JPH06344391A - Gas venting device in mold - Google Patents

Abstract

PURPOSE:To mold a product of good quality by discharging gas generated at the time of injection to the outside of a mold without allowing the same to flow in the cavity of the mold. CONSTITUTION:A gas venting route 2 is provided to a sprue or runner part 1 and air injection routes 4 for injecting air into respective cavities 3 are provided to the respective cavities 3. Air pressure control devices 5 for controlling the pressure of air are provided to the air injection routes 4. Air pressure sensors 6 for detecting the pressures of air at every cavities 3 are arranged to the respective cavities 3. A control device 7 performing operational processing on the basis of the air pressure signals S1, S2 from the air pressure sensors 6 and sending control signals S3, S4 to the air pressure control devices 5 so as to equalize the air pressures in the cavities 3 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degassing device in a mold for preventing resin gas generated during injection from flowing into a cavity and preventing the cavity wall from being contaminated by the gas.

[0002]

2. Description of the Related Art Conventionally, for example, in a device disclosed in Japanese Patent Laid-Open No. 2-217218, there is provided gas detection means for detecting a gas pressure at an extreme end located substantially at the extreme end from a resin inlet in a cavity space, It is provided with an insert which is directly connected to a hydraulic cylinder and can open and close the outermost end so that gas is discharged from the outermost end to the outside of the mold.

Further, as shown in the plan view of the main part of the mold shown in FIG. 4, a gas vent passage 2 for venting gas is provided in the sprue or runner portion 1 through an air vent 8, and an air vent is provided in the cavity 3. An air injection path 4 for injecting air through 8 is provided around the cavity 3, and air pressure is applied from the side of the cavity 3 to prevent gas generated during injection from flowing into the cavity 3 from the sprue or runner portion 1. Some are designed to vent gas.

[0004]

However, the above-mentioned Japanese Unexamined Patent Application Publication No.
In the conventional apparatus described in Japanese Patent Laid-Open No. 217218, when the gas for releasing the gas from the outermost end portion of the cavity passes through the cavity, the gas adheres to the wall surface to contaminate the cavity wall surface, and the corrosion is large. There was a drawback that

On the other hand, in the conventional apparatus shown in FIG. 4, in a multi-cavity mold for injecting air from each of the plurality of cavities 3 and drawing air from the sprue 1 and the air vent 8,
When branching the air to be injected into various cavities and injecting it into each cavity 3, an air vent 8 for injecting air into each cavity 3
If the clearance is different, the air pressure in each cavity 3 is different, and the air moves from the higher air pressure side to the lower air pressure side. Therefore, the generated gas in the cavity 3 with low air pressure stains the walls of the cavity 3. There was a problem.

The present invention has been made in view of the above-mentioned conventional problems, and discharges the gas generated at the time of injection to the outside of the mold without flowing into the mold cavity to mold a high quality product. It is an object of the present invention to provide a degassing device for a mold capable of performing the above.

[0007]

In order to solve the above problems, the present invention, as shown in FIG. 1, provides a gas vent passage 2 for venting gas in a sprue or runner portion 1 and each cavity 3 An air injection path 4 for injecting air into each cavity 3 is provided for each cavity, and an air pressure adjusting device 5 for controlling the air pressure is provided in each of these air injection paths 4 to detect the air pressure for each cavity 3. An air pressure sensor 6 is installed in each cavity 3 for
A control device 7 is provided which performs arithmetic processing on the basis of the air pressure signals S1 and S2 from the above and sends control signals S3 and S4 to the air pressure control device 5 so that the air pressures in the respective cavities 3 become equal, A degassing device in the mold was constructed.

[0008]

According to the degassing device in the die having the above-described structure, air is drawn from the gas vent passage 2 by the vacuum pump and air is injected from the air inlet passage 4 with the die closed. The air pressure sensor 6 of each cavity 3 detects the air pressure in the cavity 3, and sends the air pressure signals S1 and S2 to the control device 7, and the control device 7 uses the air pressure signals S1 and S2 to determine the cavities. The control signals S3 and S4 are sent to the air pressure adjusting device 5 so that the air pressure inside the cavity 3 becomes the same, and the air pressure injected into the cavity 3 is adjusted. This prevents gas or the like generated at the time of injection from flowing into the cavity 3 having a low internal pressure in the cavity 3, so that the walls of the cavity 3 are not contaminated with the gas.

