JP3345341B2 - Sheet heating control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for heat-forming a three-dimensional molded article from a thermoplastic resin sheet or a fiber-reinforced composite sheet mainly composed of a thermoplastic resin. When heating
When the heater temperature rises, during the calculated power supply time,
The present invention relates to a sheet heating control method that sets a power supply to an indirect heating heater to a rated voltage or more to shorten a heater startup time and prevent overheating of a heater heating unit.

[0002]

2. Description of the Related Art Conventionally, as a method of heat-forming a thermoplastic resin sheet or a fiber-reinforced composite sheet mainly composed of a thermoplastic resin, a method of indirectly heating a material by using an infrared rod-shaped heater to carry out molding. There is (for example,
-276490).

[0003]

However, in the above-described conventional heat molding method, when the heat capacity of the heating element is large in the indirect heating heater, it takes one to three hours for the heater temperature to rise to a predetermined temperature after the power is turned on. It takes 2 minutes. For this reason, it is necessary to turn on the heater power several minutes before starting the molding. Also, when changing the heater temperature setting, after changing the set value, it is necessary to similarly wait several minutes until the temperature becomes stable.

An object of the present invention is to eliminate the above-mentioned problems and to provide a sheet heating control method capable of quickly and accurately controlling the rise of a heater.

[0005]

In order to achieve the above object, the present invention provides: [1] a three-dimensional molded article formed by heating a thermoplastic resin sheet or a fiber-reinforced composite sheet mainly composed of a thermoplastic resin. In the sheet heating control method, when heating the sheet using an infrared rod-shaped heater, when the heater temperature rises, the equation ΔS = (Ta−Ts) / Kb (ΔS:
Operating time, Ta: heater set temperature, Ts: at start of operation
Heater temperature, Kb: average startup speed)
By setting the power supply to the indirect heating heater to a rated voltage or more during the operating time, the heater startup time is shortened and overheating of the heater heating section is prevented.

[2] In the sheet heating control method according to the above [1], the power supply voltage to the heater is equal to or higher than the rated voltage of the heater, and the control output is performed by duty control.
During start-up operation, a voltage higher than the rated voltage of the heater is supplied, and during normal heating operation, the duty ratio is reduced so that the output becomes the rated output.

[3] In the sheet heating control method according to the above [1], the power supply voltage to the heater is equal to or higher than the rated voltage of the heater, and the control output is performed by duty control.
During the start-up operation, the heater temperature is set to a smooth and fast rise by changing the voltage equal to or higher than the heater rated voltage.

[4] In the seat heating control method according to the above [1], two power supply systems are provided for the heater, and a voltage equal to or higher than the rated voltage of the heater during the start-up operation, and a rated voltage of the heater during the heating operation. Is switched.

[5] The method for controlling the heating of a sheet according to the above [1], wherein the heaters are switched in series or in parallel in units of two, and a voltage twice as high as a rated voltage and a rated voltage are used. It is.

[0010]

[0011]

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an outline of a sheet forming machine showing an embodiment of the present invention.

In this figure, 1 is a thermoplastic resin sheet to be molded or a fiber reinforced composite sheet mainly composed of a thermoplastic resin, 2 is a molded product, 3 is a temperature controlled by an electric heater or a chiller unit or the like. The mold (female), 4 has a lower mold (male) whose temperature is controlled by an electric heater or a chiller unit as in the upper mold (female) 3, and 5 has a temperature controlled by an electric heater or a chiller unit or the like. Lower frame,
6 is a sheet stacking device, 7 is a sheet lifting device, 8 is a cylinder for lifting and lowering the sheet, 9a and 9b are heaters 9 for indirect heating.
Upper and lower heaters.

10a is a drive rack for the upper heater 9a, 10b is a drive pinion for the upper heater 9a, 11 is a cylinder for raising and lowering the lower heater 9b, 12 is a cylinder for raising and lowering the upper die 3, and 13 is a lower frame 5 , A reference numeral 14a denotes a molded product removal device, 15a denotes a driving belt for removing the molded product, and 15b denotes a pulley for removing the molded product.

Although not shown in the drawing, a device for transporting the sheet 1 from the sheet stacking device 6 to the heater 9 for indirect heating → the forming section → the unloading device 14 is used. FIG. 2 is a configuration diagram of the lower heater of the indirect heater according to the embodiment of the present invention.

In this figure, 20 is a block of an indirect heater, 21 is a near-infrared rod heater, 22 is a glass tube, 23 is a coil heater, 24 is an end of the near-infrared rod heater, 25 is a tungsten terminal, and 26 is a tungsten terminal. Lead wire.

