JPH0655391B2 - Sandwich injection molding method and sandwich molding injection head used for the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sandwich injection molding method and a sandwich injection molding injection head used for carrying out the method.

[Conventional technology]

Conventionally, the following (a) and (b) are known as injection heads of injection molding machines for sandwich molding.

(A) The inner nozzle, which is concentrically arranged in the outer nozzle and is slidable in the axial direction thereof, is rotatable by the rotating means, and the resin passage is opened and closed by the rotation of the inner nozzle, and the inner nozzle is also opened. An operating rod for opening and closing the nozzle hole of the inner nozzle is provided therein (JP-A-59-220341).

(B) An annular insert concentrically arranged in the injection head is provided slidably in the axial direction, and a needle having a connection passage is rotatably provided in the annular insert, and the needle is rotated to rotate the needle. A configuration in which the gas or the third resin can be supplied by opening and closing the connection passage (see Japanese Patent Laid-Open No. 63-94805).

[Problems to be Solved by the Invention] In the above-mentioned conventional techniques (a) and (b), at the time of molding, the resin at the time of the previous molding remains in the nozzle hole, and the remaining resin is At times, when the resin that forms the skin layer (skin material) is injected, it mixes with each other and fills the mold cavity, so parts such as different colors occur in the skin layer of the molded product and the surface coating of the molded product occurs. There was a problem that it had to be done.

The present invention has been made in view of the problems of the above-mentioned conventional techniques, in which the resin at the time of the previous molding does not remain in the nozzle hole, and the skin layer of the molded product does not have a color difference portion or the like. It is an object of the present invention to provide a sandwich injection molding method and a sandwich injection molding injection head used for the same.

[Means for Solving the Problems]

In order to achieve the above object, the sandwich molding injection head of the present invention is such that an inner cylinder having an inner cylinder nozzle hole at the tip end is inserted through a torpedo in an injection head body provided with a nozzle tip having a nozzle hole at the tip end. By inserting and reciprocatingly moving in the axial direction, an outer passage is formed between the inner peripheral surface of the injection head body and the outer peripheral surface of the inner cylinder, and a tip notch is formed at the tip of the inner cylinder. By inserting a needle having a portion so as to be reciprocally movable in the axial direction, an inner passage is formed between the inner peripheral surface of the inner cylinder and the outer peripheral surface of the needle, and the inner cylinder is A second drive device for reciprocating between an outer passage closed position where the tip surface abuts the inner tip surface of the nozzle tip and an outer passage open position where the inner cylinder is separated from the inner tip surface of the nozzle tip by a predetermined distance. , The needle A first drive device for reciprocating between a position where the tip of the needle reaches the tip of the nozzle hole and a position where the tip of the needle does not come off from the inner cylinder nozzle hole of the inner cylinder in the outer passage open position It is a thing.

Further, the sandwich injection molding method of the present invention uses the above sandwich injection molding injection head, retracts the inner cylinder together with the needle to the outer passage open position to communicate the outer passage and the nozzle hole, and the outer passage to the skin layer. The forming molten resin is pressed into the mold to form a skin layer, and then the inner cylinder is advanced together with the needle to the outer passage closed position to block the nozzle hole from the outer passage, The core layer-forming molten resin is pressed into the mold to inject it into the mold to form the core layer wrapped with the skin layer, and then the inner cylinder is retracted again with the needle to the outer passage open position. To communicate the outer passage with the nozzle hole, press the molten resin for forming the skin layer into the outer passage and inject it into the mold to form the remaining skin layer, and then again After advancing the cylinder with the needle to the outer passage closed position, the needle is advanced to a position where the tip reaches the tip of the nozzle hole, thereby closing the inner cylinder nozzle hole and removing the residual molten resin in the nozzle hole. To remove.

[Action]

When the inner cylinder is retracted together with the needle by the driving of the second driving device and the inner cylinder is moved to the outer passage open position separated from the inner surface of the tip of the nozzle tip by a predetermined distance, the outer passage is communicated with the nozzle hole. In this state, the skin layer-forming molten resin can be pressed into the outer passage and injected into the mold to form the skin layer.

When the inner cylinder is advanced together with the needle by the drive of the second drive device and the tip of the inner cylinder is brought into contact with the inner surface of the tip of the nozzle tip (hereinafter, referred to as "outer passage closed position"), the outer passage and the nozzle hole. Are blocked and the outer passage is closed. However, since the inner passage and the inner cylinder nozzle hole are communicated with each other through the tip notch of the needle, the inner passage and the nozzle hole are communicated with each other.

