JPH07164484A - Shut off nozzle for sandwich molding - Google Patents

Abstract

PURPOSE:To provide a shut off nozzle for sandwich molding which can change the thickness of a skin layer by moving an inner nozzle and a core needle in two or three strokes at a changeable speed and adjusting the amount of a resin to be injected into a cavity in the course of injection. CONSTITUTION:Hydraulic cylinders 39, 43 of two or three stages for operating an inner nozzle 29 and a core needle 33 are used to adjust the movement of pistons engaged in the cylinders. In this way, since the amount of a core material to be injected into a skin material can be adjusted by operating the core needle 33 and the inner nozzle 29 with their operating strokes moved in two or three stages, the skin layer of the skin material is gradually expanded by the injection of the core material to change the skin layer's thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called sandwich-forming shutoff nozzle for performing two-layer molding with a skin layer and a core layer.

[0002]

2. Description of the Related Art A conventional sandwich molding shut-off nozzle 101, as shown in FIGS. 10 and 11, is an injection device (not shown) for molding a skin layer, an injection device for molding a core layer, and both injection devices. Similarly, a common nozzle hole 103 for injecting a plastic material in a softened state into a cavity (not shown), an injection device for molding a skin layer and a skin flow path for guiding the skin material 105 to the nozzle hole 103 are reciprocated. The inner nozzle 107 that is inserted as much as possible to open and close the skin flow path, and the core nozzle hole 1 from the injection device for molding the core layer that is in the inner nozzle 107.
It has a core needle 113 that is inserted into a core channel that guides the core material 111 to 09 so as to be capable of advancing and retracting and that opens and closes the core channel. In molding the sandwich molded product, first, the core nozzle 113 is used to close the core nozzle hole 109, the nozzle hole 103 is opened, and the skin material 105 is injected into the cavity in a short shot state for a predetermined time from the start of injection. Core nozzle hole 109 after elapse of t
The core material 1 inside the skin material 105 that is injected in a short shot state into the cavity by opening the
11 is injected to fill the entire cavity, and finally a product in which the core material 111 is covered with the skin layer of the skin material 105 is formed.

[0003]

However, since the inner nozzle 107 and the core needle 113 both open and close their respective flow paths in the first-stage strokes L and I, the skin layer of the molded product does not have a constant thickness. The characteristics of the molded product could not be maintained.

That is, since the temperature of the resin material in the cavity is high on the gate side and decreases toward the end, the skin layer tends to gradually become thinner from the cavity end to the gate side, and the inner nozzle 107 that has been once opened or closed, or the inner nozzle 107. The core need 113 could not adjust the amount of resin material injected into the cavity during injection, and could not change the thickness of the skin layer.

The object of the present invention is to eliminate the above-mentioned drawbacks, to move the inner nozzle and the core needle respectively in a two-step stroke or a three-step stroke, and to make the moving speed variable so as to inject the amount of resin material to be injected into the cavity. The purpose of the present invention is to provide a shut-off nozzle for sandwich molding in which the thickness of the skin layer formed on the surface of the molded product can be freely changed by adjusting the above.

[0006]

In order to achieve the above object, the present invention provides an injection device for molding a skin layer, an injection device for molding a core layer, and a plastic material softened in the cavity from both injection devices. A common nozzle hole for injecting the skin layer, an inner nozzle that is inserted into the skin channel between the injection device for molding the skin layer and the nozzle hole so that the skin channel can be opened and closed, and the inner nozzle There, a core needle that is inserted into a core channel that guides the core material from the injection device for molding the core layer to the nozzle hole so as to be able to advance and retreat, and that opens and closes the core channel, and the forward and backward operation of the inner nozzle and the core needle. In a sandwich molding shut-off nozzle having a cylinder for performing the above, and a hydraulic circuit connected to the cylinder, the opening / closing stroke of the core needle is It was shut off nozzle, characterized in that controlling a two-step opening by an amount predetermined fully opened to open the nozzle hole all the half-open.

Further, instead of controlling the opening / closing stroke of the core needle in two stages, half-opening can be controlled in two stages, and the control can be performed in three stages as a whole. Then, the core needle can be moved from the fully opened position where the nozzle hole is fully opened to the half opened position where the nozzle hole is half opened at an arbitrary timing during injection. Further, the shut-off nozzle is characterized in that the core needle is moved from the half open position to the full open position instead of moving from the fully open position to the half open position.

