JPH071102A - Injection molding method - Google Patents

Abstract

PURPOSE:To prevent the galling to a pressurizing pin by secondarily pressurizing molten metal injected into a cavity so as to supplement the shortage of the forming pressure. CONSTITUTION:In a hole 11 opened toward a product shape part 5a of the cavity 5, the secondary pressurizing pin 12 for secondarily pressurizing the molten metal is arranged so as to be freely slid, and the secondary pressurizing pin 12 is connected with a vibration exciter 15 for generating mechanical vibration or ultrasonic vibration. Then, after filling by injection the molten metal in the condition of retiring from the cavity surface C to the tip surface 12a of the secondary pressurizing pin 12, by advancing the tip surface 12a of the secondary pressurizing pin 12 till the position becoming the same surface as the cavity surface C, the secondary pressurization is given to the molten metal. At the same time, the secondary pressurizing pin 12 is vibrated with the vibration exciter 15 to prevent the galling to the secondary pressurizing pin 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method in which a molten metal injected into a cavity of a mold is secondarily pressurized to prevent galling of a pressure pin which compensates for insufficient molding pressure.

[0002]

2. Description of the Related Art In a conventional injection molding method, when a molten metal is filled into a cavity from a gate portion of a narrow passage to manufacture a molded product, the gate portion cools and solidifies faster than the cavity portion, and a sufficient feeder effect is obtained. However, defects such as shrinkage cavities (casting cavities) and cracks are generated, and therefore, for example, Japanese Patent Laid-Open No. 3-124358.
An injection molding device such as that of No. 1 has been proposed. After filling the cavity with molten metal, this device inserts a feeder rod at a position where a defect is expected to occur, and mechanical or ultrasonic vibration is applied to the molten metal via this feeder rod to generate bubbles (gas). (Holes) are removed so as to suppress the generation of various defects as described above. A specific structure is that a feeder is provided at a position near the gate of the runner communicating with the cavity, and the feeder bar of the feeder is movable toward and away from the melt in the runner. A vibration generator is provided in the vicinity of the feeder and the vibration transmission rod of the vibration generator is movable back and forth toward the molten metal of the runner portion.
Then, the vibration of the vibration generator is transmitted from the vibration transmission rod to the feeder bar to remove the bubbles in the molten metal.

[0003]

However, in the case of the above apparatus, since the position of the feeder rod is the runner portion which communicates with the cavity through the narrow gate portion, the effect of the feeder is difficult to sufficiently reach the cavity. There was a problem. In other words, this feeder bar is used in a state of being inserted into the molten metal, so that the product shape part impairs the product shape and can be used only in the runner part, which is a non-product shape part. .

[0004]

In order to solve such a problem, the present invention provides an injection molding method in which a molten metal injected and filled in a cavity of a mold is secondarily pressurized by a pressure pin. Was slidably provided in a hole opened toward the cavity surface of the product shape portion, and the pressure pin was connected to the vibration device. Then, after the molten metal is injected and filled with the tip end surface of the pressurizing pin immersed in the cavity surface, the tip end surface of the pressurizing pin is advanced to a position flush with the cavity surface to pressurize, and at the same time, The vibrating device vibrates the pressure pin to prevent galling on the pressure pin. Further, the vibration by the vibrating device was mechanical vibration or ultrasonic vibration.

[0005]

Function: A pressurizing pin that is slidable is provided in a hole that opens toward the cavity surface of the product-shaped portion, and pressurizing with this pressurizing pin enables effective feeding of molten metal. At this time, the shape of the product is not damaged by making the tip surface of the pressure pin flush with the cavity surface in the pressurized state. Further, by vibrating the pressure pin by the vibrating device, it is possible to prevent galling of the pressure pin.

[0006]

Embodiments of the injection molding method of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a mold state diagram showing a process of injecting and filling molten metal, and FIG. 2 is a mold state diagram showing a state in which a pressure pin is advanced.

As shown in FIG. 1, for example, when a fixed mold 1 is clamped and a movable mold 2 which can be opened is attached to respective support plates 3 and 4, and both molds 1 and 2 are clamped. The cavity 5 is formed on the mating surface.

