JPH05131505A - Injection molded product - Google Patents

Abstract

PURPOSE:To reduce the processing cost of an injection molded product and carry out easily releasing the molded product out of a mold and handling thereof by adopting a new gate sealing method resistant to high pressure and also carry out the mold processing of good efficiency. CONSTITUTION:An injection molded product consists of a molded product 101 corresponding to the cavity shape of a mold, a resin section 102a corresponding to a valve storing section of the mold and molded integrally with the molded product 101 and a valve exposing section 102 with a valve 4, a part 4a of which is exposed from said resin section 102a. A constricted section 103 can be formed between the molded product 101 and the valve exposing section 102. The valve exposting section 102 can be utilized for ejection. A part 4a of the valve 4 exposed from the resin section 102a is provided with its outer diameter equal to the inner diameter of a gate 10, and the center of the valve 4 is preferably located on the axis of the valve exposing section 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection-molded product, and more particularly to an injection-molded product molded by gate sealing during injection molding.

[0002]

2. Description of the Related Art Generally, an injection-molded product is injection-filled with a molten resin in a cavity formed between a fixed mold and a movable mold, and the resin is solidified to be molded into a shape corresponding to the shape of the cavity. However, there are many problems that the molded product is distorted or deformed due to the contraction of the resin during the cooling or the reverse flow of the resin to the sprue side, and the molding accuracy is lowered.

Therefore, recently, in the molding process of injection-molded products such as optical lenses which require high molding accuracy,
In order to prevent the resin filled in the cavity from flowing backward due to the pressure change on the cavity side, it has been proposed to add a gate sealing function to the injection molding die to solve the above problem. Examples of this type of injection-molded article and its processing method include the following.

First, the one disclosed in Japanese Patent Laid-Open No. 48-7949 discloses a method in which a cavity block provided in a mold body is moved by a piston to seal a gate, and injection molding is carried out by the mold. The product is cut from the runner at the gate portion when the gate is sealed during cooling. Further, in the one disclosed in Japanese Patent Application Laid-Open No. 58-94436, a fixed mold and a movable mold are provided with a fixed sleeve and a movable sleeve that surround a cavity and form a gate between the concave and convex portions adjacent to the cavity. In the mold, the movable sleeve is pressed against the fixed sleeve in a mold closed state to seal the gate, prevent resin from flowing back from the gate in the pressure and compression process, and remove the molded part from the gate. It eliminates the need for removal processing. The injection-molded product molded by the mold is cut from the runner at the gate portion when the gate is sealed during cooling.

The one described in Japanese Patent Laid-Open No. 58-94440 pushes up a movable sleeve similar to the above and cuts the resin in the gate portion by closely fitting the convex and concave portions, and removes the gate portion after taking out the molded product. The treatment is not necessary, and the scratches, dirt, dust, etc. generated by the removal treatment are prevented. In the one disclosed in Japanese Patent Laid-Open No. 61-47227, the movable core is retracted by the pressure of the resin injected into the cavity, and the retracting movement of the core is transmitted to the backflow preventer by the direction changing means to prevent the backflow preventer. Is moved to the inside of the gate to seal the gate, and the resin in the cavity and the resin in the runner portion are cut during molding to prevent processing and deformation of the molded product due to post-processing.

[0006]

However, such an injection-molded article produced by the conventional injection molding process is large and expensive in that the mold requires a pressure compression mechanism and the like, and the gate seal is used. The molding process is complicated because the stopping mechanism is operated by an external force. Therefore, the molding cost of the injection-molded product is high.

Further, there is a problem that it is not easy to take out the molded product main body cut at the gate portion from the mold, and thereafter handle and position it. On the other hand, in order to perform highly accurate molding while eliminating the above-mentioned pressure and compression process, it is sufficient to inject and fill the resin into the cavity at a very high pressure and seal the gate. Since it was not possible to seal with the above-mentioned various gates driven from, it was not possible to obtain excellent transferability by using a simple mold without a pressure and compression mechanism.