[0008]

The opening and closing strokes of the core needle and the inner nozzle can be controlled in two steps of full opening for fully opening the nozzle hole and half opening for opening a predetermined amount, or in two steps of half opening, and can be controlled in three steps as a whole. Since the amount of the core material injected into the skin material can be adjusted, the thickness of the skin layer that is gradually thinned on the surface of the molded product can be changed by the core material injected into the skin material. .

[0009]

1 to 5, an injection molding machine 1 is composed of an injection device 3 and a mold clamping device 5, and the injection device 3 includes a skin injection device 7 and a core injection device 9. It consists of Further, the mold clamping device 5 has a fixed die plate 11
And a movable die plate 13 that is movable in the left-right direction in FIG. 1 with respect to the fixed die plate 11. Moving die plate 1 relative to fixed die plate 11
In the state where the mold 3 is clamped (state of FIG. 1), the fixed die plate 11 and the movable die plate 13 form a cavity 15.

A skin material S is provided in the skin injection device 7.
A rotatable screw 17 for inflowing is introduced, and a skin flow path 19 is formed on the outer peripheral portion of the screw 17. Similarly, a rotatable screw 21 for inflowing the core material C is inserted into the core injection device 9, and the core passage 2 is provided on the outer peripheral portion of the screw 21.
3 is formed.

An outer nozzle 25 is provided at the tip of each of the skin injection device 7 and the skin injection device 9.
The cavity 15 is provided at the tip of the outer nozzle 25.
A common nozzle hole 27 for injecting the softened plastic material is provided therein. The outer nozzle 2
An inner nozzle 29 that can move forward and backward is inserted in the unit 3. A skin passage 31 through which the skin material S flows is formed on the outer circumference of the inner nozzle 29 and the inner circumference of the outer nozzle.
It communicates with the skin flow path 19.

A core needle 33 capable of advancing and retracting is inserted in the inner nozzle 29. This core needle 3
A core nozzle hole 35 is provided at the tip of the nozzle 3. A core passage 37 through which the core material C flows is formed between the outer periphery of the core needle 33 and the inner periphery of the inner nozzle 29. The core passage 37 communicates with the core nozzle hole 35 and the core passage 23. Has been done.

At the rear end (right end in FIG. 1) of the inner nozzle 29, a core needle advance / retreat control hydraulic cylinder 39 is provided.
And a piston 41 is mounted in the core needle advance / retreat control hydraulic cylinder 39, and is integrated at the rear end of the core needle 33.
Moreover, an oil chamber 43 for retracting the core needle and an oil chamber 45 for advancing the core needle are formed across the piston 41.

An inner nozzle advancing / retreating control hydraulic cylinder 4 is provided at the rear of the core needle advancing / retreating control hydraulic cylinder 39.
7 is provided. A piston 49 is mounted in the inner nozzle advancing / retreating hydraulic cylinder 47, and the inner nozzle retracting oil chamber 51,
An oil chamber 53 for advancing the inner nozzle is formed.

A half-opening control piston 55 is mounted in the core needle retreating oil chamber 45, and a half-opening oil chamber 57 is formed in the rear portion of the half-opening control piston 55.

With the above configuration, the core needle advancing oil chamber 45 of the core needle advancing / retreating control hydraulic cylinder 39 and the inner nozzle retreating oil chamber 51 of the inner nozzle advancing / retreating control hydraulic cylinder 47 are not shown in FIG. By applying pressure oil from the hydraulic circuit, the piston 41 fixed to the rear end of the core needle 33 is pressed toward the nozzle side (left direction in the drawing), the core needle 33 closes the core nozzle hole 35 in the inner nozzle 29, and the inner nozzle 29 Piston 49 provided at the rear end is on the side opposite to the nozzle (rightward in the figure)
Then, the inner nozzle 29 is retracted from the nozzle hole 27 and the nozzle hole 27 is fully opened, and the skin injection device 7 starts the injection of the skin material S into the mold cavity 17.

As shown in FIGS. 2 and 6, the skin material S
When a predetermined time T1 has elapsed from the start of injection, the pressure oil acts on the core needle retreating oil chamber 43 of the hydraulic cylinder 39 to move the piston 41 to the right in the drawing,
Core injection hole 9 with core nozzle hole 35 fully open
Then, the core material C is injected into the skin material S that has been injected in the mold cavity 17 in a short shot state.

