JPH0649307B2 - Method for manufacturing double-layer injection molded product and molding die - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a two-layer injection molded product and a molding die, and more particularly to a slide metal slidably provided between a fixed die and a movable die. The present invention relates to a novel improvement for continuously obtaining a two-layer injection-molded product without taking out a core-molded product from the mold through a mold.

[Prior Art] There are various methods of manufacturing a double-layer injection molded product of this type that have been conventionally used, but a typical one of them is a molding method by insert molding as a general method. is there.

In this insert molding method, a core molded product is molded in one mold in advance, the core molded product is taken out from one mold, transferred to the other mold to be insert molded, and the other mold is molded. A two-layer molded product was manufactured by injecting molten resin into the space of the mold.

[Problems to be Solved by the Invention] The conventional two-layer injection molded article manufacturing method and molding die have the following problems because they are configured as described above.

(1) Since the molded core product has to be taken out of the mold and transferred into the mold for the next insert, foreign matter may be mixed in during this transfer, resulting in a defective product. It had occurred.

(2) In addition, since the welding strength on the surface of the core-molded product decreases during transfer, insert molding must be performed by heating the core-molded product in advance, resulting in a decrease in molding efficiency and automation of molding. It was extremely difficult.

(3) In addition, in this insert molding, since the pin marks for holding the core molded product remain in the two-layer injection molded product, it is not possible to obtain a molded product in which the outer periphery is completely enclosed. As a post-process, the work of containing the pin marks was required.

The present invention has been made to solve the above problems, and in particular, through a slide mold slidably provided between a fixed mold and a movable mold, a center core molded product is removed from the mold. A method for producing a two-layer injection-molded product and a molding die, which are capable of continuously obtaining a two-layer injection-molded product without taking out the product and also obtaining a two-layer injection-molded product having a good outer shape without leaving pin marks on the skin forming layer Intended to provide a type.

[Means for Solving the Problems] A method for manufacturing a two-layer injection-molded article according to the present invention includes an ejector pin projecting from a movable die inside a cavity for molding a core of a slide die slidably provided in a fixed die. The first step of injecting a molten resin from an injection device in a state of inserting a core to form a core molding product, and after the completion of the first step, the mold is opened and the slide mold is slid to form the core core. A second step of positioning the product in the skin forming cavity of the slide mold; injecting a molten resin into the space between the core molded product and the skin forming cavity, and applying the molten resin to the outer periphery of the core molded product. It is a method comprising a third step of forming the skin forming layer and arranging the ediectapine in the movable mold.

More specifically, it is a method in which the injection device is composed of a pair and injects different materials so that the core molded article and the skin forming layer are made of different materials.

A molding die for a two-layer injection-molded product according to the present invention includes an injection device that is joined to a fixed spool of a fixed mold, and a cavity for forming a core and a skin molding that is slidably provided on the fixed mold through a sliding means. And a movable mold which is joined to the slide mold and has ejector pins that can be inserted and removed freely.

More specifically, the injection device is composed of a pair and ejects different materials.

[Operation] In the method for producing a two-layer injection-molded article and the molding die according to the present invention, first, the slide die is moved to one side,
The ejector pin is projected from the movable mold and inserted into the core molding cavity.

In the above state, by injecting the molten resin from the injection device into the core molding cavity, a core molded product is molded,
After completion of this core molding, after opening the movable mold and opening the mold, the slide mold is moved to the other side, and the core molded product locked to the ejector pin corresponds to the skin forming cavity. It will be in the state of doing.

In the above-mentioned state, by closing the movable mold and closing the mold, the core molded product is suspended by the ejector pin through the space in the skin forming cavity, and the molten resin is injected into this space by the injection device. To form a skin forming layer on the outer periphery of the core molded article.

In this case, when forming the skin forming layer, the projecting ejector pins are housed in the movable mold so that the core forming product and the skin forming layer do not leave a pin mark on the outer periphery of the core forming product. A two-layer injection molded product consisting of

Further, in the case of the two-head configuration in which a pair of injection devices are provided, different resin materials can be injected, so that the core molded product and the skin molding layer can be made of different materials.

[Examples] Hereinafter, preferred examples of a method for producing a two-layer injection-molded article and a molding die according to the present invention will be described in detail with reference to the drawings.

1 to 12 are for showing a method for producing a two-layer injection-molded article and a molding die according to the present invention. FIG. 1 is a plan view with a partial cross-section showing the entire structure, and FIG. To 9th
Up to the figure, a process explanatory view showing a molding state, FIG. 10 is a plan view with a partial cross section showing another embodiment, FIG. 11 is a plan view with a partial cross section showing another embodiment, and FIG. FIG. 12 is a cross-sectional view showing a state of being molded by the molding die of FIG. 11.

