JPH02247Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a synthetic resin injection molding machine.

[Prior art and its problems]

In a synthetic resin injection molding machine, synthetic resin powder is sent from a material tank to a hopper placed on a heating cylinder, where it is temporarily stored, and from there, it is sequentially filled into the heating cylinder for injection molding.
Instead of just one type of synthetic resin material, for example, many types of synthetic resin with different colors are placed in each material tank, and when a certain color is molded for a predetermined number of shots, the next one is used. Color changes are often performed by sending colored items to a hopper. Therefore, when changing colors, residual materials adhering to heating cylinders and hoppers mix into new products of other colors, but products with mixed colors are defective, so molding yields can be improved. In order to achieve this, it is necessary to minimize the amount of residue that adheres to heating cylinders, hoppers, etc.

By the way, this hopper is often made of transparent Pyrex glass so that you can visually confirm the presence and type of material inside.
Static electricity is generated when the synthetic resin powder moves in contact with the inner wall of the glass hopper. For this reason, even if the inside of the hopper was emptied when changing colors, powder adhered to the inner wall, resulting in a large number of defective products with different colors mixed in, and a low molding yield. Conventionally, this adhering powder was removed by wiping it off manually, but this work was complicated and took a long time.

[Purpose of invention]

The present invention was developed based on these circumstances, and it is possible to easily and reliably remove the residual synthetic resin powder that adheres to the hopper, and to create an injection molding machine with a high molding yield. The purpose is to provide.

[Structure of the idea]

The structure of the present invention is that synthetic resin powders of different colors and other types are alternately fed from two or more material tanks into a hopper installed over the opening of a heating cylinder, and from these hoppers the synthetic resin powder is transferred to the heating cylinder. In an injection molding machine that fills and molds,
A suction device is connected to the hopper, a gap is formed between the lower end of the hopper and the opening of the heating cylinder, and this gap is covered with a belt-shaped rotating shutter, which is used when switching from synthetic resin powder to another type of material. The rotary shutter is rotated to open a gap, and air is introduced into the hopper through the gap and raised along the inner wall of the hopper, thereby removing synthetic resin powder adhering to the inner wall.

〔Example〕

The present invention will be specifically described below based on embodiments shown in the drawings.

A plurality of material tanks 1 are arranged in parallel, and synthetic resin powder materials of different colors are stored inside each tank. These materials are sent into a transparent glass hopper 3 by air through a pipe 2. A slide gate 4 is provided below each material tank 1, and one material is molded into a predetermined number of shots. Then, that slide gate 4 is closed, and the other slide gate 4 is opened to send another material to the hopper 3.

The hopper 3 is installed on the opening 5a of the heating cylinder 5, and the material inside is sequentially filled into the heating cylinder 5 and injection molded. The hopper 3 is connected to a suction device 7 via a pipe 2, and when the suction device 7 is operated, air inside the pipe 2 and the hopper 3 is sucked. A material sensor 6 is attached to the outer wall of the hopper 3, and when the material in the hopper 3 decreases, the sensor 6 detects this.
In response to this signal, material is sucked from the material tank 1 and replenished.

Between the lower end of the hopper 3 and the opening 5a, a second
As shown in the drawings and FIG. 3, a large number of gaps 9 each having a vertical width of about 2 mm are formed at equal intervals all around the circumference. This gap 9 is covered with a belt-shaped rotary shutter 8, and holes 8a, which are equal to the gap 9, are formed in the shutter 8 at the same intervals as the gap 9. Therefore, when the shutter 8 rotates a little and the phases of the gap 9 and the hole 8a match, the inside of the hopper 3 communicates with the outside, as shown in FIGS. 4 and 5.

When the number of shots made of one material reaches a predetermined number, the slide gate 4 is closed. At this time, material powder adheres to and remains on the inner walls of the material supply pipe 2 and hopper 3. and,
When the suction device 7 is operated, the air inside the pipe 2 is suctioned, and the adhering powder is also suctioned and removed at the same time.
However, since one end of the hopper 3 is closed by the heating cylinder 5, the inside becomes an air pocket and almost no air is sucked in.
Powder still adheres to the inner wall.

Next, after cleaning the inside of the material supply pipe 2, a pipe cleaning valve 4a provided at the rear of the tank 1 is installed.
is closed, and at the same time, the shutter 8 rotates and the gap 9 is opened. Therefore, air enters the interior through the gap 9 and rises along the inner wall. Therefore, powder adhering to the inner wall is easily suctioned and removed. When the cleaning inside the hopper 3 is completed, the shutter 8 rotates again to close the gap 9, and the material in the other material tank 1 is sent to the hopper 3 and molded with a new material.

Next, another embodiment will be described based on FIGS. 6 and 7. The lower end of the hopper 3 and the upper end of the opening 5a are kept at a distance of about 2 mm by a spacer 10, forming a gap 9. There is. A spiral protrusion 11 with a large pitch is formed on the outer periphery of the opening 5a, and a corresponding groove is formed on the inner surface of the shutter 8, so that when the shutter 8 rotates, it moves up and down. There is.

During injection molding, the gap 9 is closed by the shutter 8, as shown in Figure 6, but during cleaning, the shutter 8 rotates, opening the gap 9 as shown in Figure 7. Air enters with force and rises along the inner wall of the hopper 3.

[Effect of idea]

As explained above, in this invention, a suction device is connected to the hopper, and the gap between the bottom end of the hopper and the opening of the heating cylinder is opened and closed by a rotating shutter. It enters the hopper and rises uniformly along the entire circumference of the inner wall from the lower end of the hopper. Therefore, the synthetic resin powder adhering to the inner wall can be reliably removed in a short time. Therefore, according to the present invention, powder remaining on the hopper can be easily and reliably removed, and an injection molding machine with a high molding yield can be provided.

[Brief explanation of the drawing]

Figure 1 is a front view, Figures 2 and 4 are cross-sectional views of essential parts, Figure 3 is a cross-sectional view taken along the line - Figure 2, Figure 5 is a cross-sectional view taken along the line - Figure 4, and Figure 6. and FIG. 7 are sectional views of essential parts of another embodiment. 1... Material tank, 2... Pipe, 3... Hopper, 4... Slide gate, 5... Heating cylinder, 5a... Opening, 6... Material sensor, 7...
...Suction device, 8...Rotary shutter, 9...Gap.

Claims (1)

[Scope of Claim for Utility Model Registration] Synthetic resin powders of different colors and other types are alternately fed from two or more material tanks into a hopper installed over the opening of a heating cylinder, and the synthetic resin powder is heated by the hopper. In an injection molding machine that fills and molds a cylinder, a suction device is connected to the hopper, a gap is formed between the lower end of the hopper and the opening of the heating cylinder, and this gap is covered with a belt-shaped rotating shutter to remove the material. When changing one type of synthetic resin powder to another type, the rotary shutter is rotated to open a gap, and air is introduced into the hopper through this gap and rises along the inner wall of the hopper, thereby removing the synthetic resin that has adhered to the inner wall. An injection molding machine characterized by removing powder.