JPH08300406A - Mold device for composite molding and two-color molding method - Google Patents

Abstract

PURPOSE: To obtain a mold device with which a high degree of freedom can be obtained in a shape of a molded piece by opposing a valve of a core to a secondary gate at first molding for closing the secondary gate with a cavity demarcating face and opposing a cavity forming face of the core to a fixed mold so as to form a secondary cavity. CONSTITUTION: A movable retainer plate 20 is made to go ahead toward a fixed retainer plate 10 so as to form a primary cavity A. A core 30 is made to go ahead toward the fixed retainer plate 10 in a state that a cavity partition face 32 faces the fixed retainer plate 10 so as to close a secondary gate 12a. In this state, a primary resin is injected into the primary cavity A from a primary gate 11a so as to perform primary molding. Next, the core 30 is retracted and sunk into a hollow 27. Successively, the core 30 is turned 180 deg. so as to make a cavity demarcating face 31 face the fixed retainer plate 10. Thereafter, the core 30 is made to go ahead toward the fixed retainer plate 10 and a secondary cavity B is formed by the cavity demarcating face 31. A secondary resin is injected into the secondary cavity B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite molding die apparatus and a two-color molding method, and more particularly to a die apparatus and a molding method that employ a core-back type composite molding system.

[0002]

2. Description of the Related Art Among the injection molding methods, a composite molding method, a so-called two-color molding method, includes an insert method, a core back method, a rotary method, a sandwich method, and a method in which these methods are combined. Of these methods, the core-back method, compared to other methods,
The finished product can be obtained while the molds are closed with one set of molds, and there is an advantage that a complicated molding machine such as a rotating mechanism other than a plurality of injection units is not required, and the cost is included. Excellent manufacturing efficiency. For this reason, the core back method is often used for molding flat designs such as audio cassette halves and video cassette halves having a window made of a transparent material in the central portion.

As the core-back type molding die apparatus described above, those shown in FIGS. 6a, 6b, 6c and 7 are conventionally known. In the figure, 10 is a fixed-side template fixed to the apparatus frame or the like, and 20 is a movable-side template supported by the fixed frame so as to be movable back and forth with respect to the fixed-side plate 10. A sprue 11 for the primary resin and a sprue 12 for the secondary resin are formed on the stationary mold plate 10. As is well known, these sprues 11 and 12 are each connected to a molten resin supply source through a nozzle or the like, and the sprue 11 is connected to the primary gate 1
1a opens into the primary cavity described below, and similarly, the sprue 12 opens from the secondary gate 12a into the secondary cavity described below.

The movable side mold plate 20 advances and retreats (moves up and down in the figure) with respect to the fixed side mold plate 10 by the mold opening / closing operation of the molding machine, and moves upward in close contact with the fixed side mold plate 10 (mold closed state, figure 6a), the upper surface (cavity defining surface) in the drawing is the fixed-side template 10
A primary cavity A is defined between the lower surface and the lower surface. In this primary cavity A, the gate 11 of the sprue 11 for primary resin is used.
a opens, and the primary resin is injected from the gate 11a during the primary molding.

Further, a hole 20a is formed in the movable mold plate 20 so as to open in the cavity defining surface of the upper surface, and the core 30 is disposed in the hole 20a so that the core 30 can be projected and retracted.
A hydraulic cylinder 40, which is connected to the lower portion of the core 30 to drive the core 30 up and down, is provided at the lower portion of the core 0a. The core 30 has a curved upper surface that is convex upward, and a concave portion 30a for forming a convex portion is formed on the upper surface. The core 30 is driven by a hydraulic cylinder 40 to move up and down and move upward (see FIG. 6a).
(See FIG. 6), the secondary gate 12a is closed, and the hole 20a of the movable-side mold plate 20 is arranged so that the upper surface thereof is flush with the lower-moving-side mold plate 20 when the secondary gate 12a is moved downward (see FIGS. 6b, c, and 7). Immerse inside to define the secondary cavity B. Secondary cavity B
The secondary resin sprue 12 is opened, and the secondary resin is injected from the gate 12a during the secondary molding. In addition,
50 is an ejector pin.

In the above-mentioned mold apparatus, molding is performed as described below. First, as shown in FIG. 6a, the movable side mold plate 20 is moved forward (moved upward) toward the fixed side mold plate 10, and the core 30 is projected to close the secondary gate 12a to define the primary cavity A. To achieve. Then, in this state, the primary resin is injected into the primary cavity A from the primary gate 11a to mold the primary molding portion A (for convenience, the same reference numerals as those of the primary cavity) are molded (primary molding).

