JP2002137260A - Gas venting device of mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently and certainly discharge the gas in a cavity. SOLUTION: A gas venting passage is formed by the intoducing passage 58b in an ejector pin 58, the discharge passage 62a in a support plate 62 and a connection tube 68. A vacuum pump 70 is connected to one end of the discharge passage 62a through the connection tube 68.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degassing apparatus for a molding die for discharging gas in a cavity of the molding die to the outside.

[0002]

2. Description of the Related Art In a molding die provided in an injection molding apparatus, in general, molding defects in an obtained molded product,
For example, there is provided a degassing device for discharging a gas in a cavity portion that causes a weld line or burning to the outside.

[0003] The degassing device is disclosed in, for example, JP-A-8-23.
As shown in JP-A-8651 and FIG. 5, it is provided in a molding die composed of a fixed die and a movable die.

In FIG. 5, an injection molding apparatus has a fixed support plate (FIG. 5) fixed to two pairs of tie bars in the apparatus.
The movable support plate (see FIG. 1) is disposed opposite to the first fixed mold 2 and the second fixed mold 4 supported by the fixed support plate and slidably supported by the tie bars. 5 (not shown in the drawing)).

The movable support plate is connected to a mold clamping cylinder (not shown in FIG. 5) for pressing or separating the movable support plate with respect to a mold group 1 and a fixed support plate, which will be described later. .

[0006] The fixed support plate has an injection portion to which an injection nozzle of an injection device (not shown) is connected.

The mold group 1 includes a first fixed mold 2 whose one end face is in contact with the fixed support plate, a first movable mold 10 whose one end face is connected to the movable support plate, and It is configured to include a second movable mold 8 and a third movable mold 6 fixed to the other end face of the second movable mold 8.

First fixed mold 2 and second fixed mold 4
A sprue 22 is formed at a position corresponding to the injection portion of the fixed support plate. The sprue 22 guides the molten molding material from the injection nozzle into a runner 24 described later.

In the portion of the second fixed mold 4 facing the third movable mold 6, a mold 12, which is a telescopic mold, is arranged. An end face of the mold 12 facing the third movable mold 6 forms a parting surface PL with a mold 14 which is a nested mold disposed inside the third movable mold 6. Further, on the parting surface PL of the mold 12, one open end of the sprue 22 is opened, and a runner 24 and a gate 26 are formed. Gate 26
Communicates with a cavity portion 28 formed between the concave portion 12a in the mold 12 and the convex portion 14a of the mold 14.

The third movable mold 6 and the mold 14 are respectively provided with a through hole 6a into which an ejector pin 18 as a projecting member disposed at a position facing the cavity 28 is slidably fitted. It has a hole 14a. One end of the ejector pin 18 is connected to the support plates 16 and 20. The support plate 20 is connected to a push rod of a mold clamping cylinder, and is moved by the mold clamping cylinder with the ejector pin 18. At the other end of the ejector pin 18, as shown in FIG.
Four equally along the circumferential direction, the flat surface portions 18a,
18b, 18c, and 18d (air vents) are formed. The depth CL of each of the flat surface portions 18a, 18b, 18c, and 18d formed by cutting a part of the outer peripheral surface flat is 0.01 to 0.01 depending on, for example, the type of the plastic material as the molding material. It is set to about 0.03 mm.

Therefore, a predetermined gap communicating with the cavity 28 is formed between each of the flat surface portions 18a to 18d and the inner peripheral surface of the through hole 14a. Is discharged to the outside.

As a result, the gap between the flat surface portions 18a to 18d and the inner peripheral surface of the through hole 14a and the gap between the outer peripheral surface of the ejector pin 18 and the inner peripheral surface of the through hole 6a cause Thus, a gas discharge path in the degassing device is formed.

The first movable mold 10, the second movable mold 8, and the third movable mold 6 are connected to a movable support plate by a connecting mechanism (not shown). When the movable support plate is moved by the cylinder portion, a state close to or away from the parting plane PL is set.

Therefore, when the mold clamping cylinder is operated and the mold is opened, the tip of the ejector pin 18 is used to move the molded product formed in the cavity 28 into the mold 1.
In order to remove the first movable side mold 10, the second movable side mold 8, and the third movable side mold 6, the mold 1
4 and project toward the molded product.

[0015]

However, when the gas in the cavity is discharged through the gap formed at the other end of the ejector pin 18 in the above-described gas venting device, the amount of gas discharged is limited by the ejector pin. There are certain limitations as it depends on the diameter of 18 and the number of flats, and may therefore not be sufficient.

