JPH06304976A - Method and device for sensing resin melting state of plastic molding machine and method and machine for plastic - Google Patents

Abstract

PURPOSE:To sense accurately the melting state of resin almost without adverse effect to the resin, based on which the reliable plasticization control is carried out. CONSTITUTION:A diversion type mixing element 20 is disposed on a screw 11. A temperature sensor 31 and a resin pressure sensor 32 are installed facing the dispersion type mixing element 20 on a barrel 10. The melting state of resin is sensed by sensing the temperature and pressure of resin passing through the dispersion type mixing element 20 by means of the sensors 31 and 32 and also the plasticizing condition is sensed by the above method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic molding method and a molding machine, and more particularly to a method and a device for detecting a molten state of a resin by a barrel and a screw, and a plastic for controlling plasticization based on the detection. The present invention relates to a molding method and a molding machine.

[0002]

2. Description of the Related Art Conventionally, in a plastic molding machine for production, it has not been possible to reliably detect a molten state of a resin. As a conventional melting state detection, a method of measuring a resin temperature at a representative point in a resin flow path after a screw tip portion with a thermocouple or the like is generally adopted.
As disclosed in Japanese Patent No. 58092, a method has been proposed in which the resin pressure in the melted portion (phase transition portion) is detected and the melted state is indirectly estimated from the output waveform.

[0003]

The method of measuring the resin temperature after the tip of the screw can know the time series variation of the resin temperature on the streamline passing through the measurement point, but the resin inside the passage part can be known. Since the temperature cannot be measured, it is impossible to know the overall state of the resin passing through. In addition, it is not possible to know whether or not melting is taking place at the desired location on the screw.

The above-mentioned method for measuring the resin pressure can detect the molten state in the middle of the screw,
Since the relationship between the resin pressure and the molten state is not a direct relationship, it has a drawback that the molten state cannot be detected more accurately than the method by measuring the resin temperature.

In order to solve the above problems, the inventors of the present invention detect the resin temperature in the screw groove with a temperature sensor provided in the barrel and grasp the molten state of the resin from the profile of the resin temperature in the screw groove. Proposed to do so (Japanese Patent Application No. 4-208410). According to this method, the molten state of the resin can be grasped with considerable accuracy, but when the screw groove is relatively deep, the molten state of the resin over the entire cross section in the screw groove can be detected more reliably. There is a drawback that cannot be done.

The present invention solves the above-mentioned drawbacks,
At a predetermined desired detection position from the middle of the screw to the tip, the resin melting state detection method and device of a plastic molding machine capable of more accurately detecting the molten state of the resin, and the resin based on this detection. An object of the present invention is to provide a plastic molding method and a molding machine that can more reliably perform plasticization.

[0007]

DISCLOSURE OF THE INVENTION The present invention for achieving the above object is a method for detecting a resin melted state of a plastic molding machine which melts and kneads a resin by a barrel and a screw fitted in the barrel and sends the resin. In, the dispersive mixing element is placed at the desired detection position from the middle of the screw to the tip, and the temperature of the resin passing through this dispersive mixing element part is detected by the temperature sensor installed in the barrel. The molten state of the resin is grasped from the temperature information obtained by.

It is preferable to detect the rotational angle position of the screw together with the detection of the temperature and synchronize the temperature information with the rotational angle position of the screw. Further, it is preferable that the pressure of the resin passing through the distributed mixing element portion is detected by a resin pressure sensor provided in the barrel, and the pressure information obtained by this detection is added to grasp the molten state of the resin.

Further, according to the present invention, in a resin molten state detecting device of a plastic molding machine for melting and kneading resin by a barrel and a screw fitted in the barrel and sending out the resin, a desired detection from the middle to the tip of the screw is performed. It is provided with a distributed mixing element arranged at a position and a resin temperature detecting device including a temperature sensor mounted on the barrel so as to face the distributed mixing element.

A rotation angle position detecting device for the screw is provided in the screw or its drive system so that the output from the resin temperature detecting device is synchronized with the rotation angle position of the screw obtained from the rotation angle position detecting device. It is preferable. Further, it is preferable to provide a resin pressure detecting device including a resin pressure sensor which is attached to the barrel so as to face the distributed mixing element and which is paired with the temperature sensor.

