JPS61144319A - Injection molding method and device therof - Google Patents

Abstract

PURPOSE:To enable molding which is homogeneous and possesses high accuracy even if resin is apt to change easily in quality (blackening) by avoiding waste of a material, by a method wherein a nozzle fitted to a plasticizing device is extended up to the inside of a mold and a gate of the nozzle and a runner are made to either communicate with each other or interrupt. CONSTITUTION:Gates 13, 13' of a nozzle 11 extended through the insides of molds 4, 6 by penetrating through a stationary platen 1 and runners 15, 15' provided on the molds 4, 6 are made commuicatable with or interruptable one another through movement of a nozzle 11 and mold break or mold release is performed by interrupting among the gates 13, 13' of the nozzle 11 and runners 15, 15' one another after completion of injection or prior to mold break. The injection nozzle 11 is extended within the molds 4, 6 by penetrating through the stationary platen 1 and a cylindrical part 12 is formed on the tip part of the nozzle, through which a plurality of the gates 13, 13' is made to open on the cylindrical part 12. A cylindrical hole part 14 coming into contact with a cylindrical part of the nozzle 11 in a sliding state is formed within the molds 4, 6 and one ends of the runners 15, 15' are made to open into the cylindrical hole part 14.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field to which the invention pertains) The present invention relates to an injection molding method and an improvement of its apparatus.

(Prior art) Conventionally, general injection molding machines include injection molding machines that use a cold runner mold that cools and solidifies the sprue runner after the injection nozzle and the molded product each time it is molded, and then releases the mold. There is an injection molding machine that uses a hot runner mold in which the sprue and runner after the nozzle are always kept in a heated state, and only the molded product is cooled, solidified, and released.

(Rji problem of prior art) In an injection molding machine using a cold runner mold, - Every time molding is performed, the sprue and runner are cooled, solidified, and released together with the molded product, so the sprue and runner become scrap other than the product. The proportion of runners is large, resulting in a large amount of material loss, and since the sprue and runners are released from the mold together with the molded product, problems such as the need for separation work after molding are inevitable.

In addition, in an injection molding machine using a hot runner mold, the sprue and runner are constantly heated, and only the molded product is cooled and solidified before being released from the mold, so the material inside the sprue and runner is used for the next process of molding. The former is more effective than the former in terms of material efficiency because it can be used for Problems such as unsolidified resin adhering to the molded product, a so-called stringing phenomenon, and resin leaking from the runner gate during mold opening were inevitable.

In order to solve these problems, some machines have already provided a shutoff valve in the runner gate part, but this requires an expensive mold due to the addition of a nozzle, and its control is also complicated.

In addition, accumulation tends to occur in the sprue and runner, which may cause the resin to change in quality, and when this is injected, there are problems such as molding defects and a decline in the quality of the molded product.
None of them were completely satisfactory.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems, and is intended to improve both the injection molding machine using a conventional hot runner mold and the injection molding machine using a cold runner mold. It is an object of the present invention to solve the above-mentioned problems by obtaining an injection molding method and apparatus that take advantage of the characteristics.

(Structure of the Invention) The present invention is characterized in that the nozzle 11 extends through the fixed platen 1 into the mold 4.13' and the mold 4.6.
The runners 15 and 15' provided in
Gate 13.13' of nozzle 11 and runner 15.15
An injection molding method in which an injection nozzle 11 is extended into a mold 4.6 through a fixed platen 1, and a cylindrical part 12 A plurality of gates 13°131 are formed in this cylindrical portion 1z.
At the same time, a cylindrical hole 14 is formed in the molds 4 and 6 to slide into contact with the cylindrical portion of the nozzle 11, and one end of the runner 15° 151 is opened in the cylindrical hole 14,
An injection molding device in which a gate 13.13' and a runner 15.15' can be communicated or shut off by advancing and retreating the nozzle 11. 0 (Example) Hereinafter, the structure will first be explained according to the embodiment shown in the drawings, and then the method of the present invention will be explained along with the operation.

Reference numeral 1 denotes a fixed platen, 2 a movable platen, and 3 a mold holder mounted on the fixed platen 1. A fixed mold 4 is mounted on the holder 3.

A mold holder 5 is mounted on the surface of the movable platen 2 facing the fixed mold, and a movable mold 6 is mounted on the holder.

7.7' is a cavity (molded product) formed when the fixed mold 4 and the movable mold 6 are closed (clamped).

8.81 is an ejector turbine provided in the movable mold 6, one end of which is extended to the cavity surface, and the ejector plate 9 attached to the other end moves forward and backward to move the cavity 7.
, 71 is released from the mold.

