JPH0741643B2 - Injection molding die, injection molding method and molded product thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an injection mold and an injection mold.
Demolding method and molded product thereof, especially gate sealing
Injection to prevent resin backflow from the cavity
Molding die and injection molding method and molding by the method
Regarding molded products.

[0002]

2. Description of the Related Art Conventionally, in the technical field of injection molding,
The resin injected into the cavity is the pressure on the runner side.
The problem of backflow under the influence of changes and distortion
Therefore, when performing precision molding, its injection
A work process for adding a gate sealing function to the molding die
Has been proposed to solve the above problems by adding
ing.

Injection molding die and injection molding method of this kind
For example, JP-A-48-7949 and JP-A-
57-34933, JP-A-57-70626
Report, JP-A-57-72831, JP-A-58-94
436, JP-A-58-94440, JP-A-58-94440
59-24620, JP-A-60-132719
Japanese Laid-Open Patent Publication No. 60-47227, Japanese Laid-Open Patent Publication No. 60-2
08214, JP-A-61-252123,
Also, as described in Japanese Utility Model Publication No. 63-77721.
Are known, and an outline of each is given below.

(1) Described in JP-A- 48-7949
For the thing, the cavity block provided in the mold body
Cooling of molten resin material by moving by tons
During the period, we will cut the resin of the gate part and seal the gate.
With this, take out the molded product and cut it after molding
It is designed to save you time. (2) The one described in JP-A-57-34933 is a compound
In a machine that simultaneously injects into several cavities,
Hydraulically-controlled flow path adjustment inside the runner communicating with Vity
Control block to open and close the runner channel diameter
However, pressure control has been performed for each cavity.
There is.

(3) Described in JP-A-57-70626
In the first type, the pin is driven by a pin driving cylinder , and the sprue portion is closed by the pin to prevent backflow of the resin in the compression process. (4) The one described in JP-A-57-72831 is an oil
The shaft is driven by the pressure cylinder
It closes the sprue part and is cooled by pressure in the compression molding method.
It is designed to prevent the resin from flowing back during the rejection process.
It

(5) Described in Japanese Patent Laid-Open No. 58-94436
The one encloses the cavity in the fixed mold and the movable mold
The gate between the uneven parts adjacent to the cavity.
A fixed sleeve and a movable sleeve for forming
Therefore, when the mold is closed, the movable sleeve becomes a fixed sleeve.
Pressure compression molding by pressing and sealing the gate
Prevent resin from flowing back from the gate during the compression process
It is like this.

(6) Described in Japanese Patent Laid-Open No. 58-94440
The one with the same movable sleeve as (5) is pushed up
The resin of the gate part is cut by the close fitting of the
It eliminates the need to remove the gate part after projecting.
It (7) The one described in JP-A-59-24620 is a key
Driven by a pressure piston after injecting resin into the cavity
The gate from the injection cylinder side to the cavity.
The gate is made to project into the runner to close the gate.

(8) Described in JP-A-60-132719
The ones listed are for the fixed mold and the movable mold respectively.
With a movable piece-shaped cavity forming mold
To move these cavity forming molds relative to the main unit.
To prevent resin backflow in the pressure cooling process.
It has become. (9) What is described in JP-A-60-208214 is
Move the fixed insert and the movable insert in parallel in the same sleeve.
This allows the cavities to be sandwiched between the fixed and movable inserts.
Move the tee away from the gate to seal the gate
It is possible to pressurize the resin in the cavity in the state
Is.

(10) Described in Japanese Patent Laid-Open No. 61-47227
In the case of the one shown in the figure, the movable core is retracted by the pressure of the resin injected into the cavity, and the retracting movement of this core is transmitted to the backflow preventer by the direction changing means. The gate is sealed with a gate to prevent backflow of the resin in the pressure step of the pressure compression molding method.

(11) Japanese Patent Laid-Open No. 61-252123
The ones listed are provided with an insert piece that is moved by a pressure cylinder.
The gate is shut off by moving the moving piece (moving in the axial direction).
It is something. By the way, these conventional examples (1) to (11)
Is a gate sealing member and a means for driving it.
A separate drive source that drives the sealing mechanism
Power from a drive source (such as a hydraulic device) is sealed.
A transmission mechanism or the like for transmitting to the construction is required. Also, this
These conventional examples (1) to (11) mainly perform injection compression molding.
The gate between the cavity and the sprue in the mold
To shut off the gate after injecting resin into the cavity
This prevents resin backflow during the pressure compression process.
Of. Therefore, the mold becomes larger and
The molding process is very
There was a problem that it became complicated.

