JPH0655600A - Control method of plasticized state of resin in molding machine with screw by measuring temperature of heating cylinder and nozzle - Google Patents

Abstract

PURPOSE:To prevent defective molding by a method wherein a thermocouple is inserted near the internal surface of a heating cylinder for an injection molding machine with a screw, the temperature and temperature change of the position of the thermocouple is measured, the plasticized state of the resin in the cylinder is detected and the number of revolutions of the screw and back pressure are changed in response to the plasticized state. CONSTITUTION:A large number of holes are bored near an internal surface from the external surface of heating cylinder 1 respectively at positions corresponding to a feed zone 2a, a compression zone 2b and a metering zone 2c in a screw 2 for the heating cylinder 1, and thermocouples 3 are inserted into the holes respectively. Temperatures near the internal surfaces of each zone 2a, 2b, 2c in the screw 2 are measured at a plurality of spots. Accordingly, a calorific value by the friction, etc., of a raw resin under the state of a solid layer, a shearing calorific value in a melting section in the cylinder 1 and the state of a temperature change at the time of a change to a liquid layer in the melting section can be detected easily, and the number of revolutions, back pressure, etc., can be set and varied so as to be brought to a plasticized state coinciding with the original function of the screw 2 in the cylinder 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention measures the melting temperature of a raw material resin in an injection molding machine or an extrusion molding machine by providing a thermocouple,
In addition to the method of detecting the plasticized state of the raw material resin based on the measurement result and the measurement, or by separately detecting the temperature of the molten resin injected from the nozzle with a thermocouple, the molding conditions are met. The present invention relates to a plasticization control method for a resin, which controls the rotation speed of the screw.

[0002]

As is well known in the prior art, in an injection molding machine or an extrusion molding machine, a heater is wound around the outer surface of the heating cylinder cylinder, and the temperature of the heating cylinder cylinder is In order to measure and control the temperature, a thermocouple is inserted and installed in the heating cylinder cylinder at a substantially central portion within its thickness. That is, the heating state of the heater is controlled so that the temperature measured by the thermocouple becomes a predetermined temperature.

In this case, the heater is mainly used as a means for preventing the temperature of the raw material resin plasticized in the heating cylinder cylinder from decreasing, and actually the plasticizing of the raw material resin is carried out. Most of the energy required for the material resin and screw generated by the rotation of the screw, or
It is covered by the heat energy generated by the friction with the inner surface of the raw material resin cylinder. Further, since the temperature measurement position by the thermocouple is near the center in the wall thickness of the heating cylinder cylinder, it depends on the amount of heat generated by the rotation of the screw and directly flowing into the raw material resin on the inner surface of the heating cylinder cylinder. At present, almost no change in temperature of the resin is detected.

Generally, in an injection molding machine or an extrusion molding machine equipped with a screw, a raw material resin is heated by frictional heat or shear heat produced by rotation of the screw to plasticize the resin from a solid layer to a liquid layer. There is. And in order to efficiently perform this plasticization, the shape of the screw is generally
In the axial direction, the screw is divided into a feed zone (feed zone), a compression zone (compression zone), and a metering zone (measuring zone).
It has a shape. However, in reality, each zone of the screw
In some cases, the raw material resin may not be in the plastic state predicted or planned at the time of design.

On the other hand, when the molten resin is filled from the nozzle of the molding machine into the mold, it is necessary to measure the temperature of the resin accurately, but in the molding machine having the conventional screw, the heat near the nozzle tip is Since the nozzle is located at a distance from the heater of the heating cylinder cylinder, it is conceivable that the temperature of the molten resin being sent will drop. However, under the present circumstances, it is the current situation that the temperature measured by the heating cylinder cylinder and the temperature of the resin injected from the nozzle are considered to be equal, and injection molding is performed.
For example, when molding a resin having a high viscosity, the fact that heat may be generated in the nozzle is not considered at all.

As described above, in conventional injection molding or extrusion molding, the temperature of the resin itself plasticized in the heating cylinder cylinder or the temperature of the molten resin itself injected from the nozzle into the mold is It has not been detected rigorously, and various problems such as molding defects such as sink marks and warps cannot be solved.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the present circumstances of detection of resin temperature and judgment of temperature condition in the conventional injection molding and extrusion molding as described above, and the inner surface of the heating cylinder of the molding machine having the screw. Nearby temperature or temperature change, or
By measuring the temperature distribution in the axial direction of the heating cylinder, the plasticization state of the resin itself in the cylinder of the molding machine and the temperature state of the molded resin itself are measured, and in addition to this, the mold is filled. An object of the present invention is to provide a method for controlling plasticization of a resin by more accurately measuring the temperature of the resin in the nozzle at the time of performing the measurement and utilizing these measured values.

