KR100371334B1 - Metallic mould for injection molding - Google Patents

Abstract

The present invention relates to a mold for gas-foam injection molding which uses a gas as a foaming material to produce a molded article. The present invention relates to a sprue and a runner injected with plastic / gas from the outside, and a plastic / gas solution injected through the sprue and runner. A first heating means which is installed in the cavity in which the desired article is filled and the desired article is formed, the gate connected between the sprue and the runner and the cavity, and the connecting portion of the gate and the cavity to prevent partial cooling. In the mold for gas-foam injection molding including a second heating means installed so as to maintain the molten state of the injected plastic / gas solution installed around the sprue and runner,

The sprue is provided with a mixing means for mixing the plastic / gas solution passing through the inside, the foaming of the gas is evenly progressed in the cavity to obtain a uniform foaming rate as a whole, improving the expansion ratio of the gas By making the structure uniform and light, there is an effect that can be produced.

Description

Mold for gas foam injection molding {Metallic mold for injection molding}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for injection molding, and more particularly, to a mold for gas foam injection molding, in which a molded article is produced using gas as a foaming material and the foaming efficiency of the gas is improved.

Plastic molding techniques include extrusion molding, injection molding, reaction injection molding and thermoforming. The plastic molding technology produces various molded articles by melting plastic granules, that is, pellets, which are mostly manufactured in a chemical plant, using electric heat and mechanical friction, and then pushing them into a mold having a desired shape by applying force.

Such plastic molding technology is a foaming technology is developed by the effort to reduce the weight of the plastic product in addition to the reduction of the material cost because the ratio of the material to the product cost is very high compared to other materials.

Foaming technology is a technology that creates a lot of fine-sized bubbles in plastic products, and mixes chemical or physical foams with pellets and heats the foam to vaporize the foams inside the product. . When bubbles are formed, bubbles occupy a large part of the product, which greatly reduces material costs, reduces the weight of the product, and has an advantage of obtaining thermal insulation performance due to bubbles.

However, the above foaming technique has been advantageous in many ways, but the partial weakness caused by the foam material is not uniformly mixed with the plastic, and the impact strength and toughness due to the small number of bubbles generated It causes a decrease in the same mechanical strength has a disadvantage that can not be used in structures that require mechanical strength.

In addition, foaming materials such as pentane and freon, which are used for foaming, are harmful to the environment, and thus the use of the foaming materials is limited. Therefore, foaming technology using gas has been developed to overcome this disadvantage.

Gas foaming technology supplies gas to the molten plastic and rotates the screw inside the cylinder to push out the plastic / gas solution to induce a pressure difference so that the gas is foamed by the pressure difference inside the plastic / gas solution. will be.

In the case of the foaming technology using such a gas, bubbles are uniformly distributed throughout the product, and the diameter of the bubbles is about tens of micrometers and the number is 10 ⁹ or more per unit volume (1 cm 3). Thus, there is an advantage that can prevent a decrease in mechanical strength pointed out as a limitation of the foaming technology.

Here, the development of a mold capable of forming a product while maximizing the advantages of the foaming technology using gas as described above is required.

For reference, FIG. 1 is an internal configuration diagram illustrating a general injection molding die.

A cavity 5 for forming a product is formed in the mold 1, and a sprue 2 into which the plastic solution is injected from the outside of the mold 1 is formed in the cavity 5. ) And runner 3 and gate 4 are connected.

Here, the sprue 2 is an inlet portion into which the molten plastic solution is injected from the plastic liquid supply device consisting of a cylinder and a screw, and the runner 3 is a passage through which the plastic solution flows into each cavity 5. The gate 4 is an inlet portion through which plastic liquid is injected into each cavity 5.

Accordingly, when the plastic solution is injected from the plastic liquid supply device through the sprue 2, the plastic solution is introduced into each cavity 5 through the runner 3 and the gate 4, and then a solidified product is formed by rapid cooling. .

Among the above-mentioned molds, a hot runner mold is used, and the heater 6 is installed in the sprue 2 and the runner 3 except for the cavity 5 and the gate portion, thereby providing the sprue 2 and the runner. (3) The waste of the plastic liquid is prevented by allowing the molten state of the plastic liquid to pass through or remaining therein to be maintained. However, using the above-described mold of the prior art, the gas is foamed using the foaming material. In this case, the foaming occurs only in the longitudinal direction due to the characteristics of the cavity 5, so that the foaming efficiency is lowered and a large weight loss cannot be obtained.

