JP2002192572A - Mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a pinhole or a weld line in a molded article, in subjecting a thermosetting resin such as BMC or the like to injection/ compression molding. SOLUTION: The venting hole 3 communicating with the cavity 13 formed between a fixed mold 11 and a movable mold 12 at a predetermined position and a closure member (valve stem) 5 for closing the venting hole 3 in a freely openable manner are provided. When a thermosetting resin raw material M is subjected to compression molding after injected in the cavity 13, the cavity 13 is evacuated through the venting hole 3, and the venting hole 3 is closed immediately before the thermosetting resin raw material M arrives at the venting hole 3 to eliminate the effect caused by the air or generated gas in the cavity 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die used for injection and compression molding of a thermosetting resin material such as BMC (bulk mold compound).

[0002]

2. Description of the Related Art As a method of molding a thermosetting resin article such as BMC, a fixed mold and a mold closed with respect to the fixed mold are used.
A movable mold is provided so that the mold can be opened freely, and a molding die is used in which a molding cavity is formed between the fixed mold and the movable mold when the mold is closed. , And the movable mold is moved before the mold closing position (for example, 10 mm).
mm position), the thermosetting resin material is injected into the cavity between the fixed mold and the movable mold, and then the mold is closed by moving the movable mold, so that the thermosetting in the cavity is performed. Compression molding of conductive resin raw material. An injection / compression molding method is known in which a thermosetting resin material in a cavity is cured, a mold is opened by moving a movable mold, and a molded product is released.

[0003]

When a molded article is injected and compression-molded using a thermosetting resin such as BMC as a raw material, the air or generated gas (e.g., volatile matter of the resin) in the cavity of the molding die is removed. Due to the influence, molding defects tend to occur, such as pinholes being generated in the molded product, and the thermosetting resin raw material being involved in air or generated gas during compression molding to generate weld lines.

The present invention has been made in view of such circumstances, and when injection and compression molding of a thermosetting resin such as BMC, it is necessary to prevent occurrence of pinholes and weld lines in a molded product. It is intended to provide a molding die having a possible structure.

[0005]

According to the present invention, there is provided a fixed mold and a movable mold in which a cavity is formed in a mold closed state. The movable mold is moved from the mold opened state toward the fixed mold, and the movable mold is closed. Before reaching the position, the thermosetting resin material is injected into the cavity between the fixed mold and the movable mold, and then the thermosetting resin material is compression-molded by moving the movable mold. A gas vent hole communicating with a predetermined position of a cavity formed between the movable mold and the movable mold, and a closing member for closing the gas vent hole in an openable and closable manner, after injecting the thermosetting resin material into the cavity, When compression molding the raw material, exhaust the inside of the cavity through the vent hole,
It is characterized by being configured to close the vent hole immediately before the thermosetting resin material reaches the vent hole.

According to the molding die of the present invention, from the time when the thermosetting resin material injected into the cavity is started to be compressed (mold closing), to the time immediately before the thermosetting resin material reaches the gas vent hole, the cavity is cooled. Since the inside is exhausted, the problem of pinholes and weld lines due to air and generated gas in the cavity can be solved, and a thermosetting resin molded article of good quality can be obtained.

The position where the gas vent hole is provided (communication position to the cavity) is preferably a portion where the raw material of the thermosetting resin merges in the cavity during compression molding, in consideration of eliminating the weld line. .

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of a main part of the embodiment of the present invention.

The molding die 10 is a die used for injection and compression molding of a thermosetting resin such as BMC.
1 and a movable mold 12.

The movable die 12 is movable in the horizontal direction with respect to the fixed die 11, and the movable die 12 is fixed to the fixed die 11 (the mold is closed).
2, a molding cavity 13 is formed. A packing 14 is provided between the fixed mold 11 and the movable mold 12. Although not shown, the movable mold 12 is provided with a projecting device for projecting and releasing the molded product remaining on the movable mold 12 when the mold is opened after injection and compression molding. .

The fixed mold 11 is provided with a degassing device 1. As shown in FIGS. 2A and 2B, the degassing device 1 includes a device main body 2, a valve stem 5, an air cylinder 6, and the like.

The apparatus main body 2 is detachably mounted on the fixed mold 11. The device main body 2 is formed with a gas vent hole 3 which has a cylindrical shape and penetrates the device main body 2, and a vacuum hole 4 communicating with the gas vent hole 3. A valve rod 5 is slidably disposed in the gas vent hole 3.

Each end face 2a, 5 of the device body 2 and the valve stem 5
“a” is processed into a shape that forms a part of the molding surface 11 a of the fixed mold 11. The device body 2 and the valve stem 5 are heat-resistant
It is made of a material having excellent wear resistance, for example, so-called tool steel or alloy tool steel.

The valve stem 5 is moved by an air cylinder 6,
An opening position where the vacuum hole 4 is opened to the gas vent hole 3 (the position shown in FIG. 2B) and a state where the vacuum hole 4 is closed and the front end surface 5a is the molding surface 11a of the fixed mold 11 (the front end surface of the apparatus main body 2). 2a) are selectively disposed at two closed positions (positions in FIG. 2A) corresponding to the closed positions.