Next, as shown in FIG. 6b, the core 30 is retracted into the movable-side mold plate 20, the secondary gate 12a is released, and the secondary cavity B in which the secondary gate 12a is opened is fixed-side mold plate. 10 and the lower surface. Then, as shown in FIG. 6c, a secondary resin is injected from the secondary gate 12a to form a secondary molded portion B (denoted by the same reference numeral as the secondary cavity) integrated with the primary molded portion A, that is, a finished product. Mold (secondary molding). After that, as shown in FIG. 7, the movable side mold plate 20 is retracted from the fixed side mold plate 10 (mold opening), and the completed product is released by an ejector pin 50 or the like and taken out.

[0008]

However, in the above-mentioned conventional mold device, the upper surface of the core 30 is not only the secondary cavity B defining surface for determining the shape of the secondary product B, but also the secondary cavity B defining surface. It must function also as a sealing member for closing the gate 12a, and the function as this sealing member must be prioritized. Therefore, the shape of the top surface of the core 30 is also a shape that can reliably close the secondary gate 12a, such as the above-described convex curved surface shape or the secondary gate 12a.
The secondary cavity B is
There is a problem that the degree of freedom in selecting the shape as the defining surface is low and the shape of the product that can be formed is limited.

That is, as an example, consider the example of FIG. 8 in which a concave portion is formed on the back surface (lower surface) of the secondary molding portion B as a product shape. It is possible to form a convex portion 39 on the upper surface of the core 30. It is essential. However, as is apparent from FIG. 8, the core 30 having the convex portion 39 first advances to the position where the secondary gate 12a is closed because the convex portion 39 first contacts the lower surface of the fixed-side template 10 during forward movement. I can't
The secondary gate 12a cannot be closed by the core 30 and cannot be practically used. Therefore, FIG.
When molding a product having a shape as shown in (1), other methods such as an insert method and a rotary method have to be adopted, and molding cannot be performed by taking advantage of the excellent characteristics of the core back method. The present invention has been made in view of the above problems, and an object of the present invention is to provide a core-back type mold apparatus and a two-color molding method, in which a large degree of freedom can be obtained in the shape of a molded product to be molded.

[0010]

In order to achieve the above object, the invention according to claim 1 is a fixed mold having a primary gate for injecting a primary resin and a secondary gate for injecting a secondary resin. A movable die that is supported so as to be able to move forward and backward with respect to the fixed die and that cooperates with the fixed die to define a primary cavity in which the primary gate opens, and a movable die that is capable of projecting and retracting from the cavity defining surface. A core that closes the primary gate when the movable mold defines a primary cavity with the fixed mold and that cooperates with the fixed mold to define a secondary cavity in which the secondary gate opens. In a compound molding die device provided with the above, a cavity is formed in the movable die, and a rotation support shaft is rotatably provided in the cavity, and the core is connected to the rotation support shaft by connecting the core to the core. The cavity partition surface and front that can close the secondary gate. A cavity defining surface that defines a part of the secondary cavity is formed at different angular positions around the rotation support shaft, and the rotation support shaft is connected to the rotation drive mechanism and the advance / retreat drive mechanism. It is possible to rotate and advance / retreat.

In the two-color molding method according to the second aspect of the present invention, the movable mold having the core having the cavity partition surface and the cavity defining surface provided so as to project and retract is advanced toward the fixed mold. After the primary mold for primary resin injection is opened by the fixed mold and the movable mold and the core is projected to close the secondary gate for secondary resin injection by the cavity partition surface, After injecting a primary resin into the primary cavity from the primary gate and then immersing the core in the movable mold to release the secondary gate, the cavity defining surface of the core faces the fixed mold. By changing the posture as described above, a secondary cavity in which the secondary gate is opened is defined, and the secondary resin is injected into the secondary cavity from the secondary gate.

[0012]

According to the inventions of claims 1 and 2,
Injecting the primary molding resin into the primary cavity During the primary molding, the valve part of the core is opposed to the secondary gate, the secondary gate is closed by the cavity partition surface, and the secondary molding resin is injected into the subsequent secondary cavity. At the time of molding, the cavity defining surface of the core is opposed to the fixed mold to define the secondary cavity. Therefore, in the core, the valve portion and the cavity defining portion have separate shapes, that is, the cavity partition surface has a shape capable of reliably closing the secondary gate,
Further, the cavity defining surface can be formed into a shape that matches the shape of the product, and products of various shapes can be molded.

