JPH0665482B2 - Injection molding method and injection molding die - Google Patents

Description

TECHNICAL FIELD The present invention relates to an injection molding method and an injection molding die.

(B) Conventional Technology For example, when a chair is manufactured by injection molding, there is a demand that it is made of a material having rigidity as a whole, and the seating surface and the ground contact surface are made of a material having elasticity. There is an injection molding method called a double injection method that achieves such an object. As shown in FIG. 6, this is a space 10 formed by forming a plurality of gates 104 and 106 in the mold 100 and forming the molds 100 and 102.
8 is provided with a movable die 112, which can be moved between a primary molding position (position where the movable die 112 is raised from the position shown in FIG. 6) and a secondary molding position (position shown in FIG. 6). It is as it is. The space 108 is a substantially round chair-shaped space,
It is formed in a shape in which a space for movably housing the movable die 112 is connected. The moving mold 112 is configured to form a primary cavity 108A with the molds 100 and 102 when in the primary molding position, and the moving mold 112 is configured to mold 100, 1 when in the secondary molding position.
02 and the end of the primary molded article together with the secondary cavity 10
8B is formed. Primary molding is performed with the primary material 130 while the movable die 112 is in the primary molding position, then the movable die 112 is moved to the secondary molding position, and the secondary material 134 is injected into the secondary cavity 108B generated by this movement. Then, the secondary molded product 110 is molded. The primary material 130 is the mold 100.
The drive device 142 of the valve 138 provided therein is switched to the supply position so as to be supplied to the primary cavity 108A. Similarly, the secondary material 134 supplies the secondary material 108 to the secondary cavity 108B by switching the drive device 144 of the valve 140 provided in the mold 100 to the supply position. When the drive devices 142 and 144 are switched to the shut-off position, the flow paths are shut off by the valves 138 and 140, and the supply of the primary material 130 and the secondary material 134 is shut off, respectively. By doing so, for example, an integral composite molded product such as a round chair using a rigid resin material as the primary material 130 for the main part and an elastic resin material as the secondary material 134 for the grounding portion is manufactured. can do.

(C) Problem to be Solved by the Invention However, in the conventional double injection method as described above, there is a problem that the shape of the joint surface and the shape of the product end are determined by the shape of the movable die 112. . That is, in the case of the round-shaped molded article shown in FIG. 6, the ground contact portion, that is, the lower end portion of the secondary molded article 110 in the figure has a radius larger than that of the cone-shaped cylindrical portion of the upper primary-molded portion. The thickness in the direction is thin. This is because, when the bonding portion is made to have a concavo-convex shape in order to increase the bonding area of the material-bonded portion, the end portion of the molded product also has a convex shape (or concave shape) conforming to the concavo-convex shape. Therefore, when used as a chair, there is a problem that the strength of the grounding portion may be insufficient. On the other hand, as shown in FIG. 7, the radial thickness of the secondary molded product 110 ', which serves as the ground contact portion of the molded product, is adjusted to the radial thickness of the conical cylinder of the primary molded product 108'. In this case, there is a problem that the upper surface of the movable die 112 'in FIG. 7 becomes flat, the adhesive area of the material joint portion becomes small, and the adhesive strength becomes small.
Therefore, if you need a material with high adhesive strength and flat end parts, you cannot use the double injection method.Therefore, you can separately mold the secondary molded product and attach it to the primary molded product with an adhesive. I was trying to glue it. Therefore, it takes time to manufacture the composite molded product. The present invention aims to solve such problems.

(D) Means for Solving the Problems The present invention solves the above-mentioned problems by configuring the movable dies arranged in the cavity of the mold as the split dies that can move relative to each other. That is, according to the injection molding method of the present invention, the movable molds (12, 14) of the split type, which are arranged to be movable relative to each other in the mold (4, 8), form a part of the wall surrounding the cavity. The primary cavity (10A) is positioned by the mold (4. 8) and the moving mold (12. 14) at the primary molding position where the uneven surface is formed.
Is formed, a primary resin (60) is injected thereto to form a primary molded product having an uneven portion corresponding to the uneven surface of the movable die, and then the movable die (12, 14) is formed with a flat surface by these. At the same time, the entire moving mold is moved to the secondary molding position where it is moved in the cavity expanding direction, and the mold (4.
8), the movable mold (12/14) and the primary molded product are formed with the concave and convex portions to form the secondary cavity (10B), and the secondary resin (70) is injected into this to form the secondary molded product (90) as the primary molding. It is formed integrally with the product (80).