Therefore, the applicant has arranged the resin supply passage.
By sealing the movable member in response to resin pressure and sealing the gate,
Minimize the mold by eliminating the drive source and transmission mechanism described above.
And eliminate the special process for gate encapsulation
An injection molding die that can be used is already in Japanese Patent Application No. 63-47441.
Is proposed in. This is designed so that the spherical valve element loosely inserted in the runner is brought into contact with the inner peripheral edge of the valve seat provided at the sprue side end of the runner, so that the spherical valve element is seated on the valve seat to seal the gate. The molten resin injected into the cavity is prevented from flowing back, and the seating of the spherical valve element prevents a sharp decrease in the resin pressure during molding and improves the precision of the molded product.

[0012]

However, even in such an injection mold, the spherical valve body is seated on the valve seat by bringing the spherical valve body into contact with the inner peripheral edge of the valve seat. Therefore , the spherical valve body and the inner peripheral edge of the valve seat are completely
It is said that if the resin pressure inside the cavity is maintained at a high pressure , the molten resin will flow backward if it is not in close contact with the circumference.
There was a problem. In order to prevent the backflow of this molten resin, it is necessary to process the inner peripheral edge of the valve seat with extremely high precision.
It was insufficient from the viewpoint of cost reduction.

Therefore, according to the present invention, highly accurate gate processing is possible.
Compact and low-cost injection that eliminates the need and has a gate sealing function
Aiming to realize a molding die, and suitable for the die
Injection molding method, and a molding molded by the method
The object is to provide a molded product that is easy to handle .

[0014]

In order to achieve the above object, the injection molding die according to the invention of claim 1 is filled with resin.
A cavity that, through the communication with an injection molding machine to the cavity
An injection molding die comprising: a resin supply passage for supplying the molten resin , and a sealing mechanism portion capable of gate-sealing by a movable member provided in a part of the resin supply passage. The member is made of a material that can be elastically or plastically deformed by the pressure of the resin, and the pressure of the resin is generated in the cavity .
Trees generated when the supply of the resin is stopped after being grown
Cavity side in the oil supply passage and opposite to the cavity
The gate is driven by the pressure difference between the two sides and is deformed as well.
The feature of the present invention is that the gate is processed at a low cost by ensuring the adhesion at the time of sealing the movable member.

Further, the invention according to claim 2 is such that the resin is filled.
A cavity, or communicates with an injection molding machine to the cavity
An injection molding die comprising: a resin supply passage for supplying the molten resin ; and a sealing mechanism portion capable of gate-sealing by a movable member provided in a part of the resin supply passage. When the movable member is made of a material that can be elastically or plastically deformed by the pressure of the resin and the cavity is filled with the resin through the resin supply passage, the pressure of the resin causes the movable member to move in the resin supply direction to move a predetermined flow. When forming the passage and completing the filling ,
The resin supply was stopped after the resin pressure was generated on the
Occasionally the cavity side in the resin supply passage and the
The gate sealing mechanism part is characterized in that it moves in a direction opposite to the resin supply direction due to a pressure difference between the side opposite to the cavity and elastically or plastically deforms to close the predetermined flow path. It is easier to downsize.

According to a third aspect of the invention, the cavity is filled.
A valve body housing section formed in a part of the resin supply passage of the resin, a valve body formed of an elastic deformation or plastically deformable material housed in the valve body housing part, the cavity relative to the valve body housing part A gate sealing mechanism composed of a gate formed on the opposite side to the gate was formed , and resin pressure was generated in the cavity.
The resin supply flow that occurs when the supply of the resin is stopped later
Between the cavity side and the opposite side of the cavity
It is characterized in that the valve body is seated on the gate due to a differential pressure to seal the gate while elastically or plastically deforming, facilitating the manufacture of the valve body and ensuring reliable gate sealing performance. I will get it.

