JPH064263B2 - Injection mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection-molding die suitable for an injection-molded article of a thermoplastic resin, particularly one that is required to be uniformly filled with a molten material. Regarding

(Prior Art) Conventionally, this type of injection molding die has been devised to be used in various ways depending on the type of product to be molded, but it is required to have a perfect circular accuracy to be used for a rotating part of a precision machine. Almost no improvement has been made for products that require uniform filling of molten material, such as parts and cover cases of electronic devices that require planar accuracy. As shown in FIGS. There is only known a mold using a multi-point pinpoint gate that is provided at several places to adjust the gate balance.

[Problems to be solved by the invention]

However, even in the mold using this multi-point pin point gate, when the molten material flows from the runner 29 into the secondary sprue 32, the runner 29 and the secondary sprue 32 are joined as shown by the arrow in FIG. The molten material flows into the secondary sprue 32 at this stage, and the molten material flows into the cavities 30 through the gates 31. Orientation appears, and the filling state is not uniform. Further, in the case of having a plurality of cavities, there is a time difference until the molten material reaches each secondary sprue, and as a result, there is a difference in the material filling rate between the cavities, which is used for the rotating part of precision machinery. Products with high concentricity and less surface deviation and cover cases for electronic devices that require flatness are difficult to obtain by injection molding.

(Means for Solving Problems) The present invention addresses such difficulties, and the gist of the present invention is to form a cavity 10 by a movable mold plate 1 and a fixed cavity plate 3 and fix it. Side cavity plate 3 and runner stripper plate 6 runner 9
In the injection mold of the sleep rate type in which the secondary side sprue 12 and the gate 11 are provided on the fixed side cavity plate 3, the jetty 13 is provided at the peripheral edge of the opening of the secondary sprue 12, and the jetty 13 A chamber 14 for the molten material is formed on the outer peripheral side of the, and the molten material flowing in via the runner 9 is once stocked in the chamber 14, and then from the gap S between the tip of the jetty 13 and the runner stripper plate 6. It is configured so that it can flow into the secondary sprue 12.

(Operation) Since the present invention is configured as described above, the molten material that sequentially flows into the runner 9 from the sprue 8 is the secondary sprue 1
2 stocked in the chamber portion 14 while being blocked by the jetty portion 13 provided at the periphery of the opening of the secondary sprue 12 immediately before flowing into the secondary sprue 12, overflowing the chamber portion 14 and flowing into the secondary sprue 12 and passing through the gate 11. To fill the cavity 10.

(Embodiment) An embodiment of the present invention will be described with reference to the accompanying drawings, in which 1 is a movable side mold plate, which is fixed to a movable side mounting plate 2.
Reference numeral 3 denotes a fixed side cavity plate, which is slidably supported by a support pin 5 fixed to the fixed side mounting plate 4. A runner stripper plate 6 is slidably supported by the support pin 5 between the fixed side cavity plate 3 and the fixed side mounting plate 4. Reference numeral 7 denotes a sprue bush fitted to the fixed side mounting plate 4, and a sprue 8 is formed on the sprue bush 7. 9 is a runner formed by the fixed side cavity plate 3 and the runner stripper plate 1
0 is a cavity formed by the movable mold plate 2 and the fixed cavity plate 3, 11 is a pinpoint gate, and 12 is a secondary sprue. Reference numeral 13 denotes a donut-shaped jetty portion provided on the peripheral edge of the opening of the secondary sprue 12, and a gap S is held between the tip of the jetty portion 13 and the runner stripper plate 6. Reference numeral 14 denotes a chamber portion formed on the outer peripheral side of the jetty portion 13.
Similarly to the jetty portion 13, the donut shape is used.

