JPH11268090A - Method and apparatus for controlling temperature of heating barrel in injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the temp. of the heating barrel in an injection molding machine preventing the heat generation of a necessary degree or more of a circuit element and reducing cost without complicating equipment cost without complicating equipment constitution to smoothly achieve injection molding of high quality. SOLUTION: The first current supply circuit 30 electrically connected to the heater group of a heating barrel through the a reversible electromagnetic switch 22 fitted with a neutral position and a circuit element 16 from a power supply wiring 12 and the second current supply circuit 32 electrically connected to the heater group of the heating barrel directly through a reversible electromagnetic switch 22 fitted with a neutral position through the power supply wiring 12 are provided. The operation of the circuit element 16 is controlled by a temp. regulator 20 and the changeover signal of each current supply circuit is generated on the basis of necessary current conductivity to selectively perform the ON/OFF control of the reversible electromagnetic switch 22 to perform the current supply changeover of the first current supply circuit 30 with the current supply circuit 32 of the second current supply passage 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the temperature of a heating barrel in an injection molding machine, and more particularly to a circuit element comprising a solid state relay (SSR) comprising a thyristor circuit or the like or a solid state contactor (SSC). The present invention relates to a method and an apparatus for controlling a temperature of a heating barrel in which a circuit element can be properly used in a current supply circuit for a heating means.

[0002]

2. Description of the Related Art Generally, when controlling the temperature of a heating barrel in an injection molding machine, a heating barrel formed on an outer peripheral portion of an injection cylinder is divided into a plurality of sections in a longitudinal direction, and independent temperature control areas are respectively formed. In addition to the setting, a temperature detector is provided for each temperature control area to detect a heating temperature, and these temperature detection signals are energized to the heating means provided in the corresponding temperature control areas via the temperature controller. ,
There is known a method and an apparatus for performing PID control so that the heating temperature in each temperature control region becomes a preset appropriate temperature.

In this case, a band heater is provided as a heating means in each of the temperature control zones, and a thermocouple is applied as a temperature detector. The temperature controller includes an A / D converter for inputting a temperature detection signal, a central processing unit (CPU) for performing temperature setting and a temperature control command for each temperature control area, and the temperature control unit. A built-in output interface and the like for outputting commands, based on the temperature control command output by this temperature controller, for selectively energizing band heaters provided corresponding to each temperature control range. , A solid state relay (SSR) or a solid state contactor (SSC) is generally used.

However, in a conventional method of controlling the temperature of a heating barrel in an injection molding machine, a control circuit for energizing a band heater as a heating means provided in each temperature control area is shown in FIG. 4, for example. It is configured as follows. That is, in FIG. 4, the band heaters 10a, 10a,
0b and 10c are connected to the electromagnetic switch 14 with respect to the power supply wiring 12.
And a circuit element 16 composed of a solid state relay (SSR) or a solid state contactor (SSC). In this case, the electromagnetic switch 14 is configured as an open / close contact that is opened / closed by the circuit element 16.

In FIG. 4, reference numeral 18 denotes a thermocouple as a temperature detector provided for each of the band heaters, and reference numeral 20 denotes a temperature controller. Reference numeral 16 controls energization of each of the band heaters 10a, 10b, and 10c via the temperature controller 20 based on a temperature detection signal of each temperature control region detected by a temperature detector including the thermocouple 18. It is configured as follows.

However, in an injection molding machine, a band heater 1 provided for each temperature control area of a heating barrel is provided.
It is required that 0a, 10b, and 10c are always controlled to a temperature that matches the molding conditions of the molding material.

A step which must be prepared before starting the operation of the injection molding machine is to raise the temperature of the heating barrel to a temperature suitable for molding the band heater in each temperature control region.

In operating the injection molding machine, a temperature controller having a screw cold start preventing function is provided so that the injection screw is not rotated until the heating barrel rises to a predetermined temperature. It has also been proposed (JP-A-62-227720).

