JPH0116578Y2 - - Google Patents

Description

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

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 step is to mold other synthetic resins. Color changes are often performed by sending colored items to a hopper. Therefore, when changing colors, residual materials adhering to heating cylinders and hoppers will be mixed 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 and hoppers.

By the way, this hopper is often made of transparent glass so that the presence and type of material inside can be confirmed visually or with a sensor, but synthetic resin powder may move when it comes into contact with the inner wall of the glass hopper. Static electricity is then generated. For this reason, even if the inside of the hopper is emptied when changing colors, powder adheres 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 the work was complicated and took a long time.

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. The structure 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 the synthetic resin powder is filled into the heating cylinder from this hopper. In an injection molding machine, a suction device is connected to the hopper and an elevating means is attached to the hopper, and when changing the material of synthetic resin powder to another type, the hopper is slightly elevated by the elevating means. A gap is formed between the lower end of the hopper and the opening of the heating cylinder, and the air that enters through the gap rises along the inner wall of the hopper due to the suction force of the suction device, removing the synthetic resin powder adhering to the inner wall of the hopper. It is characterized by being

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 forced into a transparent glass hopper 3 through a pipe 2 by air, but a slide gate 4 is provided under each material tank 1, and one material is fed into a predetermined number of shots. Once molded, the slide gate 4
is closed and another slide gate 4 is opened to pump another material into 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 in 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. As shown in FIG. 2, an air cylinder 8 is attached to the hopper 3, and the cylinder 8 allows the hopper 3 to move up and down. Therefore, the pipe 2 connected to the hopper 3 becomes a flexible pipe 2a from the middle. Note that the means for raising and lowering the hopper 3 is not limited to the air cylinder 8, and any means such as a cam mechanism may be used.

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, when the inside of the material supply pipe 2 has been cleaned, the slide gate 4a provided in the middle of the pipe 2 is closed, and at the same time, the air cylinder 8 is activated, as shown in FIG. , Hopper 3
increases slightly. Therefore, a gap 9 is formed between the lower end of the hopper 3 and the opening 5a of the heating cylinder 5, but since the material supply pipe 2 is closed by the slide gate 4a, air can enter the gap 9.
It enters the interior more forcefully 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 cylinder 8 is activated and the hopper 3 descends, and when its lower end comes into close contact with the opening 5a,
The material in the other material tank 1 is pumped and molded with a new material.

As explained above, the present invention connects a suction device to the hopper and attaches an elevating means such as an air cylinder to raise the hopper slightly when changing the material of synthetic resin powder to another type. Since air is introduced into the interior through the gap formed between the lower end and the opening of the heating cylinder, the air rises uniformly from the lower end of the hopper along the entire circumference of the inner wall. 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 drawings]

FIG. 1 is a front view, and FIGS. 2 and 3 are sectional views of main parts. 1... Material tank, 2, 2a... Pipe, 3...
...Hopper, 4,4a...Slide gate, 5...
...Heating cylinder, 5a...Opening, 6...Material sensor, 7...Suction device, 8...Air cylinder, 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 into a cylinder, a suction device is connected to the hopper and a lifting means is attached, and when switching from synthetic resin powder to another type of material, the hopper is moved by the lifting means. It rises slightly to form a gap between the lower end of the hopper and the opening of the heating cylinder.
An injection molding machine characterized in that the air entering through the gap rises along the inner wall of the hopper by the suction force of the suction device, and synthetic resin powder adhering to the inner wall of the hopper is removed.