JPH07144332A - Straight-hydraulic molding method and straight-hydraulic mold - Google Patents

Abstract

PURPOSE:To obtain a molded product free from strain or warpage by a method wherein a plurality of core pins are introduced into a cavity from one shaping surface of the cavity under pressure until brought into contact with the other shaping surface thereof when the molding material enclosed in the cavity is melted and allowed to recede after the completion of molding. CONSTITUTION:When pressure is applied after a molding material 6 is charged to move an upper mold 11 so as to bring the same into contact with a float mold 2, the float mold 2 is supported by springs 33 to form a gap 34 between the float mold 2 and a lower mold 3. When the molding material 6 is melted and pressure is further applied, the springs 33 are contracted to reduce the gap 34 and the core pins 5 provided to the lower mold 3 in an erected state penetrate into the molten molding material 6 to come into contact with the shaping surface 13 of a cavity plate 11. After the completion of molding, pressure is reduced to raise the upper mold 1 and the resistance force of the core pins against a molded product overcomes the resistance force bringing the molded product into close contact with the cavity plate 11 to release the molded product. When pressure is further reduced, the core pins 5 recede and the molded product is engaged with a cavity plate 21 to be released from the core pins 5 by uniform force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct pressure molding method for molding a plate-shaped molded article having a large number of through holes, and a direct pressure molding die for carrying out this method.

[0002]

2. Description of the Related Art Conventionally, injection molding has been mainly used as a method for molding a plate-shaped molded product having irregularities or through holes on its surface. However, molding by an injection molding machine has a problem that a weld line is generated in a molded product.
Molded products such as filters for liquid crystal panels have a thin plate and have a light-transmitting property, so that not only the weld line has a reduced light-transmitting property, but also the refractive index of the transmitted light is changed and it is not practical.

Therefore, when a plate-shaped molded article having a large number of through holes as shown in FIG. 4 is formed by a direct pressure forming method in which no weld line is generated, a large number of pins for forming the through holes exist. When the molded product is released from the pin after the completion of molding, there is a problem that the molded product is distorted or warped due to the resistance of the pin, which impedes the release of the molded product.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a direct pressure molding method and a direct pressure molding method capable of reliably releasing a molded product without distortion or warpage. The purpose is to provide a mold.

[0005]

A direct pressure molding method according to the present invention is a direct pressure molding method for molding a molded article having a large number of through holes, in which a molding material enclosed in a cavity (9) is melted. After a plurality of core pins (5) are press-fitted into the object from the shaping surface (16) of the moving-side die to the shaping surface (16) of the fixed-side die facing the shaping surface (16), the moving side is moved. It is characterized in that the core pin (5) is retracted from the shaping surface (13) to the shaping surface (16) with respect to the molded product remaining in the mold.

A direct pressure molding die according to the present invention comprises a lower die (3) and a return pin (3) provided upright on the lower die (3).
2) and the spring (3) that engages the return pin (32)
A direct pressure molding die comprising a floating die (2) supported by 3) and an upper die (1) having a cavity located above the floating die (2) provided on the floating die (2). The floating mold (2) is obtained by penetrating the through hole (17) and clamping the mold.
A plurality of core pins (5) protruding from the mold and contacting the shaping surface (13) of the upper mold (1) are erected on the lower mold (3).

[0007]

According to the direct pressure molding method of the present invention, when the molding material enclosed in the cavity is melted, a plurality of core pins are press-fitted from one shaping surface until they come into contact with the opposite shaping surfaces. As a result, the core pin can move in while pushing away the molten molding material in the cavity, and the molded product can be released from the mold by retracting the core pin after the molding is completed.

According to the molding die of the present invention, a plurality of core pins that penetrate through the through holes provided in the floating die and project from the floating die when the die is clamped and contact the shaping surface of the upper die are provided. Since it is erected on the lower mold, when forming a molded product with a through hole, the core pin can be pushed in while pushing away the molten molding material in the cavity, and the core pin should retreat after molding. Thus, the molded product can be released from the mold.

Preferably, the plurality of core pins (5) standing on the lower mold (3) have a mortar-shaped recess (15) on the top surface (14) at the tip thereof, and in addition, It is preferable to have a knockout pin (27) protruding from the recess (15) in the top surface (14).

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

[0011]

1 and 2 are sectional views of a direct-pressure molding die according to the present invention. FIG. 1 shows the die when it is opened and FIG. 2 shows it when the die is clamped. Further, FIG. 3 is an enlarged view of the tip end portion of the core pin, (a) shows a state in which the core pin is embedded in the through hole,
(B) is a state where the core pin is in contact with the shaping surface, (c)
FIG. 4 is a diagram showing a state in which a knockout pin in a core pin is protruding.

As shown in FIGS. 1 and 2, the direct pressure molding die used in the direct pressure molding machine according to the present invention includes an upper die (1), a floating die (2) and a lower die (3). Composed of and.

The upper die (1) is a die mounting board (10).
A cavity plate (11) that is attached to the mold and is replaced according to the shape of the molded product is embedded.

A cavity plate (21) facing the cavity plate (11) embedded in the upper mold (1) is embedded in the floating mold (2). The cavity plate (21) is provided with an air vent (8) so that when the mold is completely closed, air existing in the cavity (9) and volatile components generated from the molding material are discharged to the outside. A groove having a depth of 0.02 mm to 0.03 mm is provided on the mold dividing surface of the air vent (8). Further, a guide bush (4) is fitted in a through hole (17) penetrating from the upper mold (1) side to the lower mold (3).

