KR20180127834A - Divided injection molding method - Google Patents

Abstract

According to the present invention, there is provided a divided injection molding method capable of preventing appearance defects due to additional structures such as ribs and bosses on the rear surface of a molded article, thereby greatly improving appearance characteristics of the molded article. According to an embodiment of the present invention, there is provided the divided injection molding method comprising: a first step of preparing a primary injection-molded product; and a second step of secondary injection.

Description

[0001] DIVIDED INJECTION MOLDING METHOD [0002]

The present invention relates to a split injection molding method capable of improving the appearance characteristics of a molded article.

When the injection molding is performed using a filler material including aluminum, appearance defects easily occur due to structures such as ribs and bosses on the back surface of a molded article to be manufactured.

In order to solve this problem, a method of removing the structure of the product has been attempted, but the removal of the structure is limited.

In addition, a double injection method has been proposed as a method for preventing appearance defects. However, in the above method, the secondary injection molding is performed after the primary injection molding using the double molding apparatus in which two molds are mounted in one injection molding apparatus. In this case, two cylinders are required There is a problem in that the working time and the process cost are increased. Also, there is a problem that the injection molded article is liable to be deformed during the cooling after the injection, and as a result, precise injection is not achieved.

An object of the present invention is to provide a divided injection molding method capable of solving the problems in the conventional injection molding and improving the appearance characteristics of a molded article.

It is still another object of the present invention to provide a divided injection molding apparatus useful for carrying out the divided injection molding method.

According to an embodiment of the present invention,

A first step of injecting a composition for injection molding from an injection cylinder into a mold and primary injection to prepare a primary injection molded product,

And a second step of further injecting the injection molding composition from the injection cylinder into the first injection molding after the first injection molding is moved, and a second injection step of injecting the composition for injection molding from the injection cylinder do.

According to another embodiment of the present invention,

A mold including at least one valve gate corresponding to the movement position of the injection molding, capable of moving the injection molding by sliding or rotating according to injection steps; And an injection cylinder connected to the mold and continuously injecting the composition for injection molding into the mold.

By the divided injection molding method of the present invention, it is possible to easily improve the appearance characteristics of a molded article without worrying about the addition of process facilities and hence the increase of the process time and cost. Particularly, the divided injection molding method of the present invention is effective in preventing appearance defects due to additional structures such as ribs and bosses on the rear surface of a molded article during injection molding of an injection molding composition containing a filler such as aluminum useful.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram schematically showing an injection molding process using a split injection molding method according to an embodiment of the present invention. FIG.
2 is a process diagram schematically illustrating an injection molding process using a divided injection molding method according to another embodiment of the present invention.

The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises", "comprising", or "having" are used to designate the presence of stated features, steps, components, or combinations thereof, and are not intended to preclude the presence of one or more other features, Components, or combinations thereof, as a matter of convenience, without departing from the spirit and scope of the invention.

Also in the present invention, when referring to each layer or element being "on" or "on" each layer or element, it is meant that each layer or element is formed directly on each layer or element, Layer or element may be additionally formed between each layer, the object, and the substrate.

The invention is capable of various modifications and may take various forms, which illustrate specific embodiments and are described in detail below. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Hereinafter, a divided injection molding method according to a specific embodiment of the present invention will be described in detail.

According to an embodiment of the present invention,

A first step (S1) of injecting a composition for injection molding from an injection cylinder into a mold and preparing a primary injection-molded product by primary injection; And

And a second step (S2) of additionally injecting the injection molding composition from the injection cylinder to the primary injection molded article after the first injection molding is moved, and then performing secondary injection.

The divided injection molding method includes: a mold including at least one valve gate corresponding to a moving position of an injection molded article, the injection mold being capable of moving the injection molded body through sliding or rotating according to injection steps; And an injection molding apparatus including an injection cylinder connected to the mold, specifically, the valve gate in the mold, for continuously injecting the composition for injection molding into the mold.

In the injection molding apparatus, the mold defines a main body type of the injection molded article, and the first part in which the first injection is performed in the first step; And a second portion for performing a secondary injection in the second step. The injection molding machine according to any one of claims 1 to 3, , And may include one or more, more specifically two or more, valve gates that operate in response to the injection conditions.

In addition, the injection cylinder may be continuously injected into a mold during the injection process, and the injection molding composition may be changed according to injection conditions.

