JP3279097B2 - Injection equipment for sandwich molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called sandwich molding injection molding apparatus in which an inner layer is made of a core resin such as recycled plastic and a surface layer is made of a skin resin such as virgin material.

[0002]

2. Description of the Related Art Conventionally, sprues and runners of injection-molded plastic molded products, defective molding products, etc. are pulverized again, and if necessary, pelletized again, mixed with virgin material and injected into the original product. Although it is recycled as a molding material, free-shot products for color change and poor surface treatment products such as coatings have color matching problems and appearance physical properties problems. It cannot be recycled as an injection molded material, and is used as a recycled material in resin molded products such as industrial pallets and civil engineering piles.

In recent years, a special injection molding machine has been used as a method of recycling such free-shot products and defective paint products which could not be recycled to the original product in terms of quality. Sandwich molding methods have been proposed. In this sandwich molding method, as shown in FIG. 5, the inner layer portion of the molded product is formed of a core resin made of a recycled material or the like that cannot be used as described above, and only the surface layer portion that can be seen by humans is newly formed. This is a method of forming with a skin resin made of a virgin material. The molded product obtained by such a sandwich molding method can exhibit not only the appearance but also the impact characteristics and the tensile characteristics as well as the quality of 100% virgin material. It is getting attention.

[0004] Conventionally, as this sandwich molding method,
Although various proposals have been made, the present inventors have disclosed in Japanese Patent Application No. 5-117.
No. 225 proposes a method. In this method, for example, as shown in FIG. 4A, a cold runner mold c and a hot runner mold d are provided on the injection side of a core mold a and a cavity mold b provided between mold mounting plates e and e. And a valve type hot runner nozzle f is provided at each gate of the cold runner type c and the hot runner type d.
1 and f2, and a skin material injection unit h for injecting a skin material and a core material injection unit g for injecting a core material are provided on the hot runner mold d.
Then, as shown in FIG. 4B, first, the hot runner d
The first side nozzle f1 is opened, and a predetermined amount of the skin material S is injected from the skin material injection unit h into the cavity i via the cold runner c and the gate j, and then the other nozzle f2
When the core material K is injected into the hot runner d2, as shown in FIG. 2 (C), the core material K is extruded from the nozzle f2 side so as to bite into the skin material S on the cold runner c side. It flows to the i side and is injected into the cavity i so as to push and spread the previously injected skin material S. As a result, as shown in FIG. 2 (D), a reclaimed material K is formed in the inner layer, and a signed switch molded product A in which the virgin material S is formed in the surface layer is injection-molded at low cost and with high precision. At the same time, the sprue m, the runner n and the like discharged are crushed again and reused as a core material.

[0005]

In the injection molding method described above, the nozzles f1 and f2 provided in the hot runner mold d and the cold runner mold c are connected at equal distances by sprues n and n. Figure 4
As shown in FIG. 2B, the previously injected skin resin enters the tip of the sprue n on the nozzle f2 side and solidifies, and as shown in FIG. 2C, the core resin from the nozzle f2 side becomes solidified. In some cases, injection becomes difficult and good injection molding cannot be performed.

Accordingly, the present invention has been devised in order to effectively solve the above-mentioned problems, and an object of the present invention is to provide a novel sandwich capable of favorably performing injection molding of a sandwich molded product with a simple structure. An object of the present invention is to provide a molded product injection device.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to an injection molding apparatus for a sandwich molded product having a surface layer made of a skin resin and an inner layer made of a core resin. A cold runner for guiding the skin resin and the core resin is connected to the cavity to be formed, and an injection gate is formed at the tip of the cavity mold in which the cavity and the cold runner are formed.
Cylindrical torso and the toby provided inside the torso
Port, piston and spring, usually
At times, the above piston is raised by the pressing force of the spring.
Close the injection gate and spray the skin resin or core resin.
When the output pressure is applied to the inside of the fuselage, the piston retracts
A nozzle for skin resin and a nozzle for core resin that open the injection gate are provided. The injection gate of the nozzle for core resin is directly connected to the cold runner, and the injection gate of the nozzle for skin resin is connected to a sprue through a sprue. Connected to the cold runner.