Therefore, the present invention reduces the processing cost of an injection molded product by performing a simple molding process with a completely new gate sealing method that can withstand high pressure, and at the same time removes the molded product from the mold. And to facilitate handling.

[0009]

In order to achieve the above object, the invention according to claim 1 provides a molded article body corresponding to a cavity shape of an injection molding die, and a resin portion integrally molded with the molded article body. And a valve body exposed portion having a valve body for gate sealing, a part of which is exposed from the resin portion on the side opposite to the molded product body.

The invention according to claim 2 is characterized in that a part of the valve body exposed from the resin portion has an outer diameter equal to the inner diameter of the valve body seating portion of the gate in the injection molding die. The invention according to claim 3 is characterized in that the center of the valve body is located on the axis of the valve body exposed portion, and the invention according to claim 4 is the molded product body and the valve body. Characterized by a constriction formed between the exposed parts,
The invention according to claim 5 is characterized in that the valve body exposed portion is a protruding portion at the time of taking out from the injection molding die.

[0011]

According to the first aspect of the present invention, by adopting a novel gate sealing method that can withstand injection filling of resin under high pressure, the processing cost of high precision injection molded products is reduced, and
Since the valve body exposed portion can be directly gripped and handled without touching the molded body, the handling can be facilitated.

According to the second aspect of the present invention, a part of the valve body exposed from the resin portion is seated on the gate to separate the molded product from the sprue side. Therefore, cost reduction can be achieved by omitting post-processing. .. In the invention according to claim 3, the center of the valve body is located on the axis of the valve body exposed portion. Therefore, the supply (injection) of the resin into the cavity becomes smooth, and so-called flow lines do not occur.

According to the fourth aspect of the present invention, since the constricted portion is formed between the molded product body and the valve body exposed portion, the gate portion is formed immediately before the cavity in consideration of the flow of the molten resin injected into the cavity. It is possible to improve the accuracy of the molded product body. According to the fifth aspect of the present invention, since the valve body exposed portion is projected when the injection molded product is taken out, the molded product can be taken out from the mold without any influence on the molded product body.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 to 4 are views showing a first embodiment of an injection-molded article according to the present invention. First, the configuration will be described. In FIG.
100 is an injection molded product, and this injection molded product 100 includes a molded product main body 101 having predetermined high-precision transfer surfaces 101a and 101b,
Valve body exposed portion 102, molded product body 101 and valve body exposed portion 102
And a constricted portion 103 provided between the two. The injection-molded product 100 is injection-molded by the injection-molding die 1 shown in FIG.
It has an optical lens shape corresponding to the shape of the cavity 8. The valve body exposed portion 102 is composed of a resin portion 102a integrally formed with the molded article body 101 via a constricted portion 103 and a spherical valve body 4 partially embedded in the resin portion 102a. The part 4a is exposed to the outside from the resin part 102a of the valve body exposed part 102. The shape of the valve body exposed portion 102 corresponds to the shape of the second runner 6 (valve body storage portion) of the injection molding die 1, and the constricted portion 103
The shape of is thin corresponding to the shape of the second gate 7 of the injection molding die 1. Further, the resin portion 1 of the valve body exposed portion 102
The part 4a of the valve body 4 exposed from 02a is the injection molding die 1
Has an outer diameter equal to the inner diameter of the inner peripheral edge 10a (valve body seating portion) of the first gate 10, and the center of the valve body 4 is the valve body exposed portion 10
It is located on or near the axis of 2. Further, the valve body exposed portion 102 is a protruding portion when the molded product is taken out from the injection molding die 1. In FIG. 1, 102
Reference numeral b is a recess corresponding to a stop pin 11 described later.

That is, the injection-molded metal article 100 includes a cavity 8 and a resin supply passage to the cavity 8 (a sprue 9, a first runner 5, a first gate 10, a second runner 6 and a second gate 7 which will be described later). ,) And a valve-seat-shaped first gate 10 provided in a part thereof, and in the resin supply passage on the cavity 8 side of the first gate 10 to the gate 10 by resin pressure from the cavity 8 side. Seatable valve body 4
And an injection molding die 1 having the above. The injection molding die 1 is specifically configured as follows.