The cavity 5 includes, for example, a product shape portion 5a and a gate portion 5b connected to the product shape portion 5a.
And a non-product shape part 5c connected to the gate part 5b. The non-product shape part 5c communicates with the injection machine 6.

The injection machine 6 comprises, for example, a sleeve 7 provided on the fixed mold 1, a plunger tip 8 sliding in the sleeve 7, and an injection plunger 10 for transmitting a driving force to the plunger tip 8. The sleeve 7 is provided with a pouring port 7a.

On the other hand, the movable die 2 has the product shape portion 5a.
Has a hole 11 opened on the cavity surface c of
A secondary pressure pin 12 as a pressure pin is slidably provided in the hole 11.

The secondary pressure pin 12 is connected to a secondary pressure cylinder unit 14 via a coupling 13, and a vibration device 15 is connected to the secondary pressure cylinder unit 14. Then, the vibrating device 15 is
For example, a mechanical vibration generator such as a vibrator is used to generate a minute vibration by high frequency, but an ultrasonic vibrator may be used.

Next, the injection molding method using the above injection molding apparatus will be described.

The fixed die 1 and the movable die 2 are clamped, and the secondary pressure pin 12 is retracted so that the tip surface 12a thereof is recessed from the cavity surface c.

Therefore, a cavity 5 is formed on the mating surfaces of the molds 1 and 2, and a part of the hole 11 communicates with the product-shaped portion 5a of the cavity 5.

Next, when the molten metal is poured from the pouring port 7a and the injection plunger 10 and the plunger tip 8 move forward to inject the molten metal into the cavity 5, the molten metal is filled in the cavity 5 as shown in FIG. Not only is it done, hole 1
It is also filled in 1.

Immediately after the injection filling is completed, the secondary pressure cylinder unit 14 is activated to move the secondary pressure pin 12 forward. At this time, the tip end surface 12a of the secondary pressure pin 12 is advanced to a position where it is flush with the cavity surface c, and at the same time, the vibration device 15 slightly vibrates the secondary pressure pin 12.

Therefore, the molten metal is subjected to the secondary pressure as the secondary pressure pin 12 moves forward, and since the portion to be pressurized is the product shape portion 5a, the pressure effect is effectively exerted and the shrinkage cavity is generated. Less likely to cause molding defects such as

Further, by vibrating the secondary pressure pin 12, the molten metal does not scratch the secondary pressure pin 12, and the secondary pressure pin 12 does not enter the molten metal of the product shape portion 5a. It is possible to manufacture sound shaped products.

[0019]

As described above, in the injection molding method of the present invention, since the pressure pin is provided in the product shape portion of the cavity, the effect of the feeder for the molten metal is effectively exerted, and shrinkage cavities, cracks, etc. Highly effective in suppressing defects. Further, since the tip end surface of the pressure pin is flush with the cavity surface, the product shape can be kept sound. At this time, the vibrating device vibrates the pressure pin, so that the pressure pin can be prevented from being scratched.

[Brief description of drawings]

FIG. 1 is a mold state diagram showing a process of injecting and filling molten metal.

FIG. 2 is a mold state diagram in which a pressure pin is advanced.

[Explanation of symbols]

 1 Fixed type 2 Movable type 5 Cavity 5a Product shape part 11 Hole 12 Secondary pressure pin 12a Tip surface 14 Secondary pressure cylinder unit 15 Vibrating device c Cavity surface

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Osamu Ito 1-10-1 Shin-Sayama, Sayama-shi, Saitama Prefecture Honda Engineering Co., Ltd.

Claims (2)

[Claims] 1. In an injection molding method in which a molten metal injected and filled in a cavity of a mold is secondarily pressurized by a pressure pin, the pressure pin is placed in a hole opened toward a cavity surface of a product shape portion. The pressure pin is slidably provided, the pressure pin is connected to a vibrating device, and the molten metal is injected and filled while the tip surface of the pressure pin is immersed in the cavity surface. An injection molding method characterized in that the pressure is applied by advancing to a position flush with the cavity surface, and at the same time the pressure pin is vibrated by the vibrating device to prevent galling on the pressure pin. 2. The injection molding method according to claim 1, wherein the vibration generated by the vibrating device is mechanical vibration or ultrasonic vibration.