JP2006341421A - Injection molding system and injection molding method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding system advantageous from an economical aspect, capable of injecting a molten resin at a high speed to shorten a filling time and capable of manufacturing a large sized thin-walled resin product of good quality, and an injection molding method using it. <P>SOLUTION: In the injection molding system having a branch mechanism 4 between an injection molding device and a mold having a plurality of sprues and a plurality of gates, the branch mechanism 4 has branch flow channels in which the molten resin is injected and the valve mechanisms 6 provided to the leading ends of the branch flow channels. Each of the valve mechanisms has a mechanism for adjusting the opening degree of each of the valves provided to the leading ends of the branch flow channels to control the injection speed of the molten resin to each of the gates from each of the valves corresponding to the elapse of time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an injection molding system and an injection molding method using the same. In particular, the present invention relates to an injection molding system capable of manufacturing a large thin resin product such as a bumper, an instrument panel or a door panel of an automobile with high quality and an injection molding method using the same.

  Conventionally, as a method of manufacturing a large thin resin product, an injection molding apparatus capable of injecting molten resin into a mold cavity from an injection unit through a runner and a plurality of gates is used. There is known an injection molding method in which an injection start order is determined in advance and molten resin is sequentially injected from each gate into a cavity according to this order.

  For example, Japanese Patent Laid-Open No. 6-64003 discloses a relatively large and thin resin product from the same resin supply path to a plurality of resin injection portions for the purpose of forming a weld mark and a flow mark without generating a weld mark or a flow mark. When the molten resin is distributed and supplied, and the resin product is molded by injecting and injecting the molten resin into the cavity according to a predetermined injection order from a plurality of resin injection parts, the molten resin injected from the preceding resin injection part However, after reaching the position of the rear order resin injection portion, the injection injection of the molten resin from the rear order resin injection portion is started. An injection molding method is described in which the total amount of molten resin distributed and supplied via the resin supply path is increased.

  Japanese Patent Laid-Open No. 6-254895 discloses a case where a relatively large and thin resin product such as a bumper is injection-molded by injecting molten resin into a cavity in a mold in a predetermined order from a plurality of gates. For the purpose of preventing the occurrence of a weld mark, warpage, etc., the second order after the flow of molten resin injected into the cavity from the first order gate reaches the position of the second order gate. The molten resin is injected and injected into the cavity from the first gate, and the molten resin from the second rank gate is diffused into the cavity while flowing out from the inside of the molten resin from the first rank gate. An injection molding method is described which causes the caulking.

  Japanese Patent Laid-Open No. 2001-54924 starts resin injection from the first gate, which is defined as the first order in the injection start order, in order to shorten the filling time and obtain a product of good quality. After that, an injection molding method is described in which the pressure inside the mold in the vicinity of the first gate is detected and the injection pressure of the injection unit is controlled so that the detected pressure inside the mold matches a predetermined pressure fluctuation pattern. Yes.

JP-A-6-64003 JP-A-6-254895 JP 2001-54924 A

  In recent years, it has been required to make a resin product thinner, to manufacture a wide resin product, and to manufacture a resin product having a complicated shape including a protruding portion, a curved portion, and the like. When such a product is manufactured by an injection molding method, it is necessary to prevent deformation such as a weld mark, distortion, warpage, and waviness in the resin product generated during the manufacturing. In order to prevent these problems, the pressure in the cavity is reduced by reducing the pressure by injecting the molten resin as fast as possible to shorten the filling time, and reducing the generation of skin layers that hinder resin injection. A method for maintaining a uniform distribution is conceivable.

The method is, for example, a method described in the above-mentioned patent publications, etc., and the flow path of the molten resin injected from each flow path is branched by an on-off valve. A method of performing injection molding while controlling is known.
However, when such molding is performed using a plurality of molds, a branch and an on-off valve must be incorporated in each mold, increasing the economic burden.

Further, in the method described in the above patent publications and the like, the control of the flow of the molten resin injected from each flow path is as follows:
Since only the opening / closing valves of the plurality of gates are opened / closed in accordance with the injection pattern of the injection molding machine, the controllable range is limited, and a product with satisfactory quality may not always be obtained.

  Under such circumstances, the object of the present invention is economically advantageous, injection that can inject molten resin at high speed to shorten the filling time, and can produce large thin resin products with high quality. An object of the present invention is to provide a molding system and an injection molding method using the same.

As a result of studies, the present inventor has found that the present invention can solve the above-mentioned problems, and has completed the present invention.
That is, the present invention
An injection molding system having a branching mechanism between an injection molding device and a mold having a plurality of sprues and a plurality of gates, wherein the branching mechanism branches and a branching channel into which molten resin is injected The present invention relates to an injection molding system that is a branching mechanism having a valve mechanism provided at the tip of the nozzle and an injection molding method using the same.