[0009]

Embodiment 1 (Structure) The degassing apparatus of this embodiment is as shown in FIG. 2, and the sprue or runner portion 1 is provided with a degassing path 2 for degassing, An air vent 8 is cut for each cavity 3, and an air injection path 4 for injecting air into the cavity 3 is provided. An air pressure adjusting device 5 for adjusting the air pressure is provided in each of the cavities 3 in the middle of the air injection path 4. One of the air vents 8 provided for each cavity 3
First, an air pressure sensor 6 for detecting the air pressure in the cavity 3 is arranged, and the air pressures in the cavities 3 become equal based on the air pressure signals S1 and S2 from the air pressure sensor 6. Control signal S3 to the air pressure regulator 5
A control device 7 for sending S4 is provided.

(Operation) In the degassing apparatus having such a configuration, air is drawn from the degassing path 2 by a vacuum pump (not shown) in a state where the mold is closed, and the air is supplied from the air injection path 4 to each cavity 3. inject. The air pressure sensor 6 of each cavity 3 detects the air pressure in the cavity 3, and sends the air pressure signals S1 and S2 to the control device 7, and the control device 7 detects the air pressure in each cavity 3 based on the signal. The control signals S3 and S4 are sent to the respective air pressure regulating devices 5 so that the air pressures become the same.

(Effect) By detecting the air pressure in each cavity 3 and adjusting the air pressure to be injected into the cavities 3 so that the air pressures in the cavities 3 are the same, the gas generated at the time of injection can be eliminated. Since the cavity 3 having a low internal pressure can be prevented from flowing into the cavity 3, the wall of the cavity 3 is not contaminated with gas.

[0012]

Second Embodiment (Structure) The gas venting device of the present embodiment is as shown in FIG. 3, and the sprue or runner portion 1 is provided with a gas venting path 2 for venting gas. A part of the cavity walls K1 and K2 of each cavity 3 is made of a porous material 9 having air permeability. The cavity wall K1 is provided with an air injection path 4 for injecting air into the cavity 3. An air pressure adjusting device 5 for adjusting the air pressure is provided for each cavity 3 in the middle of the air injection path 4. An air pressure sensor 6 for detecting the air pressure in the cavity 3 is arranged on the cavity wall K2 of each cavity 3, and each cavity 3 is based on the air pressure signals S1 and S2 from the air pressure sensor 6.
A control device 7 is provided which sends control signals S3 and S4 to the air pressure control device 5 so that the air pressures therein become equal.

(Operation) In the degassing apparatus having such a structure, air is drawn from the degassing path 2 by a vacuum pump (not shown) with the mold closed, and the air is supplied from the air injection path 4 to each cavity 3. inject. The air pressure sensor 6 of each cavity 3 detects the air pressure in the cavity 3, and sends the air pressure signals S1 and S2 to the control device 7, and the control device 7 detects the air pressure in each cavity 3 based on the signal. The control signals S3 and S4 are sent to the respective air pressure regulating devices 5 so that the air pressures become the same.

(Effect) By detecting the air pressure in each cavity 3 and adjusting the air pressure to be injected into the cavities 3 so that the air pressures in the cavities 3 are the same, the gas generated at the time of injection can be eliminated. Since the cavity 3 having a low internal pressure can be prevented from flowing into the cavity 3, the wall of the cavity 3 is not contaminated with gas.

[0015]

As described above, according to the apparatus for venting gas in a mold of the present invention, since pressurized air is injected into the cavity, even if the speed of passing through the sprue and runner portion is increased. No gas flows into the cavity. Also, because the air pressure between each cavity is controlled to be the same,
The generated gas will not be entrained and flow from the cavity with high air pressure to the cavity with low air pressure. As a result, the mold is not contaminated by the generated gas, and a molded product of good quality can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing the concept of a gas venting device of the present invention.

FIG. 2 is a plan view showing a gas venting device according to a first embodiment of the present invention.

FIG. 3 is a plan view showing a gas venting device according to a second embodiment of the present invention.

FIG. 4 is a plan view showing a main part of a conventional mold.

[Explanation of symbols]

 1 sprue (runner part) 2 degassing path 3 cavity 4 air injection path 5 air pressure regulator 6 air pressure sensor 7 controller S1, S2 air pressure signal S3, S4 control signal

Claims (1)

[Claims] 1. A spout or runner is provided with a gas vent passage for venting gas, and an air injection passage for injecting air into each cavity is provided for each cavity.
An air pressure control device for controlling the air pressure is provided in each of these air injection paths, an air pressure sensor for detecting the air pressure of each cavity is arranged in each cavity, and based on a signal from the air pressure sensor. A degassing device in a mold, which is provided with a control device that performs arithmetic processing and controls the air pressure adjusting device so that the air pressure in each cavity becomes equal.