JP3256035B2 - Injection mold overflow device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overflow device for an injection mold.

[0002]

2. Description of the Related Art In a conventional in-line screw type injection molding machine, after a molten molding material such as resin is plasticized and melted by a screw in a cylinder barrel, a nozzle at the tip of the cylinder barrel is opened. The nozzle is advanced together with the cylinder barrel, the nozzle is brought into close contact with the injection molding die, and the cavity in the die is injection-filled with the molten molding material. In such injection molding, when the molten molding material solidifies to form slag, the slag flows into the cavity together with the molten molding material during the injection process and mixes with the molded product to deteriorate the quality. Cause Therefore, in order to prevent the slag from being mixed into the molded product, a slag reservoir is formed in the middle or at the end of the flow of the molten molding material to capture the slag.

That is, in a conventional injection molding machine,
Since it is assumed that a melt molding material having a relatively high viscosity such as a resin is used, the slag reservoir 51 attached to each of the cavities 50 having a rectangular shape as shown in FIG. And the flow a of the molten molding material filled from the gate 52
To capture almost the end. Since the melt molding material having a relatively high viscosity is inferior in flowability, after flowing into the cavity 50 from the gate 52, the tip gradually forms a convex curved surface while the slag generated by cooling or the like is positioned at the tip. Therefore, the slag is satisfactorily captured in the slag reservoir 51.

However, in such a conventional overflow device for an injection mold, a cavity 5 is provided.
In the case of injecting a low-melting-point metal material having a small viscosity because the slag reservoir 51 attached to 0 is provided with the slag reservoir 51 only on the front side facing the gate 52,
There is a technical problem that the slag flowing into the cavity 50 cannot be satisfactorily captured. That is, since the low melting point metal material is injected at a high speed and has excellent fluidity, after flowing into the cavity 50 from the gate 52, the metal material advances linearly and at a high speed flow b, and the gate 52
After colliding with the front side surface of the cavity 50 in the vicinity of the cavity 50, the light is reflected and reaches the gate 52 side as backflow c. For this reason, slag is not captured well in the conventional slag reservoir 51, and there is a technical problem that the slag is mixed unevenly in the molded product to deteriorate the quality.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional technical problem.
It is as follows. The invention according to claim 1 is a molten low melting point formed around the cavity 10 between the fixed mold 6 and the movable mold 7 for injection molding and filled in the cavity 10 through the sprue 9 and the gate 11. An overflow device for an injection molding die for receiving a part of a metal material.
An injection molding die overflow device, comprising a slag reservoir 13 for catching a low-melting metal material reflected after collision on a front side surface of the injection molding die. The low melting point metal material can be a metal or an alloy having a melting point of 650 ° C. or less.

[0006]

[Function] If the low melting point metal material is injected from the sprue 9,
It flows into the cavity 10 through the gate 11. While the low-melting metal material flows through the flow path composed of the sprue 9 and the like, the tip of the flow of the molten low-melting metal material is oxidized in a high temperature state to form a slag and form the gate 1.
Reach one. This slag flows into the cavity 10 directly from the gate 11, a part of the slag travels as a linear and high-speed primary flow, and is reflected after colliding with the front surface of the cavity 10 facing the gate 11, and is reflected. Form the next stream. A slag reservoir 13 is formed in front of the secondary flow, that is, for example, at both corners on the rear side near the gate 11 of the cavity 10, so that the slag at the leading end of the secondary flow is well captured by the slag reservoir 13. Is done.

[0007] In this manner, the slag that is present in a relatively large amount at the tip of the secondary flow of the molten low-melting metal material is reliably trapped in the slag reservoir 13, and the low-melting metal having no oxide in the cavity 10. Only the metallic material fills well. The slag reservoir 13 usually has a knock pin,
Since the air in the cavity 10 escapes from the periphery of the knock pin, the filling property is improved by the presence of the slag reservoir 13. Then, the above operation can be obtained by using the low melting point metal material as a metal or an alloy having a melting point of 650 ° C. or less.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show an overflow device for an injection mold according to an embodiment of the present invention. In FIG. 3, reference numeral 6 denotes a fixed mold, and a movable mold 7 is arranged to face the fixed mold 6. The fixed mold 6 includes a fixed mold plate 6.
a, fixed-side mounting plate 6b, sprue bush 6c,
It has a locating ring 6d and a guide pin bush 6e, and has a conventionally known structure except for a section screen of slag reservoirs 12, 13 described later.