[0008]

The structure of the invention of claim 1 made for the purpose of solving the above-mentioned problems, has a heating cylinder in a molding machine having a screw, the outer surface of the cylinder up to the vicinity of the inner surface of the cylinder. A hole is drilled from the side and a thermocouple is installed in this hole, the temperature change measured by the thermocouple and the amount of heat of a certain unit flowing into the resin on the inner surface of the heating cylinder cylinder, which is obtained by numerical calculation in advance, Comparing with a temperature change curve (a curve of temperature rise due to the amount of heat flowing into the cylinder, the time derivative of the temperature rise corresponds to the amount of heat input, and the absolute value of the temperature corresponds to the temperature of the inner surface of the cylinder). Cylinder-
The heat generated during plasticization and the temperature of the resin are measured, and the plasticization status in each zone of the screw is detected from the status of the change in the temperature distribution in the axial direction of the cylinder, and this plasticization is performed. When the situation is not proper, the plasticization condition is changed correspondingly to obtain the proper plasticization state (the plasticization state matching the original function of each zone in the screw). is there.

Further, according to a third aspect of the present invention made to solve the above problems, the temperature change of the resin in the nozzle is measured by the same method as in the case of the heating cylinder cylinder. By measuring the temperature rise when the resin passes through the nozzle and the heat rise due to shearing, the temperature of the resin when it is actually filled in the mold is detected more accurately, and the molding conditions in the molding machine are set. It is characterized by improving.

By using each temperature measuring method according to the present invention, it is possible to measure the plasticized state in the heating cylinder in the injection molding machine or the extrusion molding machine and the resin temperature at the time of injection from the nozzle. The plasticized state of the raw material resin in these molding machines can be accurately grasped. Further, this allows the plasticizing conditions of the molding machine to be changed so that the raw material resin is in the original plasticized state, and as a result, the temperature of the molten resin filled from the nozzle into the mold can be accurately grasped. Therefore, it becomes possible to always maintain a better molding state.

[0011]

Embodiments of the present invention will now be described with reference to the accompanying drawings. As shown in FIG. 1, in the embodiment of the present invention, in a heating cylinder 1 of an injection molding machine or an extrusion molding machine, a feed zone 2a, a compression zone 2b, a metering zone 2a of a screw-2 are used. A large number of holes from the outer surface to the vicinity of the inner surface of the cylinder-1 are formed at the portions corresponding to 2c at equal pitches as an example, and thermocouples 3 are inserted and installed in these holes, respectively, and the screw in the heating cylinder cylinder-1 is installed. -The temperature near the inner surface of each zone 2a, 2b, 2c of -2 shall be measured at multiple points. In FIG. 1, 4 is a band heater in which plural cylinders are wound in the axial direction, 5 is a nozzle at the tip of the cylinder 1, and 6 is a hopper for the raw material resin P.

When the screw-2 rotates, the resin P of the hopper 6 is conveyed from the feed zone 2a of the screw-2 to the nozzle 5 side through the compression zone 2b and the metering zone 2c. During this time, the resin P is plasticized and is injected in a molten state from the nozzle 5 into a mold (not shown).

The plasticization of the resin P is performed by the heat generated by the friction between the resin P and the inner surface of the heating cylinder 1 due to the rotation of the screw-2. As shown in FIG. 2, the resin P that has been heated to be in a plasticized state causes an arbitrary thermocouple 3 in the compression zone 2b of FIG. In this state of temperature increase, if the plasticizing conditions (screw rotation speed, back pressure, etc.) are appropriate, the pre-calculated heat quantity of the unit unit shown in FIGS. It is proportional to the temperature rise state when flowing in over time. That is, in order to measure the temperature near the inner surface of the cylinder-1 by the thermocouple 3 in the compression zone 2b, the temperature increase state of the resin P which is being plasticized in the cylinder-1 corresponds to the resin P. This means that the state brought about by the amount of heat actually flowing into the cylinder-1 can be grasped.

That is, for example, the compression zone 2b
At a certain position of the thermocouple 3, as shown as an example in FIG. 4, the amount of heat flowing into the resin P in the cylinder-1 calculated in advance based on the rotation speed of the screw, the back pressure, etc. When differentiated with respect to time, the total amount of heat shown in FIG. 4 is the total amount of heat flowing in per unit time as shown in (a) to (f) of FIG. On the other hand, the actual state of the temperature rise of the resin P caused by the inflowing heat quantity per unit time shown in (a) to (f) of FIG.
It is measured that the temperature rise state shown in (f) is exhibited. Then, the total of the individual temperature rises shown in (a) to (f) of FIG. 4 becomes the temperature rise state of FIG. 2 detected by the thermocouple 3 with time. In the present invention, each zone of the screw-2 is
In 2a to 2c and the nozzle 5, temperature measurement is performed by the same method as described above.