In view of the above problems, the present invention is a molding die degassing apparatus for discharging gas in a cavity of a molding die to the outside, and sufficiently and reliably discharges gas in a cavity. It is an object of the present invention to provide a degassing device for a molding die that can perform the method.

[0017]

In order to achieve the above-mentioned object, a degassing apparatus for a molding die according to the present invention forms a molded product molded in a cavity formed inside the molding die. A gas vent passage provided inside the protruding member protruding from the mold and discharging gas in the cavity, and a suction / discharge unit connected to the gas discharge unit in the gas vent passage and suctioning and discharging the discharged gas. It is configured with.

[0018]

FIG. 1 schematically shows a first embodiment of a degassing apparatus for a molding die according to the present invention, together with an injection molding apparatus having the same.

In FIG. 1, the injection molding apparatus has a fixed support plate (FIG. 1) fixed to two pairs of tie bars in the apparatus.
And a movable support plate (see FIG. 1) which is disposed opposite to the first fixed mold 40 and the second fixed mold 42 supported by the fixed support plate and slidably supported by the tie bars. 1 is not shown), and a mold group 41 held between the movable support plate and the fixed support plate.

The movable support plate is provided with a mold group 41 described later.
And a mold clamping cylinder (not shown in FIG. 1) for pressing or separating the movable support plate with respect to the fixed support plate. On the other hand, the fixed support plate has an injection portion to which an injection nozzle of an injection device (not shown) is connected.

The mold group 41 includes a first fixed mold 40 whose one end face is in contact with the fixed support plate, a first movable mold 48 whose one end face is connected to the movable support plate, and It includes a second movable mold 46 and a third movable mold 44 fixed to the other end face of the second movable mold 46.

A sprue 52 is formed inside the first fixed mold 40 and the second fixed mold 42 supported by the first fixed mold 40 at a position corresponding to the injection portion of the fixed support plate. ing. The sprue-52 is formed of an introduction passage 40a inside the first fixed mold 40, a passage 50a communicating with the introduction passage 40a, and a passage 50a of the mold 50 described later. The sprue 52 guides the molten molding material from the injection nozzle into the second fixed-side mold 42 into a runner 50R described later.

In a portion of the second fixed mold 42 facing the third movable mold 44, a mold 50, which is a telescopic mold, is disposed. An end surface of the mold 50 facing the third movable mold 44 forms a parting surface PL with a mold 56 which is a nested mold disposed inside the third movable mold 44. Further, on the parting surface PL of the mold 50, one opening end of the sprue-52 is opened, and a runner 50R and a gate 50G are formed. The gate 50G is provided between the recess 50b in the mold 50 and the mold 5.
6 and communicate with the inside of the cavity 54 formed between the projections 56b.

The third movable mold 44 and the mold 56 are respectively provided with a through hole 44a into which an ejector pin 58 as a projecting member disposed at a position facing the cavity 54 is slidably fitted. It has a hole 56a. One end of the through hole 56a is open at a predetermined distance from the gate 50G in the cavity 54.

As shown in FIG. 2, the ejector pin 58 is a tubular projecting member having an introduction passage 58b therein. A large diameter portion 58a is provided at one end of the ejector pin 58 that communicates with the introduction passage 58b. The gas-liquid separation member 60 is provided in the large diameter portion 58a. The gas-liquid separation member 60 has, for example, a pore diameter of 0.0.
It is made of a porous material having a porosity of about 1% and having a porosity of about 10%.

On the other end side of the ejector pin 58,
Flange part 5 connected to support plates 60 and 62
8c is formed. The support plate 62 is connected to a push rod 64 of the mold clamping cylinder, and is moved by the mold clamping cylinder with the ejector pin 58. As shown in FIG. 3, a discharge passage 62a having one end communicating with the introduction passage 58b of the ejector pin 58 is formed inside the support plate 62. Discharge passage 6
At the other end of 2a, a vacuum pump 7 as suction and discharge means is provided.
0 is connected via a connection tube 68.

Therefore, when the vacuum pump 70 is activated at a predetermined timing, the gas in the cavity 54 is forcibly discharged through the introduction passage 58b, the discharge passage 62a, and the connection tube 68 of the ejector pin 58. Will be done.

That is, the gas vent passage portion is connected to the ejector pin 5
8 are formed by the introduction passage 58b, the discharge passage 62a, and the connection tube 68.

The first movable mold 48, the second movable mold 46, and the third movable mold 44 are connected to a movable support plate by a connecting mechanism (not shown). When the movable support plate is moved by the cylinder portion, a state close to or away from the parting plane PL is set.

When the mold clamping cylinder is operated and the mold is opened, the tip of the ejector pin 18 is moved to the third movable side so as to remove the molded product formed in the cavity portion 54 from the mold 56. With the movement of the mold 44, the mold 5
6 and project toward the molded product.

