JP3744983B2 - Resin temperature control method and injection molding machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection molding machine that melts and injects a resin and a resin temperature control method.
[0002]
[Prior art]
Conventionally, as a method for controlling the temperature of a resin when the resin is melted and injected, there is an invention described in, for example, JP-A-6-246785.
In the above-described invention, a heater and a temperature sensor are provided in the plasticizing cylinder and the nozzle portion of the injection device, and the temperature measured by the temperature sensor is controlled to be maintained within a predetermined range.
[0003]
[Problems to be solved by the invention]
However, the invention described in JP-A-6-246785 has the following drawbacks.
That is, the place where the temperature sensor senses the temperature is the surface layer portion of the plasticizing cylinder, and the molten resin temperature is not directly measured. For this reason, the temperature is controlled at a value different from the actual resin temperature depending on the mounting method and mounting position of the temperature sensor, the contact state with the metal part of the plasticizing cylinder, the performance and type of the temperature sensor, and the like.
[0004]
Therefore, even in the same type of molding machine, if the molding machines are different, even if the resin temperature is set similarly, the actual molten state (viscous state) of the resin cannot be made the same. That is, when the molding machine is changed, the molding conditions are different in spite of the same type of molding machine, and there is a drawback in that the conditions must be reset. As described above, this is because the molten state of the resin is different for each molding machine.
[0005]
The problems of claims 1 to 5 are that a resin temperature control method and injection molding that can easily and extremely accurately set the molten state of a resin with the same type of molding machine, even if the injection molding machines are different. It is in the offer of the machine.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a plasticizing cylinder having a through hole, a heating source provided in the plasticizing cylinder for melting the resin in the through hole, provided in the plasticizing cylinder, and in the through hole. A resin temperature detecting means for detecting the temperature of the resin, a nozzle that is an injection port of the resin provided at a tip of the plasticizing cylinder, and a through-hole of the plasticizing cylinder are rotatably fitted, and the resin is A screw that extrudes toward the injection port, a radiant power detection mechanism that detects the amount of force when the resin is injected , a control means that controls the heating source, and a resin temperature at which a predetermined radiant power amount is obtained, The injection molding machine is characterized by comprising a step of obtaining at the time of purging, wherein the control means controls the heating source so that the temperature of the resin is maintained at the time of actual molding after the purging .
[0007]
According to a second aspect of the present invention, in the resin temperature control method for controlling the temperature of the molten resin when the molten resin in the plasticizing cylinder is injected from the nozzle , the resin temperature when the predetermined amount of radiant power is obtained is determined at the time of purging. A resin temperature control method comprising: a step of determining and a step of heating the molten resin so that the resin temperature is reached at the time of actual molding after the purge .
[0008]
When the resinous melt inside plasticizing cylinder Ru is emitted from the nozzle, the extrusion force of the screw necessary for the injection in accordance with the molten state of the resin (viscous state) changes. When the resin temperature is high and the viscosity is low, the screw extrusion force required for resin injection is small. Conversely, when the resin temperature is low and the viscosity is high, the screw extrusion force required for resin injection is large. .
[0009]
That is, there is a correlation between the amount of force required for resin injection and the viscosity of the resin. Therefore, in the first and second aspects of the invention, the amount of spray output when the resin is injected from the nozzle is determined, purge is performed, and the temperature of the heating source provided in the plasticizing cylinder is controlled so as to achieve the force. To do. The monitor value of the temperature sensor at this time is stored, and the temperature is controlled so as to be the temperature at the time of actual molding.
[0010]
According to a third aspect of the present invention, there is provided a plasticizing cylinder having a through-hole, a heating source provided in the plasticizing cylinder for melting the resin in the through-hole, provided in the plasticizing cylinder, and provided in the through-hole. A resin temperature detecting means for detecting the temperature of the resin, a nozzle that is an injection port of the resin provided at a tip of the plasticizing cylinder, and a through-hole of the plasticizing cylinder are rotatably fitted, and the resin is A screw that pushes out toward the injection port, a rotational torque detection mechanism that detects rotational torque when the screw is rotated to plasticize the resin, a control means that controls the heating source, and a predetermined torque force the resin temperature when the, comprising the step of determining during the purge, the control means, at the time of actual molding after the purge control means controls the heat source so that the resin temperature An injection molding machine for.
