JPH11198181A - Nozzle structure of injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent stringiness from developing at the periphery of a nozzle when a mold is opened after a molding is solidified in an injection mold. SOLUTION: In the nozzle 13 of a nozzle member 7 abutting against a sprue, a stinginess controlling part 20 is provided. As this stringiness controlling part 20, a fusiform spindle-like part 20a locating at the center of the nozzle 13 and a plurality of partitioning plate parts 20b..., each of which radically extends from this spindle-like part 20a so as to connect to the peripheral surface of the nozzle 13, are provided, resulting in preventing stringiness from developing from the neighborhood of the center part, which has a higher resin melting temperature in a resin passage 12, at a mold opening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle structure communicating with a sprue of an injection mold.

[0002]

2. Description of the Related Art Conventionally, after injection molding is performed in an injection molding die, as shown in FIG. 6, when a fixed mold 51 and a movable mold 52 are opened to take out a solidified molded product, the molded product comes into contact with a sprue 53. Since the temperature is hardly lowered in the resin passage 55 of the nozzle member 54 and the like, the resin P is stretched around the nozzle 56 so as to be dragged by the molded product Pc, and a stringing phenomenon occurs. There is a possibility that it may be rejected by adhering to the surface. Therefore, the present applicant has proposed a technique as disclosed in Japanese Patent Application No. Hei 7-26618.

FIG. 7 is a cross sectional view of a nozzle.
As shown in FIG. 7A and FIG. 7B which is a longitudinal sectional view of the nozzle, a plate-shaped partition portion 57 is provided at the center of the nozzle 56, and stringing occurs near the central portion o where the degree of resin melting is high. I try to prevent it.

[0004]

However, in the case of the above technique, only the thickness of the plate crosses the central portion o where the degree of melting of the resin is high, and the molten resin is completely cut off to prevent the occurrence of stringing. Has limitations.

Accordingly, an object of the present invention is to prevent the occurrence of stringing around a nozzle when a molding die is opened after a molded product is solidified.

[0006]

In order to achieve the above object, according to the present invention, in the first aspect, a stringing suppressing portion for suppressing the occurrence of stringing is provided in a nozzle communicating with a sprue of a mold. In the nozzle structure,
A shaft portion which is disposed in the center of the nozzle along the axial direction and the upstream side of the resin flow is tapered, and a plurality of partition plate portions extending radially from the shaft portion to partition the nozzle passage into a plurality of partition passages. It was constituted by.

As described above, by disposing the shaft portion at the central portion in the nozzle, a tensile force is not directly applied to the central portion of the resin passage having a high degree of melting, thereby suppressing the occurrence of stringing from the molten resin. I do. At this time, by tapering the tip of the shaft-like portion, the resin near the center can be separated smoothly, which is effective in preventing stringing.

[0008] Further, the partition plate may be provided at two places in a direction crossing the diameter, or may be provided at four places in a cross shape.
Further more may be provided. Such a shaft portion and a partition plate portion may be formed integrally with the nozzle member, or a member formed separately from the nozzle member may be fitted and fixed to the nozzle.

According to the present invention, the upstream end of the resin flow is formed at an acute angle in the thickness direction. When the upstream end is formed to have an acute angle as viewed from the plate thickness direction, the entire resin in the nozzle can be smoothly divided in conjunction with the tapered shape of the shaft portion.

According to a third aspect of the present invention, the downstream end of the shaft is tapered. In a fourth aspect, the thickness of the partition plate is tapered toward the downstream side. I made it. When the downstream side of the shaft portion or the partition plate portion is made thinner in this manner, the flow of the separated resin is performed smoothly, which is effective in suppressing stringing.

[0011]

Embodiments of the present invention will be described with reference to the accompanying drawings. Here, FIG. 1 is a longitudinal sectional view of an injection molding die, FIG. 2 is an enlarged view for explaining a nozzle structure according to the present invention, FIG. 3 is an enlarged view of a stringing suppressing portion, and FIG.
FIG. 5 is a perspective view for explaining the structure of the stringing suppressing portion.

The nozzle structure of the injection molding die according to the present invention is characterized in that, after the injection-molded molded product is solidified, when the mold is opened to take out the molded product, the unsolidified resin around the nozzle is pulled, so-called stringing. This is an effective technique for preventing the problem described above, and is particularly characterized by the structure inside the nozzle.

As shown in FIG. 1, the injection mold 1 includes a fixed mold 2 and a movable mold 3. When the fixed mold 2 and the movable mold 3 are clamped, a cavity 4 and a cavity 4 are formed. The runner 5 communicating with the fixed mold 2 is defined.
Are formed with a sprue 6 for guiding the molten resin to the runner 5 and a concave portion 8 for accommodating the nozzle member 7.

The nozzle member 7 is positioned at the center in the radial direction of the concave portion 8 and at a predetermined position in the axial direction by the spacer 10 in the intermediate portion and the bush 11 in the opening portion. As shown in FIG. With the nozzle 13 at the tip of the resin passage 12 formed at the center of the nozzle 7 connected to the sprue 6, the tip surface of the nozzle member 7 can be brought into close contact with the bottom of the recess 8. A heater 14 shown in FIG. 1 is wound around the outer periphery of the nozzle member 7.