[0008]

As described above, the present invention relates to a core resin nozzle.
By directly connecting the injection gate to the cold runner, the skin resin injected earlier from the skin resin nozzle does not solidify at the injection tip of the core resin nozzle, and the core resin injection from the core resin nozzle can be prevented. Well done. Also, set the injection gate of the skin resin nozzle
By connecting to the cold runner through a roux , the previously injected skin resin solidifies with a sprue ,
The core resin injected later flows back through the sprue and the skin
It does not enter the resin nozzle .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the injection apparatus according to the present invention. As shown, the injection device includes a cavity 1 for forming a sandwich molded product, and a gate 2.
The hot runners 6a, 6 are formed in the cavity mold 4 and the core mold 50 in which the cold runner 3 continuous with the hot runners 3 is formed.
The hot runner mold 7 in which b is formed is provided in a stacked state. Further, a core resin injection unit 10a for injecting a core resin and a skin resin injection unit 10b for injecting a skin resin are provided at the nozzle touches 9a and 9b of the hot runners 6a and 6b. 6b are supplied with a core resin and a skin resin, respectively. The cavity mold 4 is provided with a core resin nozzle 8a for injecting a core resin and a skin resin nozzle 8b for injecting a skin resin. The core resin or the skin resin sent from the hot runners 6a and 6b is provided. Are injected into the cold runner 3 at different times.

The cavity mold 4 and the core mold 5 are provided with a plurality of water passages 11 through which cooling water flows. The core mold 5 and the cavity mold 4 are cooled to cool the resin in the cavity 1 or the cold runner 3. The solidification rate has been increased. Further, as shown in FIG. 2, the core mold 5 can be moved to and away from the cavity mold 4 by movable means (not shown).

The core resin nozzle 8a and the core resin
As shown in FIG. 3 (A) , the resin nozzle 8b has a configuration in which a toe beat 14, a piston 15, and a spring 16 are provided in a cylindrical body 13 having an injection gate 12 formed at the tip. ing. Normally, the tip of the piston 15 closes the injection gate 12 due to the pressing force of the spring 16. However, when resin pressure is applied to the inside of the body 13, as shown in FIG. The piston 15 retreats in the direction of the arrow in the drawing, the gate 12 opens, and the resin in the body 13 is injected from the gate 12. When the resin pressure decreases, the piston 15 is automatically pushed by the force of the spring 16 to open the gate 12. They are completely sealed.

Further, as shown in FIG. 1, nozzle core resin
Injection gate 12 of the tip portion of the Le 8a whereas is connected directly to the cold runner 3 side, the skin resin nozzle 8
injection gate 12 of b of the tip portion is connected to the cold runner 3 through the spool Le over 17 Purageto tip extension, so the injection distance between the skin resin and the core resin to the cold runner 3 side is different ing.

The core mold 5 is provided with a plurality of extrusion pins 19 for extruding the resin solidified in the cavity 1 and the cold runner 3 to facilitate removal.

Next, the operation of this embodiment will be described.

As shown in FIG. 1, a core resin injection unit 10a and a skin resin injection unit for injecting a core resin and a skin resin, respectively, which have been heated and melted, are previously applied to the nozzle touches 9a and 9b of the hot runner mold 7, respectively. After connecting 10b, first, a predetermined amount of skin resin is injected from the skin resin injection unit 10b. Then, the skin resin passes through the hot runner 6b and passes through the nozzle 8 for the skin resin.
b, is injected from the injection gate 12 to the cold runner 3 side via the sprue 17 by the resin pressure, and is further injected into the cavity 1 through this. At this time, as described above, since the injection gate 12 of the skin resin nozzle 8b is automatically closed due to a decrease in the resin pressure, the skin resin from the cold runner 3 side is closed. Backflow is prevented. Also, a part of the skin resin on the side of the cold runner 3 flows backward from the injection gate 12 of the core resin nozzle 8a due to the injection pressure, and the core resin is removed.
Although it may be mixed into the fat nozzle 8a, there is no problem because the core resin is originally made of recycled resin as described above.

