JPH09286045A - Apparatus and method for supplying resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always uniformize the molten state of a resin during plastication and weighing by providing the upper barrel opened to the upper port of a lower barrel extending in the axial direction of a screw and freely movable in the axial direction of the screw to a resin supply apparatus and connecting a resin supply hopper to the rear end part of the upper barrel. SOLUTION: When plastication and weighing are started, a hydraulic cylinder 40 is operated to move an upper barrel 1A to an advance limit position and a required amt. of the resin pellets in a hopper 10 are subsequently supplied to the barrel being the internal space between the movable upper barrel 1A and a fixed lower barrel 1B. The resin supplied from a resin supply port with the advance of weighing in a weighing process is stored in a front resin sump while melted by the heat of friction generated by the rotation of a screw 2 and the heat transfer of the heater around the barrels and the screw 2 retreats. Therefore, the upper barrel 1A is moved rearward so as to be linked to the retreat operation of the screw 2 corresponding to the advance degree of the weighing process to be allowed to retreat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin supply device and a resin supply method in a screw in-line type injection device used in an injection molding machine or a blow molding machine, and more particularly to a resin supply method during plasticization and measurement. It is intended to improve the quality of the molded product by keeping the molten state uniform.

[0002]

2. Description of the Related Art A screw-in-line type injection device in an injection molding machine or a blow molding machine has a nozzle 3 at its tip and a temperature control device (heater 1) at its outer periphery, as shown in FIG.
It comprises a barrel 1 with 1). This barrel 1
It is arranged so that the nozzle 3 can be attached to the material injection port of the die 4. The resin fed from the hopper 10 into the barrel 1 is transferred from the material supply section to the compression section by the screw 2 which is rotationally driven by the hydraulic motor 5, and the groove depth of the screw groove is gradually reduced in the compression section. Receives compression. In this process, the resin between the flights 20 of the screw 2 transfers heat from the inner wall surface of the barrel 1 by the heater 11 and the resin itself due to the rotating action of the screw 2, and between the resin and the barrel 1 or the screw 2. The generated frictional heat (generated by shearing energy) forms a molten melt film on the inner wall surface of the barrel 1,
Furthermore, it is collected by the flight 20, and the flight 20
A melt pool is formed on the surface. Thus, the resin in the barrel 1 in the process of promoting plasticization is composed of three parts, a melt film, a melt pool, and a solid bed which has not yet reached the melting point, and as the screw 2 rotates, While being transferred further forward, the unmelted portion (solid bed) is continuously melted by the heating from the heater 11 and the rotating action of the screw 2.
In order to obtain a homogeneous molten plasticized resin by removing the unmelted portion in the measuring section of the screw 2.

[0003]

In the conventional injection apparatus as described above, since there is only one resin supply port, the screw is retracted in the plasticizing and measuring step of the resin, so that the screw located in front of the supply port. Since the length gradually becomes shorter, the effective screw length decreases. As a result, the preheating time of the supplied resin and the amount of heat generated by shearing between the screw and the inner peripheral surface of the barrel are reduced, and the resin temperature and resin physical property values change between the beginning of plasticization measurement and the end of plasticization measurement. As a result, it becomes difficult to uniformly supply the molten resin, and as a result, the molten state of the resin injected into the mold or die becomes non-uniform, and the physical properties of the molded product cannot be kept uniform throughout the product. However, there is a problem that a product of good quality cannot be obtained.

[0004]