Furthermore, the present invention is a plastic molding method in which a resin is melted and kneaded by a barrel and a screw fitted in the barrel and is sent out, and the resin is dispersed at a desired detection position from the middle to the tip of the screw. Type mixing element is arranged, the temperature of the resin passing through this distributed type mixing element part is detected by a temperature sensor provided in the barrel, and the number of rotations of the screw and the barrel based on the temperature information obtained by this detection. temperature,
At least one of the head resin pressure and the resin supply amount is controlled.

Also in this plastic molding method, it is preferable to detect the rotation angle position of the screw as well as the temperature and synchronize the temperature information with the rotation angle position of the screw. Further, the pressure of the resin passing through the distributed mixing element portion is detected by a resin pressure sensor provided in the barrel, and the rotation speed of the screw and the temperature of the barrel are detected based on the pressure information and the temperature information obtained by this detection. It is preferable to control at least one of the head portion resin pressure and the resin supply amount.

Furthermore, according to the present invention, in a plastic molding machine for melting and kneading a resin by a barrel and a screw fitted in the barrel and feeding the resin, the plastic molding machine is arranged at a desired detection position from the middle of the screw to the tip. A resin temperature detection device including a dispersion type mixing element, a temperature sensor attached to the barrel so as to face the dispersion type mixing element, and an output from the resin temperature detection device is fetched as temperature information. A control device for controlling at least one of the number of revolutions of the screw, the temperature of the barrel, the resin pressure in the head portion, and the resin supply amount based on a relationship given in advance.

Also in this plastic molding machine, a screw rotation angle position detecting device is provided in the screw or its drive system so that the temperature information is synchronized with the screw rotation angle position obtained from the rotation angle position detecting device. It is preferable to configure. Further, a resin pressure detection device including a resin pressure sensor mounted on the barrel in a pair with the temperature sensor so as to face the distributed mixing element is provided, and the control device outputs the output from the resin pressure detection device as pressure information. It is preferable to take in and control at least any one of the number of rotations of the screw, the temperature of the barrel, the resin pressure in the head portion, and the resin supply amount based on the pressure information and the temperature information.

[0015]

The dispersion type mixing element is composed of a large diameter cylindrical portion called a blister ring or a dispersion ring provided in the middle or tip of the screw as is well known, and further, a plurality of large diameter cylindrical portions are provided on the surface of the large diameter cylindrical portion. For example, a groove is provided to allow resin to pass through a relatively narrow gap along the inner surface of the barrel. The resin passing through the gap and the groove has a relatively thin resin flow, so that the temperature of almost the entire resin passing therethrough is
It is detected by a temperature sensor provided on the barrel. Since the temperature of the resin and the molten state have a correspondence relationship, it is possible to grasp almost all of the resin passing through the molten state of the resin from the detected temperature information.

Since the rotational angle position on the circumference of the distributed mixing element has a constant relationship with the screw groove on the upstream side, the temperature information is synchronized with the rotational angle position of the screw to prevent the resin in the screw groove from moving. It is possible to know the distribution of the molten state.

Further, by detecting the resin pressure passing through the dispersion type mixing element portion, the molten state can be more surely grasped and the filling state of the resin in the screw groove can be known.

Furthermore, the plasticization (melting) of the resin is
It is related to the number of rotations of the screw, the temperature of the barrel, the resin pressure of the head portion, and the amount of resin supplied. Therefore, the relationship between these and temperature information or pressure information is given to the control device in advance, and the rotation speed of the screw or the like is controlled based on the detected temperature information or pressure information to melt the resin to a desired level. It can be sent to the downstream side of the distributed mixing element in a state.

[0019]

Embodiments of the present invention will be described below with reference to FIGS.
Will be described with reference to. In FIG. 1, 10 is a barrel into which a screw 11 is fitted. A T-die 13 is attached to the tip of the barrel 10. The screw 11 is rotated by a motor 15 via a speed reducer 14 at an appropriate rotation speed.

A plurality of heaters 16 are mounted on the outer periphery of the barrel 10, and a hopper 17 is provided near the base end of the barrel 10. A fan 18 for external cooling is provided for these heaters 16. Each heater 16 and fan 18 is controlled by a temperature controller 19 which is operated by a controller (CPU) 37 via an output interface 45 and a distribution controller 47, as will be described later.
It is selectively operated and its output is controlled to maintain the temperature of the barrel 10 at a predetermined value for each heater 16.

