JPH07148786A - Injection molding apparatus - Google Patents

Abstract

PURPOSE:To provide an injection molding apparatus by which the color and kind of resin of a molded product can be easily changed by easily and rapidly removing the old resin remaining in the mold apparatus and eliminating the wastefulness of resin/time. CONSTITUTION:In an injection mold wherein a gate 7 is opened and closed by the needle valve 16 provided in the resin passage 13 opened to a heat insulating space in a vertically movable manner and the alignment of the needle valve with the gate 7 is performed by the outside diameter of the needle valve 16 and the inside diameter of the resin passage 13 in the vicinity of the gate 7, at least one groove 21 for allowing a molten resin to flow back to the outer periphery of the needle valve 16 is provided and the space excepting the resin passage 13 of the heat insulating space 11 is filled with a heat insulating material composed of a non-meltable material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an injection molding die device for opening and closing a gate with a needle valve.

[0002]

2. Description of the Related Art An injection molding die apparatus for opening and closing a gate with a needle valve is disclosed in, for example, Japanese Patent Laid-Open No. 59-15073.
No. 6 is proposed. FIG. 3 is a vertical cross-sectional view of a conventional injection molding die apparatus having the above-described structure, and FIG. 4 is an enlarged view of the main parts thereof.

The injection molding die apparatus 1 comprises a fixed die plate 2, a movable die plate 3 and a drive unit 4. The movable mold plate 3 is processed by a male mold and is supported so as to be movable up and down with respect to the fixed mold plate 2 which is processed by a female mold, and between the movable mold plate 3 and the fixed mold plate 2. A cavity 5 having a shape corresponding to the molded product is formed.

A recess 6 is formed on the upper surface of the fixed mold plate 2,
A gate 7 that opens to the cavity 5 is formed at the bottom of the recess 6.

Further, the runner member 8 and the drive unit 4 are attached to the fixed mold plate 2, and the drive unit 4 is arranged above the runner member 8. The runner member 8 is formed with a distribution resin passage 10 which communicates with an injection nozzle (not shown).

The nozzle bush 9 is constructed by integrally assembling an inner cylinder portion 9a and an outer cylinder portion 9b, and comprises a runner member 8
The heat insulating space 11 having a predetermined size is formed below the inside of the recess 6 while being located inside the recess 6 while being attached to the fixed mold plate 2.

A band heater 12 is wound around the outer periphery of the nozzle bush 9, and a resin passage 13 that vertically penetrates the nozzle bush 9 and the runner member 8 is formed by branching from the distribution resin passage 10.

The band heater 12 is connected to a heater drive circuit (not shown), and heat is supplied by power supply from the heater drive circuit to heat the resin in the resin passage 13.

The resin passage 13 is provided at its lower end with a guide member 14 having a conical shape for reducing the center, and the guide member 14 is separated from the resin passage 13 by 120 degrees as shown in FIG. And three grooves 15 are evenly formed in the vertical direction.

A needle valve 16 is vertically movably inserted through the resin passage 13 through a guide bush (not shown).

The needle valve 16 has a resin passage 1 at the top.
The large diameter portion 16a loosely inserted into the large diameter portion 13a of No. 3 has a small diameter portion 16b (diameter: D1) which can be fitted to the small diameter portion 13b (diameter: D2) in a substantially liquid-tight manner in the lower portion. A gate seal portion 16c capable of opening and closing the gate 7 is formed at the lower end of the portion 16b.

Liquid-tight fitting is possible because the diameter D1 of the small diameter portion 16b of the needle valve 16 and the resin passage 13 are set.
This is because the diameter D2 of the small-diameter portion 13b is exactly D1 <D2, but is substantially equal (see FIG. 2).

The needle valve 16 has its upper end inserted through an insertion hole 17 formed in the runner member 8 and engages with the drive unit 4 to be driven by the drive unit 4, and is vertically displaced to move the gate 7 at the lower end. Open and close.

As the drive unit 4, for example, an air cylinder having a conventionally known structure can be used.