Further, the injection molding die of the present invention for carrying out the above method is provided with a die (4, 8) and a primary molding position and a secondary molding position which are provided in a space (10) formed thereby. And a movable mold (12, 14) movable between the molds, and the movable mold (12, 14) and the movable mold (12, 14) when the movable mold (12, 14) is located at the primary molding position. 14) forms the primary cavity (10A), and the movable mold (12.
14) is intended to be configured such that the secondary cavity (10B) is formed by the space created by the movement of 14) at the secondary molding position. , A mold moving mold (12) movably fitted in the space (10) of the mold (4, 8) and a male moving mold (14) fitted in the mold (4) and relatively movable. , Both mobile type (12
14) is the primary cavity (1) at the primary molding position.
0A) forms a concave-convex surface, while the relative position is set so as to form a flat surface in the secondary cavity (10B) at the secondary molding position. The reference numerals in parentheses indicate the corresponding members of the embodiment.

(E) Action By placing each movable mold in the mold at the primary molding position, an uneven surface is formed at the end of the primary cavity, and the primary resin is injected into the primary cavity to form the primary molding having the uneven surface at the end. Mold the product. Next, by placing each movable mold at the secondary molding position, a flat portion is formed at the end of the secondary cavity having an uneven surface, and the secondary resin is injected into the secondary cavity so that the secondary end having a flat end is formed. The molded product is integrally molded with the primary molded product. By doing so, since the primary molded product and the secondary molded product are melt-bonded to each other in a wide bonding area by the uneven surface, it is possible to form a strongly bonded composite molded product, which is formed by the secondary molded product. The end of the composite molded article can be flat without any unevenness.

