JP2002192573A - Mold for molding plastics and method for manufacturing molded article using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for molding plastics capable of allowing the gas remaining in a cavity to escape positively and rapidly to enhance the filling efficiency of a plastic material into the cavity, and capable of preventing the generation of defectiveness or the generation of gas scorching, and to provide a method for manufacturing a molded article using the mold. SOLUTION: The mold for molding plastics consists of a fixed mold 2 and a movable mold 3, and an ejector pin 6 for taking out a molded article from the mold is provided to the movable mold. In order to positively and rapidly discharge the residual gas in the cavity 4 of the mold extruded by the molten plastic material 5 charged in the cavity 4 from the gap between the ejector pin and the ejector pin insertion hole 7 formed to the movable mold, vertical grooves are formed to the ejector pin at a predetermined interval from the vicinity of the tip coming into contact with the cavity of the ejector pin over length exceeding the length corresponding to the thickness of the movable mold, or the ejector pin is formed so as to become finer than the thickness of the tip part thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to thermoplastic resins such as general-purpose resins, engineering plastics, plastics having special properties such as fluorine resins and silicon resins, rubber-like elastic polymers such as thermoplastic elastomers, and thermosetting. The present invention relates to a plastic molding die for molding a compression molded product, a transfer molded product, an injection molded product, and the like made of various plastic materials such as a conductive resin, and a method for producing a molded product using the mold.

[0002]

2. Description of the Related Art Conventionally, for example, in plastic injection molding, a plastic material is filled into a cavity in a mold composed of a fixed mold (core side) and a movable mold (cavity side) via a sprue, a runner and a gate. In addition, a molded product is ejected from a mold by an ejection pin fitted into an ejection pin insertion hole formed in a movable mold.

[0003]

In plastic injection molding, it is important to escape gas in a cavity in a mold and to spread a plastic material to every corner of the cavity. However, due to the mold structure, the gas in the cavity does not escape to the end, which causes defects such as short shots and weld lines generated in the process of flowing the molten plastic material in the cavity, or gas burns. Therefore, the range of molding conditions is narrow, which is one of the causes of the occurrence of defects. In the case of precision plastic molded articles, the filling time of the plastic material into the cavity is very short, that is, less than 1 second, and the gas remaining in the cavity cannot be completely removed. Therefore, the incidence of defective products was high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a cavity through a gap between an ejection pin inserted into an ejection pin insertion hole formed in a movable mold during molding and the insertion hole. Actively and rapidly escapes gas remaining in the cavity, improves the efficiency of filling the cavity with plastic material, and prevents the occurrence of defects such as short shots and weld lines in the flow process and the occurrence of gas burns. It is an object of the present invention to provide a plastic molding die which can be used and a method for producing a molded product using the mold.

[0005]

A plastic molding die according to the present invention comprises a fixed die and a movable die, and the movable die has a protruding pin for taking out a molded product from the die. In the above, the residual gas in the cavity extruded by the molten plastic material filled in the cavity of the mold is positively and rapidly discharged from the gap between the ejection pin and the ejection pin insertion hole formed in the movable mold. For this reason, the protruding pin is formed with a vertical groove at a predetermined interval from the vicinity of the tip in contact with the cavity side to a length exceeding the length corresponding to the thickness of the movable mold, or is formed thinner than the thickness of the tip. It was done.

Further, in the plastic molding die according to the present invention, a circumferential annular groove is formed on the peripheral surface or side surface of the protruding pin near the tip which is in contact with the cavity side, or the protruding pin has an axial center. On the other hand, a transverse groove is formed on the outer surface in the vertical direction, and a longitudinal groove connected to the annular groove or the transverse groove is formed from the annular groove or the transverse groove to a length exceeding the length equivalent to the thickness of the movable mold. It is.

[0007] The plastic molding die according to the present invention comprises:
In a plastic molding die comprising a fixed die and a movable die, the movable die having a protruding pin for taking out a molded product from the die, a cavity extruded by a molten plastic material filled in the cavity of the die. In order to positively and rapidly discharge the remaining gas in the gap between the ejection pin and the ejection pin insertion hole formed in the movable mold, the ejection pin in contact with the cavity side is formed on the inner wall of the ejection pin insertion hole. A streak-shaped vertical groove is formed at a predetermined interval from a position corresponding to a position inward from the tip to the end surface of the movable die.