Accordingly, the air and the gas in the cavity 54 are reliably discharged to the outside, and the problem that the solid matter of the gas blocks the gas vent passage is reliably prevented.

As a result, the stagnation of the gas is reduced, so that the corrosion of the inner wall surface of the mold and the occurrence of burrs and the like of the obtained molded product can be reduced, and the gas is driven to the end of the cavity portion 54. When the gas is compressed by the molding material, a situation in which heat is generated is eliminated, so that generation of new gas in the cavity portion 54 is prevented.

FIG. 4 schematically shows a second embodiment of a degassing apparatus for a molding die according to the present invention, together with an injection molding apparatus having the same. In FIG. 4, the same components as those in the example shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

In the example shown in FIG. 1, a gas vent passage is formed by the introduction passage 58b, the discharge passage 62a, and the connection tube 68 of the ejector pin 58. Instead, in FIG. The withdrawal passage portion is an introduction passage 80b for the ejector pin 80, a suction port 80d,
And the connection tube 82.

As shown in FIG. 4, the ejector pin 80 is a tubular projecting member having an introduction passage 80b therein. A large diameter portion 80a is provided at one end of the ejector pin 80 which communicates with the introduction passage 80b. A gas-liquid separation member 86 is provided in the large diameter portion 80a.

The gas-liquid separation member 86 is made of, for example, a porous material, similar to the above-described gas-liquid separation member 60, and allows a gas having a predetermined molecular weight such as air to pass therethrough and prevents the passage of a liquid. Is done.

On the other end side of the ejector pin 80,
Flange 8 connected to support plates 60 and 62
0c is formed. The support plate 62 is connected to a push rod 64 of the mold clamping cylinder, and is moved by the mold clamping cylinder with the ejector pin 80. A suction port 80d is provided at an intermediate portion of the ejector pin 80 along the axial direction. Suction port 80d
Is connected to a vacuum pump 84 as a suction / discharge means via a connection tube 82.

Accordingly, when the vacuum pump 84 is activated at a predetermined timing, the gas in the cavity 54 is forcibly discharged through the introduction passage 80b of the ejector pin 80, the suction port 80d and the connection tube 82. The Rukoto.

As described above, the gas vent passage is formed by the introduction passage 80b of the ejector pin 80, the suction port 80a, and the connection tube 82.

As a result, also in this embodiment, the same operation and effect as those in the above-described first embodiment can be obtained.

[0041]

As is apparent from the above description, according to the degassing apparatus for a molding die according to the present invention, a degassing passage portion provided inside the projecting member and discharging gas from the cavity portion, Since a suction / discharge means for suctioning and discharging the discharged gas is provided, which is connected to the gas discharge portion in the extraction passage portion, the gas in the cavity portion can be sufficiently and reliably discharged.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a degassing apparatus for a molding die according to the present invention, together with a main part of an injection molding apparatus to which the apparatus is applied.

FIG. 2 is a sectional view showing an ejector pin used in the example shown in FIG.

FIG. 3 is a perspective view showing a support plate used in the example shown in FIG.

FIG. 4 is a sectional view showing a second embodiment of a degassing apparatus for a molding die according to the present invention, together with a main part of an injection molding apparatus to which the apparatus is applied.

FIG. 5 is a cross-sectional view showing a conventional molding-mold degassing device together with a main part of an injection molding device to which the device is applied.

FIG. 6 is a diagram showing an appearance of an ejector pin used in the example shown in FIG.

[Explanation of symbols]

 58, 80 Ejector pin 58b, 80b Inlet passage 62a Discharge passage 68, 82 Connection tube 70, 84 Vacuum pump

Claims (6)

[Claims] A gas vent passage provided in a protruding member for projecting a molded product from a molding die in a cavity formed in the molding die, and discharging a gas in the cavity; A suction / discharge unit connected to a gas discharge unit in the gas release passage to suction and discharge the discharged gas. 2. The degassing device for a molding die according to claim 1, wherein said gas discharge portion is provided at an intermediate portion of said projecting member. 3. A gas-liquid separating member is provided at an end of the protruding member on the side opposite to the cavity portion, for allowing the gas to pass through the gas venting passage portion and preventing a predetermined liquid from passing therethrough. 2. The method according to claim 1, wherein
Or a degassing device for a molding die according to claim 2. 4. The apparatus according to claim 1, wherein said gas-liquid separation member is made of a porous material. 5. The degassing device according to claim 1, wherein the projecting member is provided at a predetermined distance from a portion of the cavity portion near the gate portion. 6. The degassing device for a molding die according to claim 1, wherein the molded product is molded from a resin material.