According to a fourth aspect of the present invention, the gate is formed as a stepped valve seat protruding inward from the inner wall of the resin supply passage, and the valve body is seated on the inner peripheral edge of the gate and elastically deformed. Alternatively, it is characterized by being plastically deformed, and further improves the sealing performance of the gate. Further, in the injection molding method according to the fifth aspect of the present invention, a split mold is prepared in which a gate and a valve body storage portion located on the cavity side of the gate are formed in a part of the resin supply passage of the resin to be filled in the cavity. Then, prior to the die clamping of the mold, a step of accommodating the elastically or plastically deformable valve element in a portion corresponding to the valve element accommodating portion in the groove forming the resin supply passage, Mold clamping to define the cavity and resin supply passage,
The step of injecting and filling the molten resin through the resin supply passage into the cavity, and the pressure of the resin in the cavity.
Occurs when the supply of the resin is stopped after the generation
The cavity side in the resin supply passage and the opposite side to the cavity
A step of causing the valve element to be seated on the gate and elastically or plastically deformed by a pressure difference between the opposite sides to seal the gate, and a step of solidifying the resin in the gate sealed state;
A step of opening the die to take out the resin and the valve body solidified in the cavity and the valve body housing portion, and is suitable for the injection molding die, and the gate processing accuracy is high. It is a molding method that can obtain high molding accuracy while omitting a special step for gate sealing at least.

The invention according to claim 6 is a molded product molded by the injection molding method according to claim 5, wherein a molded product body corresponding to the shape of the cavity, and the valve body.
A valve body exposed portion which is integrally molded with the molded product body corresponding to the storage portion and in which a portion of the elastically or plastically deformable valve body is exposed. It is a molded product that is easy to handle and can be used for gripping or positioning the exposed portion.

The movable member and the valve body are ejected.
Even if the temperature exceeds the temperature of the molten resin
It also has high heat resistance that can maintain the material properties.
Is preferred.

[0020]

EXAMPLES Hereinafter, specific examples will be described based on examples of the present invention. 1 to 4 are views showing an embodiment of an injection molding die according to the invention described in claims 1 to 4. In addition, this real
The injection molding die according to the embodiment is the injection according to the invention of claim 5.
It is a mold for carrying out the molding method, and the method according to claim 6.
It also serves as a mold for molding the mounted molded product.

First, the structure will be described. In FIGS. 1 to 4, reference numerals 1 and 2 denote a pair of split molds that form an injection molding mold, and the molds 1 and 2 are in contact with each other on a parting surface to communicate with the cavity 3 and the cavity 3. Resin supply consisting of a sprue 4, a runner 5, and a second gate 6
And a passage 10 . The runner 5 communicates with the cavity 3 at one end through the second gate 6 and communicates with the sprue 4 at the other end. Cavity for runner 5
A step-like first gate 8 projecting inward of the resin supply passage 10 is provided on the side opposite to 3, and the first gate 8 is
Inner peripheral edges 8a, 8b facing the spherical valve body 7 (movable member)
(Molds 1 and 2 are formed for each half circumference, and one annular inner circumference
It forms the edge. )have. This first gate
Reference numeral 8 is a valve for seating the spherical valve body 7 on its inner peripheral edges 8a, 8b.
I'm sitting. A stop pin 9 as a supporting member is provided in the runner 5. The stop pin 9 is injected and filled with molten resin into the cavity 3 via an injection nozzle (not shown), the sprue 4 and the runner 5, The spherical valve body 7 is supported while passing this molten resin. Spherical valve element 7 provided in a part of resin supply passage 10,
The top pin 9 and the first gate 8 are connected to the first gate 8
A sealing mechanism portion 11 capable of further sealing the cavity 3 side is configured.

The spherical valve body 7 is a part of the resin supply passage 10.
It is loosely inserted into the runner 5 (valve housing) and
Resin is filled in the cavity 3 through the supply passage 10.
The pressure of the resin,
To the left) and move to the first gate 8
When the resin filling is completed while forming the passage
In the direction opposite to the resin supply direction (to the right in FIG. 1)
Move to close the specified flow path and seal the gate
You can

Further, the spherical valve body 7 is a material that retains predetermined material characteristics in a temperature environment that is equal to or higher than the temperature of the injected molten resin (heat resistant material whose heat resistant temperature is equal to or higher than the temperature of the molten resin).
And is formed of a material that is elastically or plastically deformable by the pressure of the injected molten resin, and when the resin is filled in the cavity 3 through the resin supply passage 10,
The spherical valve body 7 is seated on the first gate 8 by the pressure of the filled resin and elastically or plastically deforms to seal the gate. Examples of the material of the spherical valve body 7 include engineering plastic having high heat resistance and relatively soft metal, and for example, Teflon or aluminum can be used. In particular, Teflon is suitable for both heat resistance and elastic force, and Teflon having a high resin temperature such as polycarbonate is also applicable.

