JP4650239B2 - Manufacturing method of resin molded products - Google Patents

Description

  The present invention relates to a method and an apparatus for producing a resin molded product in which a boss portion having an annular cross section is projected from the back side surface of a plate-like main body portion.

For example, in a resin molded product used for various components of an automobile, a cross section from the back side surface of the plate-shaped main body portion of the resin molded product is used for attaching the resin molded product to another component or for reinforcement. A boss portion having an annular shape is projected.
As a method of manufacturing a resin molded product having such a boss portion, for example, there are methods disclosed in Patent Documents 1 and 2.

In Patent Document 1, when a resin molded product is injection-molded, when the molten resin forming the resin molded product is being cooled and solidified, a compressed gas is supplied to the inside of the boss portion. It is disclosed that the vicinity of the base is pressed against the mold. Moreover, in patent document 2, when manufacturing the resin molded product provided with the boss | hub part, a tubular pin and an inner pin are arrange | positioned in the inner part of the cavity which forms a boss | hub part, and it compresses from the clearance gap between a tubular pin and an inner side pin. It is disclosed that gas is supplied to press the molten resin filled in the cavity.
And in these patent documents 1, 2, in a plate-shaped main-body part, the distortion state, such as a sink (dent formed in the surface), arises in the front side surface on the opposite side to the back side surface which stands | installs a boss | hub part. To prevent that.

However, in order to effectively prevent the occurrence of a strain state such as sink marks on the front side surface of the resin molded product having the boss portion, the conventional method for producing a resin molded product is not sufficient.
That is, in the above conventional method for producing a resin molded product, only the inner bottom portion of the boss portion is pressed by the compressed gas, and it is possible to prevent the occurrence of sink marks or the like on the front side surface corresponding to the inner portion of the boss portion. This is not sufficient to prevent the occurrence of sink marks or the like on the front side surface corresponding to the outer portion of the boss portion. Moreover, when pressing only the inner bottom part of a boss | hub part with compressed gas, there exists a possibility that compressed gas may infiltrate into the inside of molten resin and may form a hollow part inside a resin molded product depending on the case.

Japanese Patent Laid-Open No. 10-86169 JP 2005-28731 A

  The present invention has been made in view of such conventional problems, and can effectively prevent the occurrence of a strain state such as sink marks on the front side surface corresponding to the entire formation position of the boss portion. An object of the present invention is to provide a method for manufacturing a molded product and a manufacturing apparatus.

The present invention is a method for producing a resin molded product by projecting a boss having a ring-shaped cross section from the back side surface of a plate-like main body,
Using a molding die formed with a body cavity for molding the plate-like body portion and a boss cavity for molding the boss portion, in the molding die, the boss cavity An inner gas nozzle is provided in the inner molding wall forming the inner peripheral surface, and an outer gas nozzle is provided on the rear molding surface for molding the back side surface of the plate-like main body portion in the main body cavity.
Filling the main body cavity and the boss cavity with a resin raw material,
Next, gas is injected from the outer gas nozzle between the back-side molding surface and the resin raw material filled in the main body cavity, and the resin raw material is injected into the plate main body in the main body cavity. Pressing the front side of the front side to the front side molding surface,
Next, the pressed state is maintained, a predetermined time has elapsed since the start of gas injection from the outer gas nozzle, and the portion of the resin raw material facing the tip surface of the inner molding wall begins to harden to form a skin layer. After starting , gas is injected from the inner gas nozzle between the tip surface of the inner molding wall and the resin material facing the tip surface, and the resin material is pressed against the front molding surface. It is in the manufacturing method of the resin molded product characterized in (Claim 1).

In the method for producing a resin molded product of the present invention, a molding die provided with the inner gas nozzle and the outer gas nozzle is used. Then, by devising the timing for blowing gas from the inner gas nozzle and the outer gas nozzle, it is possible to effectively prevent the occurrence of distortion such as sink marks on the front side surface of the resin molded product.
In manufacturing a resin molded product, first, a resin raw material is filled into the body part cavity and the boss part cavity. At this time, the filling of the resin raw material into the boss cavity can be performed through the body cavity.

Next, gas is injected from the outer gas nozzle between the back-side molding surface in the main body cavity and the resin raw material filled in the main body cavity. At this time, the resin raw material in the main body cavity is pressed against the front molding surface in the main body cavity.
Next, gas is injected from the inner gas nozzle between the front end surface of the inner molding wall and the resin material facing the front end surface. At this time, the resin raw material in the main body cavity is pressed against the front molding surface in the main body cavity.

