JPH054259A - Injection hollow mold - Google Patents

Abstract

PURPOSE:To surely pour hollow-forming fluid in synthetic resin and prevent the fluid from leaking. CONSTITUTION:A groove 31 is provided around a fluid pouring port 10, through which hollow forming fluid 930 is poured. Further, a recessed part 71 is provided between the groove 31 and a runner 21. At the pouring of the fluid, the fluid tends to escape along the boundary between a mold 62 and the synthetic resin in the runner 21. However, due to the solidified layer of synthetic resin formed in the groove 31, resistance develops in the fluid. As a result, by the groove and the recessed part 71, the flow path of the resin is connected to the synthetic resin in the runner 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection hollow molding die, specifically, a fluid injection port portion for injecting a fluid for forming a hollow portion into a softened synthetic resin injected into a cavity. Concerning the structure of.

[0002]

2. Description of the Related Art Hollow molded articles made of synthetic resin are produced by injecting a softened synthetic resin into a cavity of a mold and injecting a fluid such as nitrogen gas or water into the synthetic resin to form a hollow inside. To produce. However, in this type of injection hollow molding die, a hardened layer is formed on the surface of the softened synthetic resin injected into the runner from the sprue. Therefore, it is difficult to inject the fluid into the synthetic resin from the fluid inlet.

Therefore, an injection hollow molding die has been devised in which a pin is arranged in the fluid inlet so as to be able to move forward and backward. As shown in FIG. 7, the injection hollow molding die includes a cavity 91 for molding a hollow molding, a sprue 92 for injecting a synthetic resin 920 in a softened state into the cavity 91, and a cavity formed by the sprue 92. 91 to softened synthetic resin 92
Runner 94 for guiding 0 and fluid 9 for forming a hollow portion
And a fluid inlet 93 for injecting 30.

Further, the fluid injection port 93 is provided with a pin 97 capable of advancing and retracting. When the synthetic resin is injected, the pin 97 protrudes from the fluid injection port 93 and the synthetic resin 920
The fluid injection port 93 is located inside and the fluid injection port 93 is closed. On the other hand, when the fluid is injected, the fluid 930 is advanced from the fluid injection port 93 into the synthetic resin 920. In FIG. 7, reference numeral 95 is a gate and reference numeral 96.
1, 962 is a forming die, and reference numeral 98 is a fluid passage.

[0005]

However, in the conventional injection hollow molding die, when a highly viscous synthetic resin is used, it is difficult to smoothly inject the fluid 930 from the fluid injection port 93 into the synthetic resin. .. Therefore, when the fluid 930 raises the injection pressure in order to perform fluid injection smoothly, the fluid 930 flows along the boundary between the mold 962 and the softened synthetic resin 920 as shown in FIG. 7 (arrow 933). ， Escape from the dividing surface to the outside.

Therefore, the injection pressure of the fluid 930 decreases. Moreover, the fluid cannot be reliably injected into the synthetic resin. As described above, it was difficult to hollow the synthetic resin with high viscosity. In view of such conventional problems, the present invention is to provide an injection hollow molding die that can reliably inject a fluid into a synthetic resin and does not cause fluid leakage.

[0007]

According to the present invention, there is provided a cavity for molding a hollow molded article of synthetic resin, a sprue for injecting a synthetic resin in a softened state into the cavity, and a synthetic state in a softened state from the sprue to the cavity. In an injection hollow molding die having a runner for guiding a resin and a fluid injection port for injecting a fluid for forming a hollow portion, in order to correct the flow path of the fluid around the fluid injection port. The injection hollow molding die is characterized in that a groove is provided and a recess is provided between the groove and the runner to prevent the fluid from leaking in cooperation with the groove.

What is most noticeable in the present invention is that the molding die is provided with a groove and a recess so as to surround the fluid injection port. The groove is for correcting the flow path of the fluid so that the fluid injected into the runner through the fluid injection port can be smoothly injected into the synthetic resin without causing leakage. The solidified layer of synthetic resin formed in the groove is used for sealing. Further, the recessed portion cooperates with the grooved portion to prevent fluid leakage. If the groove is larger than the runner, the sealing cannot be performed with the synthetic resin, so the recess is provided. When the above runner is installed on the upper mold (see Fig. 2)
In some cases, it may be installed in the lower mold.

