JPS60212315A - Double-layers injection molding machine - Google Patents

Abstract

PURPOSE:To provide an injection molding machine which enables a double-layer molding simultaneously with one mold cavity by arranging a resin injection nozzle in a double construction, inner and outer, while the inner nozzle is movable forward and backward and a valve is provided to stop the injection from the inner nozzle. CONSTITUTION:The tip of an inner nozzle 13 is made movable forward and backward with respect to an outer nozzle while a valve rod 14 is provided to stop injection closing a nozzle hole 10 of the inner nozzle 13. An outer nozzle 10 is pressed on a nozzle hole running through a cavity 22 of an outer die 4 while the inner nozzle 13 advances to a part of the cavity 22, a condition under which a resin is injected both from between 13c the outer nozzle 10 and the inner nozzle 13 and an internal hole 13b of the inner nozzle 13. When the resin almost fills the cavity 22, the inner hole 13b is closed with the valve rod 14 while the inner nozzle 13 is retracted so that the tip thereof flushes the outer nozzle 10. Then, external resin alone is injected to complete the molding.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection molding apparatus for performing two-layer molding of a molded article in the field of plastic molding.

(Conventional technique 10:) Conventionally, to perform two-layer molding, the outer layer was first injected, as in step 4 of molding key tops of a typewriter, and then the outer layer molded product was held in the male die of the mold and rotated. There is a method in which the outer layer is injection molded in a separate mold cavity.

(Object of the Invention) The present invention provides a novel apparatus for performing two-layer molding by simultaneously injecting two types of resin into one mold cavity.

(#1 composition of the invention) The present invention performs 2N injection molding by advancing and retracting the nozzle.
This is a device that performs φ in two cavities.

(Embodiment 1. Example) An example will be described according to the drawings. 1 in the 1st □□□
2 is a fixed plate fixed to the machine base, and 2 is a movable plate that reciprocates along the stay 8. 4 is a fixed side mold fixed to a fixed platen l, and 5 is a four movable side mold fixed to a movable platen. 6 is a first heating cylinder that melts the inner layer, 7 is a second heating cylinder that melts the outer layer, 8 is a first screw that rotates and reciprocates within the first heating cylinder 6, and 9 is a second heating cylinder. This is a second screw that rotates and reciprocates within the heating cylinder 7. IO is a nozzle body, 10a is an inner hole of the nozzle body IO (hereinafter referred to as the nozzle body inner hole), and 11 is a first resin passage that communicates the molten resin in the first heating cylinder 6 with the nozzle body inner hole 10a. 12 is a second resin passage that communicates the molten resin in the second heating cylinder 7 with the nozzle body inner hole 10a. Reference numeral 13 denotes an internal nozzle movably pushed into the nozzle body inner hole 10a of the nozzle body 1o. 14 is the tip hole 1 of the internal nozzle 13
It is a valve stem for opening and closing 3a, and penetrates through the center of the internal nozzle 13. 15 is the inner hole 1B of the internal nozzle 13
'b and the outer diameter of the valve stem 14,
It can communicate with the first resin passage 11. A second cavity 16 is provided between the nozzle body inner hole 10a and the outer diameter 18c of the tip of the internal nozzle 13, and can communicate with the second resin passage 12. 17 is a cylinder connected to the nozzle body 1o, and the 1 cylinder 17 has a first cylinder chamber 18 and a second cylinder chamber 18.
It consists of a cylinder chamber 19, in which the rear end piston portion 18d of the internal nozzle 18 is inserted and fitted into the first cylinder chamber 18, and the piston FA14C of the valve rod 14 is fitted into the second cylinder chamber 19. Numeral 20 is a nut that determines the forward limit of the valve stem, and is screwed onto the rear end of the valve stem 14. 21 is a bolt that determines the retraction limit of the valve stem 14.

Next, the operation will be explained. Move the movable platen 2': i: forward to close the mold, let oil flow into the oil hole 18a of the first cylinder chamber 18 using a pump (not shown), and move the internal nozzle 13 forward to close the tip of the internal nozzle. Protrude into the mold cavity to a predetermined position. By adjusting this position, the thickness of the layer can be changed. At this time, the valve rod 14 is in the retracted position, leaving the inner hole 13b of the internal nozzle 13 open. Next, the resin melted in the first heating cylinder 6 is injected by advancing the first screw 8, and the first layer resin 23 is injected into the mold cavity 22 from the first cavity 15 through the first resin passage 11. At the same time, the molten resin in the second heating cylinder 7 is injected by advancing the second screw 9, and passes through the second resin passage 12 to the second resin.
24″ft of second layer resin from void 16: mold cavity 2
Inject into 2. In the present invention, the thickness of the second layer resin 24 is determined by the position where the tip of the internal nozzle 18 protrudes into the mold cavity 22. After injecting a predetermined amount of the first layer resin 23 and the second layer resin 24, oil is caused to flow into the oil hole 19a in the second cylinder chamber 19, and the valve stem 14 is advanced to open the tip hole 18a of the internal nozzle. Close, then inner nozzle 1
3 to the 4th UA with the tip hole 18a closed by the valve stem 14.
As shown in the figure, the tip of the internal nozzle 13 is moved back, and a small amount of the second M resin 24 is injected from the second cavity 16 through a small gap on the outside of the tip of the internal nozzle 13 to replenish the filled part and molded. After holding the pressure until the product cools down, open the mold and remove the molded product.

(Effects) The present invention makes it possible to carry out two-layer molding by simultaneously injecting two types of resin, completes the molding in a short cycle, and adjusts the thickness of the layers. be.

[Brief explanation of drawings]

The first figure is a front view including a partial sectional view of the device showing an embodiment of the present invention, and FIGS. 2N to 4 are enlarged sectional views of main parts showing the operating state. 1: Fixed plate 2: Movable plate 6: 1st heating theory 7: 2nd heating cylinder 1O: Nozzle body 11: 1st resin passage 12: 2nd resin passage 13 2nd internal nozzle 14: Valve 17: Cylinder 18: No. 1 cylinder chamber 19: 2nd cylinder chamber applicant
Nagomi Seisakusho Co., Ltd.

Claims (1)

[Claims] The fixed plate, which is fixed to the machine base and which attaches the fixed side mold, and the movable plate, which attaches the movable side mold, reciprocate along the stay, and the mold clamping device that clamps the mold and injects molten resin into the mold cavity. An internal nozzle is inserted into the internal hole of the nozzle body, and the internal nozzle and the first resin passage communicating with the first heating cylinder can be opened or closed by reciprocating movement of the internal nozzle. The passage between the inner hole of the main body and the outer periphery of the inner nozzle and the second resin passage communicating with the second heating cylinder can be opened or closed by the reciprocating movement of the inner nozzle, and the tip of the inner nozzle is inserted into the mold cavity. A two-layer injection molding machine characterized in that the internal nozzle is advanced to a predetermined position and the inner hole of the internal nozzle is closed at the tip of the valve stem.