JP2003170479A - Method and apparatus for gas exhaust in mold and injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently exhaust a gas generated in a cavity 4 of a mold at the time of molding and to obtain a stable molding in the injection molding machine for molding, for example, a resin. <P>SOLUTION: An apparatus for gas exhaust in the mold comprises a gas exhaust valve 7 provided near the filling unit of an end of the cavity 4 of the mold to exhaust the gas in the cavity 4 from the valve 7 at the time of molding. The apparatus further comprises a pressure sensor 13 provided at a position near a gate 5 of the cavity 4. Thus, at the time of molding, after the pressure of resin 20 is sensed by the sensor 13, the valve 7 is closed to surely mold the resin 20 so as not to leak the resin 20 from the valve 7. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degassing method and device for discharging gas generated in a molding die, and an injection molding machine equipped with this device.

[0002]

2. Description of the Related Art For example, in an injection molding machine for resin molding, gas is generated from the resin injected into a mold, and therefore it is necessary to provide a gas releasing means for discharging this gas.

Conventionally, as a gas venting means for this die, there is a method in which a gas escape groove in the form of an air vent is provided on the parting surface of the die and a gas is sucked from this gas escape groove by a vacuum device or the like.

[0004]

However, in such a conventional degassing method, when molding is continued for a long time, gas is accumulated in the gas escape groove on the parting surface of the die, and even if it is sucked, it is sufficient. Sometimes it was impossible to vent gas.

Further, according to this method, if the shape of the parting surface of the die is simple, the parting surface can be easily sealed with a sealing material, but if the shape of the parting surface is complicated, the parting surface can be easily sealed. However, there is a problem that sufficient degassing cannot be performed because it cannot be completely sealed.

The present invention has been made in view of the above problems, and an object thereof is to provide a degassing method capable of reliably discharging the gas generated in the mold.

[0007]

In order to solve the above-mentioned problems, the present invention provides a gas vent valve for discharging the gas in the mold in the vicinity of the end filling portion inside the mold and the gas inside the mold. A pressure sensor that detects the pressure of the molding material filled in the mold is located closer to the gate than the vent valve, the gas vent valve is opened when the molding material is injected into the mold, and then the pressure of the molding material is detected by the pressure sensor. Is detected, the gas vent valve is controlled to be closed.

As described above, according to the present invention, a gas vent valve is provided in the vicinity of the end charging part inside the die, and the gas in the die is exhausted from this gas vent valve, so that sufficient gas venting is performed. Can be done. Further, in the present invention, after the resin is injected into the mold, the pressure sensor detects the pressure of the resin to close the gas vent valve, so that the resin does not leak from the gas vent valve.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a vertical sectional view of a mold in an injection molding machine for resin molding to which the present invention is applied, and FIG. 2 is a horizontal sectional view. In the figure, 1 is a mold as a whole, 2 is an upper mold (cavity block), 3 is a lower mold (core block)
Then, a resin, which is a molding material, is injected from the runner portion 5 through the gate 6 into the cavity (molding space) 4 formed between the upper mold 2 and the lower mold 3 for molding.

Inside the mold 1, the gas vent valve 7 is faced near the end filling portion of the cavity 4 (the portion where the resin injected from the gate 6 is finally filled).
Is provided. In this example, the gas vent valve 7 is symmetrically arranged at two positions equidistant from the gate 6 as shown in FIG. 2, and the gas in the cavity 4 is discharged to the outside from the gas vent valve 7 during molding. It has a structure (the detailed structure of the gas vent valve 7 will be described later). still,
In this example, the gas vent valve 7 is provided on the lower die 3 side, but it may be provided on the upper die 2 side.

Further, inside the mold 1, a pressure sensor 13 is provided facing the position near the gate 6 of the cavity 4. The pressure sensor 13 detects the pressure of the resin with which the cavity 4 is filled, and the opening / closing of the gas vent valve 7 is controlled based on a signal from the pressure sensor 13 at the time of molding as described later. There is. The gas vent valve 7 is also provided on the lower die 3 side, but it goes without saying that it may be provided on the upper die 2 side.

FIG. 3 shows the detailed structure of the gas vent valve 7. The gas vent valve 7 opens and closes the gas vent port 8 facing the cavity 4, and an air cylinder device 9 is employed as its operating mechanism.

In this air cylinder device 9, a piston 11 is reciprocally incorporated inside a cylinder portion 10, and a gas vent valve 7 is formed at the tip of a piston rod 11a extending integrally from the piston 11. .
The air supplied from the air pump (not shown) is the first
The piston 11 reciprocates by being fed into the cylinder portion 10 from the air supply pipe 12a or the second air supply pipe 12b, and thereby the gas vent valve 7 is opened and closed.

FIG. 3A shows a state in which the gas vent valve 7 is closed, that is, in this case, air is sent from the first air supply pipe 12a, while the second air supply pipe 12b is opened to the atmosphere. Therefore, the piston 11 is pushed downward in the figure, and the gas vent valve 7 closes the gas vent port 8.

When the air supply is switched from this state and the air is sent from the second air supply pipe 12b as shown in FIG. 2B and the first air supply pipe 12a is opened to the atmosphere, the piston 11 is pushed upward. Then, the gas vent valve 7 opens the gas vent port 8, that is, the gas vent valve 7 is opened. Then, by opening the gas vent valve 7 in this manner, the gas in the cavity 4 is discharged from the gas vent port 8 to the exhaust pipe 8
It is discharged through a.

