JPH052494B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to an injection mold, and in particular, it has a plurality of resin passages, and by injecting a plurality of types of resin, a product with a corresponding layer structure can be obtained. Regarding molds for.

(Prior Art) Conventionally, one known mold of this type includes a central resin passage having an outlet at its tip and at least one peripheral resin passage opening into the resin passage. Further, a stem is disposed within the central resin passageway so as to be movable along its axis, and this stem is operated by an actuating member such as a hydraulic cylinder to prevent communication between all of the central resin passageway and the peripheral resin passageway and the outlet. It is designed to reciprocate between a closed position and a fully open position that allows communication.

(Problems to be Solved by the Invention) As a specific example of such a mold, as shown in FIG. When supplying resins A and B to the resin passages 52 and 53 and resin C to the central resin passage 51 to obtain a three-layer molded product, the following steps are taken, for example.

That is, the stem 54 is connected to the outlet 55 and the entire resin passage 5.
1, 52, and 53, and in this state (1) Injection of resin A (2) Injection of resin A, B, and C (state shown in the upper half of Figure 8) (3) Injection of resin A (the state shown in the lower half of FIG. 8) is performed in sequence.

However, in this case, the steps (1), (2), and (3) above are all performed with the stem 54 in the fully open position, so when resin A is injected, resins B and C will also flow due to being dragged by this. , after filling is completed, resin A,
B and C will be mixed together, making it impossible to obtain a good molded product.

It is an object of the present invention to solve the above-mentioned conventional problems and to provide an injection mold that can produce good molded products without disturbing the resin.

(Means for Solving the Problems) The invention for achieving the above object is characterized in that a stop member is provided for bringing the stem between its fully closed position and its fully open position.

(Operation) The stop member brings the stem into an intermediate position, which allows communication between the outlet and only one of the peripheral resin passages, and when injecting resin from this peripheral resin passage, other resins are drawn in. It won't happen.

(Example) An embodiment shown in the drawings will be described below.

1, 2 and 3, a hot runner mold for injection molding is shown, which comprises a central resin passage 1 with an outlet 5 at its tip and in this example two peripheral resin passages 2, 3. , the resin passages 2 and 3 open into the resin passage 1 at different positions in the axial direction thereof. A stem 4 is disposed within the central resin passage 1 so as to be movable along its axis, and the rear end of this stem is connected to a piston 7 of a fluid pressure cylinder 6. 8,
Reference numeral 9 denotes holes for supplying fluid to the front and rear surfaces of the piston 7, respectively, and the stem 4 is in a fully closed position where fluid is supplied to the holes 9 to prevent communication between the outlet 5 and the resin passages 1, 2, and 3. (Fig. 1), and by supplying fluid to the hole 8, the outlet 5 and the resin passage 1,
It is designed to move back and forth between a fully open position (FIG. 2) that allows communication with 2 and 3. 15 is a cavity, and 16 is a heater.

The above structure is the same as the conventional one, and in this invention, a fluid pressure cylinder 10 that constitutes a stop member is further provided behind the fluid pressure cylinder 6, and the piston 11 whose pressure receiving area is larger than that of the piston 7 is a cylinder. It is possible to protrude into the room of 6. Reference numeral 12 denotes a hole for supplying fluid to the rear side of the piston 11. By supplying fluid to this hole 12 and the hole 8, the piston 11 protrudes into the chamber of the cylinder 6 and collides with the piston 7. The stem is adapted to stop at an intermediate position between the fully closed position and the fully open position, ie, a position that allows communication between the outlet 5 and the resin passage 2 only.

FIG. 7 shows the injection state of resin A. In this case, by bringing the stem 4 to an intermediate position, only resin A is injected without dragging resins B and C.

Figures 4 to 6 show a further embodiment in which a coil spring 30 forming a stop member is incorporated within the cylinder 26 for moving the stem 4 between a fully closed position and a fully open position. That is, the spring 30
is a spring receiving plate 32 that moves along the wall surface of a recess 31 provided in the piston 27 and the guide rod 33;
is located between.

In this embodiment, the stem 4 is moved to the fully closed position (FIG. 4) by supplying fluid to hole 29 and to the fully open position (FIG. 5) by supplying fluid to hole 28. Similar to the previous embodiment, but when the supply of fluid to the hole 28 is stopped in the fully open position shown in FIG. 5, the piston 27 is brought to the intermediate position by the spring force of the spring 33, as shown in FIG. .

In the above embodiment, two peripheral resin passages are shown, but there may be one or three or more peripheral resin passages.

(Effects of the Invention) As described above, according to the present invention, since the stop member that brings the stem to an intermediate position between the fully closed position and the fully open position is provided, the outlet and surrounding resin passages are closed at the intermediate position of the stem. You can only communicate with them. Therefore, other resins are not dragged along by the flow of the resin passage, and a good molded product can be obtained.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing one embodiment of the present invention, respectively showing a fully closed position, a fully open position, and an intermediate position of the stem, and FIGS. 4 to 6 are sectional views showing other embodiments, respectively. A cross-sectional view corresponding to Figures 1 to 3,
FIG. 7 is a sectional view showing the effect of the present invention, and FIG. 8 is a sectional view showing a conventional example. 1... Central resin passage, 2, 3... Peripheral resin passage, 4... Stem, 5... Outlet, 6... Fluid pressure cylinder (operating member), 10... Fluid pressure cylinder (stopping member).

Claims (1)

[Claims] 1. A central resin passageway having an outlet at its tip, at least one peripheral resin passageway opening into the resin passageway, and a stem movably disposed within the central resin passageway on its axis; The stem can be placed in a fully closed position where communication between the central resin passage and all of the peripheral resin passages and the outlet is prevented, and a fully open position where communication between the central resin passage and all of the peripheral resin passages and the outlet is permitted. and an actuating member for reciprocating movement between the injection molds, characterized in that a stop member is provided for bringing the stem to an intermediate position between a fully closed position and a fully open position. 2. The injection mold according to claim 1, wherein the actuating member is a fluid pressure cylinder, and the stem is connected to a piston of the hydraulic cylinder. 3. The injection mold according to claim 2, wherein the stop member comprises a hydraulic cylinder, the piston of which is capable of abutting against the piston of the actuating member. 4. The injection mold according to claim 2, wherein the stop member comprises a spring incorporated within the piston of the actuating member.