Next, when the injection of the skin resin is completed in this manner, the core resin is injected from the core resin injection unit 10a.
And then sent to the plastic gate 8a, then similarly injected by the resin pressure from the injection gate 12 of the core resin nozzle 8a to the cold runner 3 side while biting into the previously injected skin resin. It flows to the cavity 1 side. At this time, when you flow into even the skin resin nozzle 8b side through the sprue 17 not injected core resin only cavity 1 side to the cold runner 3 side,
The sprue 17 has a diameter smaller than that of the cold runner 3 and the cavity 1 and has a conical shape opened toward the cold runner 3. Since the solidification of the skin resin has already started at this portion, the core resin is Skin through parts
It does not flow back to the resin nozzle 8b and enter the skin resin. The hot runners 6a and 6b through which the resin flows , the nozzle 8a for the core resin, and the nozzle for the skin resin
The inside of the cavity 8b , the cold runner 3, and the cavity 1 are made substantially vacuum by a conventional suction means (not shown), so that the resin can be easily injected into the cavity 1.

By performing such injection, in the cavity 1, a sandwich-like injection is carried out so as to sandwich the core resin with the skin resin, and further, the core die 5 and the cavity die 4 through which cooling water flows. This is solidified by cooling, and then, as shown in FIG. 2, the core mold 5 is separated from the cavity mold 4 to obtain a sandwich molded product having an inner layer made of a core resin and a surface layer made of a skin resin. Will be done. Further, the cold runner 3a obtained simultaneously with the sandwich molded product is taken out from the cold runner 3a by the extrusion pin 19 at the same time as the sandwich molded product is taken out, and then pelletized again to be regenerated as a core resin.

As described above, the present invention relates to the spraying of the core resin nozzle.
By connecting the exit gate directly to the cold runner,
The skin resin injected earlier from the skin resin nozzle will no longer solidify at the injection tip of the core resin nozzle ,
Injection of the core resin from the core resin nozzle is performed well, and the injection gate of the skin resin nozzle is sprued.
By connecting the cold runner through, from entering the skin resin nozzle <br/> the core resin skin resin injected earlier is injected at a later solidified sprue flows back sprue It can be prevented in advance.

[0020]

In summary, according to the present invention, since injection molding can be carried out reliably with a simple structure, a high quality sandwich molded product can be easily and inexpensively obtained. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a state in which a core mold is separated from a cavity mold and a cold runner is removed.

FIG. 3 is a longitudinal sectional view showing the structure and operation of a plagate.

FIG. 4 is a process chart showing an example of injection molding of a conventional sandwich molded product.

FIG. 5 is an explanatory view showing an example of a sandwich molded product.

[Explanation of symbols]

Reference Signs List 1 cavity 2 cold runner 8a core resin nozzle 8b skin resin nozzle 12 injection gate 17 sprue

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Munemura, 8 clay bowls in Fujisawa City, Kanagawa Prefecture Isuzu Central Research Institute Co., Ltd. (72) Hiroshi Suzuki 8 clay bowls in Fujisawa City, Kanagawa Prefecture Isuzu Motors Limited Fujisawa In the factory (56) References JP-A-47-13243 (JP, A) JP-A-60-174622 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/14- 45/37

Claims (1)

(57) [Claims] 1. An apparatus for injecting a sandwich molded product having a surface layer portion made of a skin resin and an inner layer portion made of a core resin, wherein a cold runner for guiding the skin resin and the core resin into a cavity for injection molding the sandwich molded product. The cavity mold in which the cavity and the cold runner are connected to each other has a cylindrical body having an injection gate formed at a tip end thereof.
Toe beat, piston and spring provided in the fuselage
Of the spring and the pressing force of the spring
This causes the piston to close the injection gate,
The injection pressure of kin resin or core resin is applied inside the body
And the skin where the piston retreats and the injection gate opens
A resin nozzle and a core resin nozzle are provided. The injection gate of the core resin nozzle is directly connected to the cold runner, and the injection gate of the skin resin nozzle is connected to the cold runner via a sprue. An injection device for a sandwich molded product, characterized in that it is made.