JPS62278012A - Molding die - Google Patents

Abstract

PURPOSE:To prevent unloaded filling, sinkage, wrinkle, cavity, weld line, fin, burn mark, britleness, strain and the damage of a mold by a method wherein injection filling is effected after discharging sealed air quickly and evacuating the inside of a cavity. CONSTITUTION:Both mold surfaces 2, 3 are approached for injection molding, a seal ring 4 is contacted and the moving operation is stopped for 7-8 seconds while keeping the clearance of 0.2mm-0.3mm between both mold surfaces. When air in a cavity 7 is intercepted from outside by the projecting part of the seal ring 4, an external evacuating device is operated and the inside air is sucked through a suction port 5. The injection port of a nozzle A is being fixed and closed already in a previous process, therefore, the air in the cavity 7 is sucked instantaneously through the suction port 5 together with air around the seal ring 4. Both mold surfaces are contacted closely while evacuating the inside of the cavity properly. The inside of the cavity 7 is evacuated, therefore, molten resin may be prevailed to fine corners while keeping flow property under a proper temperature.

Description

Detailed Description of the Invention 2. Detailed Description of the Invention (Field of Industrial Application) This invention relates to a mold apparatus for vacuum forming an injection mold.

-2,- (Conventional technology and problems) During injection molding of synthetic resins, fine mixes, rubber, alloys, etc., the air that is sealed in the space inside the cavity 7 has various negative effects on the molded product. Ta. FIG. 3 shows a part of the conventional type, and the dividing line 8 where the upper and lower molds meet is called a parting. Fixed template 2
and the movable mold plate 3 are each cut into a necessary shape suitable for the molded product, and this part is called a cavity 7. During molding, when both mold surfaces are closed, the air sealed inside, sometimes with moisture added to the mold temperature, reaches 60°C to 90°C.
The mold is in contact with the mold surface and thermally expands.

When a molten resin at a high temperature of 120° C. to 200° C. is injected therein, it further thermally expands and increases the resistance pressure, thereby slowing down the entry speed of the resin. While some of the parts were injected into the details, some parts of the product solidified, resulting in defective molded products with insufficient filling, sink marks, wrinkles, cavities, weld lines, and flow marks. If you increase the injection pressure or increase the melting temperature to avoid this, you will end up with flakes, uneven color, and burns, and if you apply holding pressure for a long time, The disadvantage was that the material became warped and hardened, making it easy to break. Sonodame air vent depth 0.02 MM ~ 0.0
A groove of approximately 3 ff1l] 5 yttyx was cut outward from the edge of the cavity 7, and air was forced out by the filling pressure. Even so, the pressure exerted on the mold during filling was unexpectedly large, causing the mold plate to warp, causing cracks to form near the center, which would bite and damage the mold surface. In order to prevent the mold from warping, a reinforcement called a support 12 is inserted between the movable mold plate 3 and the movable mounting plate 10, but if the mold is distorted and damaged by biting, it will be difficult to repair. There is a dimensional error in the molded product that cannot be corrected.

A major problem was how such sealed air could be successfully extracted during the short time period between each shot.

For this reason, various inventions have been made regarding methods for removing air.

For example, (1) JP-A-53-80462 (2) JP-A-53-80462
5-82625 etc.

Each of these had the following drawbacks.

In the item (1) above, the seal cylinder device has round grooves cut in both the upper and lower parting lines of the mold, and seal cylinder tags are layered in the round grooves. In this case, there is a risk that the mold will fall off due to the constant opening and closing of the mold. Also, regarding the method of suctioning the air vent, set the depth of the air vent to Q, l rapt~
Although it is indicated that the width should be wide enough to accommodate the flow rate of 0.5 mm, this results in formation of cracks and requires post-finishing processing, which increases costs.

In the case of (2) above, the suction cylinder and pinuton are difficult to adjust to various capacities of molded products.

It is inconvenient to change molds and is difficult to apply to other types of molds.

The air vent is easy to pinch first. There was such a thing.

(Object of the Invention) In order to solve the problems of the prior art, the present invention quickly discharges the sealed air to create a vacuum inside the cavity 7 and then performs injection filling to avoid any unfilled, sink, wrinkle, nest, or weld. It is intended to prevent lines, cracks, burns, brittleness, warping, and mold damage.

-5,- (Means for Solving the Problems) The present invention takes into account the above-mentioned problems and uses a simple and inexpensive device and method to solve the problem of cracks, unfilled spots, sink marks, wrinkles, nests, and welds. This was an attempt to solve problems such as lines, brittleness, distortion, burns, etc., and mold damage.

In the embodiments described below, the injection material is synthetic resin, but it can also be applied to other injection materials, such as fine ceramics, rubber, and alloys.

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of the molding die. In the figure, A is the nozzle of the molding machine. From there, the molten material is injected into the cavity 7 through the spout/L/13, the runner 15, and the goo (C) by injection pressure. Alternatively, it may be directly injected into the cavity 7 using a device called runnerless. A fixed mold plate mounting plate 1 is a plate that is fastened to a fixed mold plate 2 with a port and is attached to a molding machine. Fixed template 2
There is a movable mold plate 3 facing the mold plate 3, and in order to produce molded products of various shapes, the necessary shapes are cut into each mold plate and mirror-finished. Or it is textured.

