JPS6037777B2 - Torpedo used for marble pattern molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a torpedo used for molding marble patterns using a raw material obtained by mixing resins of two or more different colors using an in-line type or torpedo type injection molding machine.

There is a known method of molding products with uneven resin flow, squeezing patterns, or marble patterns using an inline screw type or plunger type injection molding machine using a raw material that is a mixture of two or more different colored resins. For example, Miseki Sho 51
There are publications such as No. 145961 and Tokusekki No. 48-4206. In the former, as shown in Fig. 1, a raw material 2 containing two or more different colored resins in a hopper 1 is charged into a barrel 4 heated by a heater 3 provided on the outer circumferential surface and weighed. After preheating, the plunger 5, which is inserted into the inner face of the barrel 4 so as to be movable in the axial direction, is moved forward in the direction of arrow a by a drive device (not shown), and the measured and preheated The resin raw material is passed from the inner diameter surface of the barrel 4 through the torpedo 7 which is positioned at the center of the inner surface and supported so that a narrow gap is formed between the barrel inner diameter surface and the outer circumferential surface. melted by
It is designed to be ejected from a nozzle 8.

However, in this method, the tip surface B of the plunger 5 is flat, and the resin raw material in contact with the surface B is preheated.
When melted by heating with the torpedo 7, voids tend to appear near the surface B, and when the resin raw material is filled into the mold, these voids are also rolled up, causing a so-called silver streak in the flow direction of the resin. Silvery white streaks appear.
This phenomenon is particularly likely to occur with materials that contain a large amount of volatile matter and moisture, such as AS, PMMA, PC, and resins that have high viscosity. As shown in FIG. 2, the latter has a structure in which the plunger of the former is roughly replaced with a screw 11, but the torpedo 12 is provided with protrusions 13 and 14, and the torpedo 12 is connected to the heating cylinder 5. It is designed to support the center of the inner diameter surface and to disperse the resin raw material.

Therefore, the resin raw material supplied from the hopper 16 is transferred forward (left side in the figure) by the transfer action caused by the rotation of the screw 1.
While being sent to the heating cylinder 5, it is heated by a heater 17 attached to the outer peripheral surface of the heating cylinder 5, and is metered into a cavity 18 in front of the screw 1. When the screw 11 is pushed forward by a drive device (not shown), the resin raw material accumulated in the cavity 18 passes through the torpedo 12 and is injected from the nozzle 19. However, when the resin raw material passes through the torpedo 12, the resin raw material
As shown by the arrow b in the figure, merging and crossing occur, and the molten resin is kneaded, making it difficult to form the marble pattern as described above.

In addition, in order to prevent kneading, the screw does not have a backflow ring, so when the screw 11 moves forward to inject the resin raw material, the backflow is large and the injection efficiency is reduced, and the repeated backflows promote melt mixing. The molten or semi-molten resin advances from the tip of the screw to the base, and due to its viscosity, the screw driving source tends to overtorque, which is a drawback. The present invention has been made in view of the above-mentioned circumstances, and it eliminates the disadvantages that conventional methods are difficult to form marble patterns and easily result in defective products such as silver streaks, and can be used for forming marble patterns. It's about providing torpedoes.

Next, one embodiment of the present invention will be explained with reference to FIGS. 4 and 5. Reference numeral 21 denotes a hopper where raw materials made by mixing resins of two or more different colors (not shown) are fed into a heating cylinder 22. be.