In addition, in the case of using the mold of the prior art, as the plastic solution flows into the mold, the foaming ratio at the gate 4 portion is greater than the foaming ratio at the end of the cavity 5 due to the flow resistance of the gate 4 portion. There is a problem of having a low value.

The present invention has been made in order to solve the above problems, while using a mold that is commonly used, while the foaming of the gas contained in the plastic solution proceeds uniformly, the foaming efficiency is increased, so that the product is light and the degree of molding is improved The object is to provide a mold for foam injection molding.

1 is an internal configuration diagram showing a typical injection molding mold,

2 is a cross-sectional view showing a first embodiment of a mold according to the present invention;

3 is a sectional view showing a second embodiment of a mold according to the present invention;

4 is a sectional view showing a third embodiment of a mold according to the present invention;

5 is a configuration diagram showing a fourth embodiment of a mold according to the present invention;

6 is a sectional view showing a fifth embodiment of a mold according to the present invention.

<Explanation of symbols for the main parts of the drawings>

50: mold 53: cavity

54: sprue 55: runner

56: gate 60: first heater

65: second heater 70, 71: mixing mechanism

72: rotating body 72a: protruding wing

74: drive mechanism 80: vacuum tank

83: vacuum pressure forming tube 85: speed control valve

90: having mechanism 91: having hammer

93: return spring 95: hydraulic device

The gas foam injection molding mold according to the present invention for realizing the above object is a sprue and runner in which the plastic / gas solution is injected from the outside, and the plastic / gas solution injected through the sprue and runner is filled with the desired First heating means, sprues and runners, which are installed in the cavity in which the article is molded, the sprue and the gate connected between the runner and the cavity, and the connection portion of the gate and the cavity to prevent partial cooling phenomenon. In the mold for gas-foam injection molding including a second heating means to maintain the molten state of the injected plastic / gas solution is installed around the sprue, Mixing to mix the plastic / gas solution passing through the sprue Means are provided. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 2 is a cross-sectional view showing the internal configuration of a first embodiment of a gas foam injection molding mold according to the present invention.

In the mold 50 of the first embodiment according to the present invention, two molds 51 and 52 are paired, and the two molds 51 and 52 are plastics injected from a plastic / gas solution supply device. The cavity 53 is formed in which the / gas solution is filled to form the desired article.

One frame 51 of the two frames is formed with a sprue 54 and a runner 55 into which the plastic / gas solution is injected from the plastic / gas solution supply device. The cavity 53 and the runner 55 are formed. Is formed between the gates 56 serving as entrances.

In particular, a first heater 60 is installed around the gate 56 and the cavity 53 to prevent partial cooling.

The first heater 60 is a means for providing heat to the extent that can prevent a partial solidification phenomenon in the cavity 53, it is preferable that the temperature can be adjusted by an external control.

The first heater 60 prevents a portion of the plastic / gas solution filled in the cavity 53 from being solidified while being partially cooled first, so that foaming of the gas in the cavity 53 is entirely performed. It is installed so that it can proceed evenly.

In addition, the first heater 60 may be installed at a connection portion between the gate 56 and the cavity 53.

This is typically due to the flow characteristics of the solution when the plastic / gas solution is injected into the cavity 53 through the gate 56 and the beginning of the cavity 53 adjacent to the gate 56 portion. Since this first starts to solidify, it is preferable to be installed at the connection portion of the gate 56 and the cavity 53 as shown in FIG.

Of course, the mold 50 as described above is provided with a cooling device to produce a molded article by cooling the plastic / gas solution.

In addition, the first heater 60 is installed at the connection portion between the gate 56 and the cavity 53 in the mold 50, and is also injected around the sprue 54 and the runner 55. The second heater 65 is installed to maintain the molten state of the plastic / gas solution. The first embodiment of the present invention configured as described above has a first heater (around the gate 56 and the cavity 53). 60 is installed so that the molten plastic / gas solution can be completely filled to the end of the cavity 53 and then the entire cavity 53 including the gate 56 portion can be cooled uniformly, thereby It is possible to improve the foaming magnification while making the foaming progress of the gas included uniformly as a whole.

