JPH05261769A - Hot-runner mold - Google Patents

Abstract

PURPOSE:To prevent gate marks or injector pin marks from being produced on the top or the side of a molded product, by a method wherein a heater is arranged by laying a manifold respectively in a stationary side of a mold and a movable mold and a gate of a movable side manifold and an injector pin are provided on the rear side of the molded product. CONSTITUTION:A movable side core is fixed to a movable retainer plate and a movable side manifold 8 is fixed to the movable side core by a bolt. An injector pin 13 is penetrated through a movable retainer plate and core and arrives at a cavity 12. A stationary side core 5 is fixed to a retainer plate. A stationary side manifold 1 is fitted to a top plate, a gap is provided between the stationary side manifold and the stationary side core 5 and made into a heat insulated condition. A resin path 10 is formed in the manifolds 1, 8, heaters 3, 15 are laid into the manifolds 1, 8 along the resin path 10. A gate 4 of the resin path 10 is connected with the rear of the cavity 12 and a parting line part of the resin path 10 is made into a form of an undercut.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate system in a hot runner for injection molding.

[0002]

2. Description of the Related Art A conventional hot runner die will be described with reference to FIG. Fixed side mounting plate 7 of hot runner die 70
A locate ring 72, on which a nozzle (not shown) of an injection molding machine is set, is attached to the upper surface 1, and fixed side mold plates 74 and 75 are attached to the lower surface via a manifold 73. A hot runner nozzle 76 is attached to the lower surface of the manifold 73, and the manifold 73 and the hot runner nozzle 76 are provided so as to communicate with the flow paths 73 a and 76 a of the molten resin.

A needle valve 77 for regulating the amount of molten resin flowing out is provided in a flow path 76a of the hot runner nozzle 76 so as to be vertically movable by a hydraulic cylinder 78, and a gate 76b at the lower end of the hot runner nozzle 76 is provided in a cavity 79. Facing. After the molten resin injected into the cavity 79 is solidified and becomes a molded product 80, an ejector pin 81 for ejecting the molded product 80 from the cavity 79 is slidably provided on the movable side mold plate 82. ..

In the hot runner die having the above-mentioned structure, the nozzle of the injection molding machine (not shown) is provided with the locate ring 7.
2, the molten resin is injected, and the cavity 79 is filled with the molten resin. After the filling of the molten resin is finished, the needle valve 77 is lowered by the hydraulic cylinder 78 and the gate 76b is closed. Molten resin cavity 7
Cool and solidify in 9 and open the mold from the parting line. After opening the mold, insert the ejector pin 81 into the cavity 7.
The molded product 80 is taken out as a product by sticking it out into the inside 9.

[0005]

However, the above-mentioned prior art has the following drawbacks. The surface defect caused in the molded product by the injection molding is considered to be a scratch due to the gate mark of the gate portion for injecting the molten resin into the cavity and the ejector pin for ejecting the molded product after the molding is completed.

However, because of the structure of the injection molding machine, the ejector pin is provided on the movable side of the molding machine.
The surface of the molded product on the side where the ejector pin abuts (the surface of the molded product on the movable side mold plate side) must be the back surface as a product. For the above reasons, if the surface of the molded product on the side opposite to the side where the ejector pin abuts (fixed mold plate side) is the external appearance of the product, the gate that injects the molten resin has a structure and the top surface of the external appearance of the product. Since it is located at, the gate mark is generated on the upper surface of the product appearance.

Therefore, the present invention was developed in view of the above-mentioned drawbacks in the prior art, and provides a hot runner mold which does not cause a gate mark on the product appearance (top surface and side surface) in terms of appearance quality. With the goal.

[0008]

According to the present invention, a manifold is embedded in each of a fixed side and a movable side of a mold, a heater is arranged in each manifold, and a gate and an ejector pin of the movable side manifold are provided. It is arranged on the back side of the molded product. According to the present invention, the gate and the ejector pin are arranged on the back surface side of the molded product, so that the gate mark of the gate portion and the scratch of the ejector pin which occur on the upper surface or the side surface of the molded product can be prevented.

[0009]

Embodiment 1 FIGS. 1 and 2 show this embodiment, FIG. 1 is a half-cut sectional view, and FIG. 2 is an enlarged sectional view of an essential part. The spacer block 1 is attached to the movable side mounting plate 16 by an AB bolt 23.
A movable side mold plate 18 is attached via 7, and a movable side insert 9 is fixed to the movable side mold plate 18.
The movable side manifold 8 is fixed by a B bolt 24. Between the movable side mounting plate 16 and the movable side template 18,
The ejector plate upper part 19 and the ejector plate lower part 20 are inserted in a state of being joined by the AB bolts 25.

The base end of the ejector pin 13 is sandwiched and fixed to the upper ejector plate 19 and the lower ejector plate 20, and the tip end of the ejector pin 13 is inserted through the movable mold plate 18 and the movable insert 9. It has reached the cavity 12. The ejector pin 13 ejects a molded product by an ejection rod (not shown) of an injection molding machine.