The temperature controller according to this proposal compares the set temperature of the setting unit with the detected temperature detected by the temperature detector, calculates and outputs an output signal so that the temperature becomes the temperature set in the temperature setting unit. And a timer that counts a predetermined set time when the temperature reaches a temperature set by the setting unit, and is activated by an output signal that is issued first when the temperature reaches a temperature set by the setting unit. A display for displaying the count time of the timer or the remaining time of the set time; and a set value of the setting unit for setting the time to be displayed on the display and the predetermined time or the remaining time of the predetermined time set in advance ( Normally 0), a signal is issued when the values match, a first comparison / determination unit for determining whether there is remaining time, and a storage unit for storing the signal generated by the first comparison / determination unit And power on A second comparison determination to determine whether a signal from the storage unit has been received and to send a screw rotation enable signal to the screw rotation drive source only when a signal from the storage unit has been received. And a container.

Accordingly, the temperature controller configured as above determines whether or not the temperature has sufficiently risen and the screw can be rotated by the two comparison / determination units, and determines whether or not the power is turned on. Since the temperature at the time when the power is turned off can be determined and controlled, it does not start before the resin temperature in the injection cylinder is sufficiently increased, and the temperature of the heating barrel is not increased. Can be started when the resin temperature in the injection cylinder has risen sufficiently, ignoring the timing of the predetermined time.

In the above-mentioned temperature control method, the relationship between the temperature at the time of temperature rise and the time is examined. As shown in FIG. 5, the set temperature level corresponding to the molding conditions and the set temperature level T0 are centered. The upper and lower allowable proportional bands Tab are set. Therefore, according to the control circuit shown in FIG. 4 described above, each band heater continues to be energized until the temperature in each temperature control region reaches the set temperature. On / off control is achieved with the opening / closing operation of the electromagnetic switch 14 based on the temperature level T0.

Next, with respect to the temperature control characteristic shown in FIG. 5, if a time section consisting of sections A, B, C, and D is set corresponding to the change, the section A is energized. ) To reach the lower limit level of the proportional band Tab, and the section B is a section from the lower limit level of the proportional band Tab to reach the set temperature level T0,
The section C is a section which exceeds the set temperature level T0 and approaches the upper limit level of the proportional band Tab, and the section D is a section where the set temperature level T0 is settled.

Here, the conversion of the duty ratio in each of the sections A, B, C, D is substantially as follows. That is, section A is 100%, section B is 20 to 60%, section C
Is 1 to 10%, and the section D is 5 to 10%.

[0014]

However, in the above-described conventional method of controlling the temperature of the heating barrel in the injection molding machine, as is apparent from the configuration shown in FIG. SS
R) or a solid state contactor (SSC) for energizing a circuit element, so that not only the energizing time for this circuit element is prolonged, but also heat generation in the circuit element progresses, and a control panel for housing and disposing the circuit element Has the drawback of raising the internal temperature to a dangerous state.

In order to avoid such a danger, it is necessary to provide a cooling means for suppressing a rise in the temperature in the control panel, for example, by mounting a radiating fan or a radiating fin in the control panel. However, in this case, there is a problem that manufacturing costs and equipment costs increase.

On the other hand, by conducting electricity efficiently,
As a method of shortening the energization time for the circuit element,
For example, in the course of injection molding by an injection molding machine, when any abnormality occurs and the work is interrupted or terminated, the heater circuit is forcibly turned off, and the temperature of the heating barrel is set to the resin in the injection cylinder. By keeping the material between the melting temperature and the softening temperature of the resin (temperature shift state), when the work is resumed, the temperature of the heating barrel does not drop below room temperature. There has been proposed a temperature control method for an injection molding machine configured so that it can be accomplished in a short time and the work can be resumed in a short time (Japanese Patent Application Laid-Open No. 4-164622).

However, even in this case, the energization of the heater is always performed by the solid state relay (SSR) or the solid state contactor (SS).
C), it is necessary to use the circuit element having an unnecessarily large capacity in consideration of the heat generation and the ambient temperature of the circuit element itself. Therefore, the cost of the circuit element is reduced. Because of the increase, there is a problem that the cost of the apparatus also increases significantly.