In this state, the core layer forming molten resin can be pressed into the inner passage and injected into the mold to form the core layer.
When the needle is advanced to the position where the tip reaches the tip of the nozzle hole by the driving of the first driving device, the inner cylinder nozzle hole is closed and the residual molten resin in the nozzle hole is projected from the nozzle hole. Can be removed.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a nozzle tip 4 having a nozzle hole 4a at its tip is dividably coupled to the injection head body 1 by screw coupling or the like, and a skin side intermediate cylinder 13 and a skin side intermediate cylinder 13 at the rear end. The core side intermediate cylinder 14 is fixed. The skin-side intermediate cylinder 13 is connected to the skin-side injection cylinder 11, and the core-side intermediate cylinder 14 is connected to the core-side injection cylinder 12.

The nozzle tip 4 has a cylindrical shape with a conical shape at the tip end side where the nozzle hole 4a is formed, and behind the nozzle tip 4, a plurality of torpedo holes 5a are formed in an annular torpedo 5 in the axial direction. Is inserted, and the torpedo 5
An inner cylinder 2 having a conical tip end is slidably inserted in the inner hole 5b in the axial direction. As a result, an outer passage 15a is formed between the inner peripheral surface of the nozzle tip 4 and the injection head body 1 and the outer peripheral surface of the inner cylinder 2, and the outer passage 15a is electrically connected by the torpedo hole 5a.

Although the rear end of the outer passage 15a is axially sealed,
The skin-side intermediate cylinder 13 is communicated with the skin-side injection cylinder 11, and the molten resin for forming the skin layer flows into the outer passage 15 a through the skin-side intermediate cylinder 13.

On the other hand, the inner cylinder 2 has an inner cylinder nozzle hole 2b at the tip thereof, and a needle 3 having a plurality of tip notches 3a formed at the tip therein is slidably inserted in the axial direction. The inner passage 16 is formed between the inner peripheral surface of the inner cylinder 2 and the outer peripheral surface of the needle 3. The inner cylinder 2 has a rear end portion which supports the needle 3 in a sealed state so as to be slidable in the axial direction, communicates with the core side intermediate cylinder 14, and is press-fitted from the core side injection cylinder 12. The core layer forming molten resin flows into the inside road 16 through the core side intermediate cylinder 14.

A slide base 9 is integrally attached to the rear end of the inner cylinder 2, and the slide base 9 is slidably arranged in a direction of an arrow shown on a cylinder head 10 provided on a main body of an injection molding machine (not shown). There is. A support frame 9 is provided at the rear end of the slide base 9.
a is installed upright, and the first cylinder 7 is attached to the support frame 9a.
Is attached and the tip of a rod 7a provided integrally with the piston 7b is connected to the rear end of the needle 3. A support frame 10a is provided upright on the cylinder head 10, a second cylinder 8 is attached to the support frame 10a, and a tip of a rod 8a integrally provided with a piston 8b of the second cylinder 8 is attached to the slide base 9a. Is connected to the support frame 9a.

This makes it possible to independently reciprocate the needle 3 in the axial direction, or simultaneously reciprocate the inner cylinder 2 and the needle 3 in the axial direction to carry out each step described below.

As is clear from the above description, in this embodiment, the inner cylinder 2
The tip surface of the inner cylinder 2 is the tip inner surface 4b of the nozzle tip 4.
Second drive device 6b for reciprocating between an outer passage closed position in contact with the outer passage closed position and an outer passage opened position in which the inner cylinder 2 is separated from the tip inner surface 4b of the nozzle tip 4 by a predetermined distance.
Is composed of a second cylinder 8, a piston 8b, a rod 8a and a slide base 9. Also, needle 3
Drive for reciprocating between the position where the tip of the needle 3 reaches the tip of the nozzle hole 4a and the position where the tip of the needle 3 does not come off from the inner cylinder nozzle hole 2b of the inner cylinder 2 at the outer passage open position. The device 6a includes a first cylinder 7 and a piston 7b.
And a rod 7a.

However, the first drive device and the second drive device are not limited to those shown in the above embodiment, and other known reciprocating drive means such as a screw nut mechanism using a motor as a drive source may be used. Further, the first drive device and the second drive device may be arranged in parallel, and the inner cylinder 2 and the needle 3 may be configured to reciprocate individually, but in this case, the first drive device and the second drive device are arranged. A control means for synchronously starting each drive source of the drive device is required.

Next, each step of the sandwich injection molding method using the sandwich molding injection head of the present embodiment will be described.