2 to 5, the injection molding die 1 is
It has a fixed mold 2 and a movable mold 3 that come into contact with and separate from the vertical direction in the figure. The fixed mold 2 has grooves 2a, 2
b, 2c, a concave portion 2d and a mold clamping surface 2e are formed, and the movable mold 3 is formed with groove portions 3a, 3b, 3c facing each of the fixed mold 2, a concave portion 3d and a mold clamping surface 3e. ing. When the mold clamping surfaces 2e and 3e of both molds 2 and 3 are brought into contact with each other, the groove portions 2a and 3a form the first runner 5, and the groove portions 2b and 3b form the second runner 6 (the resin supply passage to the cavity. The groove 2c and 3c form the second gate 7, and the recesses 2d and 3d form the cavity 8 in which a molded product is formed. Further, a sprue 9 which is an inlet of the molten resin is formed in the fixed mold 2, and the sprue 9 communicates with the cavity 8 via the first runner 5, the second runner 6 and the second gate 7. There is.

Further, between the first runner 5 and the second runner 6, that is, with respect to the second runner 6, a cavity 8 is formed.
A step-like first gate 10 protruding inward from the inner walls of the runners 5 and 6 is formed on the side opposite to the first runner 5, 6, and the first gate 10 has a valve seat-like shape facing the spherical valve body 4. It has an inner peripheral edge 10a. The inner peripheral edge 10a of the first gate 10 is a sharp edge, but the edge may be chamfered. The width of the chamfer in that case, that is, the inner peripheral edge
Two faces forming 10a (fixed mold 2 side and movable mold 3
The width of the chamfer on the side) is preferably small, for example, 1 mm or less.

Reference numeral 11 is a stop pin
11 is supported by the fixed mold 2 so as to project into the groove 2b. The spherical valve element 4 is housed in the second runner 6 between the stop pin 11 and the first gate 10, and the spherical valve element 4 stops when the molten resin flows into the cavity 8. When the resin abuts against and is locked out of the cavity 8 and flows out of the cavity 8, the resin is seated in a liquid-tight manner by being pressed against the stepped inner peripheral edge 10a of the first gate 10.

That is, the injection molding die 1 comprises a movable spherical valve body 4, a second runner 6 for accommodating the movable spherical valve body 4, a first gate 10 on which the spherical valve body 4 can be seated and pressure-contacted, and a spherical valve body. Four
The sealing mechanism portion 15 including a stop pin 11 that restricts the movement of the sealing mechanism portion toward the cavity 8 side is provided.
When the resin is filled in the cavity 8 through the first runner 5 and the second runner 6, 15 makes the spherical valve body 4 sit on the first gate 10 by the high pressure of the resin filled in the cavity 8. It is designed to seal the gate.

Next, the operation will be described together with the forming process. First, before mold clamping of the fixed mold 2 and the movable mold 3 (prior to mold clamping), the runner forming groove portions 2a, 2b.
Part 2 corresponding to the second runner 6 (valve housing)
The spherical valve body 4 is stored in b. Next, the molds 2 and 3 are clamped to define the first runner 5, the second runner 6, the gate 7 and the cavity 8.

In this state, a molten resin is injected from an injection molding nozzle (not shown), and this resin is passed from the sprue 9 to the first runner 5, the first gate 10, the second runner 6, and the second gate 7. The molten resin is sequentially introduced, and the molten resin is injected into the cavity 8 via these. At this time, as shown in FIG. 3, the spherical valve element 4 pressed against the stop pin 11 by the pressure F of the inflowing molten resin is
It does not hinder the molten resin flowing from the runner 5 into the second runner 6 having a small pressure.