As shown in FIGS. 3 and 6, the skin material S
When a predetermined time T2 has elapsed from the start of injection, the pressure oil acts on the core needle retreat oil chamber 43 and the half-opening oil chamber 57 of the core needle advancing / retreating control hydraulic cylinder 39 to move the core needle 33 for a predetermined stroke. While moving backward (to the right in the figure), the half-opening control piston 55, which has been pressed to the rear end of the core needle forward / backward control hydraulic cylinder 39, is moved forward by a predetermined amount (to the left in the figure).
Then, the core nozzle hole 35 is opened by a predetermined amount, and the core material C is injected into the mold cavity 17 as a so-called half-opening.
Is adjusted to compensate for the drawback that the thickness of the skin layer Sa formed on the surface of the product formed in the mold cavity 17 becomes gradually thinner from the cavity end to the gate side as described above.

Subsequently, as shown in FIGS. 4 and 6, when a time t1 has elapsed from the start of injection of the skin material S, pressure oil acts on the inner nozzle advancing oil chamber 53 of the inner nozzle advancing / retreating control hydraulic cylinder 47 to cause the piston 49, That is, the inner nozzle 29 is pushed toward the nozzle to close the nozzle hole 27, the supply of the skin material S to the mold cavity 17 is stopped, and only the core material C is supplied from the half-open core nozzle hole 35.

Further, as shown in FIGS. 5 and 6, when time t2 elapses from the start of injection of the skin material S, pressure oil acts on the core needle advancing oil chamber 45 of the core needle advancing / retreating control hydraulic cylinder 39. The piston 41 advances to close the core nozzle hole 35 in which the core needle 33 is half-opened, and pressure oil acts on the oil chamber 51 for retreating the inner nozzle of the hydraulic cylinder 47, causing the piston 49 to retreat and the inner nozzle 29 to open the nozzle hole 27. Is opened for a predetermined time t3, the supply of the core material C into the mold cavity 17 is stopped, and only the skin material S is supplied from the reopened nozzle hole 27 to the runner portion of the mold cavity 17, and the product material pouring is performed. It covers the core material C exposed at the inlet.

In the above description, the opening / closing stroke of the core needle 33 is switched depending on the time from the start of the injection of the skin material S, but this switching is not limited to this, and the arbitrary timing during injection, for example, the timing shown in the following items. Can be done at. When the screw position from the start of injection reaches the specified position. When the injection speed reaches a preset speed. When the injection pressure reaches a preset set pressure. When the mold cavity pressure reaches a preset pressure. When the mold opening amount reaches a preset value. Etc.

The opening / closing stroke can be varied as shown in FIG. 7 by connecting the core needle 33 to the piston 41 via the connecting portion 57.

That is, a flange 59 is provided at the rear end of the core needle 33, a threaded portion 63 is provided at the tip of the rod 61 of the piston 41, nuts 65 and 67 are screwed together, and a flange 69 and nuts 65 and 6 are coupled by a coupling 69.
7 is inserted and joined, and the tip of the rod 61 and the flange 59
The gap δ formed between the pistons 41 fixed to the rod 61 by the nuts 65 and 67 is not shown in the figure to the core needle advance / retreat control hydraulic cylinder 39 to which the piston 41 is slidably fitted. The half-open position can be adjusted by causing pressure oil to act from the hydraulic circuit to move the piston 41 back and forth.

Although the above description has been made with respect to the control for changing the core needle 33 from full open to half open, conversely, the control from half open to full open can of course be performed at any timing during injection as described above.

Further, if a flow rate control valve is provided in the pressure oil circuit acting on the hydraulic cylinder 39, the moving speed of the core needle 33 can be made variable.

Although the above description has described the core needle 33, the inner needle 29 may be used instead of the core needle 33, and the same control as described above can be performed. As for the opening / closing stroke of the inner nozzle 29, as shown in FIG. 8, the half-opening control piston 55 is provided in the hydraulic cylinder 71 so as to face the rear end surface 49C of the piston 49 that controls the forward / backward movement of the inner nozzle 29. A half-open stroke adjusting rod 73 is screwed into the inside of the half-opening control piston 55 via a screw portion 75 so that a length δ protruding from an end surface 49D of the half-opening control piston 55 facing the piston 49 can be adjusted. The position is fixed by a matching nut 77.

The case where the opening / closing stroke of the core needle 33 and the inner nozzle 29 is controlled in two steps has been described above, but the opening / closing stroke is not limited to this, and the opening / closing stroke may be controlled in three steps. In this case, as shown in FIG. 9, a hydraulic cylinder 79 and its piston 81 may be further provided behind the half-opening control piston 55 to form a second half-opening piston 81.