The groove is provided in the mold on the fluid injection port side. The width of the groove portion is preferably set within the range of 1 to 10 mm. If the width of the groove is narrower than 1 mm or wider than 10 mm, the desired effect cannot be obtained. The depth of the groove is preferably set within the range of 2 to 15 mm. If the groove depth is deeper than 15 mm, it becomes difficult to release the molded product from the mold. If the depth of the groove is less than 2 mm, the desired effect cannot be obtained.

The above-mentioned concave portion is, for example, as shown in the embodiment,
There are a case where it is provided on a forming die on the side opposite to the groove portion so as to face the groove portion, and a case where it is provided on a forming die on the same side as the groove portion. The depth of the recess is sufficient as long as the synthetic resin layer is formed. In the present invention, as the synthetic resin,
Examples include polypropylene, ABS, polyamide, and soft vinyl chloride resin. The fluid includes gas bodies such as nitrogen gas, carbon dioxide gas and air, as well as gas bodies liquefied under high pressure and liquids such as water. Further, examples of the hollow molded product obtained by the injection hollow molding die include an assist grip and a console box.

[0011]

In the present invention, when the synthetic resin is injected, the synthetic resin in the softened state is injected from the sprue into the runner. At this time, the synthetic resin also flows into the groove and the recess. When injecting fluid, inject the fluid into the runner from the fluid inlet. At this time, part of the fluid tends to flow along the boundary between the mold and the softened synthetic resin. However, a solidified layer of synthetic resin is formed in the recess. Therefore, resistance acts on the fluid in the recess. Therefore, a part of the fluid is straightened into the synthetic resin in the runner by the recess and the groove. Since the recess is formed, the fluid does not escape from the dividing surface of the mold.

Therefore, the fluid can be reliably injected into the synthetic resin. Also, fluid leakage does not occur. Also,
Even if the injection pressure of the fluid is increased, the flow of the fluid is reliably corrected into the synthetic resin in the runner without passing through the groove due to the resistance of the groove. Therefore, according to the present invention, it is possible to provide an injection hollow molding die capable of reliably injecting a fluid for forming a hollow portion into a synthetic resin and preventing fluid leakage.

[0013]

EXAMPLE An injection hollow molding die according to an example of the present invention will be described with reference to FIGS. As shown in FIG. 1, the injection hollow molding die of this example has a cavity 91 for molding a hollow molding of synthetic resin, a sprue 92 for injecting a softened synthetic resin into the cavity 91, The runner 21 for guiding the softened synthetic resin from the sprue 92 to the cavity 91, and the fluid 93 for forming the hollow portion
And a fluid inlet 10 for injecting 0. A groove 31 for correcting the flow path of the fluid 930 is provided around the fluid inlet 10. Also, the groove 3
A concave portion 71 that cooperates with the groove portion 31 to prevent the fluid 930 from leaking is disposed between the runner 21 and the runner 21.

The sprue 92 is formed on the molding die 61 as an upper die. The runner 21 is formed by a recess provided in the molding die 61 and an upper surface of a molding die 62 as a lower die. In addition, the cavity 91
Is formed by a mold 62 and a mold 63. The fluid inlet 10 has a runner 21 as shown in FIG.
Is provided in the injection nozzle 1 which is installed in the mold 62 facing the above.

The injection nozzle 1 has a cylinder bore 1 inside.
Nozzle body 11 forming 10 and the cylinder bore 1
It has a plunger 12 which is inserted into the inside of the nozzle body 10 so as to be movable back and forth, and a cap 13 which is screwed into the nozzle body 11. Then, in the cylinder bore 110, the injection fluid chamber 111
To form. An injection fluid nozzle 4 is connected to the injection fluid chamber 111 via a passage 113. The injection fluid nozzle 4
Is for supplying a fluid 930 such as nitrogen gas into the injection fluid chamber 111 at the time of fluid injection.