When the pressure of the molten resin filled in the cavity 8 reaches the set pressure, the injection of the injection nozzle is stopped. When the pressure in the first runner 5 starts to drop due to the stop of the injection, as shown in FIG. 4, the molten resin tends to flow backward from the second runner 6 having a large pressure to the first runner 5 having a smaller pressure than this. At this time, the spherical valve body 4 is pressed against the first gate 10 by the reverse flow pressure F'and is pressed against and seated on the first gate 10. In this state, the semi-solidified layer is formed by the solidification of the resin on the edge surface of the inner peripheral edge 10a which is the valve seat.
This semi-solidified layer is a very thin film of resin that is solidified by contacting the wall surface of the mold, and is called a skin layer. Normally, a very large force is required to crush the semi-solidified layer formed on the flat surface, but in the present embodiment, the semi-solidified layer is formed on the edge surface of the stepped inner peripheral edge 10a which is a sharp edge. Therefore, the semi-solidified layer can be easily crushed with a small force. Therefore, the spherical valve body 4 is
The resin is easily seated on the gate 10 in a liquid-tight manner, and the resin flowing back from the gap of the semi-solidified layer is completely sealed in a short time, that is, the first gate 10 is reliably sealed. Thus, the resin pressure in the cavity 8 and the first runner 5 immediately after the injection is stopped.
By utilizing the differential pressure of the resin pressure of, the spherical valve body 4 can be pressed against and seated on the first gate 10 to seal the gate.

In such a gate-sealed state, the cavity 8 is formed.
When the resin inside is cooled and solidified while being kept at a predetermined pressure, the fixed mold 2 and the movable mold 3 are opened, and the injection molded product 100 can be taken out. At this time, since the spherical valve body 4 is seated in the first gate 10 in a liquid-tight manner, the solidified resin is in a state of being cut off before and after the first gate 10, and the molding in the cavity 8 is completed. Item body 101
(Product part) and resin part 102a in the second runner 6
Then, the constricted portion 103 in the gate 7 is integrated with the valve body 4 to form the injection molded product 100.

Next, an injection pin or the like (not shown) projects the valve body housing portion 102 or grips the valve body housing portion 102, so that the injection-molded product 100 is taken out from the grooves 2b, 2c and the recess 2d. As described above, in this embodiment, the spherical valve body 4 is housed in the second runner 6 of the injection molding die 1, and a gate cutting mechanism that requires an external force and a complicated mechanism for crushing are provided. Without
Using a completely new small sealing mechanism 15, the first gate
The resin before and after 10 is cut at the time of gate sealing. Therefore, the injection-molded product 100 taken out of the mold does not require post-processing, and in combination with the simplification of the gate sealing structure, low-cost molding processing can be realized.

Further, as described above, the spherical valve body 4 is housed in the second runner 6 prior to the mold clamping of the fixed mold 2 and the movable mold 3, and the resin pressure is applied to the spherical valve body 4. Since the gate is sealed when the injection into the cavity 8 is completed, the number of man-hours for sealing (and cutting) the gate is reduced, and the first gate can be reliably discharged even with a high injection resin pressure.
It becomes possible to seal 10. As a result, it is possible to perform injection molding with a high degree of formation excellent in transferability without providing a pressure compression step during cooling, and it is possible to eliminate the pressure compression mechanism by hydraulic pressure or the like, which results in cost reduction. Will be larger.

Furthermore, in this embodiment, the injection molded product 100 can be handled by directly grasping or protruding the valve body exposed portion 102 without touching the molded product body 101, and therefore the injection molded product 100 is injection molded. It is easy to take it out of the mold 1 and handle the injection-molded product 100, and it is possible to easily position the injection-molded product 100 when it is assembled. Further, since the center of the valve body 4 is located on or near the central axis of the valve body exposed portion 102, the supply (injection) of the resin into the cavity 8 is smooth, and so-called flow lines are prevented from occurring. Since the constricted portion 103 is formed between the molded product body 101 and the valve body exposed portion 102, in consideration of the flow of the molten resin injected into the cavity 8, the gate portion is provided immediately before the cavity 8. A certain second gate 7 can be formed, the molding accuracy of the molded product body 101 can be further improved, and the valve body exposed portion can be formed if necessary.
The 102 can be easily separated from the molded article body 101.