Here, the size and heat capacity of the first heater 60 may be adjustable according to the characteristics of the mold, such as the size of the cavity 53 and the size of the gate 56 of the molded product.

The second heater 65 installed as described above serves to prevent the plastic / gas solution passing through the sprue 54 and the runner 55 or the remaining plastic / gas solution from being solidified. The heater 65 may not be installed as needed.

In particular, the mixing mechanism 70 for mixing the plastic / gas solution passing through the sprue 54 is installed, the mixing mechanism 70 is re-mixed and evenly mixed plastic / gas solution injected from the outside At the same time to form a mixing ratio to reduce the temperature difference between the outer portion and the central portion of the sprue (54).

The mixing mechanism 70 may be formed by forming a spiral protrusion on the inner surface of the sprue 54 or may be formed by a spiral groove.

Figure 3 is a cross-sectional view showing the internal configuration of a second embodiment of a mold for gas-foam injection molding according to the present invention.

The mold of the second embodiment according to the present invention is configured differently from the mixing mechanism of the first embodiment described above, and the mixing mechanism 71 rotates the sprue 54 itself while the protruding blades 72a inside the plastic / gas solution are rotated. It is configured to be mixed.

That is, the mixing mechanism 71 in the second embodiment is rotatably installed at the sprue 54 forming portion of the mold, and has a rotating body 72 for mixing the plastic / gas solution and from the outside of the mold to the inside. It is comprised by the drive mechanism 74 connected and driving the rotation body 72 rotationally.

The rotating body 72 may be supported by a bearing 73 or the like in the mold, and a second heater 65 ′ may be installed therein. The rotating body 72 is formed in a cylindrical shape to form a sprue hole 54 'through which the plastic / gas solution passes, and the plastic / gas solution inside the sprue hole 54'. A plurality of protruding vanes 72a are formed to be remixed.

The drive mechanism 74 is formed with a gear tooth 72b on the circumferential surface of the rotating body 72, the gear tooth 72b is engaged with a drive gear 74a rotatably coupled to a mold. The drive gear 74a is rotated by the electric motor 74c or the like.

Thus, when the plastic / gas solution is injected through the sprue hole 54 ', the rotating body 72 is rotated by the drive mechanism 74, causing the inner protruding vanes 72a to remix the plastic and the gas. do.

Figure 4 is a cross-sectional view showing the internal configuration of a third embodiment of a gas foam injection molding mold according to the present invention.

In the mold of the third embodiment according to the present invention, the control valve 75 is installed to adjust the opening area into which the plastic / gas solution is injected at the end of the sprue 54 in the mold of the first embodiment.

That is, the control valve 75 is preferably made of a solenoid valve operated by external control so that the opening and closing speed and the opening area can be easily adjusted.

Such a control valve 75 is configured to function as an orifice in the sprue 54 so that a pressure difference occurs when the plastic / gas solution passes, so that the expansion ratio of gas in the cavity 53 is increased. It will play a role.

Figure 5 is a cross-sectional view showing the internal configuration of a fourth embodiment of a gas foam injection molding mold according to the present invention.

In the mold of the fourth embodiment according to the present invention, the first heater 60 is installed at the connection portion between the gate 56 and the cavity 53 as in the first embodiment, and the sprue 54 and The second heater 65 is installed around the runner 55.

In particular, the vacuum pressure forming tube 83 is connected to the vacuum tank 80 at the rear portion of the cavity 53, and the vacuum pressure forming tube 83 on the vacuum pressure forming tube 83 is about the negative pressure, that is, the vacuum speed. A speed control valve 85 for adjusting is installed.

The configuration of the fourth embodiment of the present invention is similar to the gas discharge pipe and the vacuum tank of the vacuum molding machine generally used in the casting molding method, but the conventional vacuum molding machine discharges the gas to the outside so that impurities do not occur inside the casting. Will have the ability to

However, the mold of the fourth embodiment according to the present invention is a mold using gas as the foaming material, and the vacuum condition in the cavity 53 is controlled through the speed regulating valve 85 to control the expansion ratio of the gas. It is configured to increase the foaming efficiency of the gas by adjusting.