Then, the inflow situation of the molten material in the mold of the present invention will be described. The molten material flowing from the sprue 8 into the runner 9 is blocked by the jetty 13 before flowing into the secondary sprue 12 and the chamber portion. Stocked in 14, jetty 13
The molten material that has overflowed in the above flows into the secondary sprue 12 through the gap S. At this time, the molten material stocked in the chamber portion 14 is the inner circumference of the jetty portion 13, that is, the secondary sprue 12 The secondary sprue 12 flows into the secondary sprue 12 from almost any position on the periphery of the opening and is filled in the cavity 10 through the gate 11. Further, the time lag that occurs when the molten material is blocked by the jetty 13 and stocked in the chamber portion 14 eliminates the time difference until the molten material reaches each secondary sprue 12.

The value of the gap S and the jetty portion 13, which are described in the present embodiment,
Regarding the shape and volume of the chamber portion 14, materials used,
It goes without saying that the size of the sprue, runner, gate, etc. is decided in consideration of the type of product.

(Effects of the Invention) The present invention relates to the movable side mold plate 1 and the fixed side cavity plate 3.
To form the cavity 10, the fixed side cavity plate 3 and the runner stripper plate 6 to form the runner 9, and the fixed side cavity plate 3 to the secondary sprue 12
In the sleep rate type injection molding die provided with the gate 11, the jetty 13 is provided at the peripheral edge of the opening of the secondary sprue 12, and the chamber 14 of the molten material is formed on the outer peripheral side of the jetty 13. After the molten material that has flowed in via the runner 9 is temporarily stocked in the chamber section 14, it can flow into the secondary sprue 12 from the gap S between the tip of the jetty section 13 and the runner stripper plate 6. The molten material flowing into the runner 9 from the sprue 8 is stocked in the chamber portion 14 before flowing into the secondary sprue 12, and the molten material overflowing the jetty portion 13 passes through the gap S to the secondary sprue. 12
At the time of flowing into the secondary sprue 12, it flows into the secondary sprue 12 under almost the same conditions from the inner circumference of the jetty 13, that is, from any part of the peripheral edge of the opening of the secondary sprue 12, and enters the cavity 10 through the gate 11 extremely. Due to the time lag that occurs when the molten material is not only filled in a uniform state but also blocked by the jetty 13 and stocked in the chamber 14,
The time difference until the molten material reaches each secondary sprue 12 is eliminated, and the variation of the filling rate between the cavities 10 is eliminated. It is an invention that exhibits excellent effects such as easily obtaining products with low plane accuracy such as a small number of products and cover cases for electronic devices.

[Brief description of drawings]

In the drawings, FIGS. 1 to 3 show an embodiment of the present invention, FIGS. 4 and 5 show a conventional example, FIG. 1 is a partially cutaway vertical sectional view showing an outline of the entire mold, and FIG. 3 is a plan view of the part and FIG.
FIG. 4 is a plan view of a main part of a conventional example, and FIG.
It is a sectional view taken along the line BB of FIG. Code table 1 movable side mold plate, 2 movable side mounting plate 3 fixed side cavity plate 4 fixed side mounting plate 5, support pin 6 runner stripper plate 7 sprue bushing, 8 sprue 9 runner, 10 cavity 11 gate, 12 secondary sprue 13 Jetty, 14 chambers 29 runners, 30 cavities 31 gates, 32 secondary sprues

Claims (1)

[Claims] 1. A movable side mold plate 1 and a fixed side cavity plate 3 form a cavity 10, a fixed side cavity plate 3 and a runner stripper plate 6 form a runner 9, and a fixed side cavity plate 3 has a secondary sprue 1.
In a sleep rate type injection molding die provided with 2 and a gate 11, a jetty 13 is provided around the opening of the secondary sprue 12, and a chamber 14 for molten material is formed on the outer peripheral side of the jetty 13. , The molten material flowing in through the runner 9 is once stocked in the chamber section 14,
An injection-molding die characterized in that it can be introduced into the secondary sprue 12 through a gap S between the tip of the jetty 13 and the runner stripper plate 6.