[0028]

As described above, the opening and closing strokes of the core needle and the inner nozzle are 2 or 3 respectively.
Since the amount of the core material injected into the skin material can be adjusted by changing the moving speed in stages, and the moving speed can be varied, the skin material gradually changes according to the core material injected into the skin material. The thickness can be changed as it is expanded.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, showing a state where a nozzle hole is fully opened and a skin material is injected into a mold cavity in a short shot state.

FIG. 2 is a diagram showing the next step of FIG. 1, showing a state in which the core nozzle holes are fully opened and the core material is injected into the skin material in the short shot state.

FIG. 3 is a diagram showing the next step of FIG. 2 and is a diagram showing a state where the core needle is half-opened.

FIG. 4 is a diagram showing the next step of FIG. 3, showing a state in which the nozzle hole is closed, the supply of the skin material is cut off, and only the core material is supplied.

FIG. 5 is a diagram showing the next step of FIG. 4, showing a state in which the supply of the core material is cut off and the skin material is injected again into the exposed portion of the core material of the molded product.

FIG. 6 is a diagram showing the open / closed state of nozzle holes and core nozzle holes, and the relationship between injection speed and injection time.

FIG. 7: Method 1 for adjusting the opening / closing stroke of the core needle
It is a figure which shows an Example.

FIG. 8: Method 1 for adjusting the opening / closing stroke of the inner nozzle
It is a figure which shows an Example.

FIG. 9 is a diagram showing an example of the present invention, and is a diagram showing an example in the case of controlling the opening / closing slosh of the core needle in three stages.

FIG. 10 is a diagram showing a conventional shut-off nozzle.

FIG. 11 is a diagram showing a relationship between an opening / closing state of a conventional nozzle hole and a core nozzle hole, and an injection speed and an injection time.

[Explanation of symbols]

 1 Injection Molding Machine 3 Injection Device 5 Mold Clamping Device 7 Skin Injection Device 9 Core Injection Device 15 Cavity 27 Nozzle Hole 29 Inner Nozzle 33 Core Needle 35 Core Nozzle Hole 39 Core Needle Advance Hydraulic Cylinder 41 Piston 43 Core Needle Backward Oil Chamber 45 Core Needle Advance Oil Chamber 47 Inner Nozzle Advance / Retract Control Hydraulic Cylinder 49 Piston 51 Inner Nozzle Retract Oil Chamber 53 Inner Nozzle Advance Oil Chamber 55 Half Open Control Piston

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Nakayama 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Denko K.K.

Claims (7)

[Claims] 1. An injection device for molding a skin layer, an injection device for molding a core layer, a common nozzle hole for injecting a softened plastic material into a cavity from both injection devices, and the skin layer molding. Inner nozzle for opening and closing the skin flow passage inserted in the skin flow passage between the injection device for injection and the nozzle hole, and the injection device for molding the core layer in the inner nozzle to the nozzle hole A core needle that is inserted into a core channel that guides a core material so as to be capable of advancing and retreating to open and close the core channel, a cylinder for performing an advancing and retracting operation of the inner nozzle and the core needle, and a hydraulic circuit connected to the cylinder. In the shut-off nozzle for sandwich molding, the opening / closing stroke of the core needle is fully opened to fully open the nozzle hole and half opened to a predetermined amount. A shut-off nozzle for sandwich molding, which is controlled in two stages. 2. The shut-off nozzle for sandwich molding according to claim 1, wherein the half-opening is further changed to two stages instead of the two-stage control of the stroke, and the stroke is controlled in three stages as a whole. 3. The sandwich according to claim 1, wherein the core needle is moved from a fully opened position where the nozzle hole is fully opened to a half opened position where the nozzle hole is half opened at an arbitrary timing during injection. Shut-off nozzle for molding. 4. The sandwich molding shutt according to claim 1, wherein the core needle is moved from a half-open position to a full-open position instead of moving the core needle from the fully-open position to the half-open position. Off nozzle. 5. The shut-off nozzle for sandwich molding according to claim 1, wherein the half-open position can be variably set. 6. The shut-off nozzle for sandwich molding according to claim 1, wherein the moving speed of the core needle is variable. 7. The shut-off nozzle for sandwich molding according to claim 1, wherein an inner nozzle is used instead of the core needle.