A hot runner block 15 is provided upstream of the nozzle member 7, and a resin passage 16 of the hot runner block 15 communicates with the resin passage 12 of the nozzle member 7.

The movable die 3 has a cavity 4
An extruding pin 17 facing the surface and an extruding plate 18 for advancing the extruding pin 17 are provided to facilitate removal of the molded product after the mold is opened.

As shown in FIGS. 3 and 4, a stringing suppressing section 20 is provided in the nozzle 13 of the nozzle member 7 at a boundary with the resin passage 12. As shown in FIG. This stringing suppressing section 20
As shown also in FIG. 5, a shaft portion 20 a located at the center of the nozzle 13, and a plurality of partition plate portions 20 b extending radially from the shaft portion 20 a and connected to the peripheral surface of the nozzle 13,
, And a part of the upper end of the shaft portion 20a and the partition plate portion 20b faces the inside of the resin passage 12.

The shaft portion 20a is tapered from the upper side (upstream of the resin) to the lower side (downstream of the resin), and the upper end and the lower end are each tapered. It has a spindle shape.

The partition plate portion 20b has a shape in which the plate thickness is tapered from the upper side (upstream of the resin) to the lower side (downstream of the resin), and the upper end is viewed from the plate thickness direction. It is sharp.

In the above nozzle structure, when the resin is injected into the cavity 4 and the molded product is solidified, the mold is opened at a stage where the vicinity of the center of the resin passage 12 of the nozzle member 7 is not completely solidified. Then, since the resin up to the vicinity of the sprue 6 including the molded product is substantially solidified, stringing is likely to occur near the center of the boundary between the nozzle 13 and the resin passage 12 in a normal case. Shape 2
0a does not directly apply a tensile force to the central portion of the resin passage 12 having a high degree of melting, and the tip of the shaft portion 20a is tapered, so that the molten resin is finely divided and stringing does not easily occur. .

Moreover, since the leading end of the partition plate portion 20b is also acute when viewed from the plate thickness direction, the entire resin is smoothly divided, and the stringing can be further suppressed. Since the lower end of the shaft portion 20a is tapered, and the thickness of the partition plate portion 20b on the lower end side is tapered, the flow of the separated resin can be made smooth.

In the embodiment, the yarn pulling suppressing portion 20 has a shape obtained by inverting the upper side shape and the lower side shape of the thread pulling suppressing portion 20 from the nozzle 13 side opposite to the resin passage 12 side. Is formed integrally with the nozzle member 7 by inserting a discharge machining tool and forming a through passage by electric discharge machining. Of course, a separate stringing suppressing portion 20 may be manufactured and fixed in the nozzle 13.

The present invention is not limited to the above embodiment. Those having substantially the same configuration as those described in the claims of the present invention and exhibiting the same operation and effect belong to the technical scope of the present invention. For example, the number of partition plates of the stringing suppression unit may be four or more or four or less.

[0024]

As described above, in the nozzle structure of the injection molding die according to the present invention, when the stringing suppressing portion is provided in the nozzle, an axially tapered tip is provided at the center of the nozzle. The nozzle passage is divided into a plurality of sections by a partition plate extending in the radial direction from the shaft-shaped section. Can be suppressed.
Further, since the tip of the shaft portion is tapered, the resin near the center portion is smoothly divided, which is effective in preventing stringing.

Further, when the upstream end of the partition plate is formed to have an acute angle as viewed from the plate thickness direction, the whole resin can be smoothly divided in combination with the tapered shape of the shaft portion. Can be done. If the downstream end portion of the shaft portion is tapered as in claim 3, or if the thickness of the partition plate portion is tapered toward the downstream side as in claim 4, the separated resin is obtained. Can be smoothed, which is effective in suppressing stringing.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an injection mold.

FIG. 2 is an enlarged view illustrating a nozzle structure according to the present invention.

FIG. 3 is an enlarged view of a stringing suppressing section.

FIG. 4 is a view taken in the direction of arrow A in FIG. 3;

FIG. 5 is a perspective view for explaining the structure of a stringing suppression unit.

FIG. 6 is an explanatory diagram of a stringing state.

FIG. 7 is a conventional view of a nozzle structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Injection molding die, 6 ... Sprue, 7 ... Nozzle member, 1
3 Nozzle, 20 Stringing suppressing part, 20a Shaft part, 2
0b: Partition plate portion.

Claims (4)

[Claims] 1. A nozzle structure in which a stringing suppressing section for suppressing occurrence of stringing is provided in a nozzle communicating with a sprue of a mold, wherein the stringing suppressing section is provided at a center of the nozzle. It is provided with a shaft-like portion arranged along the axial direction and the upstream side of the resin flow tapering, and a plurality of partition plate portions extending radially from the shaft-like portion to partition the nozzle passage into a plurality of partition passages. Characteristic nozzle structure of injection mold. 2. The injection molding die nozzle structure according to claim 1, wherein the partition plate is formed such that an upstream end portion of the resin flow has an acute angle when viewed from a plate thickness direction. Nozzle structure of molding die. 3. The nozzle of an injection molding die according to claim 1, wherein the downstream end of the shaft-like portion is tapered. Construction. 4. The nozzle structure of an injection molding die according to claim 1, wherein a thickness of the partition plate is tapered toward a downstream side. The nozzle structure of an injection mold is characterized by the following.