Thereby, in this invention, the resin raw material which faces the front end surface in an inner side molding wall in the state which pressed the resin raw material located in the vicinity of the outer peripheral surface of the cavity for boss | hub parts to the front side molding surface in the cavity for main body parts ( The resin raw material located on the inner peripheral side of the boss portion cavity) can be pressed against the front side molding surface in the main body portion cavity.
Therefore, in the resin molded product molded by the manufacturing method of the present invention, it is effective that a strain state such as sink (dent formed on the surface) is generated on the front side surface corresponding to the entire formation position of the boss portion. Can be prevented.

The reference invention is an apparatus for manufacturing a resin molded product in which a boss portion having a cross-sectional ring shape is projected from the back side surface of a plate-like main body portion,
A mold formed by forming a cavity for a body part for molding the plate-like body part and a cavity for a boss part for molding the boss part;
An inner gas nozzle provided in an inner molding wall that forms the inner peripheral surface of the boss cavity;
The main body cavity has an outer gas nozzle provided on a back molding surface for molding the back side surface of the plate-shaped main body,
After injecting gas between the back side molding surface and the resin raw material filled in the main body cavity by the outer gas nozzle, the inner gas nozzle causes the tip surface of the inner molding wall and the tip surface to A resin molded product manufacturing apparatus is characterized in that a gas is injected between the resin raw materials facing each other .

  The apparatus for producing a resin molded product of the present invention has a molding die provided with the inner gas nozzle and the outer gas nozzle, and the outer gas nozzle fills the back side molding surface in the main body cavity and the main body cavity. After the gas is injected between the resin raw materials, the gas is injected between the front end surface of the inner molding wall and the resin raw material facing the front end surface by the inner gas nozzle.

Thereby, also in the present invention, the resin raw material (boss) facing the front end surface of the inner molding wall in a state where the resin raw material positioned on the outer peripheral side of the boss cavity is pressed against the front molding surface of the main body cavity. The resin raw material located on the inner peripheral side of the part cavity can be pressed to the front molding surface in the body part cavity.
Therefore, in the resin molded product molded by the manufacturing apparatus of the present invention, it is possible to effectively prevent the occurrence of a distortion state such as sink marks on the front side surface corresponding to the entire formation position of the boss portion.

A preferred embodiment of the present invention described above will be described.
In the present invention, the resin molded product may be a radiator grille, a back garnish, a side molding, a wheel cover, an instrument panel, or the like.
Moreover, the said boss | hub part can be used as the attachment part for attaching a resin molded product to another component. When the boss part is used as the attachment part, for example, a screw hole can be formed in the inner peripheral surface of the boss part, and a screw arranged in another part can be screwed into the screw hole.

In addition, the plate-like main body portion does not necessarily have to be the entire resin molded product, and may be a part of the resin molded product. In the case where the plate-like main body portion is a part of the resin molded product, it is preferable that the plate-like main body portion is surrounded by a protruding wall portion protruding from the back side surface as described later.
Moreover, the gas injected into the mold can be a high-pressure gas such as air.

  The timing for injecting the gas from the inner gas nozzle into the mold can be after the gas injected from the outer gas nozzle has spread all around the outer periphery of the boss cavity. In addition, the timing of starting the gas injection from the inner gas nozzle into the mold is after the gas has spread over the entire area between the back side molding surface of the main body cavity and the resin raw material filled in the main body cavity. It can also be.

In the above invention, the plate-like body portion is surrounded by a protruding wall protruding from the rear surface, the cavity for the body portion, the projecting wall portion for forming the projection wall portion It is preferable that when the resin cavities are continuously formed and the resin raw material is filled into the main body cavities, the resin raw materials are also filled into the protruding wall cavities. In the above reference invention, the plate-like main body is surrounded by a protruding wall that protrudes from the back side surface thereof, and the protruding wall for molding the protruding wall is formed in the main body cavity. It is preferable that the working cavity is continuously formed .

  In these cases, the gas injected between the back side molding surface in the main body cavity and the resin raw material filled in the main body cavity from the outer gas nozzle is filled in the protruding wall cavity. It is possible to easily prevent the resin material from reaching the front molding surface in the main body cavity.

In the present invention, a rib cavity for forming a reinforcing rib at the root portion of the boss portion is formed at the root portion of the outer peripheral surface of the boss portion cavity. When the resin raw material is filled into the cavity and the boss cavity, the resin raw material is preferably filled into the rib cavity. In the above reference invention, it is preferable that a rib cavity for forming a reinforcing rib is formed at the root portion of the outer peripheral surface of the boss portion cavity .
In these cases, in the molded resin molded product, the root portion of the boss portion can be reinforced by the reinforcing rib.