5 to 9 are views showing a second embodiment of the injection-molded article according to the present invention. First, in FIG. 5, reference numeral 200 denotes an injection-molded product. This injection-molded product 200 has a predetermined-shaped molded product body 201, a valve body exposed portion 202, and a space between the molded product body 201 and the valve body exposed portion 202. And a constricted portion 203 provided. This injection-molded product 200 is an injection-molding die 20 shown in FIG.
Is injection-molded, and its shape corresponds to the shape of the cavity 25 of the injection-molding die 20. The valve body exposed portion 202 is composed of a resin portion 202a integrally molded with the molded product body 201 via a constricted portion 203 and a spherical valve body 23 partially embedded in the resin portion 202a. The part 23a is exposed to the outside from the resin part 202a of the valve body exposed part 202. The shape of the valve body exposed portion 202 corresponds to the shape of the runner 26 of the injection molding die 20, and the shape of the constricted portion 203 corresponds to the shape of the second gate 27 of the injection molding die 20. Further, the portion 4a of the valve body 23 exposed from the resin portion 202a of the valve body exposed portion 202 is equal to the inner diameter of the first gate 30 of the injection mold 20 (the inner diameter at the position where the valve body 23 is seated). It has an outer diameter, and the center of the spherical valve body 23 is located on the axis of the valve body exposed portion 202. Further, the valve body exposed portion 202 is a protruding portion when the molded product is taken out from the injection molding die 20. In FIG. 5, 202b is a recess corresponding to a stopper 29 described later.

That is, the injection-molded metal product 200 includes a cavity 25 and a resin supply passage to the cavity 25 (a sprue 28 described later, a first gate 30, a valve body storage chamber 24, a runner).
26 and the second gate 27), a valve seat-shaped first gate 30 provided in a part of the first gate 30 and a cavity 25 from the first gate 30.
Is formed in the resin supply passage on the side of the cavity 25, and is formed by an injection molding die 20 having a valve body 23 that can be seated on the gate 30 by resin pressure from the cavity 25 side. The mold 20 is configured as follows.

In FIG. 6, 21 is a fixed mold, 22 is a movable mold, and the spherical valve body 23 is housed in the valve body housing portion 24a of the fixed mold 21 before the mold clamping. The fixed mold 21 and the movable mold 23 are clamped together to form a cavity 25, a runner 26, a valve body storage chamber.
When the 24 and the first gate 30 are defined, the molten resin P is supplied from the sprue 28 to the valve body storage chamber 24, as shown in FIG. 7. At this time, the spherical valve body 23 separates from the first gate 30, which is the valve seat, by the supply pressure of the molten resin P, and contacts the stopper 29. Since the stopper 29 is arranged so as to allow the molten resin P to pass therethrough, the molten resin P in the valve body accommodating chamber 24 is supplied into the cavity 25 via the second gate 27.

When the molten resin P is filled in the cavity 25, the supply of the molten resin P from the sprue 28 side is stopped,
The molten resin P tries to flow back to the sprue 28 side, but at this time, as shown in FIG. 8, the spherical valve body 23 is seated on the tapered first gate 30 in a liquid-tight manner to close the runner 26. After the runner 26 is closed and the resin P in the cavity 25 is cooled and solidified, the injection mold 20 is opened, and the molded product body 20 molded in the cavity 25 is opened.
1 can be taken out.

Next, when the push-out pin 31 is projected into the valve body accommodating chamber 24, the resin portion 202 of the valve body exposed portion 202 which is solidified while being integrally connected to the molded product body 201 in the second gate 27.
a floats up with the molded product body 201. At this time, the resin portion 202a of the valve body exposed portion 202 and the resin 205 on the sprue 28 side
Are completely separated from each other by the spherical valve body 23 that is in pressure contact with the first gate 30, and as shown in FIG. 9, a portion 23a of the spherical valve body 23 is located at the right end of the resin portion 202a in the figure. Is exposed, and a molded product 200 in which the molded product body 201 and the resin portion 202a are integrated is completed.