As described above, in the divided injection method according to one embodiment of the present invention, one injection molding process is divided into one injection molding, and one injection molding composition is continuously injected using one injection cylinder, And injecting the injected composition for injection molding according to the injection conditions set for each injection step. Accordingly, when one injection molded article is manufactured, it can be sequentially injected by dividing into an outer surface and an inner surface. As a result, the appearance characteristics of a molded article can be greatly improved through a multi-stage split injection process And the cycle time can be reduced in the production of a thick molded article.

Hereinafter, the divided injection molding method according to the present invention will be described in more detail. In a first step (S1), a primary injection molding is prepared through a primary injection molding process.

The first step may be performed according to a conventional injection molding method. More specifically, the injection molding composition may be injected into a mold through one or more valve gates in an injection cylinder of the split injection molding apparatus, Followed by molding to produce a primary injection-molded product.

Wherein the composition for injection molding is a filler; And a thermoplastic or thermosetting polymer resin for injection molding. The type and content of the filler and the polymer resin may be determined depending on the use and improved properties of the molded article to be finally produced.

As the filler, an inorganic filler or an organic filler may be used. More specific examples include metals such as aluminum, copper, and manganese, or alloys thereof; Inorganic particles such as silicate minerals, silicon carbide, titanium oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, crystalline silica, alumina, or graphite; Or an organic / inorganic fiber such as glass fiber or carbon fiber, and any one or a mixture of two or more thereof may be used.

Specific examples of the polymer resin include acrylonitrile-butadiene-styrene resin, acetal resin, acrylic resin, polyethylene, polypropylene, polyamide, polyethylene terephthalate, polycarbonate, polyphenylene sulfide, polyphenylene oxide, phenol Resin, urea resin or epoxy resin, and any one or a mixture of two or more thereof may be used.

In view of being able to exhibit a more improved appearance characteristic than the application of the divided injection molding method of the present invention due to the fact that a metal-like appearance can be realized, the polymer resin includes acrylonitrile-butadiene-styrene resin , Polycarbonate or polyamide may be used. Aluminum, silicate minerals or organic / inorganic fibers can be used as the filler which can further improve the effect when used in combination with the above.

In addition, the injection step in the step 1 may be carried out in a first part of the mold which defines the body shape of the injection-molded article.

The injection process may be performed according to a conventional injection method, and the injection conditions may be determined in consideration of a combination of the use, shape, physical properties and the composition for injection molding of the molded article to be manufactured.

Next, in the second step, the primary injection molded product manufactured in the step 1 is moved, and the injection molding composition is further injected in the step 1 to perform secondary injection molding.

Specifically, after the mold including the primary injection molding or the primary injection molding is moved, the injection molding composition in the step 1 is further continuously injected into the primary injection molding in the mold, and the secondary injection Or by injection molding according to the conditions.

Thus, the composition for injection molding in step 2 is not introduced from the injection cylinder existing separately from the injection cylinder in step 1, but is continuously injected from the injection cylinder in step 1 above. The injection molding composition through the injection cylinder in step 2 is performed by operating the valve gate located corresponding to the positionally moved primary injection molding among the plurality of valve gates provided in the injection mold in the set injection condition .

The positional movement of the primary extrudate may be rotated or slid into the primary injection mold itself in the mold, or may be rotated or slid into the entire mold including the primary injection mold. Specifically, the positional movement of the primary injection-molded article itself in the mold may be achieved by rotation or sliding of the core connected to the primary injection-molded article in the mold, or by taking out the primary molded article by the robot and moving the position . The positional movement of the entire mold can be performed by a moving mold connected to the mold, such as a mold turning.

The injection process in step 2 may be carried out in a second part of the mold which defines the shape of the additional structure on the body of the injection molded article.

Accordingly, the composition for injection molding is injected into the second part of the mold and subjected to secondary injection molding in accordance with the set injection conditions. At this time, the injection condition can be determined by taking into consideration the use of the molded article to be manufactured, the form, the physical properties, and the injection moldable composition.

Meanwhile, in the present invention, the additional structure on the body of the injection-molded article may be a structure such as a rib or a boss.

Depending on the shape of the final molded article, step 2 may be repeated two or more times, wherein the positional movement of the primary extrudate may vary from step 2 to step 2, And may be periodically reciprocated between fixed positions by the number of times. In addition, the injection molding composition injected at every repetition of Step 2 is injected into the additional portion of the third portion, the fourth portion, etc., which defines the shape of the additional structure on the main body.

Thus, even if the secondary injection step in the step 2 is repeated two or more times, the injection molding composition is continuously injected through the same injection cylinder, so that the injection molding process and the structure of the apparatus are simple. In addition, since the injection molding process in the previous step is cooled and the subsequent injection process is performed before the injection molding is cooled, precise injection is possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram schematically illustrating an injection molding process when a position is moved by rotation of a mold in a split injection molding method according to an embodiment of the present invention. FIG. FIG. 1 is an illustration for illustrating the present invention, but the present invention is not limited thereto.

