JP2002011766A - Injection molding method for thermosetting resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem of no stable execution of the molding of a conforming article due to the narrowing of a connecting passage connecting to molds and the resultant lowering of a vacuumizing pressure by the method wherein residues including gas developed in the mold are evacuated by an evacuating device. SOLUTION: In an injection molding device for filling molten resin in the molds through injection with an injecting device by the opening, closing and clamping of the molds attached to a fixed platen and to a movable platen, in order to remove sludge due to gas developing during the injection and filling of the molten resin and the residues of fins from the molds, the residues including the gas developing in the molds are evacuated with the injecting device in order to blow out the air for discharging the residues from within the connecting passage connected to the molds to the outside of the molds under the state that the molds are opened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting resin injection molding method, and more particularly to a BMC (Bulk Molding Component).
nd) It relates to an injection molding method for performing negative pressure suction in a molding die.

[0002]

2. Description of the Related Art BMC, which is a thermosetting resin, is obtained by adding calcium carbonate, glass fiber, silica, styrene monomer or the like as a filler to unsaturated polyester and kneading it into a mud or putty. In the molding of the BMC, the connection between the mold and the vacuum device is connected so that the gas generated from the cavity of the mold can be sucked.
As disclosed in Japanese Patent No. 207625, a device is provided which surrounds the periphery of the mold and enables suction of generated gas, and the mold surrounded by the device is connected to a vacuum device to perform gas suction. By doing so, the molten BMC is injected and filled into the cavity of the mold by the injection device, and the generated gas is suctioned by the vacuum device under the negative pressure, thereby eliminating the blistering and clouding on the surface of the molded product. You can.

[0003]

As described above, in the injection molding method for a thermosetting resin having the above-mentioned structure, a vacuum device is used to suck a residue containing gas generated in a mold, so that the residue is connected to the mold. Dirt adheres to the inside of the connection passage, the passage area becomes narrow, the negative pressure suction force decreases, the pipes and the like need to be replaced, and molding of non-defective products due to interruption of molding cannot be performed stably. Make the problem an issue.

[0004]

According to the present invention, a mold is mounted on a fixed plate and a movable plate, the mold is opened and closed, and the mold is closed. In the injection molding method of performing injection molding in a mold to perform molding, a gas generated in the mold by a vacuum device is used in order to remove sludge and residue generated by burrs due to gas generated during the injection filling from the mold. The remaining residue is suctioned under a negative pressure, and air is blown from the inside of the connection passage connected to the mold to the outside of the mold when the mold is open. Then, the negative pressure suction and the air blowing operation by the vacuum device are performed using the switching valve.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a circuit diagram of negative pressure suction and air blowing required for performing injection molding of a thermosetting resin according to an embodiment of the present invention. Reference numeral 1 denotes a mold. A fixed mold 1A is attached to the fixed board 2, and a movable mold 1B is attached to the movable board 3. The mold opening / closing and mold clamping are performed by moving the movable platen 3 toward and away from the fixed platen 2 whose position is fixed by a mold clamping driving means not shown in the figure. As the mold clamping drive means, any mechanism may be used regardless of a hydraulic or electric mechanism such as a hydraulic cylinder mechanism, a toggle link mechanism, and a ball screw mechanism.

The injection device 4 is a device that heats and melts phenol or BMC of a thermosetting resin and injects and fills the cavities of the mold 1 (fixed mold 1A, movable mold 1B). For example, the injection device 4 of the BMC injection molding machine presses the BMC into the heating cylinder by a pressure hopper (not shown), performs measurement by a plunger or a screw incorporated in the heating cylinder, and measures the tip of the heating cylinder. This is an apparatus for injecting and filling BMC into the cavity of the mold 1 from the nozzle.

In the mold 1, sludge due to BMC gas injected and filled by the injection device 4 and residue due to burrs are generated. Therefore, a vacuum device 5 for sucking the residue from the cavity of the mold 1 is connected. As the vacuum device 5, a hydraulic, hydraulic, or air vacuum pump, a vacuum generator that generates a negative pressure by a Venturi effect by simple air blowing, or the like is used. It does not matter which device is used as long as negative pressure suction is possible.

Here, an example of the structure of the movable mold 1B in the mold 1 will be described with reference to FIG. BMC which is molten resin
Is injected and filled into the cavity 9 from the injection device 4 through the sprue 6, the runner 7, and the gate 8. In the example,
This is a mold for taking two molded products by a side gate, and is provided with a seal ring 10 for shutting off outside air and sucking a negative pressure in a mold closed state. The vent hole 11 for sucking a negative pressure by connection with the vacuum device 5 is provided with a hole so as to communicate with the vent chamber 12. The gas vent 13 is provided at a portion of the molded product where gas escape is poor, and is provided to eliminate blistering and clouding on the surface of the molded product. The vent chamber 12 is provided between the cavity 9 and the seal ring 10, and a concave portion is provided around the cavity 9 so that suction can be performed from any part of the cavity 9. The thickness (gap) of the gas vent 13 is actually set to 0.05 to 0.1 mm so that the gas can escape. However, burrs are generated depending on the molded product, and the vacuum containing the vacuum device 5 sucks the burrs containing gas through the vent holes 11. Further, the generated gas becomes sludge by accumulating and becomes a residue. A passage of a vent hole 11 for sucking such a residue under negative pressure and a filter 1 described later.
A passage including up to 5 pipes and an internal passage of a hose is called a connection passage.