Particularly, in the composite molding die apparatus according to the first aspect of the present invention, the movable die is provided with a cavity in which the core is rotatable, and the cavity is connected to the rotation drive mechanism and the advancing / retracting drive mechanism. Arrange the rotation support shaft, and attach the core to this rotation support shaft.
Since the rotation support shaft is driven by each drive mechanism, it can be achieved with a simple structure without increasing the size, and modification from an existing mold device can be easily performed. In addition, the scope of the above claims,
Although it is described that the gate is formed in the fixed type and the core is supported in the movable type, this description prevents the sentence from being difficult to understand by the alternative description. The object to be provided can also be achieved by appropriately selecting.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show an embodiment of a composite molding die device according to the present invention, in which FIG. 1 is a front sectional view, FIG. 2 is a side view in which a part is cut away, and FIGS. 3a, b, c, 4a, b,
c and FIGS. 5a, 5b, and 5c are front cross-sectional views of essential parts showing the operation in alphabetical order in time series. It should be noted that the same parts as those of the conventional mold device shown in FIGS. 6, 7 and 8 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIGS. 1 and 2, the fixed side template (fixed type) 10 is attached to the fixed side mounting plate 18 via a runner stripper plate 19, and the movable side template (movable type).
20 is a movable side mounting plate 28 via a spacer block 29.
Attached to. The fixed side mounting plate 18 has a nozzle 11
b and 12b are provided, and these nozzles 11b and 12b penetrate the runner stripper plate 19 and are connected to the sprues 11 and 12, respectively.

A cavity 27 having a substantially circular cross section is formed in the movable side mold plate 20 so as to penetrate left and right in FIG. 2, and a plane penetrating from the cavity 27 to the upper surface at the center of the cavity 27 in the longitudinal direction. A sliding hole 26 having a substantially rectangular shape as viewed is formed. Cavity 27
A rotation support shaft 61 is rotatably arranged substantially in the center,
A core 30 is arranged in the sliding hole 26 so as to be movable up and down in the figure, and a rotation support shaft 61 penetrates through the core 30 so as to prevent relative rotation by a spline or the like and to be relatively displaceable in the axial direction. Etc. are fixed in the longitudinal direction.

As shown in FIGS. 1 and 3 and the like, the core 30 has a prismatic shape with a diagonal dimension smaller than the diameter of the hollow portion 27 and a substantially square shape in a front view, and a plane in which the dimensions from the four corner portions are equal. The rotation support shaft 61 penetrates the visual center position. The core 30 serves as a cavity defining surface 31 having a convex portion 39 formed on one surface, and a surface facing the cavity defining surface 31 (a surface 180 degrees apart around the rotation support shaft 61) is a concave portion 38. Is formed as the cavity partition surface 32. As will be described later in detail, the cavity defining surface 31
The convex portion 39 imparts a concave shape to the secondary molded portion B, and the concave portion 38 of the valve portion 32 surrounds the secondary gate 12a and closes the secondary gate 12a.

Both ends of the rotary support shaft 61 project laterally from the movable template 20, and the projecting ends are supported by bearings 62, 62, respectively. Bearing portion 62, 62
Are vertically movably mounted by actuators 63 and 63, respectively, to rotatably support the rotation support shaft 61,
At least one bearing 62, 62 has a built-in rotary actuator such as a motor for rotating the rotation support shaft 61. A rotary actuator of these bearings 62, 62 is connected to a controller (not shown) and is controlled by the controller to rotate the rotation support shaft 61.

The actuators 63, 63 are each composed of a hydraulic cylinder or the like, and have spacer blocks 29, 2 respectively.
It is fixed to the side of 9. These actuators 63, 6
3 is connected to a controller (not shown) and is controlled by the controller to move the rotation support shaft 61 up and down integrally with the core 30, that is, to move the core 30 forward and backward with respect to the fixed-side template 10. The bearings 62, 62 described above constitute a rotary drive mechanism, and the actuators 63, 63 constitute an advance / retreat drive mechanism.