6 is a cross-sectional view showing the internal configuration of a fifth embodiment of a gas foam injection molding mold according to the present invention.

In the mold of the fifth embodiment according to the present invention, the first heater 60 is installed at the connection portion between the gate 56 and the cavity 53 as in the first embodiment, and the sprue 54 and The 2nd heater 65 provided around the runner 55 was not installed as needed.

In particular, a mechanism 90 having a circumference of the cavity 53 to shake the plastic / gas solution injected therein is installed.

The excitation mechanism 90 has an excitation space portion 58 formed outside the cavity 53 and an excitation hammer provided in the excitation space portion 58 and colliding against a wall toward the cavity 53. (91), a hammer operating mechanism introduced into the excitation space 58 from the outside of the mold to operate the excitation hammer 91, and a hammer 91 provided in the excitation space 58 It consists of a return spring (93).

The hammer actuating mechanism is configured to generate the excitation force by providing the hydraulic pressure in the rear excitation space portion of the excitation hammer 91 by the hydraulic pressure provided from the hydraulic device 95, or the rod behind the excitation hammer 91. Is connected may be configured to generate the excitation force using the linear movement force of the rod.

Therefore, the mold of the seventh embodiment according to the present invention is a plastic / filled in the cavity 53 by impacting the cavity 53, such as foaming increases when the carbonated beverage is shaken or impacted from the outside By forcibly vibrating the gas solution, it is possible to increase the expansion ratio of the gas.

Since the heater is installed at the inlet of the cavity, the mold for gas foam injection molding according to the present invention constructed and operated as described above uniformly progresses the foaming of gas in the cavity to obtain a uniform foaming ratio as a whole. There is an advantage to this.

In addition, the gas foam injection molding mold according to the present invention has a spherical mixing device or orifice valve is installed in the sprue is uniformly remixed while the plastic / gas solution is injected, and the pressure change is increased, so that the foaming of the gas is made uniform In addition, there is an advantage that the gas foaming efficiency is improved.

In addition, the gas foam injection molding mold according to the present invention is provided with a vacuum pressure forming mechanism or an excitation mechanism in the cavity is configured to form or shake the negative pressure in the cavity, thereby improving the foaming ratio of the gas to improve the structure There is an advantage to produce a uniform and light molded article.

Claims (10)

Between the sprue and the runner into which the plastic / gas solution is injected from the outside, the cavity into which the plastic / gas solution injected through the sprue and the runner is filled to form a desired article, and between the sprue and the runner and the cavity A first heating means installed at a connecting portion of the gate and the cavity to prevent partial cooling, and to maintain a molten state of the injected plastic / gas solution installed around the sprue and runner. In the mold for gas-foam injection molding containing two heating means, The sprue is a mold for gas foam injection molding, characterized in that the mixing means for mixing the plastic / gas solution passing through the inside is installed. The method of claim 1, The mixing means is a gas foam injection molding mold, characterized in that formed on the inner surface of the sprue by any one of a spiral groove portion or a projection. The method of claim 1, The mixing means is rotatably installed on the sprue and at the same time a plurality of wing parts protruding to mix the plastic / gas solution inside the sprue, and connected to the inside from the outside of the mold to drive the rotary body rotationally Mold for gas-foam injection molding comprising a drive means to make. The method of claim 1, A gas foam injection molding mold, characterized in that the valve means is installed at the end of the sprue to adjust the opening area in which the plastic / gas solution is injected. The method of claim 1, The mold for gas foam injection molding is a gas foam injection molding mold, characterized in that the gas discharge pipe is connected to the vacuum tank in the cavity, the valve means for adjusting the gas discharge rate is installed on the gas discharge pipe. The method of claim 1, Gas foam injection molding mold, characterized in that the means is installed around the cavity to shake the plastic / gas solution injected therein. The method of claim 6, The excitation means includes an excitation space portion formed outside the cavity, an excitation hammer provided in the excitation space portion and colliding with a wall on the cavity side, and introduced into the excitation space portion from the outside of the mold. And a hammer operating means for operating the hammer, and a return means for repositioning the hammer provided in the excitation space portion. delete delete delete