Below, the example concerning the manufacturing method and manufacturing apparatus of the resin molded product of this invention is demonstrated with drawing.
In the manufacturing method and the manufacturing apparatus 1 of the resin molded product 8 of this example, as shown in FIG. Manufacturing.
As shown in FIG. 2, the manufacturing apparatus 1 includes a molding die 2 in which a body portion cavity 21 for molding a plate-like body portion 81 and a boss portion cavity 22 for molding a boss portion 82 are formed. have. In the molding die 2, the inner gas nozzle 3 is provided in the inner molding wall 23 that forms the inner peripheral surface 231 of the boss portion cavity 22, and the back side surface 802 of the plate-like body portion 81 in the body portion cavity 21. The outer gas nozzle 4 is provided on the back-side molding surface 202 for molding.

In forming the resin molded product 8 using the manufacturing apparatus 1, first, as shown in FIG. 3, the resin raw material 80 is filled into the main body cavity 21 and the boss cavity 22.
Next, as shown in FIG. 4, gas G is injected from the outer gas nozzle 4 between the back-side molding surface 202 in the main body cavity 21 and the resin raw material 80 filled in the main body cavity 21. The raw material 80 is pressed to the front side molding surface 201 for molding the front side surface 801 of the plate-like main body 81 in the main body cavity 21. Next, as shown in FIG. 5, gas G is injected from the inner gas nozzle 3 between the front end surface 233 of the inner molding wall 23 and the resin raw material 80 facing the front end surface 233, Press against the front molding surface 201 in the main body cavity 21.

Below, it explains in full detail with FIGS. 1-6 about the manufacturing method and manufacturing apparatus 1 of the resin molded product 8 of this example.
In the manufacturing method of the resin molded product 8 of this example, the surface side 801 of the resin molded product 8 is sinked (formed on the surface) by devising the timing at which the gas G is blown from the inner gas nozzle 3 and the outer gas nozzle 4. It effectively prevents the occurrence of distortion such as dents.
The manufacturing apparatus 1 of this example performs injection molding of the resin molded product 8. The injection pressure of the resin raw material 80 injected into the mold 2 is, for example, 30 to 50 MPa, and the heating temperature of the resin raw material 80 injected into the mold 2 is, for example, 200 to 250 ° C. The gas G blown out from the inner gas nozzle 3 and the outer gas nozzle 4 is a high-pressure gas of 5 to 15 MPa.

Although illustration is omitted, each of the inner gas nozzle 3 and the outer gas nozzle 4 is configured to perform blowing and blocking of the gas G by valves that open and close the flow path of the gas G, respectively. Further, the timing of blowing the gas G from the inner gas nozzle 3 and the outer gas nozzle 4 can be controlled by a control means such as a sequencer (programmable controller).
Then, the control means in the manufacturing apparatus 1 fills the main body cavity 21 with the resin raw material 80 and blows the gas G from the outer gas nozzle 4 into the mold 2 after a predetermined time has elapsed. Thereafter, the gas G is blown out from the inner gas nozzle 3 into the mold 2 after a predetermined time has elapsed.

  The timing for starting the injection of the gas G from the outer gas nozzle 4 into the mold 2 can be made after the resin raw material 80 is filled in the entire main body cavity 21 and boss cavity 22. The timing for injecting the gas G from the inner gas nozzle 3 into the mold 2 is, for example, that the surface portion of the molten resin that contacts the surface of the mold 2 begins to harden to form a skin layer (cured portion). After you start. The timing for starting the injection of the gas G from the inner gas nozzle 3 can be, for example, when 1 to 5 seconds have elapsed after the injection of the gas G from the outer gas nozzle 4 is started.

As shown in FIG. 2, the inner gas nozzle 3 includes a gas passage hole 241A formed in the inner molding wall 23 that forms the inner peripheral surface 231 of the boss cavity 22, and a cylindrical body 242A disposed in the gas passage hole 241A. A gap 243A through which the gas G passes is formed. Further, the outer gas nozzle 4 has a gap through which the gas G passes between the gas passage hole 241B formed in the back side molding surface 202 in the main body cavity 21 and the cylindrical body 242B disposed in the gas passage hole 241B. 243B is formed.
In addition, the outer gas nozzle 4 of this example was formed in one place of the cavity 21 for main body parts. On the other hand, the outer gas nozzle 4 can also be formed at a plurality of locations in the main body cavity 21.

Further, as shown in FIG. 1, a protruding wall portion 811 protruding from the back side surface 802 is formed around the plate-like main body portion 81 of the resin molded product 8 to be molded in this example. And the back side surface 802 of the plate-shaped main body part 81 is surrounded by the protruding wall part 811 all around.
As shown in FIG. 2, the main body cavity 21 is continuously formed with a protruding wall portion cavity 211 for forming the protruding wall portion 811.