The switching of the air supply for opening / closing the gas vent valve 7 is performed by the operation of a solenoid valve (not shown). The switching operation of the air supply by the electromagnetic valve, that is, the opening / closing operation of the gas vent valve 7 is controlled by a signal from a control unit (control means such as a microcomputer) of the molding machine.

FIG. 6 is a time chart of the opening / closing control of the gas vent valve. As shown in this time chart, the gas vent valve 7 is used in the pressure sensor 1 during the resin injection process.
3 is controlled so as to be closed after a predetermined time t has elapsed after detecting the pressure of the resin.

The opening / closing control of the gas vent valve 7 will be described in more detail. First, in the mold clamping process of the mold, when the upper mold 2 and the lower mold 3 are closed, a mold clamping signal is transmitted from the molding machine, and based on this. A solenoid valve for opening and closing the gas vent valve is actuated by a control signal from the controller to open the gas vent valve 7.

When the mold clamping is completed, the resin is injected from the injection unit of the plasticizer into the mold, and the injected resin 20 flows from the mold spool to the runner section 5, as shown in FIG. Further, it passes through the gate 6 and is filled in the cavity 4. Meanwhile, the gas is pushed out into the cavity 4 as the resin flows. The pushed gas is discharged from the gas vent valve 7 and discharged from the mold plate gas escape circuit to the outside of the mold.

In the resin injection step, the pressure of the resin 20 is detected by the pressure sensor 13 when the resin 20 passes over the pressure sensor 13 incorporated in the mold, and the signal from the pressure sensor 13 is detected. In the control unit, a timer incorporated therein operates, and a signal is sent to the solenoid valve for opening and closing the gas vent valve after the time t for timer completion preset by this timer has elapsed,
The gas vent valve 7 is controlled to be closed immediately before the resin 20 reaches the gas vent valve 7.

By controlling the gas vent valve 7 in this manner, the resin 20 does not leak from the gas vent valve 7 even after the resin 20 reaches the gas vent valve 7, as shown in FIG. Molding is performed.

In this case, the timer completion time is set by performing preliminary molding in advance and grasping the time from when the pressure sensor 13 detects the pressure of the resin 20 to when the resin 20 reaches the degassing valve 7. Try to set the time based on. By setting a time near the limit here,
It is possible to efficiently discharge a large amount of gas that has flowed into the cavity 4.

After the injection of the resin is completed, the holding pressure,
After the cooling time elapses, the mold is opened and the molded product is ejected (removed), and then the molding process from mold clamping is repeated. In this continuous molding, the gas is exhausted from the gas vent valve 7 in each molding step, so that the gas is sufficiently vented.

As described above, in the mold of this example, the gas vent valve 7 performs sufficient degassing during molding, so that stable molding is possible. And further in this mold,
Since the gas vent valve 7 is closed when the pressure sensor 13 detects the pressure of the resin during molding, the resin does not leak from the gas vent valve 7, and more stable molding is performed.

Although the embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to this embodiment and various other embodiments can be adopted.

[0027]

As is apparent from the above description, according to the present invention, the gas generated in the mold during molding can be sufficiently discharged, and the resin leaks from the gas vent valve for discharging the gas. Since it does not exist, stable molding can be performed, which is a great effect for improving the quality of the molded product.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a mold showing an embodiment of the present invention.

FIG. 2 is a transverse sectional view of the same.

FIG. 3 is a vertical cross-sectional view showing a detailed structure of the gas vent valve, in which (A) shows the gas vent valve in a closed state and (B) shows it in an open state.

FIG. 4 is an explanatory diagram of a resin injection process, showing a state in which a gas vent valve is open.

FIG. 5 is an explanatory view of a resin injection process, showing a state in which a gas vent valve is closed.

FIG. 6 is a time chart of opening / closing control of a gas vent valve.

[Explanation of symbols]

1 ... Mold, 2 ... Upper mold (cavity block), 3 ...
Lower mold (core block), 4 cavity, 5 runner section, 6 gate, 7 gas vent valve, 13
pressure sensor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeru Tateno             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F-term (reference) 4F202 AP03 AR07 CA11 CB01 CP03                 4F206 AP035 AR074 JA07 JM04                       JN26 JP11 JP17 JQ81

Claims (3)

[Claims] 1. Molding in which a gas vent valve for discharging gas inside the mold is provided near the end filling portion inside the mold, and the mold is filled in a position closer to the gate than the gas vent valve inside the mold. A pressure sensor that detects the pressure of the material is provided, the gas vent valve is opened when the molding material is injected into the mold, and then the gas vent valve is closed by the pressure sensor detecting the pressure of the molding material. The method of degassing the mold so that it is controlled as described above. 2. Provided near the end filling portion inside the die,
A gas vent valve that discharges the gas in the mold, a pressure sensor that is installed inside the mold closer to the gate than the gas vent valve, and that detects the pressure of the molding material filled in the mold. A mold comprising: a control means that opens the gas vent valve when injecting the molding material, and then controls the gas vent valve to be closed when the pressure of the molding material is detected by the pressure sensor. Degassing device. 3. A mold, a gas vent valve provided near the end filling portion inside the mold, for discharging gas in the mold, and provided inside the mold at a position closer to the gate than the gas vent valve. By using a pressure sensor that detects the pressure of the molding material filled in the mold, and opening the gas vent valve when injecting the molding material into the mold, and then detecting the pressure of the molding material with the pressure sensor. An injection molding machine equipped with a mold degassing device comprising: control means for controlling the gas vent valve to be closed.