[0011]
According to a fourth aspect of the present invention, in the resin temperature control method for controlling the temperature of the molten resin when the molten resin in the plasticizing cylinder is injected from the nozzle by a screw, the resin temperature at the time of a predetermined torque force is purged. And a step of heating the molten resin so as to reach the resin temperature at the time of actual molding after the purge.
According to a fifth aspect of the present invention, in the resin temperature control method according to the second or fourth aspect, the step of obtaining the resin temperature includes the step of setting the predetermined radiant power amount or torque force, a step shall be specified general resin temperature as a resin temperature of provisional measures the injection force or torque force, the resin of the temporary until the measured value coincides with the predetermined injection force amount or the predetermined torque force and step temperatures may varying, when the value obtained by the measurement is coincident with the predetermined injection force or the predetermined torque force, the resin temperature of the temporary, which is characterized in that it comprises the step of setting the resin temperature It is.
[0012]
When plasticizing the resin continuously by rotating the screw within the plasticizing cylinder, rotational torque for rotating the screw in accordance with the molten state of the resin (viscous state) changes. When the resin temperature is high and the viscosity is low, the rotational torque when rotating the screw is small. Conversely, when the resin temperature is low and the viscosity is high, the rotational torque when rotating the screw is large.
[0013]
That is, there is a correlation between the rotational torque when plasticizing the resin and the viscosity of the resin. Therefore, in the inventions of claims 3 and 4, the rotational torque value of the screw at the time of plasticizing is determined, and the plasticizing cylinder is set so that the rotational torque value detected at the time of actual plasticizing becomes the set value. The temperature of the heating source provided in is controlled. The monitor value of the temperature sensor at this time is stored, and the temperature is controlled so as to be the temperature at the time of actual molding.
Further, in the invention of claim 5, in the resin temperature control method of the invention of claim 2 or claim 4, the resin temperature is set to a predetermined radiant output amount or torque force, and a general resin of the resin set the temperature as a resin temperature of provisional measures the injection force or torque forces, ging a resin temperature of said temporary until measured boss had value matches the predetermined injection force or the predetermined torque force, the measuring When the calculated value coincides with the predetermined radiant power amount or the predetermined torque force , the temporary resin temperature is obtained by setting the resin temperature.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
1 is a schematic configuration diagram of an injection molding apparatus before purging used in the present embodiment, FIG. 2 is a schematic configuration diagram of the injection molding apparatus after purging, FIG. 3 is a flowchart, and FIG. 4 is a graph. Reference numeral 1 denotes a plasticizing cylinder, and band heaters 3 a to 3 e as heating sources are fixed to an outer peripheral portion of the plasticizing cylinder 1. Thermocouples 4a to 4e, which are resin temperature detecting means for detecting the temperature of the plasticizing cylinder 1, are embedded in the plasticizing cylinder 1 near the band heaters 3a to 3e. Further, a through hole 1a is bored in the plasticizing cylinder 1 at the axial center. A screw 2 is rotatably fitted in the through hole 1a, and the screw 2 can extrude the molten resin 9 in the plasticizing cylinder 1 in the axial direction.
[0015]
A nozzle 10 that is an injection port for the molten resin 9 is provided at the tip of the plasticizing cylinder 1. A load cell 5, which is a radiation output detection mechanism that detects the force when the molten resin 9 is injected, is fixed to the root portion of the screw 2. Further, the rotation of the motor 6 is transmitted to the screw 2 through the gear 7. Further, when the screw 2 is pressed by the hydraulic device 8, the molten resin 9 in the plasticizing cylinder 1 is pushed out from the nozzle 10. Reference numeral 11 denotes a control device (control means). By inputting the detection value of the amount of fired output from the load cell 5 and the temperature value of the plasticizing cylinder 1 from the thermocouples 4a to 4e to the control device 11, the band heaters 3a to 3e are input. To control the temperature. FIG. 3 shows a flowchart of a control method using the control device 11.