  According to the present invention, in particular, large thin resin products such as automobile bumpers, instrument panels and door panels can be manufactured with high quality.

  The injection molding system according to the present invention includes a branched flow path for injecting molten resin and a valve mechanism provided at the tip of the branched flow path between an injection molding apparatus and a mold having a plurality of sprues and a plurality of gates. Is an injection molding system having a branching mechanism.

  When the molten resin is injected into the mold from a small number of injection molding devices by the branch mechanism, the molten resin can be branched into a large number of flow paths and injected, thereby increasing the pressure in the mold. Can be greatly reduced.

  In addition, the valve mechanism provided at the tip of the branched flow path of the branch mechanism has a mechanism for adjusting the opening of the valve, so that the injection operation of the injection molding machine is simply controlled. However, it is possible to realize the fluid state of the resin in various molds.

  By using the valve adjusting mechanism of the branch mechanism, in addition to the injection control of the conventional injection molding machine, the order and flow rate of the molten resin injected into the mold are adjusted, and the molten resin in the mold is adjusted. The flow state can be controlled, and the injection pressure can be reduced and the burrs can be reduced in a wider range than the conventional methods as necessary for the control and filling of the weld position.

  The molten resin is heated using a heater inside the branch mechanism, and the temperature of the molten resin is controlled to a temperature not lower than the melting point of the molten resin and not causing excessive deterioration in a normal molding cycle. Therefore, it is maintained in a molten state that can withstand continuous molding.

  The branching mechanism of the injection molding system of the present invention is used by being attached between an injection cylinder and a mold of an injection molding apparatus. The shape may be any shape, and when it is necessary to inject molten resin from various locations of the mold, the shape is preferably a branched tubular shape.

  If the effect of branching and injecting can be obtained simply by branching and injecting from one side of the mold, the injection mechanism provided on one side of the branching mechanism is used as a mechanism for attaching the branching mechanism to the mold. There are a mechanism for attaching to the stationary side plate of the injection cylinder of the machine and a mechanism similar to the conventional mechanism for attaching the stationary side plate and mold of the injection molding machine provided on the other side.

  The valve mechanism provided at the tip of the branched flow path included in the branch mechanism may be on the side attached to the mold of the branch mechanism, or may be in the middle of the branched flow path. The method for controlling the valve mechanism is preferably a method for controlling each branched flow path, and for economic reasons or control reasons, it may be a method for controlling several branched flow paths collectively. Good.

Examples of the injection molding method using the injection molding system of the present invention include various methods, for example, the following methods.
Resin injection is started from the first gate determined in the first order of the injection start order, and the second order is reached when the molten resin flow reaches the gate (subsequent order gate) determined after the second order. Subsequent gate valves are opened and resin injection is started. Further, in the vicinity of the first gate in the cavity, after the resin injection is started from the first gate, the pressure in the mold (pressure of the molten resin) in the cavity is detected by a predetermined pressure detecting means. Then, the valve opening degree of the first gate is controlled (feedback control) so that the detected in-mold pressure matches a predetermined pressure fluctuation pattern. Further, depending on the case, it is possible to optimize a wide range by controlling the injection pressure and the injection speed together.

  These injection pressure fluctuation patterns are determined in advance prior to the start of molding, and various patterns can be adopted according to the shape, size, etc. of the resin product. A pattern that maintains a predetermined value, a pattern that changes the in-mold pressure into a quadratic curve with time, and the like can be employed.

  When multiple stages of injection are performed using a plurality of gates and it is difficult to design an injection pattern with simple feedback control, for example, a self-convergence type injection described in JP-A-2005-007860 A method of controlling using a manufacturing parameter obtained by analyzing in advance using a pattern optimization program is preferable. The self-converging type injection pattern optimization program, for example, in order to control the occurrence of welds when performing injection molding using a mold having a plurality of resin inflow paths to a cavity, Self-converging injection pattern that can determine the inflow of molten resin, manufacturing parameters set over time, and a combination of numerical analysis methods that calculate the injection molding process and computer-aided optimization methods It is an optimization program.

In general, when a resin product having a complicated shape including a wide resin product and a protruding portion or a curved portion is manufactured by injection molding, it is difficult to inject molten resin into the end portion, the protruding portion, and the curved portion in the cavity. So-called short shots are likely to occur. Conventionally, in order to suppress the occurrence of this short shot, the runner is extended and gates are added. However, the equipment cost is increased and the mold has a complicated shape.
On the other hand, according to the injection molding method of the present invention, after the molten resin is injected from the first gate, the adjustment is made by the valve mechanism so that the molten resin is injected from the subsequent gate, or the timing at which the injection is stopped. By adjusting the gate for each gate, it is possible to easily and reliably fill the ends, protrusions, and curved parts in the cavity with molten resin, and increase the equipment cost and make the mold complicated Etc. can be suppressed.