In order to solve such problems and enable plasticizing and metering of a resin having a uniform molten state, the apparatus of the present invention (first invention) uses an injection molding machine or A resin supply device for a screw in-line type injection device of a blow molding machine, the supply device including a lower barrel extending in the screw axial direction and having an upper opening, and fitted in an opening of the lower barrel. An upper barrel movable in the screw axis direction is provided, and a hopper for supplying resin is connected to the upper rear end of the upper barrel. Further, in the device of the present invention (second invention), the moving means of the upper barrel is a fluid pressure cylinder,
Alternatively, a combination of an electric motor and a ball screw mechanism is used. Furthermore, in the method of the present invention (third invention), a method for supplying resin in a screw-in-line type injection device of an injection molding machine or a blow molding machine equipped with the supply device of the first invention, in which plasticization measurement is started In some cases, the resin was supplied while the upper barrel was moved forward, and the resin was supplied while the upper barrel was gradually retracted during plasticization and weighing.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the resin feeding apparatus and feeding method of the present invention, in the initial stage of plasticization measurement, the upper barrel is moved forward in the screw axial direction with respect to the lower barrel, and the resin is fed from the resin feeding port approached forward. Is supplied and plasticization is measured. Then, the resin is supplied while retracting the upper barrel in the screw axial direction during the plasticizing and weighing. As described above, the resin supply position at the start of measurement is set at the front position, and the resin supply position is gradually retracted in accordance with the screw that retreats as the measuring process progresses. The screw length in front of the mouth is kept substantially the same, and the amount of heat applied to the resin is made constant so that the molten state of the resin is kept almost constant and the resin temperature is made uniform.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 5 relate to the present invention, FIG. 1 is a vertical cross-sectional view of a resin supply device (in the initial state of plasticization measurement), and FIG. 2 is a vertical cross-sectional view of a resin supply device (at the end of plasticization measurement). 2), FIG. 3 is a front sectional view taken along line AA of FIG. 2, FIG. 4 is a front sectional view of a resin supply device showing another embodiment, and FIG. 5 shows a correlation between a screw position and a resin temperature. It is a graph shown.

As shown in FIGS. 1 to 3, a resin supply device 1
00 is a pair of upper and lower barrels 1, that is, a lower barrel 1B having a groove-shaped opening in the upper part in the screw axial direction, and fitted in the opening of the lower barrel 1B so as to be movable in the screw axial direction. An upper barrel 1A is provided, and a screw 2 extending in the screw axial direction is provided in an inner space of the upper barrel 1A and the lower barrel 1B so as to be rotatable by a hydraulic motor 5 and to be able to move forward and backward by a hydraulic cylinder 6. It Then, as a moving means of the upper barrel 1A, a hydraulic cylinder 40 is arranged at a rear end portion of the upper barrel 1A, and a piston rod 40a is connected to the upper barrel 1A.

A resin supply port 30 is provided above the rear end of the upper barrel 1A, and a hopper 1 is provided above the resin supply port 30.
Resin pellets are fed into the barrel 1 via 0. A feeder (not shown) is provided at the lower discharge port of the hopper 10. The inner front end of the barrel 1 is formed in a tapered shape, and the screw head 2a, which is the front end of the screw 2, faces each other. FIG. 1 shows the initial state of plasticizing and weighing, and the screw 2
Shows the state at the forward limit position, while FIG. 2 shows the state at the end of plasticizing and metering, and shows the state where the screw 2 is at the backward limit position. Generally, the total screw retreat amount during measurement is about 6 times the screw pitch, so it is desirable to determine the length of the barrel 1 (the upper barrel 1A and the lower barrel 1B) in consideration of the moving amount.

As shown in FIG. 3, the joint between the upper barrel 1A and the lower barrel 1B is constructed so as to fit into the stepped groove to keep the circular shape of the internal cavity cross section, but the molten resin is injected by screw rotation. In order to prevent the upper barrel 1A from being lifted by the injection pressure during operation and being separated from the lower barrel 1B, an annular band (belt) (not shown) is provided on the outer circumference of the upper barrel 1A and the lower barrel 1B in the screw axial direction. Arrange a plurality. Alternatively, the joining portion of both barrels 1A and 1B may have a structure as shown in FIG. 4 to prevent the upper barrel 1A from coming off the lower barrel 1B.

As means for moving the upper barrel 1A in the screw axial direction, in addition to the hydraulic cylinder 40 and the air cylinder shown in FIGS. 1 and 2, the rotating operation of the electric motor is converted into reciprocating movement by a ball screw mechanism, and the upper barrel is moved. You may move 1A forward and backward. Also, without providing the hydraulic cylinder 40 independently,
The upper barrel 1A may be directly connected to the motor seat 5a of the hydraulic motor 5 so that the upper barrel 1A retracts in synchronization with the retreat of the screw 2 (that is, the hydraulic cylinder 6 also serves as a moving means of the upper barrel 1A). To).