Therefore, as a result of intensive studies, the present inventor has found that in controlling the temperature of the heating barrel in an injection molding machine, a reversible electromagnetic switch with a neutral position and a solid state relay (SSR) or a solid state contactor ( A first energizing circuit electrically connected to a heater group of the heating barrel via a circuit element made of SSC), and directly from the power supply wiring to a heater group of the heating barrel via a reversible electromagnetic switch with a neutral position. A second energizing circuit that is electrically connected to control the operation of the circuit elements by a temperature controller so that each of the heater groups has an appropriate set temperature; The reversible electromagnetic switch is selected by generating a switching signal for each of the energizing circuits on the basis of the energization rate. If the power supply is switched between the first and second power supply circuits by performing on / off control in a controlled manner, the circuit elements can be avoided particularly during temperature control at which a high power supply rate is obtained. It has been found that by directly energizing the heater group by the second energizing circuit, heat generation due to long-time energization of the circuit element can be prevented.

That is, in this case, in the temperature controller, only when the injection molding machine starts molding and when molding is restarted, the second energizing circuit is turned on until the heating temperature in each temperature control region reaches a preset temperature. Can be set to generate a switching signal for on / off control of the reversible electromagnetic switch with a neutral position so that the circuit element is in a conducting state. As a result, unnecessary heat generation in the circuit element can be prevented. It has been found that high-quality injection molding suitable for the characteristics of an injection-molded product can be smoothly achieved without complicating the equipment configuration in the control panel and the like, reducing the apparatus cost.

Therefore, an object of the present invention is to provide a heating device provided with a circuit element comprising a solid state relay (SSR) or a solid state contactor (SSC) in order to control the heating temperature of a heating barrel in an injection molding machine to a set temperature. In the energizing circuit of the means, it is possible to prevent unnecessary generation of heat of the circuit element, reduce the equipment cost without complicating the equipment configuration in the control panel and the like, and adapt to the characteristics of the injection molded product. It is an object of the present invention to provide a method and an apparatus for controlling a temperature of a heating barrel in an injection molding machine which can smoothly achieve high-quality injection molding.

[0021]

In order to achieve the above object, a method for controlling the temperature of a heating barrel in an injection molding machine according to the present invention comprises the steps of: Each temperature control area is set by dividing into a plurality of sections, and a temperature detector is provided for each temperature control area to detect a heating temperature, and these temperature detection signals are transmitted to the corresponding temperature via a temperature controller. In the method of controlling the temperature of the heating barrel in the injection molding machine, the heating means provided in the control area is energized and the heating temperature in each temperature control area is controlled to be a preset temperature.
A first energizing circuit electrically connected to a heater group of a heating barrel from a power supply wiring via a circuit element including a reversible electromagnetic switch with a neutral position and a solid state relay (SSR) or a solid state contactor (SSC); A second energization circuit that is electrically connected from the power supply wiring to the heater group of the heating barrel directly via a reversible electromagnetic switch with a neutral position, and controls the operation of the circuit elements by a temperature controller, A switching signal for each of the energizing circuits is generated on the basis of the energization rate, and the reversible electromagnetic switch is selectively turned on / off to energize the first energizing circuit and the second energizing circuit. Switching is performed.

In this case, in the temperature controller, only when the injection molding machine starts molding and when molding is restarted, the second energizing circuit is turned on until the heating temperature in each temperature control region reaches a preset temperature. It can be set to generate a switching signal for on / off control of the reversible electromagnetic switch with a neutral position.

Further, in the present invention, the apparatus for performing the temperature control method may include dividing a heating barrel formed on an outer peripheral portion of an injection cylinder into a plurality of sections in a longitudinal direction to set respective temperature control areas. In addition, a temperature detector is provided for each temperature control area to detect a heating temperature, and these temperature detection signals are energized by heating means provided in the corresponding temperature control areas via a temperature controller, and each temperature is detected. In a temperature control device of a heating barrel in an injection molding machine configured to control a heating temperature in a control area to a preset temperature, a reversible electromagnetic switch with a neutral position and a solid state relay (SSR) from a power supply wiring. Or solid state contactor (SS
A first energizing circuit electrically connected to the heater group of the heating barrel via a circuit element comprising C), and electrically connecting the heater group of the heating barrel directly from the power supply wiring via a reversible electromagnetic switch with a neutral position. A second energizing circuit connected to the reversible electromagnetic circuit. The temperature controller controls the operation of the circuit elements and generates a switching signal for each energizing circuit based on a required energization rate. It is characterized in that the switch is selectively turned on / off to switch the energization between the first energizing circuit and the second energizing circuit.