The outer peripheral surface of the heating cylinder 22 is provided with heaters 23 to 25.
are installed so that the temperature can be controlled independently. Further, a screw 26 is installed on the inner wall surface so that it can move back and forth in the axial direction and is rotatably inserted.
The heated resin raw material is transferred forward (towards the left in the figure), and a predetermined amount is measured and accumulated in the cavity 27 in front of the screw 26, and the resin raw material that has been accumulated in a predetermined amount is is pushed by the forward movement of the screw 26, passes through the torpedo 28, and is injected from the nozzle 29. The torpedo 28 is iron-fixed to the inner surface of the heating cylinder in front of the advance limit of the screw 21 (the position indicated by the chain line), and is inserted from one end facing the screw 26 as shown in FIG. One or several holes penetrating the pond end on the nozzle side,
Alternatively, one or more grooves are provided parallel to the axis of the outer circumferential surface, and the accumulated and preheated resin raw material is passed through the hole or inside by the forward action of the screw 26 into the cavity 27, and 50 to 8000 as is clear from the test results described later than the screw 26 portion of the heater 25.
The height of the torpedo 28 is increased to facilitate melting and to prevent resin flows passing through the torpedo 28 from merging or intersecting.
This makes it possible to create marble patterns, etc. Further, the screw 26 has L/D=10 to 13, and the compression ratio and non-return valve are not provided so that the raw materials are kneaded and the silver streak etc. are not generated, and the L/D is close to the tip of the screw.
/D = 2 to 3 have a structure without flight screws, leaving L / D = 2 to 3 on the screw tip side, and flights are provided for L / D: IQ saturate that reaches the base where the resin raw material supply castle is located. It only functions to transport the resin raw material.

With the above configuration, the following characteristics were confirmed.

{1' Silver Streak has appeared.

[2] Kneading is difficult to occur, and uneven flow and marple patterns are likely to occur.By controlling the temperature of the heater in the torpedo part, the patterns and uneven flow can be easily adjusted. ■ Since the resin raw material is melted within the torpedo and the screw remains solid, there is no backflow, resulting in good injection efficiency and no kneading due to backflow.

■ The screw part is solid and does not become a highly viscous molten state, so the rotational torque of the screw is small.

Next, the results of comparison between an example according to the present invention and a conventional example will be shown below. Raw materials: PC (manufactured by Mitsubishi Kasei) 1 Barex natural grade 702OHF...95% brown 7027A.
...3% Black 7030A...2% Molded product; Handbag holder 1. Example 1 is a conventional test, in which the toe beat and screw are convenient for conventional odor kneading molding.2. Measurement felling 2 is a conventional test, tow beat is conventional, screw to soto 1 tip is flat and solid 3. Example 3 is a test based on the present invention, and 4. Example 4 is a test according to the present invention K in which torbeed was used as a polymorph.5. Practical example 5 is a test according to the present invention K, in which a toe heat multi-groove structure is used.6. Outline Medium × Kawafu - Yoshi ○... Yoshihiragi Ri...As is clear from the captain test results, the embodiments of the present invention not only have a superior appearance to the molded products compared to the conventional method, but also have better screw drive performance. I can't see overtorque.

In addition, the set temperature of the heater can be set relatively low, and in particular, the screw part transfers the resin raw material in a solid state, and the torpedo part is kept about 60 to 70 degrees higher than the screw head part, that is, about 50 to 80 degrees higher. Since it is made to melt easily, it can be said that the molding of the maruffle pattern is very good.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conventional device. FIG. 2 is a diagram showing another conventional example. FIG. 3 is an explanatory diagram of a conventional torpedo. FIG. 4 is a diagram showing one embodiment according to the present invention.
FIG. 5 is a diagram showing a modification of the torpedo according to the present invention.
23-25... Heater, 26... Skrill, 28... Torpedo. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1 Using an in-line screw type or plunger type injection molding machine, two colors are placed in one heating cylinder that is kept approximately 50 to 80°C higher than the heating range of the screw or plunger part and whose heating is controlled separately from the screw heating part. When a raw material containing a mixture of resins of different colors as mentioned above is used to perform fine molding with uneven flow, drawing patterns, marble patterns, etc., the melting of the resin raw material is promoted and the kneading of the molten resin is prevented. A torpedo, which is fitted in front of the screw or plunger and has one or more holes or holes extending in the axial direction of the outer circumferential surface between one end facing the screw or plunger and the other end facing the injection nozzle. A torpedo characterized by having one or more grooves.