The lower mold (3) is a mold mounting plate (10).
A return pin (32), which is attached to the mold and supports the floating mold (2), and a plurality of core pins (5) used to form through holes of the molded product are erected. Return pin (32)
A spring (33) is engaged with the mold, and when no pressure is applied to the mold, its elasticity forms a space (34) between the mold and the floating mold (2). The core pin (5) slides in the guide bush (4) fitted in the through hole (17) of the floating mold (2), and the mold is clamped to lock the floating mold (2).
It protrudes from the surface of the cavity plate (11) embedded in and is brought into contact with the shaping surface (13) of the upper mold (1). As shown in FIG. 3, the core pin (5) has a top surface (1
4) has a mortar-shaped recess (15), and has a knockout pin (27) protruding from the recess (15) of the top surface (14).

Further, guide pins (12) (31) and guide bushes (23) (24) for supporting and fitting the movement of the molds are inserted in each mold.

Next, the direct pressure molding method will be described. For example, a method of forming a surface filter of a liquid crystal panel as shown in FIG. 4 will be described.

Bulk molding compounds and sheet molding compounds made of thermosetting resins are mainly used as molding materials for moldings. As thermosetting resins, phenol, polyester, urea, melamine, etc. may be used alone or modified. is there. As shown in FIG. 1, a phenol resin molding material (6) of a bulk molding compound is put into a cavity (9) of an opened direct pressure molding die. This molding material (6) was preheated at 90 ° C. After the injection of molding material (6),
By applying pressure, the upper mold (1) moves until it contacts the floating mold (2), and the parting surface (7) is closed. At this time, the floating mold (2) is supported by the elasticity of the spring (33) that engages with the return pin (32), and forms a space (34) between the lower mold (3).

When the molding material (6) is melted by heating the mold, pressure is further applied. When the elastic force of the spring (33) is inferior to the applied pressure, the spring (33) begins to contract and the gap (34) becomes smaller. When the gap (34) becomes smaller, the core pin (5) standing on the lower mold (3) protrudes from the surface of the cavity plate (21) along with its movement and is enclosed in the cavity (9) to melt the molding material ( Enter in 6). The core pin (5) advances in the cavity while pushing away the molding material (6), and the shaping surface (1) of the cavity plate (11) is
Contact 3). At this time, as shown in FIG. 2, the inside of the cavity (9) is in a sealed state, but since the air vent (8) is provided on the surface of the cavity plate (21), the air existing in the cavity (9) is Emit volatile components generated from the molding material and the molding material to the outside. In addition, excess air or resin can be stored in the mortar-shaped recess (15) at the tip of the core pin (5). Also, this recess (15)
As a result, the material of the core pin (5) is easily cut.

As described above, the heat and pressure molding is carried out at a molding temperature of 160 ° C. and a molding pressure of 230 kg / cm ² for 4 minutes.

After the completion of molding, when the pressure is reduced and the mold is opened, the upper mold (1) rises, but the resistance of the plurality of core pins (5) to the molded product causes the molded product to move into the cavity plate (1).
The molded product is released from the cavity plate (11) of the upper mold (1) because it has a higher resistance than the resistance force in close contact with (1).
When the pressure is further reduced, the core pin (5) retracts, the molded product is locked to the cavity plate (21), and a uniform force is applied to the molded product by the cavity plate (21) and released from the core pin (5).

After removing the released molded product, the knockout pin (27) projects from the recess (15) of the top surface (14) of the core pin (5) and remains in the mortar-shaped recess (15). ) Is removed.

The molded product obtained as described above had a good appearance with no distortion or warpage.

[0024]

As described above, according to the direct pressure molding method and the direct pressure molding die of the present invention, even in the case of a molded article having a large number of through holes, the resin filling property is improved and the appearance is improved. It is possible to obtain a molded product that is excellent and has no cracks, flaws, or distortion.

Further, by using the core pin (5) according to the present invention, excess air and resin in the mold can be stored and removed in the recess (15) of the top (25) of the core pin (5). .

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a direct pressure molding die according to the present invention.

FIG. 2 is a cross-sectional view when the direct pressure molding die in FIG. 1 is closed.

FIG. 3 is an enlarged view of a tip end portion of a mold pin used in an example.

FIG. 4 is a partially cutaway perspective view of an embodiment of a molded product.

[Explanation of symbols] 1 upper mold 2 floating mold 3 lower mold 4 guide bush 5 mold pin 6 molding material 7 parting surface 8 air vent 9 cavity 10 mold mounting board 11 cavity plate 13 shaping surface 14 top surface 15 concave part 16 shaping surface 21 cavity plate 26 slug 27 knockout pin 32 return pin 33 spring 34 void

Claims (2)

[Claims] 1. A direct pressure molding method for molding a molded article having a large number of through holes, wherein a plurality of core pins (5) are attached to a molten material of a molding material enclosed in a cavity (9) on a moving side mold. From the shaping surface (16) of (1) to the shaping surface (16) of the fixed-side mold that contacts the shaping surface (16), the core pin (5) is pressed against the molded product that remains in the moving-side mold. A direct-pressure molding method, wherein the molding surface is retreated from the shaping surface (13) to the shaping surface (16). 2. A floating mold (3) supported by a lower mold (3), a return pin (32) standing on the lower mold (3), and a spring (33) engaging with the return pin (32). In a direct pressure molding die including 2) and an upper die (1) having a cavity located above the die, a through hole (17) provided in the floating die (2) is penetrated to form the die. A plurality of core pins (5) protruding from the floating die (2) when tightened and contacting the shaping surface (13) of the upper die (1) are erected on the lower die (3). Direct pressure molding die.