A control chamber 112 is formed in the cylinder bore 110. The control fluid nozzle 5 is connected to the control chamber 112 via a passage 114. The control fluid nozzle 5 is for supplying a control fluid 50 such as air or oil into the control chamber 112. In addition, a pin 121 for opening and closing the fluid injection port 10 is provided at the tip of the plunger 12.
Is provided.

The pin 121 has a solid structure, and its outer diameter is substantially the same as the inner diameter of the fluid injection port 10. The tip of the pin 121 is formed in a steeple shape. When the synthetic resin is injected, the pin 121 has such a length that it protrudes from the fluid injection port 10 and is located in the synthetic resin 920 layer. In this example, the pin 121 is the runner 2
Approximately one-third of the diameter of the At this time,
The clearance between the pin 121 and the fluid inlet 10 is about 0.01 mm. Also, the pin 121 is
At the time of injecting the fluid, the fluid injecting port 10 is retracted to open the fluid injecting port 10.

As shown in FIGS. 2 and 4, the groove 31 is formed on the upper surface of the nozzle body 11 of the injection nozzle 1. The groove portion 31 is formed in a rectangular shape so as to surround the fluid injection port 10. The width of the groove 31 is 2 mm, and the depth of the groove 31 is 2 mm. A circular weir 32 is provided on the upper surface of the nozzle body 11 between the fluid inlet 10 and the groove 31.

As shown in FIGS. 2 and 3, the concave portion 71 is formed on the lower surface of the molding die 61 so as to face the groove portion 31. The recess 71 includes a sprue 92 and a runner 2.
1 and across. The depth of the recess 71 is 2 mm. Others are the same as in the conventional example. In FIG. 1, reference numeral 41 designates a cylinder containing a fluid such as nitrogen gas,
Reference numeral 42 is a pressure reducing valve, reference numeral 43 is a check valve, reference numeral 44 is a piston type accumulator for fluid pressurization, and reference numerals 45 and 46.
Indicates a solenoid valve.

The injection hollow molding die of this example is constructed as described above, and therefore exhibits the following operational effects. That is, when the synthetic resin is injected, the control fluid 50 is first injected from the control fluid nozzle 5 into the control chamber 112 as shown in FIG. As a result, the plunger 12 moves forward and the pin 121 is fitted into the fluid injection port 10. As a result, the pin 121 closes the fluid injection port 10.

Then, the synthetic resin 920 in a softened state is injected from the sprue 92 into the runner 21. Runner 21
The synthetic resin 920 injected inside passes through the runner 21 and is short-shot filled into the cavity 91.
At this time, the synthetic resin 920 injected into the runner 21
A part of this flows into the groove 31 and the recess 71. Therefore, the groove 31 and the recess 71 are filled with the softened synthetic resin 920.

On the other hand, at the time of fluid injection, the control fluid 50 in the control chamber 112 is drained. Then, the fluid 93 in the cylinder 41
0 is supplied to the injecting fluid nozzle 4 via the accumulator 44, and the injecting fluid chamber 111 is further supplied from the injecting fluid nozzle 4.
A fluid 930 is jetted in. At this time, the fluid inlet 10
Is closed by a pin 121. Therefore, the pressure in the injection fluid chamber 111 becomes high and the plunger 12 is retracted. As a result, as shown in FIG.
Goes back from the fluid injection port 10 and the fluid injection port 10 is opened. At this time, a soft uncured channel 1210 is formed from the fluid injection port 10 to the inside of the synthetic resin layer at a position where the pin 121 is removed.

Therefore, the fluid 930 in the injection fluid chamber 111
Is the above-mentioned flow path 1 as indicated by reference numeral A in FIG.
It is injected into the softened synthetic resin 920 from the tip of 210. At this time, a part of the fluid tries to flow along the boundary between the upper surface of the injection nozzle 1 incorporated in the molding die 62 and the solidified layer 921 of the synthetic resin 920 in the runner 21.

