of the device after startup, a large load is applied. The recovery is quick even for fluctuations in the power consumption, and the maximum current consumption is reduced by configuring the heating device using a small output heater, or the maximum current consumption is reduced by limiting the current to the same ratio for all heaters. The temperature controllability of the heater does not deteriorate as in the case of
[0050]
The heating device of the present invention can be applied not only to the reflow furnace as described above but also to a curing furnace for curing, for example, a thermosetting resin.
[0051]
【The invention's effect】
According to the first aspect of the present invention, the controller controls the total power consumption of the heaters in the furnace body to a certain value or less, and the power consumption decrease in the heater located below the conveyor is positioned above the conveyor. By using the heater effectively, it is possible to start up the device in a short time while keeping the maximum current consumption at startup of the device below the upper limit, thereby preventing power failure due to excessive current consumption. Since the power supply facility does not have to be changed to a large capacity, the facility cost can be reduced. In particular, as the temperature rises, control is performed to reduce the power supplied to the heater located below the conveyor , and the reduced power is supplied to the heater located above the conveyor. Since the individual heaters start up in order so that the sum of the values does not exceed a certain upper limit value, it is difficult to set an appropriate start-up time as in the case of starting up a plurality of heaters in order at predetermined time intervals. Can solve sex. That is, since it is not necessary to store the apparatus start-up time in the apparatus in advance, it is not necessary to conduct an experiment for the determination, and furthermore, the optimal start-up control can be performed even when the set temperature changes or the apparatus state changes .
[0052]
According to the invention 請 Motomeko 2 wherein, after device start-up also be controlled individually so as not to exceed the upper limit the total power supplied to the heaters can be prevented even power failure after device start-up At the same time, power can be supplied to the necessary heaters to quickly recover the decrease in furnace temperature.
[0053]
According to the third aspect of the present invention, by limiting the number of simultaneously energized heaters during pulse control by the calculation function of the controller, it becomes possible to supply a sufficient current to a heater having a large temperature drop. Rapid temperature recovery is possible even when the temperature drops. That is, in the normal operation state of the device after starting up the device, a heater full of the heater output can be supplied to the heater where the temperature has dropped significantly due to the passage of the substrate, etc. The recovery is fast and the maximum current consumption is reduced by configuring the heating device with a small output heater, or the maximum current consumption is reduced by limiting the current to the same ratio for all heaters. It can prevent that the temperature controllability of a heater deteriorates.
[Brief description of the drawings]
FIG. 1A is a schematic diagram showing an embodiment of a heating device according to the present invention, and FIG. 1B is a characteristic diagram showing its control characteristics.
FIG. 2 is a block diagram of the heating device.
FIG. 3 is a characteristic diagram showing current / power measurement data during sequential start-up operation and conventional sync start-up operation according to the present invention.
[Explanation of symbols]
W Work
11 Furnace
12 conveyor
13-16 heater
19 Controller

Claims (3)

A furnace body;
A plurality of heaters that are positioned below the conveyor to heat the workpiece along the conveyor that conveys the workpiece in the furnace, and a plurality of heaters that are positioned above the conveyor to heat the workpiece ,
A controller for controlling power supplied to a plurality of heaters located below and above the conveyor ,
The controller
A plurality of heaters are provided by supplying necessary power to a heater located below the conveyor among the plurality of heaters when starting up the apparatus, and restricting power supplied to at least one of the heaters located above the conveyor. Control so that the total power supplied to the battery does not exceed a predetermined upper limit,
As the temperature rises, the temperature is used as a switching parameter to control the power supplied to the heater located below the conveyor to be reduced, and the reduced power is supplied to the heater located above the conveyor. A heating device. The controller
The power supplied to each heater is individually controlled so that the sum of the power supplied to the plurality of heaters does not exceed a predetermined upper limit value during the temperature adjustment operation after starting up the apparatus. 1 Symbol placement of the heating device. The controller
The pulse of the heater is controlled,
Calculation to limit the number of heaters that are energized simultaneously at the time of temperature control operation after startup of the system to the number obtained by dividing the upper limit current by the maximum current consumption and multiplying by the total number of heaters and rounding off the decimal part. It has a function. The heating apparatus of Claim 2 characterized by the above-mentioned.

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