As described above, also in this embodiment, a small injection molding die capable of gate-sealing without using an external force.
The injection molded product 200 is molded by 20. Therefore, it is possible to reduce the number of special steps for gate encapsulation and perform low-cost molding processing, and it becomes possible to take out and handle the injection-molded product 200 very easily, and the same effects as the above-described example can be obtained. ..

[0033]

According to the first aspect of the present invention, the molding cost is reduced by adopting a new gate sealing method that can withstand injection filling of resin under high pressure. can do. Further, since the valve body exposed portion can be directly grasped or handled without touching the molded article body, the handling and positioning can be facilitated.

According to the second aspect of the invention, since the molded product is separated from the sprue side by the valve body of the valve body exposed portion, the machining cost can be reduced by omitting the post-machining. According to the third aspect of the invention, since the center of the valve element is located on the axis of the valve element exposed portion, it is possible to smooth the resin supply to the cavity and prevent the occurrence of so-called flow lines. it can.

According to the fourth aspect of the present invention, since the constricted portion is formed between the molded article body and the valve body exposed portion, the flow of the molten resin injected into the cavity is taken into consideration immediately before the cavity. The sprue part can be formed, and the molding accuracy of the molded article body can be improved. According to the fifth aspect of the present invention, since the valve body exposed portion is projected when the injection molded product is taken out, the molded product can be easily taken out from the mold without any influence on the molded product main body. ..

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of an injection-molded article according to the present invention.

FIG. 2 is a sectional view of an essential part of the injection molding die.

FIG. 3 is a diagram showing a valve body and a gate as a valve seat when molten resin is injected into a cavity of the mold.

FIG. 4 is a diagram showing a valve body and a gate when the gate is sealed.

FIG. 5 is a front view showing a second embodiment of the injection-molded article according to the present invention.

FIG. 6 is a cross-sectional view of a main part of the injection molding die.

FIG. 7 is a diagram showing a valve body and a gate as a valve seat when molten resin is injected into the cavity.

FIG. 8 is a diagram showing a valve body and a gate when the gate is sealed.

FIG. 9 is an explanatory view of a step of taking out the injection molded product.

[Explanation of symbols]

 1, 20 Injection mold 2, 21 Fixed mold 3, 22 Movable mold 4, 23 Spherical valve body (valve body) 5 First runner (resin supply passage) 6 Second runner (resin supply passage, valve body storage) Part) 7, 27 second gate (resin supply passage) 8, 25 cavity 10, 30 first gate (gate) 10a inner peripheral edge part (valve body seating part) 15 sealing mechanism part 24 valve body storage chamber (valve) Body storage) 26 Runner (resin supply passage) 100, 200 Injection molded product 101, 201 Molded product body 102, 202 Valve body exposed part 102a, 202a Resin part 103, 203 Constricted part P Molten resin

Continuation of front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location // B29L 11:00 4F (72) Inventor Toshihiro Kanamatsu 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company In Ricoh

Claims (5)

[Claims] 1. A molded product main body corresponding to a cavity shape of an injection molding die, a resin part integrally molded with the molded product main body, and a part of the resin part exposed on a side opposite to the molded product main body. An injection molded product, comprising: a valve body exposed portion having a valve body for gate sealing. 2. The injection according to claim 1, wherein a part of the valve body exposed from the resin portion has an outer diameter equal to the inner diameter of the valve body seating portion of the gate in the injection molding die. Molding. 3. The injection-molded product according to claim 1, wherein the center of the valve body is located on the axis of the valve body exposed portion. 4. The injection-molded article according to claim 1, wherein a constricted portion is formed between the molded article body and the valve body exposed portion. 5. The injection-molded article according to claim 1, wherein the valve body exposed portion is a protruding portion when taken out from the injection-molding die.