JP3189260B2 - Mold for molding and molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a molding die and molding method for performing molding of a resin, to mold and molding method of a molded article having a particularly thick portion.

[0002]

2. Description of the Related Art Generally, in a resin injection molded product using a molding die, a cavity is formed between molds that can be opened and closed with each other, and the resin is injected and filled into the cavity when the mold is closed. And the cavity has
The thick part of the molded article is formed as a recess. In such a concave portion, the resin shrinks more than other thin portions, and there is a problem that shrinkage during cooling causes sink marks on the surface of the thick portion of the molded product. Therefore, conventionally, the one of the mold body formed of the recess, provided with retractably a pushing member serving push pin Nde extraordinary in recess, provided advancing drive means serving hydraulic cylinder for push driving the push pin, After the cavity is filled with the resin, while the resin is soft, the pushing pin is pushed into the recess toward the other mold, and a thick portion of the resin is formed between the tip of the pushing pin and the other mold. Was compressed to prevent sink marks generated on the surface of the molded article due to the compression.

[0003]

In the above prior art, the pushing pin is pushed into the resin, thereby compressing the resin in the thick part of the molded product to prevent shrinkage due to shrinkage. The compression works only in the direction in which the push pin is pushed in, and only the portion between the tip of the pin and the other mold body is compressed, so that there is a problem in that the range of the effect of preventing sink marks is limited.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a molding die and a molding method capable of preventing sink marks occurring in a thick portion of a molded product. I do.

[0005]

Means for Solving the Problems A molding die according to the present invention comprises:
A molding die, comprising: a plurality of molds which can be opened and closed with each other and form a cavity therebetween when the mold is closed, wherein a resin is filled in the cavity to form a molded product, and the molding die is formed in the cavity. a recess comprising a thick portion of the article, provided in the mold body while the formation of the recess, the recess bottom surface of the resin skin freely advance and retreat in the concave house towards the mold of the other side
A pushing member that breaks a layer and is pushed into the recess, advance / retreat driving means for driving the pushing member, an air blowing hole provided at the tip of the pushing member, and a resin filled in the cavity, The pushing direction of the pushing member from the air blow hole
Air blowing means for blowing compressed air into the apparatus.

The molding method of the present invention can be opened and closed with respect to each other.
Molds that form a cavity between each other when the mold is closed
The cavity is filled with resin to form a molded product.
A molding method using a molding die to be shaped, wherein the molding
The mold is formed in the cavity and has a thickness of the formed product.
And a concave part that is to be
And pushes back and forth into the recess toward the other mold.
Member, forward and backward driving means for driving the pushing member,
An air blowing hole provided at a tip of a pushing member;
Air is blown into the resin filled in from the air blow hole.
Air blowing means for filling the cavity with resin.
After filling, while this resin is soft,
Breaking the skin layer and pushing the pushing member into the recess,
Almost simultaneously with this pushing, the air is blown from the air blow hole into the resin.
This is a molding method in which compressed air is blown into the mold.

[0007]

According to the molding die and the molding method of the present invention, after the resin is molded in the cavity, while the resin is soft, the pushing member is broken into the skin layer on the lower surface of the recess to be pushed into the recess. The resin is compressed, and the resin in the thick part of the molded product is compressed by blowing air from the air blowing hole at the tip of the pushing member. Since this air also spreads in the lateral direction with respect to the axial direction of the pushing member, the resin is compressed in a wide range, and sinks generated in the thick portion of the molded product are prevented in a wide range.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a molding die according to the present invention will be described below with reference to FIGS. In the figure, reference numeral 1 denotes a fixed mold that forms the back surface of the molded product, and 2 denotes a movable mold that forms the front surface of the molded product.
The movable mold 2 moves upward and downward in the figure to open and close, and forms a molded product-shaped cavity 3 therebetween when the mold is closed. The fixed mold 1 has a gate 4 opening to the cavity 3 and a valve pin 5 for opening and closing the gate 4. On the other hand, the movable mold 2
Has a protruding pin 6 whose tip faces the cavity 3. The cavity 3 is formed with a cylindrical recess 8 to be a thick portion 7 of a molded product. For example, if the molded product is a cassette half of a video tape cassette, the thick portion 7 forms a cylindrical portion for positioning. The movable die 2 provided with the recess 8, the pusher member serving pusher pin 9 of retractably provided in the recess 8, see the tip of the push pin 9 is extraordinary in the lower surface of the recess 8, advancing drive By means of a hydraulic cylinder 10 as a means, it is advanced and retracted toward the fixed mold 1 side. The pushing pin 9 has an air passage inside.
The air passage 11 has a cylindrical shape, and a plurality of filter-shaped air blowing passages 12 are formed at the front end of the air passage 11. The front end of the air blowing passage 12 faces the recess 8 of the cavity 3. Further, a compressor 14 is connected to a base end of the air passage 11 as an air blowing means for blowing out compressed air from the air blowing hole 13. Further, each of the diameter of the air blowing hole 13 is formed, for example, about 0.03 mm by a Turkey be formed to the diameter of this degree, PS-based and P
Even if the cavity 3 is filled with the resin J having a P-based viscosity, the resin J does not enter the air blowing holes 13.