FIG. 2 is a plan view of the fixed mold plate. Although the cavities 7 vary depending on the molded product and are not uniform, the figure shows two molds. A square groove 4' is cut around the cavity 7, and the seal cylinder 4 is disposed so as to slightly protrude therein, and a suction hole 5 is formed between the edge of the cavity 7 and the seal cylinder 40 as appropriate. Drill a hole at the position using a drill of an appropriate diameter so as to penetrate through the 11111 side of the mold. Attach bracket 6 to the outside. The seal cylinder 4 is commonly called an O-ring, and its material is fluororubber, silicone rubber, or the like. Heat resistance 200''C to 240'C, stiffness JIS
There are H570 or H89Q, etc.

The cross section is circular. For example, when using an 8-speed O-linda, the square groove 4' has a width of 8. / Depth should be 7 to 7.3 birds. The portion that protrudes beyond the square groove 4' is called a crushing portion and serves as a seal.

FIG. 3 is a partially sectional view of a main part showing a state in which a conventional fixed mold plate 2 and a 1liJ@ mold plate 3 are combined.

-Otsuichi FIG. 4 is a sectional view of a part of the second embodiment.

This is provided with a fixed mold plate 2 and a seal ring 4, and a movable mold plate 3.
A case is shown in which a suction hole 5 is provided on the side.

FIGS. 5 and 6 are partial sectional views of essential parts of the third embodiment.

The seal ring holder 4 in this embodiment has a rectangular or approximately oval cross section, and has a step-shaped notch provided at the periphery of either the fixed mold plate 2 or the movable mold plate 3 of the mold, into which the seal ring is inserted. 4 is arranged. The seal ring 4 is fitted so as to protrude by 1 to 2 m, and is held down with a presser plate B to be installed. This is suitable for large-sized cases where O-rings are not used. The clearance between the parting lines 8 on both mold surfaces can be set to be large, allowing for good air circulation and rapid pressure reduction from the suction holes 5. Moreover, this method is easy in terms of mold work. To attach the sealing 4, a long piece may be cut diagonally at both ends and then glued.

(Function) Due to injection molding, both mold surfaces are close to each other and the seal ring 4 is in contact, so the clearance between both mold surfaces is 0.2 myR-Q, 3 yp.
Stop operation for 7-8 seconds while maintaining tm.

Some injection molding machines are equipped with mold protection devices and can also be set to 0.1 ytttn.

Further, the electric system may be stopped using a limit switch. The low-pressure mold protection alarm device is originally a device to prevent accidents called Paris jamming and double pressing.

The air inside the cavity 7 is shut off from the outside by the sheet and the protrusion of the cylinder 4, and the air inside is sucked. Since the injection hole of the nozzle A has already been solidified and closed in the previous step, the air in the cavity 7 is instantly drawn into the suction hole 5 together with the air on the inner surface of the seal cylinder 4.

If a vacuum gauge is provided between the pressure reducer and the pressure reducer, it is possible to switch to high-pressure mold clamping operation while monitoring the degree of vacuum.

At this time, the pressure inside the cavity 7 is appropriately reduced, and both mold surfaces are brought into close contact.

The periphery of the cavity 70 and the suction hole 5 are completely closed, so that even when the next injection and filling is performed, there will be no leakage of molten material and no backflow of air.

-9,- Since the inside of the cavity 7 is evacuated, the molten resin spreads over the details while maintaining fluidity at an appropriate temperature. Previously, it was thought that the gas generated from molten resin was only a small amount, and most of it was sealed air, and many defective molded products were produced in humid seasons, but this compressed Since there is no air to resist, the injection and filling time is quick, and the next process of cooling and mold opening can be carried out smoothly.

The present invention can be applied to other injection materials such as fine ceramics,
As mentioned above, the present invention can also be applied to equipment for injection molding of rubber, alloys, etc.

(Effects) Conventional problems such as insufficient filling, sink marks, scorching, wrinkles, sea urchin p-drain lines, embrittlement, scorching, cracks, and cracks that are considered to be the effects of sealed air gas can be solved by this mold device. Conventionally, a large amount of pressure was applied to the mold, which caused warpage and distortion in the fixed mold plate 2 and the movable mold plate 3, leading to the occurrence of cracks. The mold surface was damaged by getting stuck in this hole, but with the present invention, production can be performed without applying much pressure -10. − Damage to the mold can be prevented.

Therefore, there is no need for the reinforcing support 12. Also,
Processing work for rubber and aluminum die-casting was a natural work process, but with the present invention, this will no longer be necessary. Green molding of fine ceramics also produces the same effects as synthetic resins using this equipment.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the molding die of the present invention. FIG. 2 is a plan view of the fixed mold plate 2. FIG. 3 is a sectional view of a part of a conventional mold. FIG. 4 is a part of the second embodiment. 5 and 6 are sectional views of the main parts of the third embodiment.
Molding machine nozzle/fixed mounting plate 2.Fixed mold plate 3.Movable mold plate 4.Seal ring 4'.Square groove
5. Suction hole 6. Bracket 7. Cavity 8. Parting line 9. Spacer 10. Movable mold plate mounting plate 11.
Push-up plate 12... Support -11, - 13... Spool 14... Guide bush B... Holding plate 15... Runner C... Gate

Claims (3)

[Claims] (1) Fixed mold plate (2) and movable mold plate (3) of the molding die
For one of the templates, insert the cavity (7
), a square groove (4') is provided to surround the square groove (4'), a seal ring (4) is placed there, and the mold is inserted from an appropriate position between the edge of the cavity (7) and the square groove (4'). Board 11
A molding die characterized in that a suction hole (5) is provided on the 111th surface. (2) The molding die according to claim 1, characterized in that the seal ring (4) is disposed in a stepped notch on the periphery of the template. (3) The molding die according to claim 1 or 2, wherein the seal ring (4) is arranged on the fixed mold plate (2) and the suction hole (5) is provided on the movable mold plate (3). .