Next, the injection molding according to the invention of claim 5
The operation will be described together with an example of the method. In this example
First, a part of the resin supply passage 10 to the cavity 3
Gate 8 and runner located on the cavity 3 side
-Preparation of split molds 1 and 2 with 5 (valve housing)
Then, prior to the mold clamping of the molds 1 and 2, the resin supply passage 10
Elastic deformation at the part corresponding to the runner 5 in the groove forming the
A spherical valve body 7 that can be shaped or plastically deformed is accommodated. Then
The molds 1 and 2 are clamped to close the cavity 3 and the resin supply passage.
The resin supply passage 10 is defined in the cavity 3 by defining the passage 10.
Through to inject and fill the molten resin. And when this filling is completed
To, together to seat the more spherical valve body 7 to the first gate 8 to the pressure of the resin filled in the cavity 3, is elastically deformed or plastically deformed to seal the first gate 8 to the liquid-tight. Next, the resin is solidified by gradually cooling in the gate sealed state, the molds 1 and 2 are opened, and the solidified resin (molded product) in the cavity 3 and the runner 5 is taken out.

Although not shown, this molded product is a cavite.
Compatible with the main body of the molded product corresponding to the shape of 3 and the runner 5.
Then, a part of the spherical valve body 7 integrally molded with the molded product body is
The exposed valve body is exposed. By the way, when the inner peripheral edges 8a and 8b of the first gate 8 have a low processing accuracy and the inner peripheral edges 8a and 8b have a step H shown in FIG. 2, for example, the runner 5 and the sprue 4 are communicated with each other in the related art. However, in this embodiment, the spherical valve element 7 is elastically or plastically deformable, and as shown in FIG. ), The spherical valve body 7 is deformed in conformity with the shape of the inner peripheral edges 8a, 8b of the first gate 8 and closely adheres to the inner peripheral edges 8a, 8b thereof, and is seated on the first gate 8 in a liquid-tight manner. As a result, the communication between the runner 5 and the sprue 4 can be reliably blocked and the first gate 8 can be reliably sealed without improving the processing accuracy of the inner peripheral edges 8a and 8b of the first gate 8. . Therefore, the molding cost can be reduced while the precision of the injection-molded product is high. In addition, the first gate 8 which is a valve seat is formed symmetrically with the parting surface in between, and the inner peripheral edge 8 of the molds 1 and 2 is formed.
This is particularly effective in the split mold as in this embodiment in which it is difficult to match a and 8b.

The inner peripheral edges 8a and 8b of the first gate 8 are also provided.
When is rounded as shown in Fig. 3 due to inadvertent handling during processing or molding, in the conventional case, the timing of interrupting the communication between the runner 5 and the sprue 4 is delayed, and the resin inside the cavity 3 is delayed. The pressure cannot be sealed. On the other hand, in this embodiment, similarly to the above, the spherical valve body 7 can be elastically or plastically deformed, so that the inner peripheral edge of the first gate 8 is caused by the resin pressure in the runner 5 as shown in FIG. The first gate 8 can be reliably sealed by being deformed according to the shapes of 8a and 8b and being closely attached to the inner peripheral edges 8a and 8b. Therefore, the communication between the runner 5 and the sprue 4 can be quickly blocked, and the resin pressure in the cavity 3 can be reliably sealed.

Further, since the material of the spherical valve body 7 is made of a material that is deformed by a predetermined resin pressure and is softer than the molds 1 and 2, it is possible to prevent the molds 1 and 2 from being damaged. You can In this way, with the injection mold of this embodiment
Means that the spherical valve element 7 is elastically or plastically deformed by the pressure of the resin.
Shaped and adheres to the inner peripheral edge portions 8a and 8b of the first gate 8.
Therefore, it is excellent even if low-precision gate processing is performed.
The gate sealing performance can be obtained and the gate
8 is damaged and the mold life is significantly reduced
Can be resolved. Furthermore, the gate sealing mechanism unit 11
Does not require external driving, and the spherical valve element 7
Since it is only inserted freely in the runner 5, the gate
The sealing mechanism 11 can be made extremely small, and the spherical valve
It is also possible to facilitate the production of the body 7.

