JPH05192983A - Method of molding synthetic resin with flow pattern - Google Patents

Abstract

PURPOSE:To miniaturize and simplify a molding apparatus and make the formation of resin flow patterns figurate and carry out check of resin flow in the cavity with a high accuracy by disposing magnets at a specified place in the cavity and injecting molten resin being dispersion-admixed with magnetic powders to be attracted by the magnetic force of the magnet into the cavity in order to be molded thereafter. CONSTITUTION:Into the cavity 3 disposed with magnets 9, when molten resin 11 being equally dispersion-admixed with magnetic power 10 is injected from a gate 4, the magnetic powders 10 in the molten resin 11 are attracted and collected together through the attractive operation of the nearest magnet 9, whereby resin flow patterns 12 by gathered magnetic powders appear clearly in the course of passing through the magnets 9. The flow patterns 12 can approximately be made into the formation of stripe patterns that are continue from the position of the magnet 9 to the proximity of end part of the cavity 3. In this way, the resin flow around an aperture 6 can be achieved readily correctly and thereby the gate 4 can be set at a desired position. In order to perform a designing effect for giving a molding appearance alteration, it is also effective at the time of making formative resin flow patterns 12 appear therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin flow pattern forming method.

[0002]

2. Description of the Related Art A method for positively forming a flow pattern of a synthetic resin is generally by multicolor molding using an injection molding machine or an extrusion molding machine, that is, a flow pattern is formed by mixing and mixing different color resins. Many things (literature unknown).

[0003]

However, the above-mentioned method requires a plurality of injection cylinders and extrusion cylinders for plasticizing resins of different colors, so that the molding apparatus becomes large-scale. Further, the resin flow pattern appearing in this molded product is indefinite. Therefore, improve the molding conditions,
The resin flow condition in the cavity may be checked for the purpose of setting the gate position, but in this case, since the flow pattern is indefinite, it is difficult to correctly grasp the resin flow phenomenon in the cavity.

An object of the present invention is to make a resin flow pattern standard and to improve the accuracy of the resin flow check in the cavity while achieving a compact and simple molding apparatus.

[0005]

The synthetic resin flow pattern revealing and molding method according to the present invention uses a molten resin 11 in which magnetic powder 10 is dispersedly mixed as a molding resin material as shown in the figure, and a cavity 3 is formed. Magnet 9 that attracts magnetic powder 10 inside
Is provided so that the resin flow pattern 12 made of magnetic powder appears on the molded product 5.

[0006]

When the molten resin 11 mixed with the magnetic powder 10 flows in the cavity 3, the magnetic powder 10 in the molten resin is attracted and gathered by the magnetic force of the nearest magnet 9 and is gathered at the trace passing through the magnet 9. The resin flow pattern 12 made of magnetic powder can be clearly displayed, and the flow pattern 12 can be formed into a streak pattern.

[0007]

As described above, according to the present invention, the resin flow pattern 12 to be formed on the molded product is to collect the magnetic powder 10 in the molten resin 11. Therefore, the resin flow pattern is formed by mixing and mixing different color resins. However, since a single injection cylinder or extrusion cylinder does not require a plurality of injection cylinders and a single molding cylinder, the molding apparatus can be downsized and simplified. Since the resin flow pattern 12 can be expressed clearly and in a substantially standardized shape, it is possible to perform a highly accurate resin flow inspection for improving the molding conditions related to the resin flow process, and to give the molded product an appearance change. This is also effective when the resin flow pattern 12 having a fixed shape is positively displayed in order to exert a design effect.

[0008]

1 and 2 show a first embodiment of the present invention. In this example, an example is shown in which the partial flow of the molten resin in the cavity 3 formed between the female mold 1 and the male mold 2 is checked. In this embodiment, a pinpoint gate is adopted as the gate 4, and a molded product 5 having a hole 6 is molded. In this case, a weld mark 7 is generated on the lower side in the resin flow direction from the position of the hole 6 in the cavity 3, but a desired position should be set to avoid a position where the weld mark 7 is not desired to be formed due to its strength or appearance limitation. When deciding, it is convenient to be able to correctly understand the flow process. In this case, the magnets 9 are arranged on both sides or one side of the hole 6 on the upstream side in the resin flow direction. 1 and 2
Inside, 16 is a runner and 17 is a sprue.

When the molten resin 11 in which the magnetic powder 10 (shown by dotted lines) is uniformly dispersed and mixed is injected from the gate 4 into the cavity 3 in which the magnet 9 is arranged at such a position, the molten resin 1
The magnetic powder 10 in 1 is attracted and gathered by the magnetic force of the nearest magnet 9, and a resin flow pattern 12 due to the crowd magnetic powder is clearly shown in the trace after passing through the magnet 9, and the pattern 12 has the magnet 9. A continuous streak pattern can be formed from the position to the vicinity of the end of the cavity 3. As a result, the resin flow around the hole 6 can be easily grasped correctly and the gate 4 can be set at a desired position.