A fixed-side mold plate 22 is attached to the fixed-side mounting plate 6, and a fixed-side insert 5 is fixed to the fixed-side mold plate 22. The fixed-side manifold 1 is attached to the fixed-side mounting plate 6, and is inserted into the fixed-side template 22 and the fixed-side insert 5.

A resin path 2 is provided inside the stationary side manifold 1.
And a heater 3 is provided inside the fixed-side manifold 1 along the resin path 2. As for the heater 3, only the heater 3a on the side in contact with the movable side is controlled by a separate circuit. A clearance is provided between the fixed-side manifold 1 and the fixed-side insert 5, and the air is thermally insulated. The fixed-side manifold 1 is positioned in the thrust and radial directions by the fixed-side mounting plate 6, and is held by the locate ring 7. Further, the nozzle 14 of the molding machine is in contact with the fixed side manifold 1.

The movable side manifold 8 has an A
It is fixed with a B bolt 24. Movable side manifold 8
Like the fixed side manifold 1, the resin passage 1
0 is formed, and a heater 15 is provided inside the movable side manifold 8 along the resin path 10. The gate 4 of the resin passage 10 communicates with the back surface (the back surface side of the molded product) of the cavity 12 formed by the fixed-side insert 5 and the movable-side insert 9. In addition, the resin road 2 and the resin road 10 P. The L (parting line) portion is formed in an undercut shape.

In the hot runner die having the above structure, after the die is first closed, the resin passages 2 and 10 are heated by the heaters 3, 3a and 15 to reach the desired set temperature of the resin. Then, the resin is injected from the nozzle 14 of the molding machine. The injected resin passes through the resin passages 2 and 10 and fills the cavity 12. When the filling is completed, the heating of the heaters 3a and 15 is stopped. As a result, the resin in the portion where the resin passage 2 and the resin passage 10 contact each other is in a semi-solidified state. After that, when the temperature of the molded product 21 in the cavity 12 reaches a temperature at which the molded product 21 can be taken out from the mold, the mold is opened and the molded product 21 is ejected by the ejector pin 13 to move the movable side insert 9
Separate from.

At this time, the resin paths 2 and 10 of P.
The resin of the L (parting line) portion is separated in a semi-solid state without being pulled by the resin of the opposite resin paths 2 and 10 due to the undercut structure provided inside each of the resin paths 2 and 10. Further, the temperature of the movable side manifold 8 forming the gate 4 with respect to the molded product 21 is set higher than the glass transition point, so that the molded product 2
1 and the resin in the movable side manifold 8 forming the gate 4 are separated.

According to this embodiment, continuous molding can be performed without filling the resin from the upper surface or the side surface of the molded product, and without impairing the appearance quality of the molded product.

[0017]

[Embodiment 2] FIG. 3 is an enlarged cross-sectional view of an essential part showing this embodiment. In this embodiment, the movable side manifold 8 in the first embodiment is eliminated, and the resin passage 32 is used instead of the cavity 12.
The difference is that it is configured with a movable side manifold 31 that communicates with the inner wall on the back side (the side surface on the back side of the molded product), and the other components are the same components, and the same components are denoted by the same reference numerals. Is omitted.

Since the resin passage 32 communicates with the inner wall on the back side of the cavity 12 in the hot runner mold having the above-mentioned structure, when the mold is opened and the molded product is ejected by the ejector pin 13 and separated from the movable side insert 9, Cavity 12 and resin path 3
2 is an orthogonal state, and the cut between the molded product and the resin in the resin passage 32 is improved.

According to the present embodiment, the upper surface and the side surface of the molded product have a product appearance, and the rear surface of the molded product has a convex shape on the rear surface, such as when the interference clearance with other parts is small. Effective when disliked.

[0020]

As described above, according to the hot runner mold according to the present invention, since the resin is not filled from the upper surface or the side surface of the molded product, the resin other than the molded product is not deteriorated without impairing the appearance quality. Continuous molding can be performed without the need for (spool).

[Brief description of drawings]

FIG. 1 is a half-cut sectional view showing a first embodiment.

FIG. 2 is an enlarged cross-sectional view of a main part showing the first embodiment.

FIG. 3 is an enlarged sectional view of an essential part showing a second embodiment.

FIG. 4 is an enlarged sectional view of an essential part showing a conventional example.

[Explanation of symbols]

 1 Fixed Side Manifold 2, 10 Resin Road 3, 15 Heater 4 Gate 5 Fixed Side Nest 6 Fixed Side Mounting Plate 8 Movable Side Manifold 9 Movable Side Nest 12 Cavity 13 Ejector Pin

Claims (1)

[Claims] 1. A manifold is embedded in each of a fixed side and a movable side of a mold, a heater is provided in each manifold, and a gate and an ejector pin of the movable side manifold are provided on a back surface side of a molded product. A hot runner mold featuring.