Next, the operation of this embodiment will be described with reference to FIGS. 3, 4 and 5. First, primary molding, that is, molding of the primary molding portion A is performed. In this primary molding, as shown in FIG. 3A, the movable side mold plate 20 is advanced toward the fixed side mold plate 10 to define the primary cavity A in which the primary gate 11a is opened, and the core 30 is divided into the cavity partitioning surfaces. 32 is made to project from the sliding hole 26 of the movable side mold plate 20 in a posture of facing the fixed side mold plate 10, and the cavity partition surface 32 is made to face the secondary gate 12a in the concave portion 38 so as to be in close contact with the lower surface of the fixed side mold plate 10. In this state, the primary gate 11
The primary resin is injected into the primary cavity A from a.

Next, after the primary resin in the primary cavity A loses fluidity, the actuator 63 causes the bearing portion 6 to move.
2, that is, the rotation support shaft 61 is moved downward. Therefore, as shown in FIG. 3b, the core 30 moves downward integrally with the rotation support shaft 61 and retracts from the fixed-side mold plate 10, and the core 30 is recessed in the cavity 27 and its four corners are retracted. Engage slidably with the peripheral surface of the cavity 27. Subsequently, the rotation support shaft 61 is driven and rotated by the bearing portion 62, and the core 30 is also rotated by the rotation of the rotation support shaft 61 as shown by an arrow in FIG. Then, as shown in FIG. 4A, the cavity defining surface 31 of the core 30 is moved to a position where it faces the fixed-side template 10.
When rotated by 80 degrees, the rotation support shaft 61, that is, the core 3
The rotation of 0 stops.

Subsequently, as shown in FIG. 4b, the actuator 63 is extended to move the bearing portion 62, that is, the rotation support shaft 61, integrally with the core 30. Therefore, the core 30 advances toward the fixed-side template 10 with the cavity defining surface 31 facing the lower surface of the fixed-side template 10,
A secondary cavity B is formed between the lower surface of the fixed mold plate 10 and the secondary gate 12a. That is, the core 30
Is positioned so that the cavity defining surface 31 is flush with the upper surface of the movable mold plate 20 to define the secondary cavity B. Then, in the secondary cavity B, the secondary gate 12a
Then, a secondary resin is injected to form a secondary molded portion B integrated with the primary molded portion A, that is, a finished product (secondary molding).

Here, in the secondary molding portion B, the concave portion Ba is formed by the convex portion 39 of the cavity defining portion 31 of the core 30. That is, since the cavity-defining surface 31 of the core 30 can be shaped independently of the valve portion 32,
Recesses Ba and the like can be formed in the secondary molded portion B, and a high degree of freedom can be obtained in the design of the secondary molded portion B.

Next, as shown in FIG. 4c, the actuator 63 is contracted to lower the rotary support shaft 61, and the core 30 is retracted into the cavity 27. After this, as shown in FIG. 5a, the ejector pin 50 is projected to release the finished product, and the bearing portion 62 causes the rotation support shaft 61 to rotate as shown by the arrow, so that the core shown in FIG. When the cavity partition surface 32 is rotated to a position where the cavity partition surface 32 faces the fixed-side template 10, the rotation is stopped. Here, since the rotation of the core 30 is performed when the ejector pin 50 is operated, it is possible to prevent the cycle time from becoming long.

Thereafter, as shown in FIG. 5c, the movable side mold plate 20 is advanced toward the fixed side mold plate 10 to define the primary cavity A, and the core 30 is moved upward to move the cavity. The partition surface 32 closes the secondary gate 11a to prepare for the next molding. And thereafter, FIG.
Repeat the process from.

As described above, in this embodiment,
The movable side mold plate 20 is advanced toward the fixed side mold plate 10 to define the primary cavity A, and the core 30 is fixed to the fixed side mold plate 10 with the cavity partition surface 32 facing the fixed side mold plate 10. The secondary gate 12a is closed by advancing in the opposite direction, and in this state, primary resin is injected from the primary gate 11a into the primary cavity A for primary molding, and then the core 3
0 is retracted (moved downward) to be immersed in the cavity 27, and then the core 30 is rotated 180 degrees to move the cavity defining surface 3
After facing 1 to the stationary mold plate 10, the core 30 is advanced toward the stationary mold plate 10 to define the secondary cavity B by the cavity defining surface 31. Then, secondary resin is injected into the secondary cavity B from the secondary gate 12a to perform secondary molding, and when the ejected product is released from the molded product by the ejector pin 50, the core 30 is rotated 180 degrees for the next primary molding. Prepare Therefore, the secondary gate 12a can be reliably closed during the primary molding, and the shape of the secondary molded portion B is not limited during the secondary molding.