Reference numeral 10 denotes a plasticizing device, and the fixed platen 1 is attached to the tip end of the plasticizing device.
An injection nozzle 11 is installed which extends through the fixed mold 4 and into the movable mold 6.

A cylindrical portion 1 is formed at the tip of the nozzle 11, and a front 131 is opened at the side surface of the cylindrical portion 12.

A cylindrical hole portion 14 is formed inside the fixed mold 4 and the movable mold 6 concentrically with the nozzle 11, and the cylindrical portion 12 movably slides into this hole portion 14. ing.

15.15' is a runner, one end of which is connected to the capacity 7.
7', and is formed at the dividing surface between the molds 4 and 6, the other end of which opens into the inner circumferential surface of the cylindrical hole 14, and communicates with the gate 13, 13' by moving the nozzle 11 back and forth. It is now blocked.

Reference numeral 16 denotes a moving device for moving the plasticizing device 10 toward and away from the molds 4 and 6, and is composed of, for example, a hydraulic cylinder or the like with one end attached to the fixed platen l and the other end attached to the plasticizing device 10. ing.

18 is a heater installed around the injection nozzle 11, and 19 is a temperature detector installed at the tip of the nozzle 11.

This invention has the configuration as described above.

Next, the molding method will be explained along with the function.

In FIG. 1, a mold clamping device (not shown) is operated to close the mold (mold clamping), and at the same time, the plasticizing device 10 is moved to the molds 4 and 6 by the moving device 16, and the injection nozzle 11 is moved to the mold 4, 6 side. 6
13°13' and runner 15.1.
5' and operates the injection device (not shown) of the plasticizing device 1O to inject the plasticized resin into the nozzle 11 (gate) 13.
．． 13' and runner 15. Capity 7 via 15'
It shows the state in which the inside of the tank is injected (filled).

In this state, a control device (not shown) controls the cavity 7 by controlling the a-adjusting device in the molds 4 and 6 while controlling the predetermined holding pressure.
．． Cooling and solidification of the resin in 71 begins.

In this process, when the predetermined holding pressure is completed, the runner 15.
Before the resin in the nozzle 15' solidifies, the moving device 16 is operated to move the injection nozzle 11 backward, and as shown in FIG. .

At this time, the resin in the runners 15 and 15' is still in an unsolidified state, so the movement of the nozzle 11 causes the resin in the runners 15 and 15' to
．． The resin inside 15' can be easily blocked.

If temperature control (cooling) is continued from this state, the resin in the capitium will solidify into the desired shape, and the runner 15.
The resin within 15' also solidifies.

However, since the resin in the nozzle 11 is heated by the heater 18, it is maintained in a molten state.

After cooling and solidifying the resin in the cavity, a mold clamping device (not shown) is activated to open the mold, and then the ejector pin 8.81 is inserted into the cavity 7.8 through the ejector plate 9.
Release the resin (molded product) that has protruded into the mold and solidified within the cavity and runner.

(Effects of the Invention) According to the present invention, the nozzle attached to the plasticizing device is extended into the mold, and the gate of the nozzle and the runner are communicated with or disconnected from each other in the mold, so that the nozzle can be integrated with the molded product. Since the length of the cold runner part molded can be shortened (reduced amount), unlike injection molding equipment using conventional cold runner molds, the runner and sprue are partially cooled and solidified and become waste material. The amount of resin is reduced, and material waste can be avoided.

The passage in the injection nozzle is relatively simple and wide, so molten resin is less likely to accumulate inside the nozzle, reducing deterioration (blackening).
Even easily molded resins can be molded homogeneously and with high precision.

Since the resin is injected from the side of the tip of the nozzle, even when injecting at high speed and high pressure, the resin pressure is less likely to be applied directly in the mold opening direction, and the occurrence of flakes from the runner section can be reduced. can.

Furthermore, like injection molding machines using hot runner molds,
There is no need for complicated mold structure or advanced control of the molding machine, and the nozzle gate and runner can be reliably sealed, which has the effect of preventing resin leakage. .

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing one embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the tip of the nozzle, with the gate and runner of the nozzle cut off.

Claims (1)

[Claims] 1) The gate of the nozzle extending into the mold through the fixed platen and the runner provided in the mold can be communicated or disconnected by moving the nozzle back and forth, and after injection is completed and before the mold is opened. An injection molding method characterized in that the nozzle gate and runner are shut off to open the mold and release the mold. 2) Extend the injection nozzle into the mold through the fixed platen, form a cylindrical part at the tip thereof, open a plurality of gates in the cylindrical part, and insert the nozzle into the mold. An injection molding apparatus characterized in that a cylindrical hole is formed in sliding contact with the cylindrical part, a runner end is opened in the cylindrical hole, and the gate and the runner can be communicated or disconnected by advancing and retreating a nozzle.