The screw 11 is a barrier type having a main flight 12A and a sub-flight 12B. As shown in a partially enlarged view of FIG. 2, the distributed mixing element 20 is provided downstream of the end of the sub-flight 12B. It is provided. The distributed mixing element 20 in this embodiment
Is a plurality of inflow grooves 22 and outflow grooves 23 alternately provided on the surface of the dispersion ring 21 with an appropriate twist angle.

A temperature sensor 31 and a resin pressure sensor 32 are attached to the barrel 10 at a position approximately in the center of the dispersion type mixing element 20 in the axial direction. Both sensors 3
1, 32 have their tips opposed to the outer periphery of the dispersion type mixing element 20, and detect the temperature and pressure of the resin passing in front of the tips.

The temperature sensor 31 is connected to a signal processor 33 which constitutes a resin temperature detecting device together with the temperature sensor 31, and the resin pressure sensor 32 is connected to a signal processor 34 which constitutes a resin pressure detecting device together therewith. The control unit (CP) is selectively switched by the switching unit 35 via the A / D converter 36.
U) 37. The switching device 35 and the A / D converter 36 are given a switching signal and a trigger signal from the control device 37, respectively.

A display member 38 for detecting the screw rotation angle position, for example, the origin, is attached to the base end of the screw 11, and a position sensor 39 is attached in pair with the display member 38. The position sensor 39 is connected to the control device 37 via a signal processor 40 which constitutes a device for detecting the rotation angle position of the screw 11 together with the position sensor 39 and the display member 38.

FIG. 3 is a general flow chart of a processing program executed by the controller 37. The temperature sensor 3 is used to set the sampling conditions in step (ST) 1.
The timing, time, etc. of taking in the outputs from 1 and the resin pressure sensor 32 are set in advance.

The sampling of ST2 takes in the resin temperature and the resin pressure from the sensors 31 and 32 in accordance with the setting of ST1, and at the same time, the related data such as the screw rotational speed (r, p, m), the barrel temperature, the output of the position sensor 39 and the like. Take in.

In ST3, it is determined whether or not sampling has been performed a preset number of times of sampling (one rotation of the screw is 1), and in ST4, the number of rotations of the screw (r, p, m taken in in ST2). ) And position sensor 39
The positions of the inflow groove 22 and the outflow groove 23 are determined on the basis of the output of 1 and the outputs from both sensors 31, 32 are synchronized with the rotational angle position of the screw 11.

At ST5, the temperature and pressure taken in from both sensors 31 and 32 are displayed graphically in correspondence with the groove position obtained at ST4, as shown in FIGS. The graphic display is performed by an output device such as the CRT display 42 and the printer 43 shown in FIG. 1, and the data is stored in the internal memory 41 and the external memory such as the floppy disk 44.

ST6 is shown in FIG. 4 from the display data of ST5.
To average temperature T _R , temperature difference R, and standard deviation σ shown in FIG.
The representative values such as are calculated and displayed, and further, the internal memory 41
Alternatively, it is stored in the floppy disk 44.

In ST7, the representative value is compared with a preset allowable value, and in ST8, the molten state of the resin is diagnosed. As a result, in ST9, external output such as alarm and control is performed. The external output is output via the output interface 45 shown in FIG. 1 to the alarm 46 and the temperature controller 1 for barrel temperature control.
9 is provided to the distribution controller 47 and the like.

The control performed in ST9 includes the control of the barrel temperature, the rotation speed of the screw 11, and the barrel 1.
No. 1 or more of the head portion resin pressure by the throttle valve (not shown) provided between the tip of 0 and the T die 13 or the resin supply amount from the hopper 17 is predetermined in relation to the diagnosis result of ST8. Control, that is, when the melting is insufficient, the barrel temperature is raised, the screw rotation speed is lowered, the head portion resin pressure is raised, and the resin supply amount is lowered.