As shown in FIG. 1, the upper heater 9a and the lower heater 9b are arranged so as to be parallel to each other. As shown in FIG. 2, the lower heater 9b (upper heater 9a) has, for example, a plurality of maximum energy sources. It comprises a near-infrared rod-shaped heater 21 having a wavelength of 1 to 3 μm.

FIG. 3 is a block diagram of a control device for an indirect heater according to a first embodiment of the present invention.

As shown in FIG. 1, reference numeral 32 denotes a contactless relay unit SSR for turning on and off the power supply.
An AC power supply 33 is connected to 32. The near-infrared rod-shaped heater 21 is a non-contact relay unit SSR32.
It is connected to the. This non-contact relay unit SSR3
Reference numeral 2 denotes output control by the CPU 34 or a cycle control unit (not shown), and functions as an energization control unit. The input unit 35 further includes an input unit 35 and a display unit 36. The input unit 35 inputs a heating condition (heater set temperature, heating time, and the like) of the sheet 1 that is a heating target.

FIG. 4 is a block diagram showing a feedback-type control device in which a heater temperature detecting device is added to the indirect heater control device according to the second embodiment of the present invention. The same parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

As shown in this figure, a temperature detecting device 31 for the near-infrared rod-shaped heater 21, for example, a thermocouple is provided, an output signal from the thermocouple is taken into the CPU 34, and the temperature of the heater is determined based on the output signal. Control is performed.

For example, the temperature of the heater immediately before the near-infrared rod-shaped heater 21 is started is detected by the temperature detecting device 31, the supply time of the power supply voltage at the time of starting the heater is calculated by the CPU 34, and the heating of the sheet is controlled. Can be

Further, the heater temperature immediately before the start of the near-infrared rod-shaped heater 21 is estimated from the previous heating setting conditions and the time from the end of the previous heating, and the supply time of the power supply voltage at the time of starting the heater is calculated. The heating of the sheet can be controlled.

FIG. 5 is a block diagram showing a control device according to a third embodiment of the present invention in which a changeover switch for supplying a different voltage to the control device for the indirect heater is added. Here, also, the same portions as those in FIG. 3 are denoted by the same reference numerals, and description thereof is omitted.

As shown in this figure, the AC power supply of the control device is divided into two systems (33-1, 33-2), and the changeover switch 4
1. For example, by switching the contactors 41 ' , different voltages can be supplied.

In particular, during the start-up operation, a voltage higher than the rated heater voltage is supplied from, for example, the first AC power supply system 33-1. During the heating operation, the heater rated voltage is supplied to the second AC power supply system 33-2. Switch to.

In this case, as shown in FIG. 5, when the heater temperature rises, the power supply to the indirect heater 9 is set to a rated voltage or higher for the power supply time calculated by the CPU 34, and the changeover switch 41 is used. By performing the switching, the startup time of the heater can be shortened, and overheating of the heater heating section can be prevented.

FIG. 6 is a diagram showing a control circuit of the indirect heater, FIG. 6 (a) is a circuit diagram in which the indirect heater can be switched in series and parallel, and FIG. 6 (b) is a circuit diagram in the case of serial connection. ,
FIG. 6C shows a circuit diagram in the case of parallel connection.

As shown in FIGS. 6B and 6C, the near-infrared rod-shaped heaters 21A and 21B are switched in series and in parallel by the contactor 41 'in units of two.
The power supply to the near-infrared rod-shaped heater can be switched between twice the rated voltage and the rated voltage.

FIG. 7 is a heating control flowchart of the indirect heater according to the embodiment of the present invention.

Hereinafter, a heating control method for an indirect heater according to an embodiment of the present invention will be described with reference to FIG.

(1) First, heating conditions such as a heater set temperature and a heating time for the sheet 1 are inputted from the input unit 35 (step S1).

(2) Next, when an operation signal is input from the operator, the operation starts (step S2).

(3) Next, the heater is started (step S3).

(4) After the start-up operation, heating under the conditions input by the input unit 35 starts (step S).
4).

(5) Heat is applied (step S5).

(6) The heating is completed (step S6).

(7) After the heating is completed, time measurement is started by the internal timer of the CPU 34 (step S7).

(8) When the next operation start signal is input, the next start operation is started (step S8).

(9) Next, calculation of a heater temperature Ts = f (ts) at the start of operation, which will be described later, is performed (step S).
9).

(10) Next, a start time ΔS =
(Ta−Ts) / Kb is calculated (Step S1)
0).

(11) Next, a start-up operation for a start-up time ΔS is performed (step S11).