1, an injection molding apparatus 100 including a mold 10 capable of being moved through rotation and an injection cylinder 20 for injecting a composition for injection molding into the mold, The molding composition for injection molding including the filler is injected from the injection cylinder 20 through the first valve gate 40a located corresponding to the position of the primary injection molding to the mold 10, (Not shown) defining a plane portion in the form of a body of the injection-molded article, and primary-side injection molding is performed to produce a primary injection-molded article 30a (Steps 1 and S1). The mold 10 is continuously moved by rotating the mold 10 including the primary injection-molded product 30a (S21) and positioned corresponding to the primary injection-molded product moved among the plurality of valve gates in the mold 10 The second and third valve gates 40b and 40c are operated to successively add the injection molding composition to a second portion (not shown) defining the shape of the additional structure on the main body 10, The secondary injection molding 30b is manufactured in an integrated form with respect to the primary injection molding 30a (S22). At this time, the second step may be repeated two or more times, and when the second step is performed once, the secondary injection molded product 30b becomes the final molded product 30.

FIG. 2 is a process diagram schematically illustrating an injection molding process when a first injection molding is moved by sliding in a mold in a split injection molding method according to another embodiment of the present invention. FIG. FIG. 2 is an illustration for illustrating the present invention, but the present invention is not limited thereto.

Referring to FIG. 2, an injection molding apparatus 100 includes a mold 110 capable of sliding the injection molding by a predetermined distance, and an injection cylinder 120 for injecting the injection molding composition into the mold The injection molding composition including the filler is injected from the injection cylinder 120 through the first valve gate 140a corresponding to the position of the mold to the first portion of the mold 110 And a primary injection molding 130a having a planar portion in the form of a body of the injection molded article is produced (Step 1, S1 '). The first and second injection molds 130a and 130b are moved by a predetermined distance by sliding the primary extrusion molding 130a (S21 '), The third valve gates 140b and 140c are operated to successively inject the injection molding composition into a second portion (not shown) in the mold 110 to perform secondary structure injection, The secondary injection-molded product 130b is manufactured in an integrated manner with respect to the injection molding part 130a (S22 '). In this case, the second step may be repeated two or more times. In the second step, the secondary molded product 130b becomes the final molded product 130 when it is performed once.

As described above, although the present invention has been described with reference to specific examples and drawings, the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

100, 200: injection molding apparatus
10, 110: mold
20, 120: injection cylinder
30a, 130a: Primary injection molding
30b, 130b: secondary injection molding
30, 130: Injection molded article
40a, 140a: a first valve gate
40b, 140b: a second valve gate
40c, 140c: a third valve gate

Claims (9)

A first step of injecting a composition for injection molding from an injection cylinder into a mold and primary injection to prepare a primary injection molded product,
A second injection molding step of injecting a composition for injection molding from the injection cylinder into the first injection molded article after the first injection molding is moved,
Wherein the injection molding method comprises the steps of:
The method according to claim 1,
The mold including a first portion defining a body shape of the injection molded article and a second portion defining a shape of the additional structure on the body,
Wherein the first step proceeds as an injection step in the first part and the second step proceeds to an injection step in the second part.
The method according to claim 1,
Wherein said position movement is performed through sliding or rotation.
The method according to claim 1,
The mold comprising at least one valve gate,
Wherein the injection of the composition for injection molding in the steps 1 and 2 is carried out through a valve gate located corresponding to the position of the primary injection-molded article.
The method according to claim 1,
Wherein the composition for injection molding is a filler; And a thermoplastic or thermosetting polymer resin.
6. The method of claim 5,
The filler is selected from the group consisting of aluminum, copper, manganese, an alloy, a silicate mineral, silicon carbide, titanium oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, crystalline silica, alumina, graphite, And at least one of the plurality of injection-molded parts.
The method according to claim 1,
Wherein the second step is repeated two or more times.
A mold having at least one valve gate corresponding to the movement position of the injection mold, capable of moving the injection mold by sliding or rotating the injection mold according to the injection step; And
An injection cylinder connected to the mold for continuously injecting the composition for injection molding into the mold,
The injection molding machine comprising:
9. The method of claim 8,
The mold defines a body shape of the injection-molded article, and includes: a first part in which a primary injection is performed; A second portion defining a shape of the additional structure on the body, the second portion proceeding with secondary injection.

Images