In FIG. 1, the reference numeral 1 designates a molding die, and the bed 2 of the molding die 1 includes a stationary plate 3 and a bolt 4.
Is fixed by.

The stationary platen 3 is provided with a stationary die 6 having a stationary spool 5, and the stationary spool 5 is provided with a nozzle 7a of an injection device 7 which is disposed so as to face the recessed portion 3a of the stationary platen 3.
Are in contact.

A pedestal 8A fixed to one end 6a of the fixed die 6 is provided with a sliding means 8 including a sliding cylinder having a piston rod 8a which can be freely moved in and out, and the piston rod 8a is independent of each other. A slide mold 11 having a core molding cavity 9 and a skin molding cavity 10 formed as described above is provided slidably in the directions of arrows A and B.

A core forming spool 9a formed in communication with the core forming cavity 9 and the skin forming cavity 10
The skin forming spool 10a formed in communication with the slide mold 11 is configured to be selectively communicated with the fixed spool 5 when the slide mold 11 moves along the arrows A and B.

A movable plate 12 is provided at a position where the slide mold 11 is joined.
The movable die 13 provided integrally with the movable die 13 is provided in the movable die 13. The ejector pin 14a of the ejector device 14 provided on the movable board 12 is movable in the guide hole 15 of the movable die 13.
Is formed so as to project into the core molding cavity 9. The tip portion 14aA is movable when the ejector pin 14a is retracted by the ejector device 14. The movable mold 13 is housed in the mold 13 and is flush with the mating surface 16 of the movable mold 13 without protruding.

In the case of molding a two-layer injection molded product using the molding die 1 shown in FIG.

First, as shown in FIG. 2, the slide mold 11 is set to the same sliding position as that in FIG. 1, and the ejector pin 14a is projected into the core molding cavity 9 and is ejected as shown in FIG. A cavity 9 for molding a molten resin from a device 7
When injected into the inside, the core molded product 20 is molded.

Next, as shown in FIG. 4, when the movable mold 13 is moved to open the mold, the core molded product 20 is moved to the ejector pin 14
The spool runner 20a is integrally fixed and locked to the tip portion 14aA of a, and the spool runner 20a is cut by a cutter (not shown).

Next, the slide mold 11 is, as shown in FIG.
The sliding die 8 slides in the direction of the arrow B, and in this state, the movable die 13 advances to its original position and the slide die 11 moves.
When joined to, the core molded product 20 and the tip portion 14aA of the ejector pin 14a are located in the skin forming cavity 10, and a space 21 is formed between the core molded product 20 and the inner wall 10b of the skin forming cavity 10. It is formed. At the same time, by injecting a molten resin into the skin forming cavity 10 via the skin forming spool 10a, a skin forming layer 22 is formed in the space 21 as shown in FIG.

As described above, in the state where the skin forming layer 22 is formed, as shown in FIG. 7, the ejector device 14 is actuated to retract the ejector pin 14a into the movable die 13 and store the ejector pin 14a. Part 14
aA is also flush with the mating surface 13a of the movable die 13, and the skin forming layer 22 has a surface flush with the mating surface 13a so that the outer surface of the core-molded article 20 is completely enclosed. Molded.

After the molding of the skin forming layer 22 is completed, the movable mold 13 is moved to open the mold as shown in FIG.
Although attached to a, the two-layer injection molded product 30 is detached from the movable mold 13 and taken out by operating the ejector device 14 to project the ejector pin 14a, as shown in FIG. it can.

Further, in another embodiment shown in FIG. 10, the hot runner block 31 is mounted in the space 6b formed in the fixed mold 6, and the molten resin injected from the injection device 7 is It can be supplied to the hollow forming cavity 9 or the skin forming cavity 10 via the runner spool 31a formed on the runner block 31.

Since the other structures are the same as those in FIG. 1, the same parts are designated by the same reference numerals and the description thereof is omitted.

Further, in another embodiment shown in FIG. 11, the skin side spool 33 is provided at a position adjacent to the fixed spool 5 of the fixed base 6.
A skin-side injection mount 34 for injecting a material for the skin-molding layer 22 different in material from the injection device 7 is fixedly disposed in contact with the skin-side spool 33.

A skin-side movable runner gate 35 formed of a recess is formed on the mating surface 13a of the movable mold 13, and a skin that penetrates the slide mold 11 is provided between the cavities 9 and 10 of the slide mold 11. A side slide runner gate 36 is formed. Since the other structures are the same as those in FIG. 1, the same parts are designated by the same reference numerals and the description thereof will be omitted.

Therefore, in the configuration shown in FIG. 11, the molten resin is first injected from the injection device 7 into the core molding cavity 9 to form the core molded product 20, and then the mold is opened to slide the slide mold 11. When moved, the state shown in FIG. 12 is obtained.