Next, the operation of the present apparatus will be described with reference to specific operational examples. The plastic molding machine used was a single screw extruder, and the screw 11 had a diameter of 90 mm and L / D.
(Screw length / Screw diameter): 32 barrier type, and the number of grooves of the dispersion type mixing element 20 is 10 in total including 5 inflow grooves 22 and 5 outflow grooves 23.

The temperature sensor 31 is an infrared radiation thermometer (wavelength 2 to 2.7 μm, response speed 10 mS, probe diameter 3.8).
mm, measurement depth 2-3 mm), and the resin pressure sensor 32 is a standard diaphragm / strain gauge type.

The resin used is polypropylene (PP),
The rheological property value is MFR6 (all pellets).

The set temperature of the barrel 10 is divided into 6 zones over the entire length, and 200, 22 are sequentially provided from the upstream side toward the head portion.
The temperature was 0, 240, 240, 220, 210 ° C.

4 to 6, the screw rotational speeds are 160, 130 and 45, respectively, under the above conditions.
r. p. in the case of a m, the resin pressure, the resin temperature and representative value indicates (mean temperature (T _R), the temperature difference (R), standard deviation (sigma)).

The screw rotation speed in FIG. p. m
In the case of No. 3, No. No. 4 of the inflow groove 22 because the resin temperature of the portion 4 (“in 3”, “in 4” in FIG. 4) is low. 1, No. Part 5 is expensive. this is,
The incompletely melted resin at low temperature formed a continuous strip from the upstream solid groove, and No. 3, No. The resin that has flowed into the inflow groove 22 of No. 4 and is almost completely melted is
o. 1, No. 5 is determined to have flowed into the inflow groove 22. In addition, No. The temperature of the inflow groove 22 of No. 2 has variations in height. This indicates that there may be a solid bed breakup.

The outflow groove 23 has a No. 1-No. 5
It is shown that the temperature of No. 1 is averaged and rises above the temperature in the inflow groove 22 on average, and the effect of the distributed mixing element is exhibited. 3, No. No. 4 through No. 4 inflow groove 22. 3, No. Probably because some of the incompletely melted resin had flowed out to the outflow groove 23 of No. 4, defects such as fish eyes and flow marks were generated in the extrusion molded product.

The resin pressure in the inflow groove 22 is higher than the resin pressure in the outflow groove 23. 3, N
o. The resin pressure in the inflow groove 22 of No. 4 is high, and there is variation as a whole. This indicates that each inflow groove 22 is sufficiently filled with resin, and the pressure becomes higher as the resin in an incompletely melted state increases.

As described above, the example shown in FIG. 4 is clearly found to be in an incomplete melted state, and the distribution of the melted state in the screw groove can be grasped.

FIG. 5 shows a screw rotation speed of 130 r. p.
m, and other conditions are the same as in FIG. As is clear from FIG. 5, it is understood that the incompletely melted state is improved by decreasing the screw rotation speed.

FIG. 6 shows a screw rotation speed of 45 rpm. p. m
4 and FIG. 5 under the other conditions. In this case, as is apparent from FIG. 6, the standard deviation σ of the resin temperature is almost zero in both the inflow groove 22 and the outflow groove 23, and it can be seen that the resin is almost completely melted.

In the above operation example, the melting state is changed by changing the screw rotation speed, but the melting state is also changed by changing the barrel temperature, the head portion resin pressure and the resin supply amount. Therefore, a desired molten state can be obtained by subjecting these to plasticization control for melting.

[0044]

As described above, according to the present invention, the molten state of the plasticized and delivered resin can be detected extremely accurately, and there is almost no adverse effect on this detection. It is possible to adopt, and by controlling the plasticization of the plastic molding in the actual machine based on the above detection result as well as the diagnosis of the molten state, it is possible to obtain the effect that better molding is possible.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a general flowchart of a processing program executed by a control device (CPU).

FIG. 4 is a diagram showing an example of a resin pressure, a resin temperature, and a representative value detected by the present invention.

FIG. 5 is a view similar to FIG. 4 when the screw rotation speed is changed.

FIG. 6 is a diagram when the screw rotation speed is further changed.
It is a figure similar to.

