JP3386379B2 - Contamination-less hopper of molding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hopper provided with a heating means which is used by connecting a lower end opening to a material inlet of a heating cylinder such as an injection molding machine or an extrusion molding machine.

[0002]

Molding materials such as plastics, which are molded by an injection molding machine or the like, are molded by plasticizing a molding material in a hygroscopic state to mold a molded article, and silver or bubbles are generated. Since most of the molding materials are defective, the moisture absorbed by a dryer is dried before being used. For this drying process, a hot air drying method is used in which heated and dried air is blown upward from the lower part of the hopper.The dry air that serves as the heating medium for the molding material is obtained by directly heating the factory air with a heater or the like. Is generated.

Since the air in this factory contains dust and carbide is generated on the heater surface, the dry air is supplied to the hopper through the filter. Even minute contaminants in dry air cannot be completely removed, and it is extremely difficult to eliminate the occurrence of defective products due to contamination.

In particular, in the molding of optical moldings and transparent products, which are also defective even with fine defects, a high-performance filter is used and frequent maintenance is performed to reduce the occurrence of defective products due to contamination as much as possible. However, as the filter becomes denser, the flow rate of dry air decreases, heating efficiency decreases, and productivity can be improved by setting an appropriate maintenance time. The amount depends not only on the environment in the factory but also on the working conditions, and is said to be technically difficult.

Furthermore, the molding material is granular, and there are large and small differences in the voids generated between the particles depending on the orientation of the particles. From the viewpoint of fluid characteristics, dry air will flow through the voids with low resistance, and thus uneven drying will occur. It is easy to occur. Although this drying unevenness is eliminated by uniformly passing dry air between the particles,
This requires a large amount of air and pressure.

The above problems in dry air are as follows.
The problem can be solved by heating the molding material with electromagnetic waves or infrared rays, heating with a heat pipe, etc., but it is difficult to use electromagnetic waves, infrared rays, etc. in terms of cost, and direct heating with a heat pipe reduces the heating range. Due to restrictions, it is generally unsuitable for heating the molding material in the hopper.

The present invention has been conceived in view of the above circumstances, and its object is to uniformly heat and dry the molding material in the hopper by direct heating by a heating medium by adopting a heating pipe, and to prevent defective products due to contamination. It is an object of the present invention to provide a hopper of a molding machine provided with a drying means having a new structure capable of preventing the occurrence of

[0008]

The present invention according to the above object is a hopper which is provided in a molding machine by connecting a lower end opening to a material charging port of a heating cylinder, the hopper having a funnel-shaped lower portion. It consists of a cylindrical main body in which a delivery cylinder is connected and a lid member having an exhaust pipe, and by the flow of the heat medium from the temperature controller to the inside and the outer periphery from the funnel-shaped lower part of the main body to the vicinity of the upper edge. In addition to arranging the heating pipe in a spiral shape, a plurality of stirring plates are provided on the inner wall of the main body so as to project vertically and horizontally at required intervals, and the molding material is heated from inside and outside of the main body for drying. is there.

Further, according to the present invention, a heating pipe for circulating a heat medium is arranged in a spiral shape inside or on the outer peripheral surface of the material delivery cylinder, and a supply pipe for supplying dry air from a temperature controller is provided on a side portion. In addition, the above-mentioned heating pipe in the main body is provided with a required number of heat radiating plates at regular intervals.

In the hopper having such a structure, the peripheral wall of the main body is heated by the outer heating pipe, and the molding material in the hopper is also heated by the peripheral wall of the main body. Together with the uniform heating, the drying efficiency is remarkably improved as compared with the case of only internal heating.

Moreover, since the molding material is heated and dried indirectly through a heating pipe, there is no molding defect due to contamination, which is a problem of direct drying with dry air. It can be used for molding to improve quality and productivity.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the drawings, reference numeral 1 denotes a hopper, which comprises a cylindrical main body 10, a material delivery cylinder 12 connected to a funnel-shaped lower portion 11, and a lid member 14 having an exhaust pipe 13. Although not shown in the figure, the lower end opening of the material delivery cylinder 12 is connected to the material inlet of the heating cylinder and provided in the molding machine.

The heat medium (liquid such as oil and water or gas such as air) from the temperature controller 2 is provided inside and outside the body 11 from the lower portion 11 to the vicinity of the upper edge and inside the material delivery cylinder 12. ) Distribution of heating pipes 21, 22, 23
Are arranged spirally at equal intervals, and a plurality of stirring plates 3, 3 are vertically and horizontally projected on the inner wall of the main body with a required interval.

The heating pipes 21, 22, and 23 are made of a pipe material having excellent thermal conductivity and corrosion resistance, and a ceramic coating is applied to the surface so that infrared heating can be used together. Further, the heat radiating plate 20 is provided at a plurality of positions of the heating pipe 21 by appropriately setting the mounting angle, whereby the contact area with the molding material is expanded to improve the heating efficiency and the flow of the molding material. The stirring effect at the time of this is obtained.