However, a part of the fluid is straightened by the weir 32 into the synthetic resin 920 in the softened state, as indicated by the symbol B in FIG. In addition, the concave portion 31
In, a solidified layer 921 of synthetic resin is formed. Therefore, resistance acts on the fluid 930 in the recess 31. Due to the resistance of the groove portion 31, it is easier for the fluid 930 to flow into the synthetic resin 920, as indicated by the symbols A, B, and C in FIG. Since the weir 32 and the groove 31 close the flow path of the fluid 930 in this manner, the fluid 930 eventually flows as indicated by the symbol A.

In this way, the groove 31 and the weir 32 correct the flow path of the fluid 930. Therefore, the fluid 930 can be reliably injected into the synthetic resin 920 in the runner 21. In addition, leakage of the fluid 930 can be prevented. The concave portion 71 is provided because the groove 31 is larger than the runner 21 and cannot be sealed with synthetic resin.
Prevent 0 leakage.

Further, the weir 32 allows the fluid inlet 10
The contact area with the synthetic resin 920 around the area becomes large. Therefore, the synthetic resin 920 around the fluid inlet 10 is easily cooled and solidified by the weir 32, and the solidified layer 921 is formed.
Is formed. Therefore, backflow of the softened synthetic resin 920 to the fluid inlet 10 can be prevented. Also, when the injection pressure of the fluid 930 is increased, the fluid 93
Due to the resistance of the groove portion 31, 0 is surely corrected into the synthetic resin 920 in the runner 21 without passing through the groove portion 31.

The fluid 930 sent into the cavity 91 in this way has no pressure drop because there is no leakage in the middle of the flow path. Therefore, the fluid 930 is smoothly injected into the synthetic resin 920 in the cavity 91. Then, the fluid 930 forms the hollow portion of the hollow molded product. After molding, take out the hollow molded product from the mold. At this time, as shown in FIG. 6, the runner portion 81 of the molded product is
In, in the position corresponding to the groove 31 and the recess 71,
The rib 811 and the plate 812 are formed. In this example, the plate 812 reinforces the rib 811 to prevent the rib 811 from being broken at the time of mold release. After forming the hollow portion as described above, the fluid in the synthetic resin 920 is recovered again in the accumulator 44 via the injection fluid nozzle 4 and the electromagnetic valve 46 (FIG. 1).

As described above, according to this example, the fluid 930 can be surely injected into the synthetic resin 920.
In addition, fluid leakage can be prevented. In addition, since fluid leakage does not occur in this way, there is no loss of the fluid 930 and the cost is reduced. Further, the fluid 930 can be stably injected into the synthetic resin 920 in the cavity 91, and the defective rate of the hollow molded product can be greatly reduced. In this example, the runner 21 and the recess 71 are
Although it is provided in the upper mold, the runner can be provided in the lower mold without being limited to this. It is also possible to provide the recess in the lower mold.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an injection hollow molding die according to an embodiment.

FIG. 2 is an enlarged sectional view of an essential part showing a state where the injection hollow molding die of the embodiment is opened.

FIG. 3 is a bottom view of the upper die of the injection hollow molding die of the embodiment.

FIG. 4 is a plan view of the lower mold of the injection hollow molding die of the embodiment.

FIG. 5 is an explanatory view of the action of fluid flow in the injection hollow molding die of the embodiment.

FIG. 6 is a partial cross-sectional perspective view of a runner portion in the molded product of the embodiment.

FIG. 7 is an enlarged sectional view of a main part of a conventional injection hollow molding die.

[Explanation of symbols]

 10. ． ． Fluid inlet, 21. ． ． Runner, 31. ． ． Groove, 71. ． ． Recess, 91. ． ． Cavity, 92. ． ． Sprue, 920. ． ． Synthetic resin, 930. ． ． fluid,

Claims (1)

Claim: What is claimed is: 1. A cavity for molding a hollow molded article of synthetic resin, a sprue for injecting a synthetic resin in a softened state into the cavity, and a cavity in a softened state from the sprue to the cavity. In an injection hollow molding die having a runner for guiding a synthetic resin and a fluid injection port for injecting a fluid for forming a hollow portion, in order to correct the flow path of the fluid around the fluid injection port. An injection hollow molding die characterized in that a groove is provided, and a recess is provided between the groove and the runner to prevent the fluid from leaking in cooperation with the groove.