Further, the plastic molding die according to the present invention is characterized in that a predetermined portion is provided on the inner wall surface of the protrusion pin insertion hole from a position corresponding to a position inward from the tip of the protrusion pin contacting the cavity side to an end surface of the movable mold. Stripe-shaped vertical grooves are formed at intervals, and an annular common groove connected to each of the striped vertical grooves is formed at a position corresponding to a position inward from the tip of the protruding pin.

[0009] A method of manufacturing a molded product using a plastic molding die according to the present invention is a method of manufacturing a plastic molded product by molding using a plastic molding machine equipped with a fixed die and a movable die. The gas remaining in the cavity extruded by the molten plastic material filled in the mold cavity is positively and rapidly discharged from the gap between the ejection pin and the ejection pin insertion hole formed in the movable mold. The molten plastic material is filled in every corner of the cavity.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference numeral 1 denotes a plastic molding die (hereinafter, referred to as a die) including a fixed die 2 and a movable die 3. The movable mold 3 has a cavity 4 for obtaining a molded product (not shown).
Is formed in the cavity 4, a thermoplastic resin such as a general resin, an engineering plastic, a plastic having a special property such as a fluororesin or a silicon resin, a rubber-like elastic polymer such as a thermoplastic elastomer, or thermosetting. Various plastic materials 5 such as conductive resin are spool
(Not shown), runner (not shown) and gate (not shown)
Is filled into the cavity 4 which becomes each molded product. The cavity 4 is a gap formed by the cavity of the movable mold 3 and the core of the fixed mold 2, and a molded product is formed by this gap. Usually, a plurality of cavities 4 are formed in a mold in consideration of production efficiency and the like.

Reference numeral 6 denotes a protruding pin that fits into a protruding pin insertion hole 7 formed in the movable die 3. The protruding pin 6 is usually used to take out a molded product from the mold 1. In addition, the residual gas extruded by the molten plastic material 5 when the molten plastic material 5 flows in the cavity 4 is supplied to the mold 1 through a gap between the ejection pin 6 and the ejection pin insertion hole 7 formed in the movable mold 3. Is characterized in that it can be actively and efficiently released to the outside.

The mounting position of the protruding pin 6 is shown as a typical example in the case where it is mounted at a position in contact with the cavity 4 side. However, this mounting position is not limited to this. And it may be a runner section, a gate section, or the like. Further, the number of the protruding pins 6 is not limited to one for one molded product, but may be plural. In addition to the round pin as in this example, the protruding pin 6 has a shape corresponding to various uses such as a square pin (see FIG. 1B) or a stepped round pin type (not shown). Also applies.

As a means for positively and efficiently releasing the residual gas to the outside of the mold, a vertical groove 6a is formed at a predetermined position on the peripheral surface or side surface of the protrusion pin 6, or a chamfer 6b is performed.
Alternatively, the corresponding portion may be formed in a shape thinner than the tip portion, or a shape obtained by combining them. Flute 6
a, the chamfer 6b or the thin portion is formed from the vicinity of the tip of the protruding pin 6 in contact with the cavity 4 side.
The vertical groove 6a is formed over a length exceeding the length corresponding to the thickness of the vertical groove 6a, or the groove is made thinner than the thickness of the tip portion so as to form a chamfer 6b or a thin shape to perform gas escape. The key points in forming the vertical groove 6a, the chamfer 6b, or the thin shape are as follows.
It is necessary to secure a sufficient gap so that the residual gas can be positively and efficiently released to the outside of the mold 1 from the gap between the ejection pin 6 and the ejection pin insertion hole 7 formed in the movable mold 3. is important. That is, the residual gas in the cavity 4 extruded by the molten plastic material 4 has a very small gap between the tip of the protruding pin 6 contacting the cavity 4 side and the protruding pin insertion hole 7. When passing, the temperature becomes high and high pressure, and then the residual gas passes through a relatively wide gap, so that a phenomenon like adiabatic expansion occurs, and the residual gas is actively and rapidly discharged to the outside of the mold. .

