JPS62178315A - Vacuum injection molding method - Google Patents

Abstract

PURPOSE:To improve productivity by making the inside of a cavity vacuous in a short period of time even if the cavity is of a complicated form, by a method wherein a seal member is fitted to a microscopic gap by surrounding a suction port and the cavity to make the inside of the cavity vacuous and molding is performed by injecting a material by pressing and piling a multistage- tiered mold so that the microscopic gap is closed. CONSTITUTION:A first seal member 14 which is fitted to a recessed groove 15 seals a microscopic gaps T.... A second seal member 23 is stuck to a recessed part 11 so as to seal up an injection nozzle 16 and sprue 6 tightly. When air is discharged by a vacuum device 22 under a state wherein microscopic gaps T... have been generated on each of mating surfaces 10, 10..., the inside of a multistage-tiered mold 1 including a cavity 9 comes vacuous. A seal member 14 is sealing a sphere of a wide plane area containing the cavity 9 and a suction port 17 by surrounding the same. As the microscopic gaps T... are formed among each of molds 2, 4, 5, which possess a sufficiently large cross-sectional area of an air passage and the air keeps discharged by flowing into the suction port 17, passage resistance is little and swift discharge of the air can be realized in large quantities.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a vacuum injection molding method for producing rubber or plastic molded articles using multistage stacked molds.

[Conventional technology and problems]

Conventionally, the method of molding rubber or plastic molded products using the vacuum injection method involves attaching a sealing member around the cavity of a mold, sucking the cavity with a vacuum pump, etc., and injecting the rubber or plastic material. Ta.

However, in multistage stacked molds, there are many mating surfaces that are in close contact with each other, and the cavity shape is often complex, such as an undercut shape. Therefore, the above method has a large air suction resistance, making it difficult to obtain a vacuum state, especially in short There were problems such as the difficulty of creating a vacuum inside the cavity in a short period of time.

〔the purpose〕

The present invention solves these conventional problems and provides vacuum injection that improves productivity by evacuating the inside of the cavity in a short time even in multi-stage stacked molds and cavities with complex shapes. The purpose is to provide a molding method.

[Means for solving problems]

The vacuum injection molding method according to the present invention is a vacuum injection molding method for molding rubber or plastic materials using multistage stacked molds, in which the overlapping surfaces of the multistage stacked molds have minute gaps. An appropriate number of elastic members are arranged between the overlapping surfaces of the multi-stage stacked molds so as to apply elastic force in the forming direction, and also to enable simultaneous suction from between the overlapping surfaces. A suction port is provided in the multi-stage stacked mold in a penetrating shape, and a sealing member is attached to the microgap surrounding the suction port and the cavity to keep the microgap airtight, and air is supplied from the suction port. After evacuation and creating a vacuum inside the cavity, the multistage stacked mold is pressed and polymerized so as to close the minute gap, and then rubber or plastic material is injected and molded into a predetermined shape.

[Effect]

Even when a minute gap is formed between the mating surfaces, it is surrounded and sealed by the sealing member, so that a large amount of air can be quickly discharged through this minute gap and the suction port.

〔Example〕

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 is a sectional view of an embodiment of the present invention showing an air discharge state, FIG. 2 is a sectional view of injection molding, and FIG. 3 is an enlarged sectional view of the main part of FIG. 1.

In FIGS. 1 to 3, 1 is a multistage stacked mold,
An upper mold 2 having a curved recess 11 in the approximate center of the upper surface, a lower mold 3, and a first intermediate sandwiched between the upper mold 2 and the lower mold 3 in an overlapping manner. It consists of a mold 4 and a second intermediate mold 5.

Further, 16 is an injection nozzle, and 6 is an upper mold 2 and a first
The sprue is provided in the intermediate mold 4 and is formed in a tapered shape downward from the deepest part of the recess 11 of the upper mold 2.

Further, numeral 7 is a launch whose base end is connected in communication with one place on the peripheral wall of the sprue 6, and whose tip is bent downward at a right angle, and the tip is connected in communication with the cavity 9 through the gate 8. The cavity 9 is formed by the lower mold 3 and the second intermediate mold 5. The case of a planar circular molded product having a convex portion on the inner circumferential surface is shown, but it goes without saying that these can be freely modified in various ways.

Therefore, a plurality of recesses 13 for storing elastic members 12 such as coil springs are provided on the upper surface of each of the first intermediate mold 4, the second intermediate mold 5, and the lower mold 3. be done.

It is desirable that a plurality of these recesses B are arranged at a constant pitch near the outer periphery of the molds 3, 4.5.

Concave grooves 15 for mounting the first seal member 14 are provided inside the concave portions 13 of the heavy molds 3, 4.5.