[0016]
A resin temperature control method using the apparatus having the above configuration will be described below.
First set the general resin temperature of the corresponding resin if (T _a ~T _e). In addition, the emission power amount (P ₀ ) at the time of purging is set.
FIG. 4 shows an example of the relationship between the resin temperature set value and the purge pressure value.
[0017]
Purge is started when the temperature of the plasticizing cylinder 1 is stabilized (see FIG. 2). A purge pressure value (irradiation output amount) necessary for purge at this time is detected by the load cell 5 (P ₁ ). In addition, the measured temperature values (t _{a to} t _e ) of the thermocouples 4 a to 4 _e at this time are also stored in the control device 11. Next, the detected value P ₁ of the purge pressure is compared with the set value P ₀ . If the detected value P ₁ is lower than the set value P ₀ , it means that the viscosity of the resin is still low. Therefore, the set value of the resin temperature is corrected to be lower (in this embodiment, −0.5 ° C. ) Conversely, because when the detected value P ₁ is higher than the set value P0 is that is still high viscosity of the resin, further corrected to a higher set value of the resin temperature (in the present embodiment + 0.5 ° C.) To do.
[0018]
After the correction, the purge pressure value at the time when the temperature is stabilized is detected and compared with the set value P ₀ again, and the above correction is repeated. The measured temperature values (t _{a to} t _e ) of the thermocouples 4 a to 4 _e are also stored in the control device 11 as needed. When the detected value P ₁ becomes a value close to the set value P ₀ (in this embodiment, set to ± 50 kg), the purge is stopped, and the temperatures of the thermocouples 4 a to 4 e stored in the control device 11 are measured. replacing the value (t _a ~t _e) a set value (T _a ~T _e).
[0019]
According to the present embodiment, even when different molding machines are used, the same molten resin state can be set easily and with extremely high accuracy if the molding machine is of the same type.
[0020]
In this embodiment, a value of 0.5 ° C. is used for temperature correction. However, this value is not particular, and for example, the correction amount is changed according to the difference amount between the detected value P ₁ and the set value P _0. The detected value P ₁ can be brought closer to the set value P _{0 more} quickly by controlling the correction value by evaluating the change amount of the difference amount. Further, FIG. 4 shows the characteristic value when the shutoff nozzle is used and the injection speed at the time of purge is 100 mm / S. For example, when an open nozzle is used, the injection speed at the time of purge is slowed, or the nozzle diameter is changed. When the thickness is increased, the purge pressure is further reduced. Even at that time, the same effect can be obtained by the above method if the conditions are the same.
[0021]
(Embodiment 2)
FIG. 5 is a schematic configuration diagram of the injection molding apparatus used in the present embodiment.
In the present embodiment, only the differences from the first embodiment will be described, the same components will be assigned the same reference numerals, and the description thereof will be omitted.
[0022]
In the first embodiment, the load cell 5 is used as means for detecting the viscosity characteristic value of the resin. However, in the present embodiment, this is abolished, and instead the rotational torque detecting mechanism 12 is provided in the motor 6. That is, the rotational torque force applied when the screw 2 is rotated during plasticization is detected by the rotational torque detection mechanism 12 of the motor 6 (for example, by measuring the driving current of the motor 6), and the value is controlled by the control device 13. To input.
[0023]
That is, the rotational torque force of the screw 2 is input as a set value, and the detected value of the rotational torque force necessary for actual plasticizing (a state in which the molten resin 9 is continuously discharged from the nozzle 10). Compare When the detected value is larger than the set value, the control device 13 is used so that the set value of the resin temperature is increased, and conversely, when the detected value is smaller than the set value, the set value of the resin temperature is lowered. To correct.