The operation of the resin supply apparatus 100 of the present invention thus constructed will be described. When starting the plasticizing measurement, as shown in FIG. 1, since the screw 2 is at the forward limit position, the hydraulic cylinder 40 is operated to move the upper barrel 1A to the forward limit position, and then the inside of the hopper 10 is moved. The required amount of the resin pellets of 1 is supplied into the barrel. During the metering, the resin supplied from the resin supply port 30 is melted by the frictional heat generated by the rotation of the screw 2 and the heat transfer of the heater 11 around the barrel 1 while being accumulated in the resin reservoir in the front. , The screw 2 retracts. Therefore, the upper barrel 1A is moved backward and retracted in association with the backward movement of the screw 2 according to the progress of the weighing process. FIG. 2 shows the state at the end of measurement.

In the resin supply apparatus 100 of the present invention in which the movable upper barrel 1A is movably arranged with respect to the fixed lower barrel 1B, the temperature of the supplied resin is measured by a thermometer 80.
To measure. Observing the distribution of the resin temperature in the resin pool in front of the screw 2, in the method of the present invention, the distance between the hopper position and the screw head 2a during the measuring process is almost equal, and therefore the temperature distribution at each position of the resin pool during the melting process of the resin. Compared with the temperature distribution of the conventional example of FIG.
As shown in (1), it is uniform, and a good molded product can be obtained. The resin temperatures in the graphs of FIGS. 5 and 6 represent the resin temperatures measured by the thermometer 80 when the screw head 2a is at the positions P1, P2, P3, and P4, respectively.
Inferring from such data, it is desirable that the distance between the resin supply port 30 and the screw head 2a be constant during the measuring process in order to make the resin melting uniform.

[0013]

As described above, in the present invention,
The molten state of the resin is almost uniform during the plasticization measurement,
A homogeneous and stable molded product quality is secured. In addition, in the case of injection molding, since the molten state of the resin is homogenized, it is easy to set the molding conditions and the operability is improved.In blow molding, the above-mentioned homogeneous molten resin passes through the storage tank of the die. Therefore, a uniform parison can be discharged, and the quality is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a resin supply device (initial stage of plasticization measurement) showing an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a resin supply device (end of plasticization measurement) showing an embodiment of the present invention.

FIG. 3 is a front sectional view taken along the line AA of FIG. 2;

FIG. 4 is a front sectional view of a resin supply device showing another embodiment of the present invention.

FIG. 5 is a graph showing a correlation between a screw position and a resin temperature showing an example of the present invention.

FIG. 6 is a graph showing a correlation between a screw position and a resin temperature in a conventional example.

FIG. 7 is an overall vertical sectional view of a conventional injection molding machine.

FIG. 8 is an overall vertical sectional view of a conventional injection molding machine.

[Explanation of symbols]

 1 Barrel 1A Upper Barrel 1B Lower Barrel 2 Screw 2a Screw Head 3 Nozzle 4 Mold 5 Hydraulic Motor 5a Motor Seat 6 Hydraulic Cylinder 10 Hopper 11 Heater 20 Flight 30 Resin Supply Port 40 Hydraulic Cylinder 80 Thermometer 100 Resin Supply Device

Claims (3)

[Claims] 1. A resin supply device for a screw in-line type injection device of an injection molding machine or a blow molding machine, the supply device including a lower barrel extending in the screw axial direction and having an upper opening. A resin supply device comprising an upper barrel fitted in an opening of a lower barrel and movable in a screw axial direction, and a hopper for supplying resin connected to an upper rear end portion of the upper barrel. 2. The resin supply device according to claim 1, wherein the moving means of the upper barrel is a fluid pressure cylinder or a combination of an electric motor and a ball screw mechanism. 3. A method for supplying resin in a screw-in-line type injection device of an injection molding machine or a blow molding machine equipped with the resin supply device according to claim 1, wherein the upper barrel is moved forward at the start of plasticizing and weighing. The method of supplying a resin, characterized in that the resin is supplied in this state, and the resin is supplied while the upper barrel is gradually retracted during the plasticizing and weighing.