Further, the injection molding method of the present embodiment has the above structure.
Suitable for injection molding dies, and processing of the first gate 8
Even if the accuracy is as low as that of the second gate 6,
Deformation of the spherical valve element 7 ensures adhesion during gate sealing
It is possible to obtain excellent sealing performance and
Specially for driving the sealing mechanism from the outside
Can be omitted, and the pressure of the filling resin is sufficient.
Therefore, high molding precision can be obtained.

Furthermore, according to the injection molding method of this embodiment,
Shaped molded parts can be gripped and positioned
Use the exposed valve body for gripping or positioning
Therefore, it is easy to handle and
Prevents damage to the high-precision transfer surface of the main body
Wear.

[0030]

According to the invention of claim 1, the pressure of the resin is
A movable member made of a material that can be elastically or plastically deformed by a force is applied to the cavity in the resin supply direction so that the differential pressure between the pressure in the resin supply passage on the cavity side and the pressure in the resin supply passage on the side opposite to the cavity. Since it is driven by, it is possible to form a small and simple sealing mechanism section that does not require external force as in the conventional case, and even if the processing accuracy of the gate to be sealed is low, Adhesiveness can be secured and excellent gate sealing performance can be obtained, die processing cost can be reduced, and further reduction of die life can be prevented.

According to the second aspect of the invention, the cavity
When filling the resin into the resin, the movable member is supplied with the resin by the pressure of the resin.
When the filling is completed, it is moved in the feeding direction to form a predetermined flow path.
To move the movable member in the direction opposite to the resin supply direction.
To close the flow path by elastic or plastic deformation
Since it is set, the gate opening / closing operation is performed only by moving the movable member.
It is possible to realize a small sealing mechanism that
Even if the processing accuracy of the gate is low, the adhesion of the movable member can be ensured.
Keeping excellent gate sealing performance, mold processing
The cost can be reduced and the die life can be shortened.
Can be prevented.

According to the invention of claim 3, the resin supply passage
A valve body storage part in a part of the passage and a cavity for the valve body storage part
And a gate located on the opposite side of the
An elastically or plastically deformable valve body is stored in the body storage part.
Since it constitutes the sealing mechanism part, external force is required.
It is possible to make a compact and simple sealing mechanism part that does not
Both have low gate processing accuracy and high injection resin pressure.
Even if the valve pressure is elastically deformed or
Delivers a reliable gate sealing function by plastic deformation
Can be made. As a result, at low cost, and transfer
To provide injection molding dies with high molding precision and high molding accuracy
Further, it is possible to prevent the mold life from being shortened.

According to the invention of claim 4, the gate is stepped.
The valve element is elastically deformed or plastic at the inner peripheral edge of the valve.
Since it is deformed and brought into close contact, gate processing
Even with a low- precision mold, the valve body can be immediately brought into close contact with the inner circumference to minimize the drop in cavity pressure, preventing deformation during cooling, and achieving higher-precision molding. The invention according to claim 5, wherein the product can be molded.
According to the method, prior to clamping the split mold, elastic deformation or plastic
The valve body that can be deformed is stored in the valve body storage section, and this valve body is
Due to the resin pressure when the injection filling into the cavity is completed,
Since the gate is sealed with a pressure-adhesive seat, precise gate processing is possible.
A reliable gate seal even with low resin pressure and high resin pressure.
Can be stopped, and the man-hour for gate sealing is small.
In addition, it is possible to perform efficient molding work.
Moreover, the molded product can be taken out very easily.

According to the invention of claim 6, claim 5
Since it is molded by the injection molding method of mounting,
A reliable gate seal even with low resin pressure and high resin pressure.
It is stopped, and a highly accurate molded product can be obtained. Well
Also, since the molded product is composed of a molded product body corresponding to the cavity shape and the valve body exposed part integrally molded with this, it is possible to directly grip the valve body exposed part without touching the molded product body. Can be handled or positioned, and the handling and positioning can be done easily, and
It is possible to prevent stains and scratches on the molded product body during handling.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of an injection molding die according to the present invention.