Since the conventional injection molding die device has the above-mentioned structure, when the needle valve 16 is lowered to close the gate 7 opening to the cavity 5,
Even if the needle valve 16 is biased as shown by the alternate long and short dash line in FIG. 4, the step portion 16d of the small diameter portion 16b that serves as a guide of the needle valve 16 contacts the conical surface 18 of the guide member 14, and the gate seal of the needle valve 16 is formed. The portion 16c does not come into contact with the conical surface 18 of the guide member 14.

Further, as shown by the chain double-dashed line in FIG. 4, the needle valve 16 is moved down while the small diameter portion 16b of the needle valve 16 is liquid-tightly fitted with the small diameter portion 13b of the resin passage 13 to close the gate 7. Then, the resin 19 which has nowhere to go on the tip side of the needle valve 16 flows backward through the three grooves 15 formed in the guide member 14 to prevent overfilling by the gate 7 and to prevent a molded product. Reduce the residual stress of.

[0017]

However, if a color change or a resin change is attempted by using the above-mentioned injection molding die device, the following inconvenience occurs.

When the needle valve 16 is lowered and the gate 7 is closed to change the color or the resin, the groove 15 is closed.
The resin that has flowed back through the needle valve 16 and has no place to go on the tip side of the needle valve 16 easily adheres to the wall surface 20 of the groove 15 and remains.

This is because the temperature of the portion of the guide member 14 adjacent to the heat insulating space 11 which is adjacent to the heat insulating space 11 as the heat insulating space 11 is cooled, in other words, the temperature of the resin of the portion 14a which is in contact with the wall surface 15 of the groove 15. Is due to the decrease of.

On the other hand, the nozzle bush 9 having the resin passage 13 inside which the needle valve 16 is inserted
Is heated from the outside by the band heater 12, and the heated resin in the resin passage 13 is in a completely molten state. Therefore, a resin different from the resin currently being supplied into the mold is supplied. At this time, the previous resin in the resin passage 13 can be completely extruded.

However, the nozzle bush 9 and the fixed mold plate 2 are
The heat insulating space 11 formed between the fixed plate molds 2 (generally, the fixed plate molds 2 are provided with cooling holes (not shown)).
Since the resin is cooled by the resin passage 13, the resin flowing into the heat insulating space 11 is normally in a solidified state because the heat insulating space 11 is in contact with the fixed plate mold 2.

However, since the heat insulating space 11 is also in contact with the resin passage 13 through which the high temperature resin flows, the resin passes through the resin passage 1
In the vicinity of 3, the resin is in a molten state, and the temperature of the resin decreases as the distance from the resin passage 13 increases, and the resin is in a semi-molten state or a solidified state.

Therefore, even when new resin is supplied for color change or resin change, the semi-molten old resin stays in the heat insulating space 11, and it is difficult to completely flush the old resin.

That is, the old semi-molten resin staying in the heat insulating space 11 and the resin adhering to the groove 15 (wall surface 20) of the guide member 14 make it impossible to change the color and the resin easily and quickly. It wastes resin and time.

The present invention has been made in order to solve the above problems. It is possible to easily and quickly remove old resin remaining in a mold device to easily change the color or resin of a molded product. An object of the present invention is to provide a mold device for injection molding that eliminates waste of time.

[0026]

In order to solve the above problems, an injection molding die according to the present invention is an injection mold in which a gate is opened and closed by a needle valve vertically movable in a resin passage opening to a heat insulating space. A molding die, in which the needle valve and the gate are aligned with each other by an outer diameter of the needle valve and an inner diameter of a resin passage near the gate, in which a molten resin is caused to flow back to the outer periphery of the needle valve. At least one groove is provided, and a space other than the resin passage in the heat insulating space is filled with a heat insulating material made of a non-melting material.

[0027]

In the injection molding die device according to the present invention, since the heat insulating space is filled with the non-melting material to form the heat insulating layer, the semi-melted layer does not occur in the heat insulating space.

Further, since the needle valve is heated in the molten resin at high temperature, when the needle valve is lowered to close the gate, the resin on the needle valve tip side where there is no place to go will be in the groove formed in the needle valve. Immediately flows back without sticking to the wall surface and remaining.