(F) Embodiment An embodiment of the present invention is shown in FIG. A fixed mold 4 having a "concave" cross section is fixed to the fixed mold mounting plate 2. The fixed mold mounting plate 2 is fixed to the fixed platen 46, and its movement in the vertical direction in the figure is restricted. The movable mold mounting plate 6 is arranged in the lower part of the figure facing the fixed mold mounting plate 2,
A movable-side mold 8 having a “convex” cross section is fixed to this. The movable mold mounting plate 6 is attached to a movable plate (not shown), and thereby, the movable mold 8 comes in contact with the fixed mold 4 at the illustrated mold closed position, and the movable mold 8 is separated from the fixed mold 4. It is possible to move between the lower mold opening position in the figure and the mold open position. The space 10 is formed by the fixed mold 4 and the movable mold 8.
Are formed. A ring-shaped movable die 12 and a male movable die 14 are fitted to each other in an annular hole of the movable side die 8. The female moving die 12 has a stepped sleeve-like cross section. The male moving mold 14 has a piston-shaped cross section, and the small-diameter piston portion of the male moving mold 14 is a female moving mold 1.
Fitted in 2. The female moving mold 12 and the male moving mold 14 have an upper primary molding position shown in FIG. 1 and a secondary molding position lower than this inside the space 10 (see FIG. 4).
It is possible to move independently between and. Movable mold 8
A ring-shaped upper oil chamber 16 is formed by the female moving die 12 and the movable die 8 and the female moving die 1 in the same manner.
2 and the male moving die 14 form a ring-shaped intermediate oil chamber 1
8 is formed, and a ring-shaped lower oil chamber 20 is formed by the movable mold 8 and the male moving mold 14. The width of the intermediate oil chamber 18 in the radial direction is made smaller than the width of the male moving die 14 in the radial direction, which restricts the moving position of the male moving die 14 in the upward direction in FIG. It has become so. The movable mold 8 is provided with an upper flow path 22 communicating with the upper oil chamber 16, an intermediate flow path 24 communicating with the intermediate oil chamber 18, and a lower flow path 26 communicating with the lower oil chamber 20. There is. By applying a fluid pressure to the upper oil chamber 16 via the upper flow path 22, the female moving die 12 can be moved downward in FIG.
Similarly, by applying a fluid pressure to the intermediate oil chamber 18 via the intermediate passage 24, the female moving die 12 is positioned at the upper position shown in FIG. 1 and the male moving die 14 is moved downward in the drawing. In addition, by applying a fluid pressure to the lower oil chamber 20 via the lower flow path 26, the male moving type 1
It is possible to position 4 respectively in the upper position shown in FIG. Female movable mold 12 and male movable mold 14 are first
As shown in the figure, when both are in the upper position, the space 10
The primary cavity 10A is formed by a part of the. A cavity (10A + 10B) is formed when the female moving die 12 and the male moving die 14 move to the lower position in the figure (see FIG. 4). That is, the secondary cavity 10B
Is the volume of the portion increased by the movement of the female moving die 12 and the male moving die 14. As shown in FIG. 5, when the female movable die 12 and the male movable die 14 are moved to the lower position, the upper surfaces of the two movable dies 12, 14 in the drawing are located on the same plane. The dimensions are set.
As shown in FIG. 4, the fixed side mold 4 is provided with a primary flow path 26 opening to the primary cavity 10A, and the primary flow path 28 is a primary injection through the flow path of the fixed mold mounting plate 2. It is connected to the device 30. The primary injection device 30 is made of the primary resin 6
It is possible to inject 0 into the primary cavity 10A via the primary flow path 28. The movable side mold 8 has a secondary flow path 32 which is open at the mating surface of the fixed side mold 4 and the movable side mold 8.
The secondary flow path 32 is connected to the secondary injection device 34 via the flow path of the fixed mold mounting plate 2. The secondary injection device 34 can inject the secondary resin 70 into the secondary cavity 10B via the secondary flow path 32. The movable mold 8 is provided with a secondary gate 36 that connects the secondary flow path 32 and the secondary cavity 10B. As for the positional relationship of the female moving die 12, the secondary gate 36 is opened when the female moving die 12 is located at the lower position shown in the figure, and the female movable die 12 is moved upward from the position shown in FIG. It is set so that the secondary gate 36 is closed in (refer to). A primary valve 38 is provided in the primary flow path 28 of the movable mold 8, and a secondary valve 40 is similarly provided in the secondary flow path 32. A primary valve opening / closing device 42 is attached to the primary valve 38, and similarly, a secondary valve opening / closing device 44 is attached to the secondary valve 40. Fixed side mold 4, movable side mold 8, female moving mold 12, male moving mold 14, primary valve 38, secondary valve 40, primary valve opening / closing device 42, secondary valve opening / closing device 44, etc. 50 are configured.

Next, the operation of this embodiment will be described with reference to FIGS. In the mold closed state shown in FIG. 2, the movable mold mounting plate 6
A mold closing force is acting on. Further, pressure oil is supplied to the intermediate oil chamber 18 and the lower oil chamber 20, whereby both the female moving die 12 and the male moving die 14 are forcibly held in the upper position shown in the figure. A convex portion is formed at the lower end of the cavity 10A in the figure by the female moving die 12 and the male moving die 14. The magnitude of each holding force by the fluid pressure is set to be larger than the downward force in the figure acting on the female moving die 12 and the male moving die 14 by the injection pressure of the primary injection device 30. On the other hand, by the primary valve opening / closing device 42, the primary valve 38 provided in the primary flow path 28 opens the flow path, and the secondary valve opening / closing device 4
4, the secondary valve 40 provided in the secondary flow path 32 is driven so as to close the flow path. As a result, the primary injection device 3
A primary resin 60 having a rigidity higher than 0 is injected into the primary cavity 10A. This state is enlarged and shown in FIG. As a result, the lower end of the primary molded product 80 in the figure is formed in a convex shape. When the primary injection is completed, the primary valve opening / closing device 42 closes the primary valve 38. Next, the pressure oil in the middle oil chamber 18 and the lower oil chamber 20 is discharged,
Pressure oil is supplied to the upper oil chamber 16. As a result, the female moving die 12 and the male moving die 14 are moved to the lower position shown in FIG. 4, the secondary gate 36 is opened, and the secondary cavity 10B is formed. The upper portion of the secondary cavity 10B in the figure is formed in a concave shape, and the lower end portion thereof is formed in a flat shape. By the secondary valve opening / closing device 44, the secondary valve 40
Then, the secondary injection device 34 injects, for example, elastic secondary resin 70 into the secondary cavity 10B to form the secondary molded product 90. This state is enlarged and shown in FIG. That is, the primary molded product 80 and the secondary molded product 90
The bonding surface with and has an uneven shape, and the lower end of the secondary molded product 90 in the figure is a flat surface. When the secondary injection ends, the secondary valve opening / closing device 44 closes the secondary valve 40. The movable side mold 8 moves downward in the figure to open the mold, and the molded product (80 + 90) is taken out.