From this, for example, in the compression zone 2b, the inner diameter of the cylinder-1 and the screw-2
Of the resin P used, or the amount of heat that flows into the resin P in the cylinder 1 due to frictional heat generated by the rotation of the screw-2 in the cylinder 1 that can be calculated in advance depending on the material of the resin P to be used. By comparing the data shown with the temperature detected by the thermocouple 3 near the inner surface of the cylinder-1 of this compression zone 2b, the temperature rise of the resin P actually measured by the thermocouple 3 is initially predicted. When there is no change in temperature rise caused by the amount of inflowing heat, the plasticizing conditions such as the rotation speed of the screw-2,
By changing the heating state of the band heater 4 up, down, or by increasing or decreasing, the actual temperature rising state is made to approach the temperature distribution brought about by the amount of heat injected into the resin that was initially calculated and predicted. The operation contents on the machine side, for example, the number of revolutions of the screw and the back pressure are controlled.

Although the above description is an example of the compression zone 2b of the screw-2, the present invention also relates to the feeding zone 2a and the metering zone 2c and the measured temperature values by the thermocouple 3, respectively. The inflow heat quantity inside the cylinder-1 obtained by calculation in advance is compared and the same operation as above is performed. Also in the nozzle 5, a thermocouple 31 is installed near the inner surface of the nozzle 5 to compare the temperature and the temperature change of the molten resin passing through the nozzle 5 with the pre-calculated amount of injected heat at this portion. The same control as in the cylinder is performed.

[0017]

As described above, by adopting the method for detecting the plasticized state according to the present invention, the amount of heat generated by the friction of the raw material resin in the solid layer state and the heat generated by the shear in the melting portion in the cylinder Since the amount of temperature and the temperature change state when the raw material resin changes from the solid layer to the liquid layer at the melting portion can be easily detected,
The raw resin is the original function of the screw in the heating cylinder (feed zone (feed zone), compression zone (compression zone), metering zone (measuring zone).
The plasticization conditions (screw speed, back pressure, etc.) can be set arbitrarily so that the plasticized state almost matches
It is possible to change it, and moreover, the temperature of the resin itself discharged from the nozzle in the mold can be accurately grasped,
An excellent effect is obtained such that temperature control can be performed in order to always realize a good molding state.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heating cylinder cylinder showing an example to which the temperature measurement of the present invention is applied.

FIG. 2 is a temperature diagram showing a temperature rising state of resin in a cylinder according to the present invention.

FIG. 3 is a temperature diagram showing a temperature rise per unit time of the temperature diagram of FIG.

FIG. 4 is a temperature diagram showing a pre-calculated inflow heat quantity in a cylinder.

FIG. 5 is a temperature diagram showing the inflow heat amount in FIG. 3 as the inflow heat amount per unit time.

[Explanation of symbols]

 1 heating cylinder cylinder 2 screw 3 thermocouple 4 band heater 5 nozzle

Claims (4)

[Claims] 1. A plasticizing state of the resin in the heating cylinder of a molding machine having a screw, in which a thermocouple is inserted and installed near the inner surface and the temperature and temperature change at that portion are measured. Is detected and the state of a plasticizing factor such as the number of revolutions of the screw or back pressure is changed in accordance with the detected plasticizing state of the resin in the cylinder. 2. A thermocouple is inserted and installed near the inner surface of a heating cylinder cylinder of a molding machine having a screw, and the time variation of the temperature distribution in the axial direction of the cylinder is measured to measure the inside of the cylinder. 2. The plasticization according to claim 1, wherein the plasticization state of the resin in the cylinder is detected, and the states of the plasticization factors such as the rotation speed of the screw and the back pressure are changed according to the detected plasticization state of the resin in the cylinder. Control method. 3. A thermocouple is inserted and installed near the inner surface of the nozzle portion of a molding machine having a screw, and the temperature and temperature change at that portion are measured to generate heat due to shearing of the molten resin passing through the nozzle. Detects the condition and temperature condition,
The heating temperature of the heating cylinder, the number of revolutions of the screw, and the heating temperature of the resin in the nozzle
A plasticization control method for controlling back pressure and the like. 4. A thermocouple is inserted and installed near the inner surface of the nozzle portion of a molding machine having a screw, and the temperature distribution in the axial direction of the nozzle is measured to measure the shearing of the resin flowing in the nozzle. Detects the heat generation and the temperature condition of the resin filled in the mold, and determines the heating temperature of the heating cylinder, screw rotation speed, back pressure, etc. according to the detected heat generation condition and temperature condition of the resin in the nozzle. The plasticization control method according to claim 3, which is controlled.