Therefore, the color change and the resin change can be performed easily and promptly, and the waste of resin and time is eliminated.

[0030]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic sectional view of an injection molding die apparatus according to the present invention.

The structures of the movable mold plate 3 and the driving device 4 of the injection molding die device 1 are the same as those of the conventional one, and therefore the description thereof will be omitted.

In the present invention, the fixed mold plate 2 arranged facing the movable mold plate 3 has the following structure.

In this embodiment, the conventional guide member 1 is used.
Instead of the groove 15 provided in FIG. 4, a plurality of grooves 21 extending in the vertical direction are provided around the small diameter portion 16b of the needle valve 16 which is always in high temperature molten resin.

In addition, the heat insulating space 11 from the conventional runner member side
Insulation space 11 formed by resin flowing into
Was filled with a material that does not produce a semi-molten state.

A material having a high heat insulating property such as a thermosetting resin or a ceramic is used as a material which does not cause a semi-molten state, and a shape matching the heat insulating space 11 excluding the resin passage 13 so that a step is not formed in the resin passage 13. And is integrally assembled with the fixed mold plate 2 and the nozzle bush 9 (see FIG. 1).

In the above structure, first, the needle valve 16 is lowered to close the gate 7, and the needle valve 1 is closed.
The resin that has gone to the tip side of the needle valve 16 flows backward through the groove 21 provided in the small diameter portion 16b of No. 6 without any delay.

After that, the needle valve 16 is raised to open the gate 7, a new resin is supplied and the resin is extruded together with the old resin which has flowed back.

By this operation, the old resin is quickly extruded, so that a new resin or a new color can be easily changed without wasting time and resin.

In addition, since the groove is formed in the needle valve 16, the groove 15 which is formed in the guide member 14 in the related art is formed.
Is unnecessary.

Further, the guide member 1 in which the groove 15 is unnecessary
4 may be formed integrally with the nozzle bush 9. In addition,
Each of the above operations is preferably controlled by a program using a sequencer or a microcomputer.

[0041]

As described above, in the injection molding die device according to the present invention, the heat insulating layer is made of a material that does not melt, and the needle valve in the hot molten resin is provided with a groove for backflowing the resin. Formed.

Therefore, the resin layer in a semi-molten state can be eliminated, and the resin can be left in the groove (wall surface) even when backflowing.
Therefore, it is possible to easily and promptly perform color change and resin change with a new resin and reduce waste of resin and time.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an injection molding die device according to the present invention.

FIG. 2 is a cross-sectional view of an essential part for explaining the relationship between a needle and a guide member of a conventional injection molding die device.

FIG. 3 is a vertical cross-sectional view of a conventional injection molding die device.

FIG. 4 is an enlarged view of a main part of a conventional injection molding die device.

FIG. 5 is a plan view showing a state in which a guide member is inserted.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Injection molding die device, 2 ... Fixed mold plate, 3 ... Movable mold plate, 4 ... Driving device, 5 ... Cavity, 6 ... Recessed part, 7 ... Gate, 8 ... Runner member, 9 ... Nozzle bush, 9a ... Inner cylinder member, 9b ... Outer cylinder member, 10 ... Distribution resin passage, 11 ...
Heat insulation space, 12 ... Band heater, 13 ... Resin passage, 13
a, 16a ... Large diameter part, 13b, 16b ... Small diameter part, 14 ...
Guide member, 15, 21 ... Groove, 16 ... Needle valve,
16c ... Gate seal part, 16d ... Step part, 17 ... Insertion hole, 18 ... Conical surface, 19 ... Resin, 20, 22 ... Wall surface.

Claims (1)

[Claims] 1. A mold for injection molding in which a gate is opened and closed by a needle valve that is vertically movable in a resin passage open to a heat insulating space, and the needle valve and the gate are aligned with each other. In an injection-molding die that uses an outer diameter and an inner diameter of a resin passage near the gate, at least one groove is provided on the outer periphery of the needle valve for backflowing the molten resin, and a space of the heat insulating space excluding the resin passage. A mold apparatus for injection molding, characterized in that a heat insulating material made of a non-melting material is filled in.