Next, molding of a molded article using the molding die.
Explaining the method , the fixed mold 1 and the movable mold 2 are closed, and the molten resin J is filled into the cavity 3 from the gate 4. The resin J comes into contact with the fixed mold 1 and the movable mold 2 constituting the cavity 3, and after the skin layer 15 is first formed on the surface, the whole is cooled and solidified, but the resin J is still soft. In the meantime, the skin layer 15 shown below
And push the push pin 9 into the recess 8. Further, almost simultaneously with this pushing, compressed air is blown into the cavity 3 from the many air blowing holes 13 at high pressure. Then, by the pushing of the pushing pin 9, the resin J in the cavity 3 is compressed between the tip of the pushing pin 9 and the movable mold 2, and the high-pressure air blown from the tip of the pushing pin 9 compresses the resin J. By doing so, sink marks generated on the surface of the molded article are prevented. In this case, the air blown out from the tip of the push-out pin 9 also spreads in the transverse direction with respect to the axial direction of the push-in pin 9 to form a cavity 16 in the resin J, as shown in FIG. The compressed air exerts a compressive force on the resin J in a wide range between the 16 hollow portions and the fixed mold 1, so that the effect of preventing sink marks extends over a wide range. Further, the cavity formed by the air blown out from the many air blowing holes 13
Numeral 16 designates a whole connected cavity, and the cavity 16 does not reach the surface of the molded product. This is because the surface of the molded product in contact with the fixed mold 1 is immediately cooled and a relatively hard skin layer 15 is shown. This is because it is formed above. On the other hand, on the other hand, air is blown into the resin J from the air blowing holes 13 to
Is formed, a skin layer in contact with the movable mold 2 below the figure
If not, the compressed air will flow between the resin J and the surface of the movable mold 2 and will not enter the resin J, but before the air is blown out, push the push pin 9 into the recess 8. Since the skin layer 15 is broken and air is blown into the soft portion of the resin J, the blown air can satisfactorily compress the resin J. Further, by pushing the push pins 9 into the recesses 8 of the cavity 3, the inside of the cavity 3 is maintained, preventing the resin J from flowing backward from the inside of the cavity 3 after the injection step, and reducing the resin J by the amount of shrinkage due to cooling. It is no longer necessary to maintain the pressure on the injection molding machine side in order to compensate for the pressure. In addition, since the compressed air is blown into the resin J in the cavity 3 almost at the same time as the pushing pin 9 is pushed, the inside of the cavity 3 is also blown by this blowing. It is held.

As described above, the molding die of the present embodiment includes the fixed die 1 and the movable die 2 which are a plurality of molds which can be opened and closed with each other and form the cavity 3 when the mold is closed. A molding die for molding a molded product by filling a resin J into the cavity, a concave portion 8 formed in the cavity 3 to be a thick portion 7 of the molded product, and a movable die 2 having the concave portion 8 formed therein. provided, the recess can be moved in the solid fixed headed recess 8 in 1
8 Break the resin 15 skin layer 15 on the lower surface and push it into the recess 8
A push pin 9 as a push member to be pushed, a hydraulic cylinder 10 as an advance / retreat drive means for driving the push pin 9, an air blowing hole 13 provided at the tip of the push pin 9, and air inside the resin J filled in the cavity. Pushing the push pin 9 from the blow hole 13
All SANYO and a blown air feed means serving compressor 14 INCLUDED direction to the compressed air, also forming side of the invention
After filling the cavity 3 with the resin J, the resin
While J is soft, break the skin layer 15 under the recess 8
Push the pushing member serving as a push pin 9 in the concave stations 8, this press
Almost at the same time as the compressed air
Is injected into the cavity 3, so that the resin J
After the resin J is molded, the pressing pins 9
Is pressed into the recess 8 by breaking the skin layer 15 on the lower surface of the recess 8 to compress the resin J in the recess 8, and further, air is blown from the tip of the push-in pin 9 to thereby increase the thickness of the molded product. 7 can be compressed, and the air blowing hole
Since the air blown out from 13 spreads also in the lateral direction with respect to the axial direction of the push pin 9, the resin J is compressed in a wide range,
The sink that occurs in the thick part 7 of the molded product is prevented.