In this case, the temperature controller controls the second energizing circuit to be in an energized state only when the injection molding machine starts molding and when molding is restarted until the heating temperature in each temperature control region reaches a preset temperature. Thus, a switching signal for on / off control of the reversible electromagnetic switch with a neutral position can be configured to be generated.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for controlling a temperature of a heating barrel in an injection molding machine according to the present invention will be described in detail with reference to the accompanying drawings in relation to an apparatus for performing the method. explain.

FIG. 1 is a system explanatory diagram showing a schematic configuration of a temperature control device for performing a method of controlling a temperature of a heating barrel in an injection molding machine according to the present invention. For convenience of explanation, FIG.
The same components as those of the conventional temperature control device shown in FIG.

That is, in FIG. 1, the temperature control device according to the present embodiment includes band heaters 10a, 10a, 10a, 10b which are disposed in respective temperature control zones formed in a heating barrel of an injection molding machine.
b and 10c are electrically connected to the power supply wiring 12 through a circuit element 16 including a reversible electromagnetic switch 22 with a neutral position and a solid state relay (SSR) or a solid state contactor (SSC). A first energizing circuit 30 and a second energizing circuit 32 that is directly electrically connected from the power supply wiring 12 via the reversible electromagnetic switch 22 with a neutral position are provided.

The band heaters 10a, 10a
Temperature detectors comprising thermocouples 18 are provided for b and 10c, respectively, based on the temperature detection signals of the respective temperature control areas detected by these temperature detectors, via the temperature controller 20, Band heaters 10a, 10b, 10
It is configured to perform energization control for c. In this case, the temperature controller 20 controls the operation of the circuit element 16 and generates a switching signal for each of the energizing circuits 30 and 32 based on a required energization rate, and outputs the neutral position. Reversible electromagnetic switch 2
2 is selectively turned on / off to switch the energization between the first energizing circuit 30 and the second energizing circuit 32.

The reversible electromagnetic switch 22 with the neutral position selectively turns on or off one of the first energizing circuit 30 and the second energizing circuit 32 and simultaneously turns off both of them. State can be set, and both are not set to the ON state at the same time.

Next, the control operation of the temperature control device having the above-described configuration will be described in detail below based on a control program shown in FIG. 2 and with reference to a control characteristic diagram shown in FIG.

In FIG. 2, simultaneously with the start of the temperature control of the heating barrel, it is determined in STEP-1 whether the temperature controller 20 is in the temperature shift state. At the start of molding of an injection molding machine that is not in a temperature shift state, or after interrupting or ending molding, and when resuming molding from a state where the heating barrel has dropped to near room temperature, in STEP-2, each temperature control area of the heating barrel The temperature of each band heater provided in the temperature detector 18 is detected by a temperature detector 18, and this temperature detection signal is
Then, in STEP-3, it is determined whether or not the temperature of each temperature control region is within the band of the proportional band Tab of the molding set temperature T0. As a result, the temperature becomes the molding set temperature T
In the case other than the band of the proportional band Tab of 0, STEP-5
In, it is determined whether the temperature of each temperature control region is above or below the proportional band Tab. As a result,
If the temperature is above the proportional band Tab, STEP-
6, the temperature controller 20 controls the reversible electromagnetic switch 22 with the neutral position,
0 and 32 are turned off (OFF in the section ii in FIG. 3).
reference). That is, energization is cut off. Further, when the temperature is below the proportional band Tab, in STEP-7, it is a case of a high energization rate, and thus the temperature controller 20 is provided with respect to the reversible electromagnetic switch 22 with the neutral position.
On / off control is performed so as to select the second energization circuit 32, and energization is continued until the temperature of each of the band heaters reaches the set temperature (see the second section i, v, and ii in FIG. 3).
).