As shown in FIG. 3 (A), pressurized fluid is supplied to the chambers on the left side of the first cylinder 7 and the second cylinder 8 in the drawing, respectively, and the piston 7b and the second cylinder 8 of the first cylinder 7 are supplied.
Both of the pistons 8b in the right direction in the drawing (hereinafter referred to as "retraction") to retract the inner cylinder 2 together with the needle 3, and the tip surface 2a of the inner cylinder 2 is separated from the tip inner surface 4b of the nozzle tip 4 by a predetermined distance. Move to the separated outer passage open position. In this state, the nozzle hole 4a and the outer passage 15a are communicated with each other, and the skin layer forming molten resin is pressed into the outer passage 15a through the skin side intermediate cylinder 13 from the skin side injection cylinder 11 and the nozzle hole 4a. Can be injected into the mold. On the other hand, the tip of the needle 3 is fitted into the inner cylinder nozzle hole 2c and does not come off.

In this state, the molten resin for forming the skin layer is press-fitted from the skin side injection cylinder 11 into the outer passage 15a so that the nozzle hole 4
A skin layer is formed by injection from a into a mold (not shown) (hereinafter referred to as "primary filling").

In this case, the inner side cylinder 2 and the needle 3 may be smoothly moved by sucking back the skin side injection cylinder 11 at the same time as the completion of the primary filling to depressurize the nozzle hole 4a and the outer passage 15a. .

Then, as shown in FIG. 3 (B), pressurized fluid is supplied to the chamber on the right side of the second cylinder 8 in the drawing, and the piston 8b of the second cylinder 8 is moved in the leftward direction in the drawing (hereinafter referred to as "forward"). .) And the needle 3 is advanced together with the inner cylinder 2 by advancing the slide base 9 via the rod 8a, and the tip surface 2a of the inner cylinder 2 is moved to the tip inner surface 4 of the nozzle tip 4.
abut b. In this state, the nozzle hole 4a is blocked from the outer passage 15a. On the other hand, the inner cylinder nozzle hole 2b and the nozzle hole 4a are communicated with each other, and the inner cylinder nozzle hole 2b and the inner passage 16 are communicated with each other through the tip notch 3a at the tip of the needle 3, so that the core side injection cylinder The molten resin for forming the core layer 12 can be pressed into the inner passage 16 through the core side intermediate cylinder 14 and injected into the mold through the nozzle hole 4a.

In this state, when the core layer forming molten resin is press-fitted into the inner passage 16 by the core side injection cylinder 12 and injected into the mold through the nozzle hole 4a, the core layer forming molten resin is primarily filled in the mold. The skin layer forming molten resin is spread from the inner side to the outer side to form a core layer wrapped in the skin layer.

After that, as shown in FIG. 3 (C), the second cylinder 8
A pressurized fluid is supplied to the chamber on the left side of the drawing, the piston 8b of the second cylinder 8 is retracted, and the slide base 9 is retracted via the rod 8a, whereby the inner cylinder 2 is retracted together with the needle 3 and It is moved to the outer passage open position similar to the state shown in FIG.

In this state, the molten resin for forming the skin layer is again pressed into the outer passage 15a from the skin side injection cylinder 11 and injected into the mold through the nozzle hole 4a. This step is to form a skin layer near the gate hole of the mold,
Only a short time is required, and the remaining skin layer is formed so as to cover the gate hole.

Next, as shown in FIG. 3 (D), the pressurized fluid is supplied to the chambers on the right side of the first cylinder 7 and the second cylinder 8 in the figure, so that the piston 7b of the first cylinder 7
Also, the piston 8b of the second cylinder 8 is advanced together to bring the tip end surface 2a of the inner cylinder 2 into contact with the tip end inner surface 4b of the nozzle tip 4 to block the nozzle hole 4a from the outer passage 15a.
Subsequently, only the piston 7b of the first cylinder 7 is further advanced to advance the needle 3 through the rod 7a until the tip of the needle 3 reaches the tip of the nozzle hole 4a. This allows
While the inner cylinder nozzle hole 2b is closed, the nozzle hole 4
The residual molten resin at the time of the previous molding remaining in a is ejected, and the resin remaining in the runner sprue portion in the mold is pushed into the mold, and at the same time, the residual molten resin in the nozzle hole 4a is removed.

〔The invention's effect〕

Since the present invention is configured as described above, it has the effects described below.