In the above-described embodiment, the concave portion 38 is formed on the cavity partition surface 32 of the core 30 and the convex portion 39 is formed on the cavity defining surface 31. It can be arbitrarily selected according to the product to be molded, and the valve 32 is also the secondary gate 1.
It goes without saying that the shape can be arbitrarily determined as long as it can close the 2a.

[0028]

As described above, according to the present invention, the cavity partition surface and the cavity partition surface, which face the fixed mold by the change of the posture thereof, are selectively formed in the core, and the cavity partition surface of the core is formed. After performing the primary molding by closing the secondary gate with, the posture of the core is changed, and the secondary cavity is defined by the cavity defining surface of the core to perform the secondary molding. Is not limited,
Two-color molding of molded products of various shapes can be performed by the highly efficient core back system.

In particular, in the invention according to claim 1, a movable mold is provided with a hollow part in which the core is rotatable, and a rotary support shaft connected to the rotary drive mechanism and the forward / backward drive mechanism is arranged in the hollow part. However, since a core is attached to this rotation support shaft and the rotation support shaft is driven by each drive mechanism to change the posture, it can be achieved with a simple structure without increasing the size, and modification from existing mold equipment is also possible. Easy to do.

[Brief description of drawings]

FIG. 1 is a front sectional view of a composite molding die device according to an embodiment of the present invention.

FIG. 2 is a side view in which a part of the composite molding die device is cut away.

FIG. 3 is a partially enlarged front cross-sectional view of the composite molding die device, showing the operation in time series in the order of a, b, and c.

FIG. 4 is a partially enlarged front cross-sectional view of the composite molding die device, showing the operation subsequent to FIG. 3 in time series in the order of a, b, and c.

FIG. 5 is a partially enlarged front cross-sectional view of the composite molding die device, showing the operation following FIG. 4 in time series in the order of a, b, and c.

FIG. 6 is a partially enlarged front cross-sectional view of a conventional composite molding die device, showing its operation in time series in the order of a, b, and c.

FIG. 7 is a partially enlarged front sectional view of the conventional composite molding die device, showing an operating state following FIG. 6.

FIG. 8 is a partially enlarged front sectional view of a virtual composite molding die device for explaining a problem to be solved by the present invention.

[Explanation of symbols]

 10 Fixed-side template (fixed type) 11a Primary gate 12a Secondary gate 20 Movable-side template (movable type) 26 Sliding hole 27 Cavity 30 Core 31 Cavity defining surface 32 Cavity partition 38 38 Recess 39 Convex (shape 50 Ejector pin 61 Rotation support shaft 62 Bearing part (rotational drive mechanism) 63 Actuator (advance / retreat drive mechanism) A Primary cavity (primary molding part) B Secondary cavity (secondary molding part)

Claims (2)

[Claims] 1. A fixed mold in which a primary gate for injecting a primary resin and a secondary gate for injecting a secondary resin are formed, and a fixed mold supported so as to be able to move forward and backward with respect to the fixed mold. A movable die that defines a primary cavity in which the primary gate opens, and a movable die that is supported by the movable die so as to be capable of projecting and retracting from a cavity defining surface of the movable die. In a composite molding die device comprising a core that closes a gate and defines a secondary cavity that cooperates with the fixed die to open the secondary gate, a cavity is formed in the movable die. A rotatably supporting shaft is rotatably disposed in the hollow portion, and the core is connected to the rotative supporting shaft so that the secondary gate can be closed in the core and a part of the secondary cavity. The cavity defining surface that defines the A compound molding die, which is formed at different angular positions around a holding shaft and is rotatable and forward / backward driven by connecting the rotary support shaft to a rotary drive mechanism and a forward / backward drive mechanism. Mold device. 2. A primary mold for injecting a primary resin by a movable mold having a core formed with a valve portion and a cavity defining portion so as to be capable of projecting and retracting, is advanced toward a fixed mold and the fixed mold and the movable mold. After defining the primary cavity with the gate opened and projecting the core to close the secondary gate for injecting the secondary resin by the valve part, injecting the primary resin from the primary gate into the primary cavity, and then , After immersing the core in the movable mold to release the secondary gate,
The core is subjected to a posture change so that its cavity defining surface faces the fixed mold to define a secondary cavity in which the secondary gate opens, and a secondary resin is formed in the secondary cavity from the secondary gate. A two-color molding method comprising injecting.