A vacuum exhaust device (for example, a vacuum pump or the like) 7 is connected to the vacuum hole 4, and an air cylinder 6 is provided.
When the valve stem 5 is moved to the open position by the drive of
The gas vent hole 3 communicates with the vacuum hole 4 to exhaust (gas vent) the cavity 13. The driving of the air cylinder 6 is controlled by a controller (not shown) at a timing described later.

Next, the operation of the degassing device 1 will be described together with the molding process.

Start of mold closing As shown in FIG. 3, the movable mold 12 is moved toward the fixed mold 11 from the state in which the molding die 10 is opened. The valve stem 5 of the degassing device 1 is in a closed position of the degassing hole 3 (FIG. 2).
(Position (A)).

Material Injection The movable mold 12 is moved 10 m from the mold closing position (the position in FIG. 1).
At the point when the position reaches m, the raw material (BMC) M is injected into the cavity 13 as shown in FIG.

Raw Material Compression / Degassing As shown in FIG. 5, the movable mold 12 is further moved toward the fixed mold 11 to start the compression molding (closing) of the raw material M.
At the same time, as shown in FIG. 5 and FIG. 2 (B), the air cylinder 6 of the degassing device 1 is driven to move the valve stem 5 to the open position of the degassing hole 3 to exhaust the gas in the cavity 13 ( Degassing).

As shown in FIG. 6, immediately before the raw material M reaches the gas vent hole 3, the air cylinder 6 of the gas vent device 1 is driven to close the gas vent hole 3. The tip surface 5a of the valve stem 5 is made to coincide with the molding surface 11a of the fixed mold 11 (see FIG. 2A).

After the closing of the movable mold 12 is completed, this state (the state shown in FIG. 7) is maintained for a predetermined time, and the raw material M that has been subjected to compression molding is cured to obtain a molded product S.

Mold Opening / Mold Release When the curing of the raw material M is completed, the movable mold 12 is moved to open the mold, and a projecting device (not shown) installed on the movable mold 12 is driven. Then, the molded product S remaining on the movable mold 12 is protruded to release the molded product S.

One cycle of molding is completed as described above, and the same steps are repeated sequentially.

Here, in the above molding process, the timing of closing the gas vent hole 3 is determined based on conditions such as the shape and capacity of the cavity 13 and the injection amount of the raw material M, for example. The time from when the process is performed to when the raw material M arrives immediately before the gas vent hole 3 may be obtained in advance by calculation, experiment, or the like, and may be set based on the time.

In the above embodiment, the degassing device 1
Position of vent hole 3 (communication position to cavity 13)
In the compression molding, the raw material M such as BMC
It is the part where it joins in. By providing the gas vent hole 3 at such a position, generation of a weld line can be more effectively prevented.

According to the embodiment shown in FIG. 1, since the apparatus main body 2, the valve stem 5 and the air cylinder 6 constituting the degassing apparatus 1 are detachably mounted on the fixed mold 11, compression is possible. When the high-pressure resin acting at the time of molding damages the distal end surface 5a of the valve stem 5 and the distal end surface 2a of the apparatus body 2,
Alternatively, in a case where the resin is deposited on the gas vent hole 3 and the gas vent device 1 malfunctions, for example, the device main body 2
Also, there is an advantage that the valve stem 5 and the like can be partially replaced.

[0028]

As described above, according to the molding die of the present invention, after the thermosetting resin material is injected into the cavity, when the material is compression-molded, the inside of the cavity is formed through the gas vent hole. Since it is configured to exhaust and close the vent hole just before the thermosetting resin material reaches the vent hole, it has been a conventional problem in injection / compression molding of thermosetting resin such as BMC. Pinholes and weld lines can be prevented from occurring, and a high-quality thermosetting resin molded product can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part of the embodiment of the present invention.

FIG. 3 is an explanatory view of a molding step.

FIG. 4 is an explanatory view of a molding step.

FIG. 5 is an explanatory view of a molding step.

FIG. 6 is an explanatory view of a molding step.

FIG. 7 is an explanatory view of a molding step.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Degassing device 2 Device main body 3 Degassing hole 4 Vacuum hole 5 Valve stem (closing member) 6 Air cylinder 7 Vacuum exhaust device 10 Molding die 11 Fixed die 11a Molding surface 12 Movable die 13 Cavity 14 Packing M Raw material (BMC) S molded product

Claims (1)

[Claims] A movable mold having a cavity formed in a mold closed state, wherein the movable mold is moved toward the fixed mold from the mold open state, and the movable mold is moved to the fixed mold before reaching the mold closed position. Injection of the thermosetting resin material into the cavity between the movable mold and the compression mold of the thermosetting resin material by moving the movable mold. Formed between the fixed mold and the movable mold. A gas vent hole communicating with a predetermined position of the cavity to be provided, and a closing member for closing the gas vent hole in an openable and closable manner. After injecting the thermosetting resin material into the cavity, when the material is compression molded, A mold for evacuating the cavity through the gas vent hole and closing the gas vent hole immediately before the thermosetting resin material reaches the gas vent hole.