In the figure, a connection passage for suctioning a negative pressure by the vacuum device 5 is provided in the movable mold 1B, but may be provided in the fixed mold 1A, or provided in both the movable mold 1B and the fixed mold 1A. You may. As another connection method, a device that surrounds the periphery of the mold 1 and allows suction of generated gas may be provided, and negative pressure suction may be performed from around the entire mold 1.

In the embodiment shown in FIG. 1, a switching valve 14 is provided in the middle of the piping between the vacuum device 5 and the mold 1. The operation of the switching valve 14 is performed by a controller not shown in the drawing, and a negative pressure suction operation for a timer set time is activated from the completion of mold closing to suck a residue containing gas in the mold cavity for the timer set time. . According to the injection molding method of the present invention, after the timer set time of the negative pressure suction operation ends, the switching valve 14 is returned to a state in which it is not excited (neutral state), and the movable mold 1B is moved from the fixed mold 1A with the start of mold opening. The switching valve 14 is switched to the pressurizing side for the time set by the timer, and the mold 1 is opened.
Air is blown from the air source 18 in order to discharge the residue from the inside of the connection passage connected to the outside to the mold.
As the switching valve 14, a manual switching valve may be used, but it is preferable to use an electromagnetic valve type. in this way,
By using the solenoid valve, the molding cycle can be automated and stable molding can be performed.

The filter 15 is provided in the middle of the pipe between the switching valve 14 and the mold 1 to prevent damage to the vacuum device 5 caused by suction of the residue from the mold 1. The residue sucked from the mold 1 adheres to the inside of the connection passage and to the filter 15, which causes a decrease in negative pressure suction force. The filter 15 needs to be replaced if clogging occurs, and when air is not blown out after the negative pressure suction according to the present invention, the filter 15 differs depending on the thermosetting resin material. The filter is replaced every 100,000 shots. Further, the replacement is not limited to the filter, and the pipes and the hose are also replaced because the residue is accumulated in the piping and the hose connected to the mold 1 and the passage is narrowed.

Another embodiment is shown in FIG. 3, members having the same reference numerals as those in FIG. 1 have the same functions. In FIG. 3, the solenoid valves of the switching valve 14 of FIG. 1 are provided as separate negative pressure suction electromagnetic valves 16 and pressurizing electromagnetic valves 17. In order to suction the residue including the gas generated in the mold 1 by the vacuum device 5 under a negative pressure, the negative pressure suction solenoid valve 1 is used.
6 is excited to perform switching, and the negative pressure suction electromagnetic valve 16 is operated by a control device (not shown) to perform the negative pressure suction operation for the timer set time.

After the suction of the negative pressure is completed, the residue adhering to the inside of the connection passage and the filter 15 is discharged from the inside of the connection passage connected to the mold 1 to the outside of the mold in an open state. Control device, pressurizing solenoid valve 17
Is excited for the time set by the timer, and the air is blown out. In actual molding, the air blowing operation is performed for each shot of the molding cycle,
The residue can be released from the inside of the connection passage connected to the mold 1 to the outside of the mold and removed. The method is not limited to every shot, and may be performed periodically if the residue is removed.

[0014]

The injection molding method for thermosetting resin according to the present invention eliminates the need for maintenance for replacing pipes, hoses and filters connected to the mold by blowing out air after completion of negative pressure suction. This allows stable molding of non-defective products without interruption.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of negative pressure suction and air blowing required for performing injection molding of a thermosetting resin embodying the present invention.

FIG. 2 is a structural view of a mold embodying the present invention.

FIG. 3 is a circuit diagram of a negative pressure suction and air blowing required for performing injection molding of a thermosetting resin according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ‥‥‥ Die 2 ‥‥‥ Fixed plate 3 ‥‥‥ Movable plate 4 ‥‥‥ Injection device 5 ‥‥‥ Vacuum device 6 ‥‥‥ Sprue 9 キ ャ ビ テ ィ Cavity 10 ‥‥‥ Seal ring 13 ‥‥‥ Gas vent 14 ‥‥‥ Switching valve 15 ‥‥‥ Filter 16 電磁 Negative pressure suction solenoid valve 17 ‥‥‥ Pressurization solenoid valve 18 エ ア Air source

Claims (2)

[Claims] 1. An injection molding method in which a mold is attached to a fixed board and a movable board, and the mold is opened and closed and the mold is closed, and a molten resin is injected and filled into the mold by an injection device. In order to remove sludge due to the gas generated therein and residue due to burrs debris, the vacuum device suctions the residue including the gas generated in the mold with a negative pressure,
An injection molding method for a thermosetting resin, wherein air is blown to discharge a residue from the inside of a connection passage connected to a mold to the outside of the mold when the mold is open. 2. The method of injection molding a thermosetting resin according to claim 1, wherein the negative pressure suction and the air blowing operation by the vacuum device are performed using a switching valve.