Specifically, the resilient members 12... placed in each of the recessed portions 13... (See figure) A small gap T is formed between the overlapping surfaces 1 and 1, even during air suction (described later).
0: It has a spring force that prevents the space from coming into close contact with each other.

Furthermore, the first seal member 14 mounted in the groove 15 seals the minute gap T. There is sufficient crushing allowance for this purpose. In the illustrated example, the concave groove 15 is a dovetail groove with an enlarged inner part, and the seal member 14 is T-shaped, but the design of each shape can of course be changed as desired.

Further, 17 is a suction port for simultaneously suctioning suction air passing through the cavity 9, each minute gap T, etc., and is connected to a blind hole 18 provided inside the lower mold 3 and each other. Holes 19 and 20° 21 formed through the molds 2 and 4.5 are connected to each other to form a single hole.

That is, the suction bow 17 is provided so as to penetrate through the molds 2, 4.5. And the suction port 17 is
It is connected to a vacuum device 22 such as a vacuum pump via a pipe 25 or the like.

Further, a second seal member 23 is provided so that the tip of the injection nozzle 16 contacts the curved recess 11 of the upper mold 2 at the base end of the sprue 6, and seals between the injection nozzle 16 and the sprue 6 during suction. is attached to the recess 11.

Therefore, a minute gap T is formed between each mating surface 10, 10...
When the air is discharged by the vacuum device 22 in a state in which ... is generated, the multistage stacked mold 1 including the cavity 9
The inside becomes vacuum. That is, the air remaining in the mold 1 passes through the micro gap T in the direction of arrow A, is sucked and collected at the suction port 17, is further sucked in the direction of arrow B, and flows inside the pipe 25 in the direction of arrow C. is sucked into the air and discharged through the vacuum device 22. That is, in order to reduce the suction resistance, each mating surface 10...
A minute gap T is forcibly formed between them to form a suction air passage. At this time, the sealing member 14 surrounds and seals a wide planar area including the cavity 9 and the suction port 17. The minute gap T is 2.4°5.
3 and have a sufficiently large air passage cross-sectional area, and are discharged after merging at the suction port 17, the passage resistance is small and a large amount of air can be discharged quickly.

The multi-stage stacked mold 1, which has been reduced to a vacuum in this way,
If the elastic members 12 are tightened using a tightening device (not shown), each mating surface 10, 10...
- Close contact. Therefore, from the injection nozzle 16, the molding material 2
When the rubber material 4 is injected, the rubber material 24 passes through the sprue 6, runner 7, and gate 8 as shown by the arrow, flows into the cavity 9, and a molded product is formed.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that the design can be changed within the scope of the invention. For example, it is preferable to use a leaf spring as the resilient member 12. It is also possible to arrange the resilient member 12 on the inner side of the seal member 14.

〔Effect of the invention〕

According to the above configuration, each mating surface 1 of the multistage stacked mold 1 is
0... form a minute gap T... without coming into close contact with each other, and furthermore, due to the sealing action of the sealing member 14, a suction air passage with a large cross-sectional area is formed between each mating surface 10, 10. Air discharge resistance is small, a large amount of air can be discharged in a short time, and a vacuum state inside the cavity 9 can be quickly created. In addition, since they are simultaneously sucked through the suction port 17, the inside of the multi-stage stacked mold 1 is always kept in a uniform vacuum state, which has the remarkable effect that a good rubber molded product can be obtained. After the air is discharged, the mating surface 10.10
Injection molding can be performed immediately by closing the minute gap T between the two, resulting in excellent work efficiency.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an embodiment of the present invention showing the state of air discharge, Fig. 2 is a cross-sectional view of injection molding, and Fig. 3 is a cross-sectional view of the air discharge state.
FIG. 2 is an enlarged cross-sectional view of the main part of the figure. 1...Multi-stage stacking mold, 6...Sprue, 10...
Matching surface, 12... Resilient member, 14... Seal member, 16... Injection nozzle, 17... Suction port, 22
...Vacuum device, 24...Molding material, T...Minute gap.

Claims (1)

[Claims] 1. A vacuum injection molding method for molding rubber or plastic materials using a multi-stage stacked mold, wherein a minute gap is formed between each mating surface of the multi-stage stacked mold. An appropriate number of elastic members are disposed between each mating surface of the multi-stage stacked mold so as to elastically bias the mold in the direction, and a suction port is provided to enable simultaneous suction from between each of the mating surfaces. is provided as a through-hole in the multi-tiered mold, and furthermore, a sealing member is attached to the micro gap surrounding the suction port and cavity to keep the micro gap airtight, and air is discharged from the suction port. After making the inside of the above cavity a vacuum,
A vacuum injection molding method characterized in that the multistage stacked molds are press-polymerized so as to close the minute gaps, and then a rubber or plastic material is injected and molded into a predetermined shape.