Thereafter, the flow returns to step S4, and is sequentially repeated.

As described above, the heating operation is started and heating is started. At this time, the power supply to the heater is set to be equal to or higher than the rated voltage for a certain period of time, so that the rise time of the heater temperature can be shortened.

On the other hand, if the heater is used at a temperature exceeding the maximum operating temperature, the life of the heater will be significantly shortened due to oxidation of the heater heating part. Set.

FIG. 8 is a timing chart (part 1) of the heating control of the indirect heater according to the embodiment of the present invention.
FIG. 8A shows the heater temperature, where a is the case of normal operation, b is the case of ΔS start operation, and c is the case where the start operation time is long. FIG. 8B is a waveform diagram of the voltage of the voltage c when the startup operation time is long, FIG. 8C is a waveform diagram of the voltage of the voltage b in the case of the ΔS startup operation, and FIG. The waveform diagrams of the voltages are respectively shown.

In the case of the first specific example (FIG. 3) and the second specific example (FIG. 4), the AC power supply 33 is set to a voltage higher than the rated voltage of the heater (for example, twice), and the control output is subjected to duty control. During the start-up operation, a voltage higher than the rated voltage of the heater (for example, duty ratio: 100% = 400% of the rated output) is supplied, and during normal heating operation, the output is output by the SSR 32 to the rated output (for example, duty ratio: 25% = 100% of the rated output).

Here, the duty control means that the control is performed by the ratio of the energizing time to the time of one cycle (duty ratio), and the average current is changed in an analog manner by digitally changing the energizing and non-energizing ratios. For example, a duty control waveform can be generated in the CPU 34.

FIG. 9 is a timing chart (part 2) of the heating control of the indirect heater according to the embodiment of the present invention.
9A shows a heater temperature, FIG. 9B shows a voltage waveform diagram for a smooth rise, and FIG. 9C shows a voltage waveform diagram when a smooth rise is not performed. I have.

As shown in FIG. 9B, by changing the supply voltage with time, a smooth and fast rise of the heater temperature can be set.

FIG. 10 is a diagram showing various control patterns of the temperature of the indirect heater according to the embodiment of the present invention.

It is necessary to set the power supply voltage and time for the heater so as not to exceed the maximum operating temperature. The rise time of the heater temperature depends on the heater temperatures T ₁ , T ₂ and T ₃ immediately before the power is turned on. Varies by. For example,
If the heater temperature of the power-on immediately before the high T _1, shorten the rise time, moderate the heater temperature of the power-on immediately before T
For ₂ is a moderate rise time, if the heater temperature of the power-on immediately before the low T _3, it is necessary to prevent the rise time becomes longer.

Therefore, the time setting of the heater supply power in the start-up operation cannot be fixed, and the heater supply power is calculated based on the immediately preceding heater temperature to control the heating of the heater. However, during the initial start-up operation, the time is constant because the heater temperature starts from normal temperature.

The heater temperature is detected by a heater temperature detector 31 (for example, a thermocouple) shown in the second specific example (FIG. 4). There is a method (in the case of the first specific example (FIG. 3)) of estimating from the time from the end (measured by the CPU internal timer). In the latter case, the setting of the heater supply power supply voltage and time in the start-up operation with respect to the estimated or detected heater temperature is determined by the following formula or a table (not shown) calculated based on the following formula.

FIG. 11 is a timing chart of the temperature of the indirect heater according to the embodiment of the present invention.

As shown in FIG.
A heater power OFF step, a startup operation step, and a seat heating step are performed.

(1) Estimation of heater temperature: Ts = f (t
s) For example, Ts = A + B × ts + C × In (Ta) + D × ts ² +
E × In (Ta) ² + F × ts × In (Ta) where Ts: heater temperature at the start of operation, ts: time from end of heating to start of operation, Ta: heater set temperature, A, B, C, D, E, F: constants.

Example: When the heater temperature is 600-400 ° C., A = -1029, B = −0.98, C = 647.6, D
= 0.0331, E = -54.81, F = -1.368 (2) Calculation of startup operation time: ΔS = (Ta−Ts) / K
b Here, ΔS: startup time, Ta: heater set temperature, K
b: Average startup speed.

(3) Supply power supply voltage at start-up operation: Va =
Kc × V Here, Va: supply power supply voltage at start-up operation, Kc: constant, V: rated voltage.

FIG. 12 is a diagram showing a heater temperature rise characteristic with and without start control.

As shown in this figure, when the start control according to the present invention is performed, the rise time of the heater in the case b is reduced to about 1/10 of the case a in which the start control is not performed.