  In using the injection molding system of the present invention, if the in-mold pressure detecting means for detecting the in-mold pressure in the cavity is incorporated in various places in the mold, the injection pattern obtained by calculation or the like as described above is used for the purpose. It becomes possible to control optimally according to.

  By using the injection molding system of the present invention, by having a plurality of gates, the pressure inside the mold can be greatly reduced and the pressure distribution in the cavity can be maintained uniformly. Of the waves, it is possible to reduce the occurrence of weld marks, warpage, and the like.

  In addition, as compared with the case where the branching mechanism used in the present invention is built in each mold or in the injection molding apparatus main body, a number of molds and a number of various injections are used as time elapses. It is economically advantageous compared to establishing a system using a molding apparatus.

A preferred embodiment of the injection molding system of the present invention is shown in FIGS.
FIG. 1 is a diagram of an injection molding machine having a branching mechanism between an injection molding device and a mold,
(1) Injection molding machine hopper,
(2) Injection cylinder,
(3) Fixed side plate,
(4) Branch mechanism,
(5) A flow path of a molten resin, the temperature of which is controlled above the melting point of the resin by a heater,
(6) A valve for controlling the injection flow rate of each branch part,
(7) Mold (mold with multi-point channel entrance (gate)),
(8) Moving side plate,
(9) Mold clamping and movable unit.

The resin charged from the injection molding machine hopper (1) is melted and kneaded by the injection cylinder (2), and the temperature is controlled above the melting point of the resin by the heater of the branch mechanism (4) attached to the fixed side plate (3). The molten resin is poured into the flow path (5).
The molten resin injected into the flow path (5) passes through the branched flow path and is clamped from the valve (6) for controlling the injection flow rate of each branch portion provided at the tip of the branched flow path. Then, it is injected into a mold (mold having a multi-point flow path entrance (gate)) (7) attached to the moving side plate (8) of the movable unit (9).

FIG. 2 is a conceptual diagram of a branching mechanism used in the present invention.
(10) A flow path of a molten resin, the temperature of which is controlled by a heater above the melting point of the resin,
(11) A valve for controlling the injection flow rate of each branch part,
(12) Consists of a resin inlet to the branch mechanism.

  The molten resin is injected from the resin inlet (12) to the branching mechanism, passes through the molten resin flow path (10) controlled by the heater to a temperature equal to or higher than the melting point of the resin, and is provided at the tip of the branched flow path. It flows to a valve (11) that controls the injection flow rate of each branch portion, and is injected from the valve (11) into the mold.

  As shown in FIG. 1, a branching mechanism as shown in FIG. 2 is attached between the injection molding apparatus and the mold, and is obtained from the result of analysis using a self-converging injection pattern optimization program in advance. By controlling using parameters, it is widely and economically advantageous, the molten resin can be injected at high speed to shorten the filling time, and a large thin resin product can be manufactured with high quality.

Figure of injection molding machine with branch mechanism between tool injection molding device and mold Conceptual diagram of branching mechanism

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection molding machine hopper 2 Injection cylinder 3 Fixed side plate 4 Branching mechanism 5 Flow path of molten resin temperature-controlled above the melting point of the resin by a heater 6 Valve for controlling the injection flow rate of each branch 7 Die with flow path entrance (gate)
8 Moving-side plate 9 Mold clamping, movable unit 10 Molten resin flow path whose temperature is controlled above the melting point of the resin by the heater 11 Valve for controlling the injection flow rate of each branching part 12 Resin inlet to the branching mechanism

Claims (4)

  An injection molding system having a branching mechanism between an injection molding apparatus and a mold having a plurality of sprues and a plurality of gates, wherein the branching mechanism has a branched channel and a branched channel into which molten resin is injected. An injection molding system which is a branching mechanism having a valve mechanism provided at the tip of the valve.   The valve mechanism has a mechanism for adjusting the opening degree of the valve provided at the tip of the branched flow path, and the injection rate of the molten resin from each valve to each gate is changed according to the passage of time. The injection molding system according to claim 1, which can be controlled.   A branch mechanism that is used by being attached between a fixed side plate and a mold of an injection cylinder of an injection molding apparatus, wherein one of the branch mechanisms has an attachment mechanism to the fixed side plate, and the other is to a mold The injection molding system according to claim 1, comprising an attachment mechanism.   The injection molding system according to claim 1, wherein a mold having a plurality of resin inflow passages is used for the cavity, and the amount of molten resin inflow into the resin inflow passages is controlled by manufacturing parameters set according to the passage of time. An injection molding method to be used, wherein the manufacturing parameter is a manufacturing parameter obtained in advance from an analysis result using a self-convergent injection pattern optimization program.

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