(G) Effect of the Invention As described above, according to the present invention, it is possible to form a joint surface of resins having different properties into a concavo-convex shape having a large bonding area, and to form a composite article having no irregularity at the end of the molded product. The molded product can be integrally manufactured in the mold. Therefore, it is not necessary to separately manufacture the parts and integrate them by adhesion.

[Brief description of drawings]

FIG. 1 is a diagram showing a partial cross section of an injection molding die according to an embodiment of the present invention, and FIG. 2 is a diagram showing a partial cross section of a state of primary molding.
FIG. 3 is a partially enlarged sectional view thereof, FIG. 4 is a partially sectional view showing a state of secondary molding, FIG. 5 is a partially enlarged sectional view thereof, and FIG. 6 is a conventional double-molding die. Partial section view, 7th
The figure is a cross-sectional view for explaining the shape of a movable product and a molded product having a shape different from that of the conventional double molding shown in FIG. 2 ... Fixed mold mounting plate, 4 ... Fixed mold, 6 ... Movable mold mounting plate, 8 ... Movable mold, 10 ... Space, 10A
...... Primary cavity, 10B …… Secondary cavity, 12
...... Female mobile type, 14 …… Male mobile type, 30 …… Primary injection device, 34 …… Secondary injection device, 36 …… Secondary gate,
38 ... Primary valve, 40 ... Secondary valve, 42 ... Primary valve opening / closing device, 44 ... Secondary valve opening / closing device, 60 ... Primary resin, 7
0: Secondary resin, 80: Primary molded product, 90: Secondary molded product.

Claims (2)

[Claims] 1. A movable mold (12, 14) of a split type, which is arranged so as to be movable relative to each other in a mold (4, 8), by which an uneven surface forming a part of a wall surrounding a cavity is formed. The primary mold position (4.
8) and the movable mold (12, 14) form a primary cavity (10A), and a primary resin (60) is injected into this to mold a primary molded product having an uneven portion corresponding to the uneven surface of the movable mold, Next, the movable die (12, 14) is positioned at the secondary molding position where the flat surface is formed by these and the entire movable die is moved in the cavity expansion direction, and the die (4.8), the movable die ( 12.14) and the concave and convex portions of the primary molded product form a secondary cavity (10B), and the secondary resin (70) is injected into this to integrate the secondary molded product (90) with the primary molded product (80). An injection molding method for a composite molded article, which comprises: 2. A mold (4.8) and a movable mold (12.14) provided in a space (10) formed by the mold and movable between a primary molding position and a secondary molding position. , The primary cavity (10A) is formed by the mold (4.8) and the movable mold (12.14) when the movable mold (12.14) is located at the primary molding position, (1
2.14) is located in the secondary molding position, the space created by the movement of the secondary molding position causes the secondary cavity (10B).
In the injection-molding die configured to form a mold, the movable die (12, 14) is movably fitted into the space (10) of the die (4, 8), and is a movable die. (12) and a male moving type (14) fitted to this and capable of relative movement.
14) is the primary cavity (1) at the primary molding position.
0A) has a concave-convex surface while the related position is set so as to form a flat surface in the secondary cavity (10B) at the secondary molding position.