Further, inside the heating pipes 21, 22 and 23, the heat medium heated to a predetermined temperature by the temperature controller 2 is circulated and circulated through the pipes on the temperature controller side, and is circulated in the hopper. The molding material can be heated and dried. The arrangement of the heating pipe 21 is not limited to the spiral shape, but may be a cross shape. Although not shown in the drawing, the outside of the main body in which the heating pipe 22 is disposed is covered with a heat insulating material together with the pipe.

On the side of the material delivery cylinder 12, a supply pipe 1 for supplying dry air from a temperature controller which also serves as a supply pipe for nitrogen gas.
5 is provided with a filter and is connected, and this supply pipe 15
From this, a very small amount of dry air or nitrogen gas of about 1 to 2 liters per minute is fed into the main body so that the water generated from the molding material is discharged from the exhaust pipe 13 of the lid member 14. Since the amount of dry air or nitrogen gas delivered through the supply pipe 15 is extremely small, contamination by contamination does not pose a problem. In addition, the exhaust pipe 1
A vacuum pump may be connected to 3 to forcibly suction.

The molding material is supplied to the hopper 1 having the above-mentioned structure by opening the lid member 14 in a constant amount, or, though not shown, a supply pipe is attached to the lid member 14 to continuously supply the material. Then do.

The heating pipe 21 is embedded in the molding material by the molding material in the hopper 1 to heat and dry the molding material by the heat medium from the temperature controller 2, and the molding material is changed by the heat medium of the heating pipe 22. It is heated by the heated peripheral wall of the main body 10 and the stirring plates 3 and 3 inside thereof.
Therefore, even if the heating range of the internal heating pipe 21 is limited, the molding material is heated from inside and outside by heating from the outer peripheral wall side, and the heating range for the molding material is the above-mentioned heat radiation. Since it is expanded by the plates 20 and 20, the heating efficiency is remarkably improved even with the indirect heating by the heating pipes 21 and 22, and the heating is uniform and uneven drying is less likely to occur. .

This heating and drying is maintained by a heating pipe 23 attached to the inside or the outer peripheral surface of the material delivery cylinder 12,
Since the molding material is also sent out into the heating cylinder in a heated state, it also serves as preliminary heating of the molding material during plasticization.

Therefore, each heating pipe 21, 22, 2
By adjusting the heat medium of the temperature controller 2 to an appropriate heating temperature and circulatingly supplying the heat medium to 3, the molding material in the hopper 1 is not affected by environmental changes such as temperature and humidity in the factory.
It is possible to heat and dry efficiently, and since the molding material and the heat medium are in non-contact with each other, contamination that would occur when dry air is used as the heat medium is completely prevented.

Further, the heating medium is heated by heating pipes 21 and 2.
By flowing from the lower part to the upper part of 2, 23, the temperature difference between the upper and lower parts is eliminated by convection, and the temperature inside the hopper is stably maintained at a constant level, which facilitates temperature management. As the temperature controller 2, a ready-made mold temperature controller can be used, and not only the stable supply of the heat medium but also the facility cost can be reduced.

As described above, according to the present invention, it is possible to prevent the occurrence of defective molding due to contamination of contaminants by dry air, to solve the defective molding due to moisture absorption, and to prevent the defective molding due to moisture absorption. It is not necessary to use a high-performance filter when molding an optical system molded product or a transparent product, and efficient molding can be performed without frequent maintenance.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view schematically showing an embodiment of the present invention.

FIG. 2 is a cross-sectional explanatory view schematically showing an embodiment of the present invention.

[Explanation of symbols]

1 hopper 2 temperature controller 3 stirring plate 10 body 11 Funnel-shaped bottom 12 Material delivery tube 13 Exhaust pipe 14 Lid member 15 Dry air supply pipe 20 heat sink 21 Internal heating pipe 22 External heating pipe 23 Heating pipe for material delivery cylinder

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 45/18 B29C 31/02 B29C 47/10

Claims (3)

(57) [Claims] 1. A hopper that is provided in a molding machine by connecting a lower end opening to a material inlet of a heating cylinder, the hopper having a funnel-shaped lower part and a cylindrical main body in which a material delivery cylinder is connected in series. A cover member having an exhaust pipe, and a heating pipe for spirally arranging a heating medium flowing from a temperature controller in a spiral shape is provided inside and outside the funnel-shaped lower part of the main body and near the upper edge. A contamination-less hopper for a molding machine, characterized in that a plurality of stirring plates are vertically and horizontally projected on the inner wall of the main body at predetermined intervals, and a molding material is heated from inside and outside of the main body to be dried. 2. A heating pipe for circulating a heat medium is arranged spirally inside or on the outer peripheral surface of the material delivery cylinder, and a dry air supply pipe from a temperature controller is provided on a side portion. A contamination-less hopper for a molding machine according to claim 1. 3. The contamination hopper for a molding machine according to claim 1, wherein a required number of heat radiating plates are provided at regular intervals on the heating pipe in the main body.