JPS6026690B2 - Manufacturing method and molding equipment for injection press-fit molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an injection press-fit molded product and a molding device thereof, which enables the molded product to be molded without providing a resin injection gate, and more specifically relates to a part of the molding device. Alternatively, a metering retention tank may be formed in an adjacent part, a certain amount of heated molten resin is filled into the metering retention tank in the parentheses, and then a metering retention tank is filled into a molding cavity formed in another part of the molding device. This injection press-fit molded product is characterized by injecting a fixed amount of molten resin, and further lowering a press plunger from above the empty chest of the molding cavity to press-fit the molten resin into the product space of the mold cavity. The present invention relates to a manufacturing method, a molding apparatus therefor, and a molded product manufactured therein.

When injection molding a conventional molded product, such as the neck of a tube, for example, as shown in FIG. 1, a core 3 having a pin 2 at the upper end is inserted into a cavity 1, and heated molten resin is injected from a runner 4. The neck part 5 of the tube was formed using the same method, and this was heat-welded to the pipe 6 inserted in advance into the gap between the cavity 1 and the core 3 to form an integrated tube. It was impossible to open 〇 during molding.

Therefore, as shown in FIG. 2, after injection molding, the upper end of the neck 5 must be cut at a certain height h and the spout 2' must be drilled, making the molding process complicated and cutting the upper end of the neck 5. It is difficult to always cut at a constant height, and the cut may be oblique or uneven.
It is difficult to seal the cap, and there is a risk that some of the poured material may remain in this area during use, resulting in deterioration and solidification.Also, if you apply cosmetics or medicines through this spout, be careful not to damage the skin. There were drawbacks such as damaging the In order to improve this drawback, as shown in FIG. 3, a cavity insert 7 is attached to the upper part of the cavity 1, so that the entire inner diameter of the spout of the neck 5 is formed by the cavity insert 7, and the bottom of the spout is A method of punching out the neck part 5 as shown in Fig. 4 has been carried out, but punching out the bottom of the spout is difficult, and in the case of a tube to be filled with a low-viscosity content, the discharge volume is low. Since the column outlet must be made extremely small in order to adjust the spout, a separately molded inner stopper 8 must be attached to the spout's inner cover, which has the disadvantage of requiring two parts and increasing costs. Ta. Furthermore, when the injection molding method described above is used, internal stress (residual stress) due to molecular orientation, overfilling, uneven cooling rate, etc. caused by injection molding accumulates inside the molded product, causing internal distortion, resulting in shape deformation and crazing. , it had the disadvantage of generating cracks, etc.

The molding method according to the present invention is a completely new technique that fundamentally improves the drawbacks of the conventional methods.

To specifically explain one embodiment of the method according to the present invention with reference to the drawings, in Figs. The upper part of the metering retention tank a is formed as a conical slope 9 for preventing backflow, and the upper end thereof is an injection molding nozzle B connected to the hemispherical connecting part 10' of the molding apparatus A. The steel ball C is inserted into the resin flow path 11 so as to be able to move up and down, and a bridge board 12 is provided at the center of the lower part to stop the descent of the steel ball C. Both sides are formed as annular channels.

Also, the left end of the horizontal space of the metering retention tank a is a conical wall 13.
The tip is connected to the molding cavity empty steel b through the sprue 14, and the horizontal space has a piston tip 15 at the left tip that can open and close the sprue 14, and there is a cartridge inside. An auto shirt piston D having a heater 16 and a spring 17 at its rear end is inserted so as to be slidable in the left and right direction, and is further inserted into a metering retention tank a.
An injection plunger F, which is raised and lowered by an injection hydraulic cylinder 8, is inserted into the lower space so that it can be raised and lowered.
Next, a screw cavity 18 is formed on the lower inner circumferential wall of the molding cavity b, and a press plunger which is raised and lowered by a press-fit hydraulic cylinder G is inserted into the upper part of the molding cavity b. A concave cavity 19 for the upper end of the tube is bored in the bottom part of the tube, and a core pin 20 is formed in the lower part of the molding cavity b to form a spout 21 in the upper end of the tube. The core 1 held is iron-filled, and a tube insert pipe J is inserted into the gap between the core 1 of the bracket and the forming device A in a state where they are iron-fitted.

When carrying out the method of the present invention using the above-mentioned molding apparatus, first, as shown in FIG. I do.