On the other hand, if the temperature is within the band of the proportional band Tab of the molding set temperature T0, in STEP-4, the temperature controller 20 is a low reversible electromagnetic switch 22 with a neutral position because it is a case of a low energization rate. On / off control is performed so as to select the first energizing circuit 30 and the solid state relay (SSR) or the solid state contactor (SSC) is controlled so that the temperature of each band heater becomes the set temperature. The operation of the circuit element 16 is controlled (see sections ii and vi in FIG. 3).

The above STEP-4, STEP-6
When the operations in STEP-7 and STEP-7 are completed, the process returns to STEP-2 again, and the temperature of each band heater provided in each temperature control area of the heating barrel is detected by the temperature detector 18, and this temperature detection is performed. The signal is input to the temperature controller 20,
The change in the temperature state is detected, and the above-mentioned STEP-1 to STEP-7 are detected.
Is repeated.

On the other hand, as in the prior art described above, for example, during the injection molding by the injection molding machine, when any abnormality occurs and the operation is interrupted or terminated, the heater circuit is forcibly turned off. Subsequently, a case will be described in which the temperature of the heating barrel is maintained in the temperature shift state and then the temperature is raised again to the set temperature, that is, molding is restarted.

To set the temperature shift state, as shown in FIG. 3, the temperature shift set temperature Ts and its proportional band Tcd are set and set, and both the energizing circuits 30 and 32 are turned off (FIG. 3).
Section iii), the temperature of the heating barrel falls to the range of the proportional band Tcd of the temperature shift set temperature Ts.

Therefore, in the above-mentioned STEP-1, it is determined that the temperature is shifted. In this case, STEP
When the temperature detected by the temperature detector 18 falls within the proportional band Tcd of the temperature shift set temperature Ts in STEP-8, in STEP-9, the temperature controller is used because it has a low duty ratio. Reference numeral 20 denotes a first energizing circuit 30 for the reversible electromagnetic switch 22 having a neutral position.
And ON / OFF control so as to select, and so that the temperature of each band heater becomes a temperature shift set temperature,
The operation of the circuit element 16 including a solid state relay (SSR) or a solid state contactor (SSC) is controlled (see section iv in FIG. 3). And the STE
P-8 and STEP-9 are cyclically repeated.

Thereafter, when the molding of the injection molding machine is restarted, the above-described control is performed from STEP-2, and the control characteristics as shown in FIG. 3 can be easily obtained.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and many design changes can be made without departing from the spirit of the present invention. It is.

[0039]

As described above, in the method and apparatus for controlling the temperature of the heating barrel in the injection molding machine according to the present invention, the heating barrel formed on the outer periphery of the injection cylinder is
Along with dividing into a plurality of sections in the longitudinal direction, each temperature control area is set, and a temperature detector is provided for each temperature control area to detect each heating temperature, and these temperature detection signals are transmitted via a temperature controller. In the method and the apparatus for controlling the temperature of the heating barrel in the injection molding machine, the heating means provided in the corresponding temperature control areas are energized to control the heating temperature in each temperature control area to be a preset temperature. A first energizing circuit electrically connected to a heater group of a heating barrel from a power supply wiring through a circuit element including a reversible electromagnetic switch with a neutral position and a solid state relay (SSR) or a solid state contactor (SSC); It is electrically connected to the heater group of the heating barrel directly from the power supply line via a reversible electromagnetic switch with a neutral position. A second current supply circuit provided by the temperature controller, controls the operation of the circuit element,
A switching signal for each of the energizing circuits is generated based on a required energization rate, and the reversible electromagnetic switch is selectively turned on / off to connect the first and second energizing circuits. By configuring to switch the energization, unnecessary heat generation of the circuit elements can be prevented, and the equipment cost can be reduced without complicating the equipment configuration in the control panel, etc. Many excellent advantages are obtained, such as high-quality injection molding suitable for characteristics can be achieved smoothly.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram of a temperature control device for implementing a method of controlling a temperature of a heating barrel in an injection molding machine according to the present invention.