By simply moving the needle inserted into the inner cylinder to move forward, it is possible to remove the resin from the previous molding that remained in the inner cylinder nozzle hole of the inner cylinder and the nozzle hole of the nozzle tip. As a result of eliminating molding defects in a shape in which the resin is mixed with the resin for forming the skin layer, it is not necessary to coat the surface of the molded product after molding, and productivity is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the tip portion of the injection head body, and FIG. 3 shows the positions of the inner cylinder and needle in each molding step,
(A) is a cross-sectional view of an essential part showing a state where the inner cylinder is retracted to the outer passage open position together with the needle, and (B) is advanced the needle together with the needle so that the tip end surface of the inner cylinder contacts the inner conical surface of the nozzle tip. A main part cross-sectional view showing a contacted state, (C) is a main part cross-sectional view showing a state where the inner cylinder is retracted to the outer passage open position together with the needle, and (D) is an inner cylinder advanced together with the needle. FIG. 6 is a cross-sectional view of relevant parts showing a state in which the tip of the inner cylinder is brought into contact with the inner conical surface of the nozzle tip, and then the needle is advanced to a position where the tip reaches the tip of the nozzle hole of the nozzle tip. DESCRIPTION OF SYMBOLS 1 ... Injection head main body, 2 ... Inner cylinder, 2a ... Tip surface, 2b ... Inner cylinder nozzle hole, 3 ... Needle, 3a ... Tip notch, 4 ... Nozzle tip, 4a ... Nozzle hole, 4b ... Tip inner surface, 5 ... Torpedo, 5a ... Torpedo hole, 5b ... Inner hole, 6a ... 1st drive device, 6b ... 2nd drive device, 7 ... 1st cylinder, 8 ... 2nd cylinder, 7a, 8a ... Rod, 7b, 8b ... Piston, Reference numeral 9 ... Slide base, 9a, 10a ... Support frame, 11 ... Skin side injection cylinder, 12 ... Core side injection cylinder, 13 ... Skin side intermediate cylinder, 14 ... Core side intermediate cylinder, 15a ... Outer passage, 16 ... Inner passage.

Claims (2)

[Claims] 1. An inner cylinder (2) having an inner cylinder nozzle hole (2b) at the tip, in an injection head body (1) having a nozzle tip (4) having a nozzle hole (4a) at the tip. An outer passage (15a) is provided between the inner peripheral surface of the injection head main body (1) and the outer peripheral surface of the inner cylinder (2) by reciprocally moving in the axial direction via a torpedo (5). And a tip notch (3) is formed at the tip in the inner cylinder (2).
By inserting the needle (3) having a) so as to be reciprocally movable in the axial direction, the inner passage (16) is provided between the inner peripheral surface of the inner cylinder (2) and the outer peripheral surface of the needle (3). The inner cylinder (2), an outer passage closed position where the front end surface (2a) of the inner cylinder (2) abuts the front inner surface (4b) of the nozzle tip (4), and the inner cylinder (2). 2) a second drive device (6b) for reciprocating between the inner surface (4b) of the tip of the nozzle tip (4) and an outer passage open position separated by a predetermined distance; and the needle (3), The tip end of (3) is reciprocated between a position where it reaches the tip of the nozzle hole (4a) and a position where it does not come off from the inner cylinder nozzle hole (2b) of the inner cylinder (2) at the outer passage open position. And a first drive device (6a) for Molding injection head. 2. An injection head for sandwich injection molding according to claim 1, wherein the inner cylinder (2) is retracted together with the needle (3) to an outer passage open position to form an outer passage (15a) and a nozzle hole (4a). And the molten resin for forming a skin layer is pressed into the outer passage (15a) to be injected into the mold to form a skin layer, and then the inner cylinder (2) together with the needle (3) is connected to the outer passage (15a). The skin is advanced by advancing to the closed position, blocking the nozzle hole (4a) from the outer passage (15a), and injecting the core layer-forming molten resin into the inner passage (16) by injection into the mold, A core layer surrounded by layers is formed, and then the inner cylinder (2) is retracted to the outer passage open position together with the needle (3) so that the outer passage (15a) and the nozzle hole (4a) communicate with each other. , The outer passage (15a) After the remaining skin layer is formed by press-fitting the molten resin for forming the inner layer and injecting it into the mold, the inner cylinder (2) is advanced again together with the needle (3) to the outer passage closed position. A sandwich which removes residual molten resin in the nozzle hole (4a) by closing the inner cylinder nozzle hole (2b) by advancing the needle (3) to a position where its tip reaches the tip of the nozzle hole (4a). Injection molding method.