On the other hand, the movable mold 7 is clamped with the fixed mold 6 to define the cavity 10 and the slag reservoirs 12, 13, and includes a movable mold plate 7a and a movable mounting plate 7b.
, Receiving plate 7c, spacer block 7d, upper ejector plate 7e, lower ejector plate 7f, core 7g, guide pin 7h, ejector pin 7i,
Dowel pin 7j, upper and lower ejector plates 7e, 7
It has a return pin 7k for returning the ejector pin 7i by the mold closing operation and a stop pin 71, and has a conventionally well-known structure except for the screens of the slag reservoirs 12 and 13.

A parting surface 5 is formed between the fixed mold plate 6a and the movable mold plate 7a, and a sprue bush 6c
The base end of the sprue 9, which is a conical space, is connected to a plurality of cavities 10 via runners 8 formed on the parting surface 5. Thus, the cavity 10
It is partitioned between the fixed mold plate 6a, the core 7g and the movable mold plate 7a.

As shown in FIGS. 1 and 2, the cavity 10 is formed through a flow path including a sprue 9, a runner 8 and a gate 11, and slag reservoirs 12 and 13 are attached to four corners of the cavity 10. I have. Cavity 10
Is for forming a rectangular thin plate-shaped molded product, and the gate 11 has a fan shape. One pair of slag reservoirs 12 is formed by connecting to both corners of the rectangular cavity 10 away from the gate 11, and as shown in FIG. 4, the non-reflective primary flow of the molten molding material filled from the gate 11. The tip of A is mainly captured. The other slag reservoir 13 mainly contains a low-melting metal material that flows from the gate 11 like a linear and high-velocity flow B and reflects after collision with the front side surface of the cavity 10 to form a secondary flow C. To capture the gate 11 of the cavity 10
Are formed by being connected to both corners close to. This other slag reservoir 13 is generally formed at the end far from the secondary flow C or at the end of the periphery of the thick portion. The size of all the slag reservoirs 12 and 13 is 3 times the volume of the cavity 10.
% Or more.

A knock pin 7j is provided on the movable mold 7, specifically, on the upper and lower ejector plates 7e and 7f. The knock pin 7j is slidably inserted into the receiving plate 7c and the movable-side mold plate 7a, and its tip faces the one slag reservoir 12 in a normal state excluding the mold opening process, and the slag received by the one slag reservoir 12 is provided. Can be projected. Of course, the other slag reservoir 13 is also provided with a knock pin 7j.

In the above-mentioned mold, the sprue 9 is connected to the runner 8 because it is used for picking up several molded products. Contact 11 directly.

Next, the operation of the above embodiment will be described. At the time of injection molding, as shown in FIG.
Is brought into close contact with the fixed mold 6 and the mold is closed and clamped. The tip of the nozzle of the in-line screw type injection molding machine (not shown) is brought into close contact with the filling port 9a at the tip of the sprue bush 6c of the fixed mold 6. Then, the nozzle is connected to the filling port 9a. On the other hand,
In an injection molding machine, a chip-shaped low-melting metal material is melt-kneaded in a cylinder barrel in advance, a predetermined amount is measured, and stored at the front end of the cylinder barrel.

In this state, if the screw in the cylinder barrel is moved forward and the measured low-melting metal material is ejected from the nozzle at a high speed, the low-melting metal material having a small viscosity is pushed into the sprue 9. It flows into the cavity 10 through the runner 8 and the gate 11 as shown in FIG. Here, the low melting point metal material is aluminum, magnesium, zinc, tin, lead, bismuth, terbium, tellurium, thallium, astatine, boronium, selenium, lithium, indium, iodine, sulfur, sodium, potassium, phosphorus, rubidium, cesium. , A metal such as francium or gallium or an alloy thereof, having a melting point of 650 ° C. or less and a viscosity of 1 poise or less is effective.
Good action is obtained for poises and below. For example, the viscosity of molten lead is 2.29 × 10 ⁻² at 400 ° C.
Poise, which is much more fluid than resin.