In this case, when the automatic shirt piston D is activated, the sprue 14 at the piston tip 15 is kept closed by the compressive force of the spring 17 since the internal pressure of the metering retention tank a is low.
Next, as shown in FIG. 6, the press plunger is moved back by the retraction operation of the press-in hot water pressure cylinder G to form the molding cavity cavity b. Next, the injection plunger F is moved forward by the high pressure of the injection hydraulic cylinder E.
moves forward, increases the internal pressure of the molten resin filled in the metering retention tank a, pushes up the steel ball C stopped on the bridge plate 12, and presses it against the conical slope 9 for preventing backflow, so nozzle B Backflow into the body can be prevented. By preventing backflow, the injection hydraulic cylinder E is moved to the piston tip 15.
The molten resin in the conical wall 13 is pressurized and becomes large against the compression ratio of the spring 17, and the auto shirt piston D retreats to the right and the sprue 14 at the piston tip 15 opens, and at the same time the molten resin flows into the molding cavity. Injected into Soratsukioka b. Next, as shown in FIG. 2, in the molding cavity cavity b, the press plunger is lowered by the operation of the press-fitting hydraulic cylinder G, and the molten resin is poured into the concave cavity 19 on the lower surface of the press plunger. Molding is performed in the space surrounded by the screw cavity 18, core 1, etc., and at the same time, this molded part and the insert pipe J are fused and integrated, so that the spout 21 as shown in FIG. With the shaped cavity 19 it is possible to obtain a precisely shaped tube K.

Although the above embodiment describes the formation of the tube K, for example, the inner stopper L having the spout 22 as shown in FIG. It is possible to easily form molded products with high precision.

As described above, in the method of the present invention, in the next step, the molten resin filled in a metering retention tank provided in a part of the molding device is sent to a molding cavity, and further, a concave cavity is formed on the bottom surface of the molten resin. Since the core is compressed and molded using a press plunger, the most important part of a molded product such as a container or Japanese cypress, such as the opening, is molded using the concave cavity of the press plunger, core pin, etc. Therefore, there is no need to process and construct this part in post-processing like in the case of a follower, and it is possible to easily and reliably manufacture extremely precise molded products in a continuous manner. Unlike conventional methods, there are no sprue marks or distortions, and since the method is molded using the method described above, there is no fear of molecular orientation phenomena that can cause internal stress and internal distortion. It has the characteristics that there is no risk of uneven molding, and since no gate is used, it is possible to completely prevent the occurrence of defective products due to uneven cooling rate.

[Brief explanation of drawings]

1 to 4 are cross-sectional explanatory views showing a conventional product and its manufacturing method, and FIGS. 5 to 9 are cross-sectional explanatory views showing the molded product of the present invention and its manufacturing method. A: forming device, B: /zuru, C: steel ball, D: piston,
E: Hydraulic cylinder for injection, F: Injection plunger, G
: Press-fit hydraulic cylinder, H: Press plunger, 1:
Core, J: pipe, K: tube, L: inner plug, a: metering retention tank, b: molding cavity, 4: runner,
5: neck, 9: mirror slope, 14: sprue, 16: heater,
19: Concave cavity, 20: Core pin, 21, 22:
spout. Figure 2 Figure 3 Figure 4 Figure 5 Figure 8 Figure 9 Figure 6 Figure F

Claims (1)

[Claims] 1. A metering retention tank provided in a part of the molding device is once filled with molten resin from an injection molding nozzle, and then the molten resin in the metering retention tank is driven from a sprue by an injection plunger. A fixed amount is injected into the molding cavity, and a press plunger with a concave cavity bored at the bottom is lowered from above the molding cavity to close the sprue and into the lower part of the concave cavity. Molten resin is press-fitted into the space defined by the concave cavity and the core by bringing the wall surface into contact with a core pin protruding from the upper end of the core inserted into the lower part of the molding cavity. A method for manufacturing an injection press-fit molded product. 2 A metering retention tank and a molding cavity cavity are bored inside the molding device, and the upper part of the metering retention tank has a conical slope for preventing backflow, and its upper end communicates with the injection molding nozzle, and the inside thereof A steel ball is inserted into the tank so as to be able to rise and fall freely, and one end of the horizontal space of the metering and retention tank is communicated with the molding cavity cavity through a sprue, and this horizontal space is always attached to the sprue side by a spring. The energized auto-shaft piston is inserted so as to be horizontally movable, an injection plunger is inserted into the lower part of the metering and retention tank so as to be movable up and down, and a concave cavity is bored at the bottom of the upper part of the molding cavity cavity. A molding device for injection press-fit molded products, which is constructed by inserting a press plunger that can be raised and lowered, and facing the plunger and fitting a core having a core pin at its upper end into the lower part of a molding cavity.