FIG. 4 and FIG. 5 show that a circumferential annular groove 9 is formed on the peripheral surface or side surface of the protruding pin 6 near the tip in contact with the cavity side, or an outer surface perpendicular to the axis of the protruding pin 6. A transverse groove 9 is formed in the annular groove or the transverse groove 9.
The vertical groove 6a connected to the movable mold 3
Is formed over a length exceeding the length corresponding to the thickness of the substrate. As a result, the residual gas introduced into the annular groove or the transverse groove 9 is discharged from any of the longitudinal grooves 6a connected to each other, and it is possible to more actively remove the residual gas.

In this embodiment, a case has been described in which a vertical groove 6a or the like is formed on the peripheral surface or side surface of the protruding pin 6 in order to positively and rapidly discharge the residual gas in the cavity to the outside of the mold. Without being limited to this, the shape of the protruding pin 6 is the same as that of the related art. Streak-shaped vertical grooves 8 are formed at a predetermined interval from the corresponding portion to the end surface of the movable die.

As in the present invention, the streak-like vertical groove 8 is formed on the inner wall of the protrusion pin insertion hole 7 because the inner wall extends from a position corresponding to a position inward from the tip of the protrusion pin to the end surface of the movable die. Enlarging the whole is also an important role in that the projecting pin insertion hole 7 serves as a guide for the projecting pin 6. If a large hole is formed in the inner wall of the protruding pin insertion hole 7, the pin is likely to bend or break when the molded product protrudes without serving as a guide. Therefore, by forming the streak-like vertical groove 8 on the inner wall of the protrusion pin insertion hole 7, the role of the guide and the positive and rapid discharge of the residual gas can be achieved.

The location where the streak-like vertical groove 8 is formed is formed in the same location as the corresponding location in the case where it is formed on the peripheral surface or side surface of the protruding pin 6. In any case, a sufficient gap is provided so that the residual gas can be positively and efficiently released from the gap between the ejection pin 6 and the ejection pin insertion hole 7 formed in the movable mold 3 to the outside of the mold 1. It is important to ensure.

FIG. 8 shows a case in which an annular common groove 10 which is provided in common with the streak-like vertical groove 8 is formed at a position corresponding to a position inward from the tip of the protruding pin 6. This annular common groove 1
The residual gas introduced at 0 is discharged from any of the continuous vertical grooves 8, which makes it possible to more actively remove the residual gas.

[0019]

As can be seen from the above description, the present invention positively removes gas remaining in the cavity from the gap between the projecting pin fitted in the projecting pin insertion hole formed in the movable mold during molding and the insertion hole. You can escape quickly and quickly. Therefore, the filling efficiency of the plastic material into the cavity can be improved, and the occurrence of defects such as short shots and weld lines and the occurrence of gas burning in the flow process can be prevented.

Further, according to the method of manufacturing a molded product using the plastic molding die according to the present invention, the efficiency of filling the plastic material is improved, and a good molded product having a low defective rate can be obtained.

According to the present invention, the molding pressure condition is relaxed, and a good molded product can be obtained even when the molding pressure is lowered. Particularly in a multi-cavity mold, the residual gas in the cavity is rapidly removed even if the molded product is located far from the center or the spool position. It is possible to eliminate residual gas,
It can sufficiently cope with high-speed molding, and the impact on this type of application is enormous.

A circumferential annular groove is formed on the peripheral surface or side surface of the protruding pin near the tip in contact with the cavity side, or a transverse groove is formed on an outer surface perpendicular to the axis of the protruding pin. A projecting pin and a projecting pin insertion hole formed in the movable mold by forming a vertical groove connected to the annular groove or the transverse groove from the annular groove or the transverse groove to a length exceeding the length equivalent to the thickness of the movable mold. The residual gas discharged from the gap between the annular groove and the transverse groove is introduced into the annular groove or the transverse groove, and is rapidly discharged to the outside from any of the longitudinal grooves connected to the annular groove or the transverse groove. In the case of only the vertical groove formed in the above, the discharge efficiency can be further improved as compared with the case where only the residual gas in the vicinity thereof is discharged.

A streak-shaped vertical groove is provided on the inner wall of the protrusion pin insertion hole formed on the movable mold at a predetermined interval from a portion corresponding to a position inward from the tip of the protrusion pin in contact with the cavity side to an end surface of the movable mold. By forming
By playing the role of a guide of the push-out pin, there is no damage such as bending of the push-out pin, and the residual gas in the cavity can be positively and efficiently discharged.