FIG. 2 is a sectional view of an essential part for explaining the operation thereof.

FIG. 3 is a cross-sectional view of an essential part when the resin is supplied .

FIG. 4 is a cross-sectional view of a main part when the gate is sealed .

[Explanation of reference numerals] 1, 2 split molds 3 cavity 5 runner (part of resin supply passage, valve body storage part) 7 spherical valve body (movable member, valve body) 8 first gate (gate, valve seat) 8a, 8b Inner peripheral edge portion 10 Resin supply passage 11 Gate sealing mechanism portion

Front page continued (72) Inventor Yasuhiro Ueshiro 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd. (72) Injury Toshiharu Hatakeyama 1-3-6 Nakamagome, Ota-ku, Tokyo In Ricoh Co., Ltd. (72) Inventor Katsunori Sudo 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. Actually open 1-156020 (JP, U) Actually open 53-111428 (JP, U) Actually open 63-118384 (JP, U) Actually open 57-15395 (JP, Y2)

Claims (6)

[Claims] And 1. A cavity filling resin, and a resin supply passage for supplying the molten resin from the injection molding machine then communicates with the cavity, the gate sealing is by a movable member provided in a portion of the resin supply passage An injection molding die having a possible sealing mechanism portion, wherein the movable member is made of a material elastically or plastically deformable by the pressure of the resin, and the pressure of the resin is generated in the cavity . Supply of the resin later
Cavity side inside the resin supply passage that occurs when stopped
And driven by the differential pressure between the cavity and the opposite side
An injection molding die, which is characterized in that it is deformed together with sealing the gate . 2. A cavity for filling the resin, and the resin supply passage for supplying the molten resin from the injection molding machine then communicates with the cavity, the gate sealing is by a movable member provided in a portion of the resin supply passage And a movable sealing member, wherein the movable member is made of a material that is elastically or plastically deformable by the pressure of the resin, and the resin is introduced into the cavity through the resin supply passage. When filling, the pressure of the resin moves in the resin supply direction to form a predetermined flow path, and when the filling is completed , after the pressure of the resin is generated in the cavity .
Inside the resin supply passage that occurs when the resin supply is stopped
Pressure difference between the cavity side and the opposite side of the cavity
The injection molding die is characterized in that it moves in a direction opposite to the resin supply direction and closes the predetermined flow path while elastically or plastically deforming. 3. A valve body accommodating portion formed in a part of a resin supply passage for a resin to be filled in a cavity, and a valve body accommodated in the valve body accommodating portion made of an elastically deformable or plastically deformable material. includes a cavity to the valve body accommodating portion and a gate formed on the opposite side, a gate seal mechanism consisting of cabinet
After the resin pressure is generated in the tee, the resin supply is stopped.
The cavity side in the resin supply passage that occurs when the
An injection molding die, wherein the valve body is seated on the gate by the pressure difference between the side opposite to the cavity and elastically or plastically deforms to seal the gate. 4. The gate is formed as a stepped valve seat protruding inward from an inner wall of the resin supply passage, and the valve body is seated on the inner peripheral edge of the gate and is elastically or plastically deformed. The injection mold according to claim 3, wherein 5. A split mold is prepared in which a gate and a valve body accommodating portion located on the cavity side of the gate are formed in a part of a resin supply passage for the resin to be filled in the cavity, and the mold is clamped before the mold is clamped. A step of accommodating an elastically or plastically deformable valve body in a portion corresponding to the valve body accommodating portion in the groove forming the resin supply passage; and the cavity and the resin supply passage by clamping the mold. Of the resin, the step of injecting and filling the cavity with the molten resin through the resin supply passage, and the step of generating resin pressure in the cavity.
Generated when the supply of the resin is stopped after
On the cavity side in the supply passage and on the side opposite to the cavity
A step of seating the valve body on the gate and elastically or plastically deforming it by a pressure difference between the gate and sealing the gate, solidifying the resin in the gate sealed state, and opening the mold to open the cavity. and injection molding method characterized by comprising the a step of retrieving the solidified resin and the valve body in the valve body housing part. 6. A molded product molded by the injection molding method according to claim 5, wherein a molded product body corresponding to the shape of the cavity and a molded product body corresponding to the valve body housing are integrally molded. And a valve body exposed portion in which a part of the elastically or plastically deformable valve body is exposed.