In the state shown in FIG. 12, the fixed spool 5 is closed,
The skin side spool 33 comes into contact with the skin side injection device 34, and the molten resin of a material different from the material from the injection device 7 injected from the skin side injection device 34 moves from the skin side slide runner gate 36 to the skin side movable. Runner gate 35
The two-layer molded product 30 is obtained by injecting it into the space 21 around the outer periphery of the core-molded product 20 through the above process, and then performing the same steps as in the embodiment of FIG.

In addition, in the other embodiments of FIG. 11 and FIG. 12, the configuration in which the material for the skin forming layer is supplied to the skin forming cavity using the skin side movable runner gate and the skin side slide runner gate has been described. A double-headed injection mount may be used as the same configuration as in FIG.

[Advantages of the Invention] Since the method for producing a two-layer injection-molded article and the molding die according to the present invention are configured as described above, the following effects can be obtained.

(1) Since the center core molding cavity and the skin molding cavity can be moved by sliding the slide mold, two layers can be formed in the same mold without removing the center core molded product from the mold. It is possible to obtain an injection-molded product, eliminate foreign matter during molding, and improve the welding strength of the surface, so that the yield and quality of the molded product can be greatly improved.

(2) Since a two-layer injection molded product can be molded by one injection molding machine, molding efficiency can be improved and automatic molding can be realized.

(3) Even for sink mark defects, which is one of the molding defects, the thick-walled molded product is divided in the thickness direction and molded twice to perform double-layer molding. A great improvement can be obtained.

[Brief description of drawings]

1 to 12 are for showing a method for producing a two-layer injection-molded article and a molding die according to the present invention. FIG. 1 is a plan view with a partial cross-section showing the entire structure, and FIG. To 9th
Up to the figure, the molding process of the mold is shown. Fig. 2 is a sectional configuration diagram showing before injection, Fig. 3 is a sectional configuration diagram showing a state of being injected into the core molding cavity, and Fig. 4 is a mold opening. FIG. 5 is a cross-sectional configuration diagram showing a state, FIG. 5 is a cross-sectional configuration diagram showing a state where the core die is moved into the skin forming cavity by moving the slide mold, and FIG. 6 is a state in which the skin forming layer is injected. FIG. 7 is a sectional view showing the state in which the ejector pin is housed in the movable mold, FIG. 8 is a sectional view showing the mold open state, and FIG. 9 is a view showing the ejector pin protruding. FIG. 10 is a sectional view showing a state in which a two-layer injection molded product is taken out, FIG. 10 is a plan view with a partial cross section showing another embodiment of FIG. 1, and FIG. 11 is another embodiment of FIG. FIG. 12 is a plan view with a partial cross section showing the molding state of FIG. 11. 5 is a fixed spool, 6 is a fixed mold, 7 is an injection device, 8 is a sliding means, 9 is a cavity for core molding, 10 is a cavity for skin molding, 11 is a slide mold, 13 is a movable mold, 14
a is an ejector pin, 20 is a molded core product, 21 is a space,
33 is a skin forming layer.

Claims (4)

[Claims] 1. A movable mold (1) is provided in a cavity (9) for molding a core of a slide mold (11) slidably provided on a fixed mold (6).
The first step of injecting the molten resin from the injection device (7) with the ejector pin (14a) protruding from 3) being inserted, and molding the core molded article (20), and the mold after completion of the first step. Open and slide the slide mold (11) to move the molded core product (20) to the slide mold (11).
A second step of locating it in the skin forming cavity (10), and injecting a molten resin into the space (21) between the core molded product (20) and the skin forming cavity (10), Core molding (2
The outer skin forming layer (22) is formed on the outer periphery of (0) and the ejector pin (14a) is positioned in the movable mold (13).
A method for producing a two-layer injection-molded article, which comprises the steps of: 2. The injection device (7) is composed of a pair and injects different materials so that the core molding (20) and the skin molding layer (22) are composed of different materials. The method for producing a two-layer injection-molded article according to claim 1. 3. An injection device (7) joined to a fixed spool (5) of a fixed mold (6), and a core provided slidably on the fixed mold (6) via sliding means (8). A slide mold (11) having a molding cavity (9) and a skin forming cavity (10), and a movable mold (13) joined to the slide mold (11) and having an ejector pin (14a) freely inserted and removed. Equipped with the ejector pin (1
4a) is a molding die for a two-layer injection-molded article, characterized in that it can be selectively positioned in the core molding cavity (9) and the skin molding cavity (10). 4. The molding die for a two-layer injection molded product according to claim 1, wherein said injection device (7) is composed of a pair and is configured to inject different materials.