Further, the protruding pin insertion hole forms a streak-like vertical groove on the inner wall surface at a predetermined interval from a portion corresponding to a position inward from the tip of the protruding pin in contact with the cavity side to an end surface of the movable die. Since the annular common groove, which is provided in common with the streak-like vertical groove, is formed at a position corresponding to a position inward from the tip of the protruding pin, the residual gas can be removed more efficiently.

[Brief description of the drawings]

1A and 1B are perspective views illustrating an embodiment of the present invention, in which FIG. 1A is a perspective view in which a groove is formed on a peripheral surface or a side surface of a round protrusion pin, and FIG. FIG. 3C is a perspective view in which a groove is formed in a surface or a side surface, and FIG. 4C is a perspective view in which a peripheral surface or a side surface of a round protrusion pin is flatly cut to form a chamfer.

FIG. 2 is a cross-sectional view showing a state in which a protruding pin attached to a mold according to the present invention is fitted to a movable mold.

3A is a cross-sectional view taken along line AA of FIG. 1A, and FIG.
FIG. 3C is a sectional view taken along line AA of FIG.

FIG. 4 is a perspective view of a protrusion pin showing another embodiment of the present invention.

FIG. 5 is a side view of FIG. 4;

FIG. 6 is a sectional view of a mold showing another embodiment of the present invention.

FIG. 7 is a sectional view taken along line BB of FIG. 6;

FIG. 8 is a sectional view of a mold showing another embodiment of the present invention.

DESCRIPTION OF SYMBOLS 1 Mold 2 Fixed mold 3 Movable mold 4 Cavity 5 Plastic material 6 Projection pin 6a Vertical groove 6b Chamfer 7 Projection pin insertion hole 8 Streak-like vertical groove 9 Annular groove or transverse groove 10 Annular common groove

Claims (5)

[Claims] 1. A plastic molding die comprising a fixed die and a movable die, wherein the movable die has a protruding pin for taking out a molded product from the die, wherein a molten plastic material filled in a cavity of the die. In order to positively and rapidly discharge the residual gas in the cavity extruded from the gap between the ejection pin and the ejection pin insertion hole formed in the movable mold, the ejection pin is movable from near the tip in contact with the cavity side. A plastic molding die, wherein vertical grooves are formed at predetermined intervals over a length exceeding a length corresponding to the thickness of the die, or formed to be thinner than a thickness of a tip portion. 2. A circumferential annular groove is formed on the peripheral surface or side surface of the protruding pin near the tip in contact with the cavity side, or a transverse groove is formed on an outer surface perpendicular to the axis of the protruding pin. 2. The plastic according to claim 1, wherein a vertical groove connected to the annular groove or the transverse groove is formed from the annular groove or the transverse groove to a length exceeding a length corresponding to a thickness of the movable mold. Mold for molding. 3. A plastic molding die comprising a fixed die and a movable die, wherein the movable die is provided with a protruding pin for taking out a molded product from the die, wherein a molten plastic material is filled in a cavity of the die. In order to positively and rapidly discharge the residual gas in the cavity extruded from the gap between the ejection pin and the ejection pin insertion hole formed in the movable mold, the cavity is formed on the inner wall of the ejection pin insertion hole. A metal mold for plastic molding, characterized in that streak-like vertical grooves are formed at a predetermined interval from a position corresponding to a position inward from a tip of a protruding pin contacting a side to an end face of a movable mold. 4. A protruding pin insertion hole according to claim 3, wherein a streak-shaped vertical groove is formed on an inner wall surface thereof at a predetermined interval from a portion corresponding to a position inward from a tip of the protruding pin in contact with the cavity side to an end surface of the movable die. 4. A plastic molding die according to claim 3, wherein an annular common groove connected to each of said stripe-shaped vertical grooves is formed at a position corresponding to a position inward from the tip of the protruding pin. . 5. A method for producing a plastic molded product by molding with a plastic molding machine having a mold comprising a fixed mold and a movable mold, wherein a cavity extruded by a molten plastic material filled in a cavity of the mold. The gas remaining in the cavity is positively and rapidly discharged from the gap between the ejection pin and the ejection pin insertion hole formed in the movable mold, and the molten plastic material is filled in every corner of the cavity. Of manufacturing molded products using a plastic molding die.