While the low-melting-point metal material flows through the flow path including the sprue 9 and the runner 8, the tip of the flow of the molten low-melting-point metal material is oxidized in a high temperature state to form a slag. The gate 11 is reached. This slag flows into the cavity 10 directly from the gate 11, and proceeds partly in a linear and high-speed primary flow B as shown in FIG. After the collision, the secondary flow C is formed. The linear and high-speed primary flow B occurs due to, for example, non-uniform opening of the gate 11. The other slag reservoir 13 is formed in front of the secondary flow C, that is, at both corners of the rear surface near the gate 11 of the cavity 10,
The slag at the tip of the secondary flow C is favorably captured in the other slag reservoir 13.

Further, the remainder of the slag flowing into the cavity 10 mainly exists at the tip of the primary flow A that spreads out without reflecting the molten molding material filled from the gate 11, so that the primary flow A When it reaches the front side face facing the gate 11, it is gradually pushed to both sides and is well captured by one of the slag reservoirs 12 formed at both corners away from the gate 11. The air in the cavity 10 and the slag reservoirs 12 and 13 is knocked by the knock pin 7j.
Since it escapes from the surroundings to the outside, the filling property is improved. In this way, a large amount of slag existing at the tips of the flows A and C of the molten low melting point metal material is accumulated in both slag reservoirs 12 and 1.
3, the cavity 10 is filled only with a low melting point metal material having no oxide.

When the low melting point metal material in the cavity 10 is solidified through the cooling process, the process proceeds to a mold opening process, in which the movable mold 7, specifically, the movable mold plate 7a is guided by the guide pins 7h. The parting surface 5 is opened by retreating along the guide pin bush 6e of the fixed mold plate 6a,
The molded product in the cavity 10 is protruded by the first ejector pins 7i attached to the upper and lower ejector plates 7e, 7f. At the same time, the upper and lower ejector plates 7e, 7
Since the knock pin 7j attached to f protrudes, the slag received in both slag reservoirs 12, 13 is protruded. Note that, in parallel with the cooling step, in the in-line screw type injection molding machine, a measuring step and an injection unit retreating step are performed.

In the above embodiment, the slag reservoir 13 for catching the low melting point metal material which is reflected after the collision with the front side surface of the cavity 10 and becomes the secondary flow C is provided at both corners near the gate 11 of the cavity 10. This is the result of the cavity 10 being rectangular. Therefore, in accordance with the shape of the cavity 10, particularly the shape of the front surface of the cavity 10 from which the low melting point metal material is reflected, the other slag reservoir 13 is placed at a position where the low melting point metal material serving as the secondary flow C can be captured. Can be formed.

[0020]

As will be understood from the above description,
According to the present invention, at the time of injection molding of a low-melting metal material, slag due to oxidation of the low-melting metal material is favorably captured in the slag reservoir. Quality degradation is eliminated.

[Brief description of the drawings]

FIG. 1 is a front view showing an arrangement of an overflow device for an injection mold according to one embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a cross-sectional view showing the injection molding die along the line III-III in FIG. 1;

FIG. 4 is an explanatory view of the operation.

FIG. 5 is a diagram showing a conventional example.

[Explanation of symbols]

5: parting surface, 6: fixed mold, 7: movable mold, 7
j: knock pin, 8: runner, 9: sprue, 10: cavity, 11: gate, 12, 13: slag reservoir.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Okimoto 1-6-1, Funakoshi Minami, Aki-ku, Hiroshima-shi, Hiroshima Japan Steel Works Co., Ltd. (72) Inventor Yasumasa Yamazaki 1-chome, Funakoshi-minami, Aki-ku, Hiroshima-shi, Hiroshima No. 6 No. 1 Inside Japan Steel Works, Ltd. (56) References JP-A-1-104454 (JP, A) JP-A-63-144852 (JP, A) JP-A-4-73120 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B22D 17/22 B22D 17/20 B29C 45/26

Claims (2)

(57) [Claims] 1. A mold is formed around a cavity (10) between a fixed mold (6) for injection molding and a movable mold (7),
An injection molding mold overflow apparatus for receiving a part of a molten low melting point metal material filled in a cavity (10) through a sprue (9) and a gate (11). An overflow device for an injection mold, comprising a slag reservoir (13) for capturing a low-melting metal material which flows into the interior of the cavity (10) and reflects after collision with the front side surface of the cavity (10). 2. The overflow apparatus for an injection mold according to claim 1, wherein the low melting point metal material is a metal or an alloy having a melting point of 650 ° C. or less.