  As shown in FIG. 6, rib cavities 25 for forming reinforcing ribs 85 at the root portions of the boss portions 82 can be formed at the root portions of the outer peripheral surface 232 of the boss portion cavities 22. In this case, when the resin raw material 80 is filled into the main body cavity 21 and the boss cavity 22, the resin raw material 80 is also filled into the rib cavity 25 and molded. , The base portion of the boss portion 82 can be reinforced by the reinforcing rib 85.

  In this example, when the resin molded product 8 is manufactured, the resin raw material 80 heated and melted into the main body cavity 21 is injected from the injection section (not shown) connected to the main body cavity 21. As shown in FIG. 3, the resin raw material 80 fills the inside of the main body cavity 21 and also fills the protruding wall cavity 211 and the boss cavity 22.

Next, as shown in FIG. 4, the gas G is injected from the outer gas nozzle 4 between the back-side molding surface 202 in the main body cavity 21 and the resin raw material 80 filled in the main body cavity 21. At this time, the gas G spreads from the position where the outer gas nozzle 4 is disposed between the back-side molding surface 202 in the main body cavity 21 and the resin material 80 facing the back-side molding surface 202. The gas G enters between the outer peripheral surface 232 of the boss cavity 22 and the resin raw material 80 facing the outer peripheral surface 232 by the resin raw material 80 filled in the boss cavity 22. In addition, the resin raw material 80 filled in the protruding wall portion cavity 211 is prevented from entering the front side molding surface 201 in the main body portion cavity 21.
Thus, as shown in the figure, the resin raw material 80 in the main body cavity 21 is pressed against the front side molding surface 201 in the main body cavity 21 by the gas G injected into the back side molding surface 202 in the main body cavity 21. Is done.

  Next, as shown in FIG. 5, after a predetermined time has elapsed from the start of gas G injection from the outer gas nozzle 4, the inner gas nozzle 3 faces the tip surface 233 of the inner molding wall 23 and the tip surface 233. Gas G is injected between the resin raw material 80. At this time, the portion of the resin raw material 80 facing the front end surface 233 in the inner molding wall 23 has started to harden and forms a skin layer. Therefore, the gas G injected from the inner gas nozzle 3 does not enter the resin raw material 80 in the main body cavity 21, and the front surface 233 of the inner molding wall 23 and the resin raw material 80 facing the front surface 233. Stay between the skin layers.

In this example, when the gas G is injected from the inner gas nozzle 3 into the mold 2, the state of injecting the gas G from the outer gas nozzle 4 into the mold 2 is maintained.
Thus, as shown in the figure, the portion of the resin raw material 80 facing the front end surface 233 of the inner molding wall 23 by the gas G injected into the front end surface 233 of the inner molding wall 23 is formed into the front side molding in the main body cavity 21. Pressed against the surface 201.

Thus, in this example, the front end surface 233 of the inner molding wall 23 in a state where the resin raw material 80 positioned on the outer peripheral side of the boss cavity 22 is pressed against the front molding surface 201 of the main body cavity 21. The resin raw material 80 (resin raw material 80 located on the inner peripheral side of the boss portion cavity 22) facing to the front side molding surface 201 in the main body portion cavity 21 can be pressed.
Therefore, in the resin molded product 8 molded by the manufacturing method of this example, it is possible to effectively prevent the occurrence of a distortion state such as sink marks on the front side surface 801 corresponding to the entire formation position of the boss portion 82. Can do.

(Comparative example)
In this comparative example, as shown in FIGS. 7 and 8, when the gas G is injected into the mold 92A from only the inner gas nozzle 3 without injecting the gas G from the outer gas nozzle 4 into the mold 92A (comparison) Example 1) As shown in FIG. 9, the case where the gas G was injected into the molding die 92B only from the outer gas nozzle 4 and the gas G was not injected from the inner gas nozzle 3 into the molding die 92B (Comparative Example 2). The state where distortion state such as sink marks has occurred in the molding of the resin molded product 8 is shown.

As shown in FIG. 7, in Comparative Example 1, in the molded resin molded product 9A, sink marks or the like are generated at the position of the front side surface 801 corresponding to the resin portion positioned on the inner peripheral side 821 of the boss portion 82. Although not present, sink marks H were generated at the position of the front side surface 801 corresponding to the resin portion located in the vicinity of the outer peripheral side 822 of the boss portion 82.
Further, as shown in FIG. 8, in Comparative Example 1, when the timing of injecting the gas G from the inner gas nozzle 3 into the mold 2 is early (a skin layer is formed on the resin raw material 80 facing the front end surface 233 of the inner molding wall 23). When the gas G was injected before being formed), it was found that the gas G entered the molten resin raw material 80 and formed the hollow portion T inside the resin molded product 8. .