[Explanation of symbols]

 10 Barrel 11 Screw 19 Temperature Controller 20 Dispersive Mixing Element 21 Dispersion Ring 22 Inflow Groove 23 Outflow Groove 31 Temperature Sensor 32 Resin Pressure Sensor 37 Control Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiro Iguchi 2068-3 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd. Numazu Plant

Claims (12)

[Claims] 1. A method for detecting a molten state of a resin in a plastic molding machine which melts and kneads a resin by a barrel and a screw fitted in the barrel and sends the molten resin to a desired detection position from the middle to the tip of the screw. Distributing type mixing element is installed in, the temperature of the resin passing through the dispersing type mixing element part is detected by the temperature sensor installed in the barrel, and the melting state of the resin can be grasped from the temperature information obtained by this detection. A method for detecting a molten state of a resin in a plastic molding machine, comprising: 2. The method for detecting a resin melting state of a plastic molding machine according to claim 1, wherein the rotational angle position of the screw is detected and the temperature information is synchronized with the rotational angle position of the screw. 3. A resin pressure sensor provided on the barrel detects the pressure of the resin passing through the distributed mixing element portion, and the pressure information obtained by this detection is added to grasp the molten state of the resin. The method for detecting a resin melted state of a plastic molding machine according to claim 1 or 2. 4. A resin molten state detecting device for a plastic molding machine which melts and kneads a resin by a barrel and a screw fitted in the barrel and sends out the resin. The device is arranged at a desired detection position from the middle of the screw to the tip. And a resin temperature detecting device including a temperature sensor attached to the barrel so as to face the same dispersing type mixing element, and a resin melting state detecting device for a plastic molding machine. . 5. A rotation angle position detecting device for a screw or a screw provided in a drive system thereof is provided, and an output from the resin temperature detecting device is synchronized with a rotation angle position of the screw obtained from the rotation angle position detecting device. The resin melted state detecting device for a plastic molding machine according to claim 4, wherein 6. A resin pressure detecting device comprising a resin pressure sensor, which is paired with the temperature sensor, and which is mounted on the barrel so as to face the distributed mixing element. 5. A resin molten state detecting device for a plastic molding machine according to item 5. 7. A plastic molding method in which a resin is melted and kneaded by a barrel and a screw fitted in the barrel and is sent out, in which a dispersion-type mixing element is provided at a desired detection position between the middle and the tip of the screw. The temperature of the resin passing through this distributed mixing element part is detected by a temperature sensor provided in the barrel, and the rotation speed of the screw, the temperature of the barrel, and the head part are detected based on the temperature information obtained by this detection. A plastic molding method comprising controlling at least one of a resin pressure and a resin supply amount. 8. The plastic molding method according to claim 7, wherein the rotation angle position of the screw is detected and the temperature information is synchronized with the rotation angle position of the screw. 9. The pressure of the resin passing through the distributed mixing element portion is detected by a resin pressure sensor provided in the barrel, and the rotation speed of the screw is based on the pressure information and the temperature information obtained by this detection. 9. The plastic molding method according to claim 7, wherein at least one of the barrel temperature, the head portion resin pressure, and the resin supply amount is controlled. 10. A plastic molding machine for melting and kneading a resin by a barrel and a screw fitted in the barrel and feeding the resin, wherein a distributed mixing element is disposed at a desired detection position from the middle to the tip of the screw. And a resin temperature detecting device including a temperature sensor mounted on the barrel so as to face the distributed mixing element, and an output from the resin temperature detecting device is fetched as temperature information, which is given in advance to this temperature information. A plastic molding machine, comprising: a controller for controlling at least one of the number of revolutions of the screw, the temperature of the barrel, the resin pressure in the head portion, and the amount of resin supplied based on the above relationship. 11. A screw or a rotation angle position detecting device of a screw provided in a drive system thereof is provided, and is configured to synchronize the temperature information with a rotation angle position of the screw obtained from the rotation angle position detecting device. The plastic molding machine according to claim 10, wherein: 12. A resin pressure detecting device comprising a resin pressure sensor, which is paired with the temperature sensor, and which is mounted on the barrel so as to face the distributed mixing element, and the control device comprises the resin pressure detecting device. The output from the detection device is taken in as pressure information, and at least one of the screw rotation speed, barrel temperature, head portion resin pressure, and resin supply amount is controlled based on this pressure information and the temperature information. The plastic molding machine according to claim 10 or 11, which is configured.