FIG. 2 is a flowchart showing one embodiment of a control program for implementing a method of controlling a temperature of a heating barrel in an injection molding machine according to the present invention.

FIG. 3 is a temperature control characteristic diagram by a temperature control method of a heating barrel in the injection molding machine according to the present invention.

FIG. 4 is a schematic system diagram of a temperature control device for implementing a method of controlling a temperature of a heating barrel in a conventional injection molding machine.

FIG. 5 is a temperature control characteristic diagram based on a heating barrel temperature control method in a conventional injection molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10a, 10b, 10c Band heater (heating means) 12 Power supply wiring 14 Electromagnetic switch 16 Circuit element (SSR, SSC) 18 Thermocouple (Temperature detector) 20 Temperature controller 22 Reversible electromagnetic switch with neutral position 30 First Energizing circuit 32 Second energizing circuit

Claims (4)

[Claims] 1. A heating barrel formed on an outer peripheral portion of an injection cylinder is divided into a plurality of sections in a longitudinal direction to set respective temperature control areas, and a temperature detector is provided for each temperature control area. Heating temperatures are detected, and these temperature detection signals are energized by the heating means provided in the corresponding temperature control areas via the temperature controllers so that the heating temperatures in the respective temperature control areas become the preset temperatures. In a method for controlling the temperature of a heating barrel in an injection molding machine, the heating barrel is controlled from a power supply wiring through a circuit element including a reversible electromagnetic switch with a neutral position and a solid state relay (SSR) or a solid state contactor (SSC). A first energizing circuit electrically connected to the heater group; and a reversible electromagnetic opening with a neutral position from the power supply wiring. A second energization circuit electrically connected directly to a heater group of the heating barrel via a heater, wherein a temperature controller controls the operation of the circuit element and performs the operation based on a required energization rate. A switching signal is generated for each energizing circuit, and the reversible electromagnetic switch is selectively turned on / off to perform energization switching between the first energizing circuit and the second energizing circuit. A method for controlling the temperature of a heating barrel in a molding machine. In the temperature controller, the second energizing circuit is energized only when the injection molding machine starts molding and when molding is restarted until the heating temperature in each temperature control region reaches a preset temperature. 2. The method for controlling the temperature of a heating barrel in an injection molding machine according to claim 1, further comprising generating a switching signal for controlling on / off of a reversible electromagnetic switch with a neutral position. 3. A heating barrel formed on an outer peripheral portion of an injection cylinder is divided into a plurality of sections in a longitudinal direction to set respective temperature control areas, and a temperature detector is provided for each temperature control area. Heating temperatures are detected, and these temperature detection signals are energized by the heating means provided in the corresponding temperature control areas via the temperature controllers so that the heating temperatures in the respective temperature control areas become the preset temperatures. In a temperature control device of a heating barrel in an injection molding machine configured to control, a reversible electromagnetic switch with a neutral position and a circuit element including a solid state relay (SSR) or a solid state contactor (SSC) from a power supply wiring. A first energizing circuit electrically connected to a heater group of the heating barrel, and a neutral position from the power supply wiring. A second energizing circuit that is electrically connected directly to the heater group of the heating barrel via a reversible electromagnetic switch; controls the operation of the circuit element in the temperature controller, and adjusts the required energization rate to A switching signal for each of the energizing circuits is generated based on the control signal, and the reversible electromagnetic switch is selectively turned on / off to perform energization switching between the first energizing circuit and the second energizing circuit. A temperature control device for a heating barrel in an injection molding machine. 4. The temperature controller controls the second energization circuit to be in an energized state only when the injection molding machine starts molding and when molding is restarted until the heating temperature in each temperature control region reaches a preset temperature. 4. The temperature control device for a heating barrel in an injection molding machine according to claim 3, wherein a switching signal for turning on / off the reversible electromagnetic switch with a neutral position is generated.