It should be noted that other than the near-infrared rod-shaped heater having a maximum energy wavelength of 1 to 3 μm (for example, a far-infrared heater having a maximum energy wavelength of 3 to 5 μm),
The rise time of the heater temperature can be shortened.

It should be noted that the present invention is not limited to the above-described embodiment, but various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0065]

As described above, according to the present invention, the following effects can be obtained.

(A) The rise control of the heater can be quickly and accurately performed.

(B) Since the rise time of the heater temperature is short, it is possible to turn off the power of the heater except for (a) the heating time, and it is possible to save energy.

(B) When changing the heater temperature setting, the time until the heater temperature stabilizes after changing the set value can be shortened.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an outline of a sheet forming machine showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a lower heater of the indirect heater according to the embodiment of the present invention.

FIG. 3 is a block diagram of a control device for a basic indirect heater, showing a first specific example of the present invention.

FIG. 4 is a block diagram showing a feedback control device in which a heater temperature detecting device is added to a control device block of an indirect heater, showing a second specific example of the present invention.

FIG. 5 is a block diagram showing a control device according to a third embodiment of the present invention, which is provided with a changeover switch for supplying a different voltage to the control device for the indirect heater.

FIG. 6 is a diagram showing a control circuit of the indirect heater according to the embodiment of the present invention.

FIG. 7 is a heating control flowchart of the indirect heater according to the embodiment of the present invention.

FIG. 8 is a timing chart (part 1) of heating control of the indirect heater according to the embodiment of the present invention.

FIG. 9 is a timing chart (part 2) of heating control of the indirect heater according to the embodiment of the present invention.

FIG. 10 is a diagram showing various control patterns of the temperature of the indirect heater according to the embodiment of the present invention.

FIG. 11 is a timing chart of the temperature of the indirect heater according to the embodiment of the present invention.

FIG. 12 is a diagram showing a heater temperature rising characteristic when starting control is performed;

[Explanation of symbols]

 Reference Signs List 1 sheet 2 molded product 3 upper mold (female mold) 4 upper mold (female mold) 5 lower frame 6 sheet stacking device 7 sheet lifting device 8 sheet lifting / lowering cylinder 9 indirect heating heater 9a upper heater 9b lower heater 10a Rack for driving the upper heater 10b Pinion for driving the upper heater 11 Cylinder for raising and lowering the lower heater 12 Cylinder for raising and lowering the upper die 13 Cylinder for raising and lowering the lower frame 14 Mold removing device 15a Driving for removing the molded product Belt 15b Pulley for removing molded product 20 One block of indirect heating heater 21, 21A, 21B Near-infrared rod-shaped heater 22 Glass tube 23 Coil heater 24 End of near-infrared rod-shaped heater 25 Tungsten terminal 26 Lead wire 31 Temperature detector ( Thermocouple) 32 Non-contact relay unit SSR 33 AC power supply 33-1 First AC Source 33-2 second AC power supply 34 CPU (central processing unit) 35 input unit 36 display unit 41 selector switch 41 'contactor

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-9-239823 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 51/42 B29C 51/46

Claims (5)

(57) [Claims] 1. A heating control method for heating a three-dimensional molded article from a thermoplastic resin sheet or a fiber-reinforced composite sheet mainly composed of a thermoplastic resin, wherein the sheet is heated using an infrared rod-shaped heater. When the heater temperature rises, the equation ΔS = (Ta−Ts) / Kb
(ΔS: Start time, Ta: Heater set temperature, Ts: Heater temperature at start of operation, Kb: Average start speed) During the start time calculated, the power supply to the indirect heater should be set to a rated voltage or more. A heating time of the heater is shortened, and overheating of the heater heating section is prevented. 2. The heating control method for a seat according to claim 1, wherein a power supply voltage to the heater is equal to or higher than a rated voltage of the heater, and a control output is performed by duty control. Wherein the duty ratio is reduced so that the rated output is obtained during a normal heating operation. 3. The sheet heating control method according to claim 1, wherein the power supply voltage to the heater is equal to or higher than the rated voltage of the heater, and the control output is performed by duty control. , Thereby setting a smooth and fast rise of the heater temperature. 4. A heating control method for a seat according to claim 1, wherein two supply power supplies are provided for said heater, and a voltage higher than the rated voltage of the heater during the start-up operation, and a voltage higher than the rated voltage of the heater during the heating operation. Heating control method for a sheet. 5. The sheet heating control method according to claim 1, wherein the heaters are switched in series and parallel in two units.
A sheet heating control method characterized by switching between a voltage twice the rated voltage and a rated voltage for use.