[0024]
According to the present embodiment, since the rotational torque force is detected as the viscosity characteristic value, a continuous viscosity characteristic value is obtained instead of an intermittent value as in the first embodiment. Therefore, the time required for optimization can be shortened.
[0025]
【The invention's effect】
Since the effects of claims 1 to 5 are controlled by the direct detection value of the resin flow, the viscosity characteristic value of the resin is controlled very accurately compared to the control by an indirect value such as a thermocouple. it can. Therefore, even if the injection molding machines are different, the same type of molding machine can easily and precisely set the molten state of the resin. As a result, even if the molding machine is changed, if it is the same type of molding machine, there is no need to re-condition.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment.
FIG. 2 is a schematic configuration diagram showing the first embodiment.
FIG. 3 is a flowchart showing the first embodiment.
FIG. 4 is a graph showing the first embodiment.
FIG. 5 is a schematic configuration diagram showing a second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Plasticization cylinder 2 Screw 3a-e Band heater 4a-e Thermocouple 5 Load cell 6 Motor 7 Gear 8 Hydraulic device 9 Molten resin 10 Nozzle 11, 13 Control device 12 Rotation torque detection mechanism

Claims (5)

A plasticizing cylinder having a through hole;
A heating source provided in the plasticizing cylinder, for melting the resin in the through hole;
Resin temperature detecting means provided on the plasticizing cylinder for detecting the temperature of the resin in the through hole;
A nozzle that is an injection port of the resin provided at a tip of the plasticizing cylinder;
A screw that is rotatably fitted in the through hole of the plasticizing cylinder, and extrudes the resin toward the injection port;
A radiation output detection mechanism for detecting a force when the resin is injected; a control means for controlling the heating source;
A step of obtaining a resin temperature at the time of purging at the time of purging, and the control means controls the heating source so as to be the resin temperature at the time of actual molding after the purging. Characteristic injection molding machine. In the resin temperature control method for controlling the temperature of the molten resin when the molten resin in the plasticizing cylinder is injected from the nozzle,
A step of obtaining a resin temperature at the time of purging with a predetermined amount of radiant power; and
And a step of heating the molten resin so as to reach the resin temperature at the time of actual molding after the purge. A plasticizing cylinder having a through hole;
A heating source provided in the plasticizing cylinder, for melting the resin in the through hole;
Resin temperature detecting means provided on the plasticizing cylinder for detecting the temperature of the resin in the through hole;
A nozzle that is an injection port of the resin provided at a tip of the plasticizing cylinder;
A screw that is rotatably fitted in the through hole of the plasticizing cylinder, and extrudes the resin toward the injection port;
A rotational torque detection mechanism for detecting rotational torque when the screw is rotated to plasticize the resin;
Control means for controlling the heating source;
A step of obtaining a resin temperature at the time of purging at a predetermined torque force,
The injection molding machine according to claim 1, wherein the control means controls the heating source so that the temperature of the resin is maintained at the time of actual molding after the purge. In the resin temperature control method for controlling the temperature of the molten resin when injection from the nozzle the molten resin in the plasticizing cylinder by the screw,
Obtaining a resin temperature at a predetermined torque force at the time of purging;
A resin temperature control method comprising a step of heating the molten resin so as to be the resin temperature at the time of actual molding after the purge. The step of determining the resin temperature includes
Setting the predetermined radiant power amount or torque force;
Setting a general resin temperature of the resin as a temporary resin temperature;
Measuring the injection force or torque forces, until the measured value coincides with the predetermined injection force amount or the predetermined torque force, the steps may varying the resin temperature of said temporary injection value the measurement is predetermined the resin temperature of the temporary, the resin temperature control method according to claim 2 or claim 4 characterized in that it comprises the step of setting the resin temperature at the time that matches the force or the predetermined torque force.

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