The magnet 9 may be an electromagnet instead of a permanent magnet. When using an electromagnet, molten resin 1
Even if the injection speed of 1 is high, the magnetic powder 10 can be aggregated with a strong magnetic force. In the case of an electromagnet, the resin flow pattern 12 can be formed intermittently (perforated) by exciting it intermittently.

The magnetic powder 10 mixed in the molten resin 11 contains, for example, ferrite, gamma-hematite, chromium dioxide, an iron oxide alloy obtained by adding or adsorbing cobalt ions or a cobalt compound to iron oxide, or pure iron as a main component. Magnetic alloy powder or the like can be used.

The mixing ratio of the magnetic powder 10 to the molten resin 11 varies depending on the molten state and the wall thickness of the molded product.
Generally, 20 to 70 wt% is appropriate, and in order to make the shade more clear, not only the color tone is changed, but also the mixing ratio is increased. The difference will occur and it will not be possible to accurately grasp. Therefore, it is preferably 50 wt%.

The shape of the molded product 5 shown in FIG. 1 is 140 mm × 1.
The box 4 has a size of 20 mm × 25 mm and a thickness of 1.5-2 mm, and the gate 4 has a diameter of 1.0 mm. Molding material is A
A BS resin (trade name: TOYOLAC 500) containing 38 wt% of agglomerate nickel powder of about 1 to 8 μ was used, and injection molding was performed at a resin temperature of 235 ° C. and a primary injection pressure of 920 Kgf / cm ² . The mold temperature at this time was 32 ° C., the cavity pressure was 490 Kgf / cm ² , and the injection speed was 0.988 cm / sec. As a result, a striped pattern as shown in FIG. 1 was obtained.

When the strength of the magnet 9 in the mold exceeds 800 Gauss, some pattern appears on the molded product.
In the above embodiment, a ferrite magnet having a size of about 4400 gauss was used. Such magnets include Alnico type, samarium cobalt type (approximately 9000 gauss) and neodymium iron boron type (12000 gauss).
Various other materials can be used.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, the magnets 9 are arranged in parallel facing the surface of the film gate 4. By arranging the magnet 9 around the gate 4 in this manner, the resin flow pattern 12 can be exposed on the entire molded product 5, and the entire flow process of the molten resin 11 in the cavity 3 can be easily and easily performed. It can be grasped correctly and is effective in improving measures against defects such as short shots and weld marks caused by the flow process.

FIG. 4 shows a third embodiment of the present invention, in which a magnet 9 is arranged around the pinpoint gate 4. Even in this case, the entire flow of the molten resin 11 in the cavity 3 can be easily and accurately checked.

FIG. 5 shows a fourth embodiment of the present invention. In this embodiment, magnets 9 are arranged around the gate 4 of the frustoconical core (male type) 2 having the protrusions 13 at a predetermined pitch, and the entire resin including the protrusions 13 in the cavity 3 is formed. The flow can be confirmed (see the resin flow pattern 12 appearing on the molded product 5 in FIG. 6). In this case, the core 2 is made of copper, aluminum, gypsum, aluminum bronze, duralumin, silmine (8
7Al, 13Cu), zinc alloy, etc. The thermal conductivity of copper and aluminum is several times that of carbon steel and stainless steel. Such a mold material is selected because the heat conductivity is good and the heat absorption from the molten resin is fast, so that the mold is cooled quickly, that is, the cooling efficiency is good, and therefore the magnet 9 is used.
This is because the durability of can be improved. In order to secure the durability of the magnet 9 and also prevent magnetic disturbance, as shown in FIG. 7, a magnetic body (SKD61) 14 such as carbon steel or stainless steel is selected as the material of the core 2, Good thermal conductor 1 such as copper or beryllium copper between magnet 9
Partial use of 5 is preferred. Needless to say, the present invention can be similarly applied to extrusion molding, cast molding, and the like other than injection molding.

[Brief description of drawings]

FIG. 1 is a plan view of a molded product showing a first embodiment.

FIG. 2 is a cross-sectional view of a mold of the molded product of FIG.

FIG. 3 is a plan view of a molded product showing a second embodiment.

FIG. 4 is a perspective view of a molded product showing a third embodiment.

FIG. 5 is a perspective view of a core showing a fourth embodiment.

FIG. 6 is a perspective view of the molded product of FIG.

FIG. 7 is a cross-sectional view showing a modified example of the core of the fourth embodiment.

[Explanation of symbols]

 3 Cavity 9 Magnet 10 Magnetic powder 11 Molten resin 12 Resin flow pattern

Claims (1)

[Claims] 1. A magnet 9 is arranged at a predetermined position in the cavity 3, and a molten resin 11 in which magnetic powder 10 attracted by the magnetic force of the magnet 9 is dispersed and mixed is injected into the cavity 3 for molding. Molding method for revealing synthetic resin flow patterns.