Further, as shown in FIG. 9, in Comparative Example 2, sink marks or the like are generated at the position of the front side surface 801 corresponding to the resin portion located in the vicinity of the outer peripheral side 822 of the boss portion 82 in the molded resin molded product 8. Although not done, sink marks H occurred at the position of the front side surface 801 corresponding to the resin portion located on the inner peripheral side 821 of the boss portion 82.
From these results, in order to effectively prevent the occurrence of a distortion state such as sink marks on the front side surface 801 corresponding to the entire formation position of the boss portion 82 in the resin molded product 8, a method for manufacturing the resin molded product 8 is described. And it turned out that it is necessary to comprise the manufacturing apparatus 1 as shown in the said Example.

The perspective explanatory view which shows the resin molded product in an Example. Cross-sectional explanatory drawing which shows the manufacturing apparatus of the resin molded product in an Example. Cross-sectional explanatory drawing which shows the manufacturing apparatus of the resin molded product of the state which filled the resin raw material in the shaping | molding die in an Example. Cross-sectional explanatory drawing which shows the manufacturing apparatus of the resin molded product in the state which inject | poured the gas in the shaping | molding die from the outer side gas nozzle in an Example. Cross-sectional explanatory drawing which shows the manufacturing apparatus of the resin molded product in the state which inject | poured the gas in the shaping | molding die from the inner side gas nozzle in an Example. The perspective explanatory drawing which shows the other resin molded product in an Example. Cross-sectional explanatory drawing which shows the manufacturing apparatus of the state which inject | poured the gas only from the inner side gas nozzle in the comparative example 1, and the sink mark generate | occur | produced. Cross-sectional explanatory drawing which shows the manufacturing apparatus of the state in which the gas was inject | poured only from the inner side gas nozzle in the comparative example 1, and the hollow part was formed. Cross-sectional explanatory drawing which shows the manufacturing apparatus of the state which inject | poured the gas only from the outer side gas nozzle in the comparative example 2, and the sink mark generate | occur | produced.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Mold 201 Front side molding surface 202 Back side molding surface 21 Body part cavity 211 Projection wall part cavity 22 Boss part cavity 23 Inner molding wall 231 Inner peripheral surface 232 Outer peripheral surface 233 Front end surface 3 Inner gas nozzle 4 Outer gas nozzle DESCRIPTION OF SYMBOLS 8 Resin molded product 801 Front side 802 Back side 80 Resin raw material 81 Plate-shaped main body part 811 Protruding wall part 82 Boss part G Gas

Claims (3)

In the method of manufacturing a resin molded product in which a boss portion having a cross-sectional ring shape is projected from the back side surface of the plate-like main body portion,
Using a molding die formed with a body cavity for molding the plate-like body portion and a boss cavity for molding the boss portion, in the molding die, the boss cavity An inner gas nozzle is provided in the inner molding wall forming the inner peripheral surface, and an outer gas nozzle is provided on the rear molding surface for molding the back side surface of the plate-like main body portion in the main body cavity.
Filling the main body cavity and the boss cavity with a resin raw material,
Next, gas is injected from the outer gas nozzle between the back-side molding surface and the resin raw material filled in the main body cavity, and the resin raw material is injected into the plate main body in the main body cavity. Pressing the front side of the front side to the front side molding surface,
Next, the pressed state is maintained, a predetermined time has elapsed since the start of gas injection from the outer gas nozzle, and the portion of the resin raw material facing the tip surface of the inner molding wall begins to harden to form a skin layer. After starting , gas is injected from the inner gas nozzle between the tip surface of the inner molding wall and the resin material facing the tip surface, and the resin material is pressed against the front molding surface. A method for producing a resin molded product. In Claim 1, the said plate-shaped main-body part is enclosed by the protrusion wall part which protrudes from the back side surface,
In the body part cavity, a protruding wall part cavity for forming the protruding wall part is continuously formed,
A method for producing a resin molded product, wherein when the resin raw material is filled into the main body cavity, the resin raw material is also filled into the protruding wall cavity. In Claim 1 or 2, the rib cavity for forming the reinforcing rib in the root part of the boss part is formed in the root part of the outer peripheral surface of the cavity for the boss part,
A method for producing a resin molded product, wherein the resin raw material is also filled into the rib cavity when the resin raw material is filled into the body cavity and the boss cavity.

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