Further, while the resin J is soft, air is blown by pressing the push-in pin 9, and the skin layer 15 is broken by the push-in of the push-in pin 9, and the air is favorably blown into the resin J. Can be. Further, since the pressure inside the cavity 3 is maintained by both the pushing of the pushing pins 9 and the blowing of the compressed air into the resin J, the holding pressure on the injection molding machine side becomes unnecessary.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the forward / backward driving means and the air blowing means are not limited to hydraulic jacks and compressors, and various types can be used. Further, the concave portion and the push pin are not limited to the cylindrical shape, and various shapes such as a prismatic shape can be used.

[0013]

The molding die according to the present invention comprises a plurality of molds which can be opened and closed with each other and form a cavity therebetween when the mold is closed. The molding is carried out by filling the cavity with a resin and molding a molded article. a mold, a recess is formed in the cavity a thick portion of the molded article, provided in the mold body while the formation of the recess, the recess house towards the mold of the other side Breaking through the resin skin layer on the bottom of the recess
And Murrell pushing member pushing in the recess, and the advancing drive means for driving the pushing member, and the air blow holes provided in the distal end of the pusher member, in the resin filled in the cavity, said from the air blow hole An air blowing means for blowing compressed air in a pressing direction of the pressing member is provided, and a molding die capable of preventing sink marks from occurring in a thick portion of a molded product can be provided.

Further , the molding method of the present invention can be opened and closed with respect to each other.
Molds that form a cavity between each other when the mold is closed
The cavity is filled with resin to form a molded product.
A molding method using a molding die to be shaped, wherein the molding
The mold is formed in the cavity and has a thickness of the formed product.
And a concave part that is to be
And pushes back and forth into the recess toward the other mold.
Member, forward and backward driving means for driving the pushing member,
An air blowing hole provided at a tip of a pushing member;
Air is blown into the resin filled in from the air blow hole.
Air blowing means for filling the cavity with resin.
After filling, while this resin is soft,
Breaking the skin layer and pushing the pushing member into the recess,
Almost simultaneously with this pushing, the air is blown from the air blow hole into the resin.
This is a molding method that blows compressed air into the
Provided is a molding method capable of preventing sink marks from occurring.
Can be

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

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

FIG. 3 is a sectional view of a main part showing one embodiment of the present invention.

FIG. 4 is a perspective view of the tip of a push pin showing one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fixed type (mold) 2 Movable type (mold) 3 Cavity 7 Thick part 9 Push pin (pushing member) 10 Hydraulic cylinder (advance driving means) 14 Compressor (air blowing means) 15 Skin layer

Claims (2)

(57) [Claims] 1. A molding die, comprising: a plurality of molds that can be opened and closed with each other and form a cavity therebetween when the mold is closed, wherein the cavity is filled with a resin to mold a molded article, A recess formed as a thick part of the molded product, and provided on one of the mold bodies having the recess formed therein ,
The recess bottom movable back and forth in the recessed house towards the mold of the other side
A pushing member which breaks a resin skin layer on the surface and is pushed into the recess, an advance / retreat driving means for driving the pushing member, an air blowing hole provided at a tip of the pushing member, in the resin filled in the cavity, the push from the air blow hole
An air blowing means for blowing compressed air in a pushing direction of the member . (2) The mold can be opened and closed with each other and can be closed between the molds when the mold is closed.
A plurality of molds forming a cavity, wherein
Using a molding die to fill the resin into a molded product
A molding method, wherein the molding die includes the cavity
And a recess which is formed in a thick portion of the formed article, and the recess
Is provided on one of the molds forming
And a pushing member that can move back and forth in the recess, and drive the pushing member.
Moving forward and backward driving means, and an empty space provided at the tip of the pushing member.
In the air blow hole and the resin filled in the cavity,
Air blowing means for blowing air from the air blowing hole,
After filling the cavity with resin, the resin softens
While padding, break the skin layer on the lower surface of the recess
The pushing member is pushed into the
The compressed air is blown into the resin from the air blow hole.
Characteristic molding method.