JPS5884741A - Structure of nozzle of injection molding machine - Google Patents

Abstract

PURPOSE:To simplify remarkably the struture of nozzles and to lower the manufacturing cost by a method wherein an oscillating valve is arranged in a nozzle passage and a mechanism is provided to open and close automatically a supply channel of raw material according to pressure. CONSTITUTION:A nozzle tip 1 having a nozzle open and connected to a sprue bush arranged at the raw material injecting part of a molding die and a nozzle body 2 having a supply end screwed in the supply system connected to the raw material supply source of an injection molding machine are combined into a unitary body. A raw material supply passage to connect the nozzle opening end to the supply end is opened in the nozzle and an oscillating valve 3 and a valve chamber 4 for storing this oscillating valve are arranged in the middle of the supply channel. The oscillating valve 3 is butted by a spring 5 to the inner wall on the side nearer to the supply end of the valve chamber 4. Injecting pressure of necessary molten raw material is kept in the molding die by the action of the oscillating valve 3 to obtain a molded product free from shrinkage voids etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a raw material injection nozzle for an injection molding machine, and in particular to a backflow prevention device that maintains the raw material in the mold at a constant pressure during the casting process after the raw material is injected into the mold. This relates to an injection nozzle with a built-in valve. Generally, a molten raw material made of styro-nope ABS or other thermoplastic resin is injected into a mold, etc., and after the raw material is solidified in the mold, the mold is opened. In an injection molding machine that produces a cast molded product, it is necessary to prevent the occurrence of shrinkage cavities caused by volumetric shrinkage when the raw material solidifies in the mold, and to completely spread the molten material throughout the entire mold. In order to supply the raw material, it is necessary to energize the inside of the mold with a constant pressure from the injection side after injecting the raw material. Therefore, conventionally, in order to apply pressure inside the mold, an on-off valve driven by a hydraulic or pneumatic cylinder is inserted into the nozzle of the injection molding machine connected to the injection port of the mold, and after the raw material is injected, A method was used in which this injection passage was shut off with an on-off valve, and the raw material injected into the mold was pressed with an on-off valve. However, this method had practical disadvantages because the structure was large and complicated. In view of the above-mentioned problems, the present invention provides a swing valve in the passage of the nozzle to adjust the raw material supply path in response to pressure. It is an object of the present invention to provide a nozzle structure for an injection molding machine that has an extremely simple structure and low manufacturing cost by conjugating a mechanism for opening and closing the mouth. I will explain in detail.

FIG. 1 is a cross-sectional configuration diagram of the nozzle part of an injection molding machine showing one embodiment of the present invention. A nozzle tip 1 having an open end, and a nozzle body 2 having a supply end screwed onto a supply system connected to a raw material supply source of an injection molding machine.
A raw material supply passage connecting the nozzle opening end and the supply end is opened therein, and a swing valve 3 and a valve chamber 4 for housing the swing valve 3 are interposed in the middle of the supply passage. Based on the configuration. , the swinging valve 3 is in contact with the inner wall of the valve chamber 4 on the side closer to the supply end by the spring 5 of
A heating element 6 is provided on the outer periphery of the nozzle tip 1 and the nozzle body 2.
2 is a sectional view showing the structure of the nozzle tip 1, and FIG. 3 is a sectional view showing the structure of the nozzle body 2. FIGS. 4(A), 4(F), and 4(C) are a left side front view, a front view, and a right side view showing the structure of the swing valve 3, respectively.

The nozzle opening end 1a for injecting molten raw material into the mold by contacting the sprue bush K''U of the 1-piece mold is located at one end, and the female screw 1b for connecting with the nozzle body 2 is screwed at the other end. The inside thereof still constitutes a part of the supply passage for the molten raw material and a part of the valve chamber.The nozzle body 2 has a male screw 2a screwed into the female screw 1b of the nozzle tip 1 at one end.
is threaded, and the other end is threaded with a male screw 2b for connection to a supply system for molten raw materials. Its interior still constitutes part of the supply passage and valve chamber, similar to the nozzle tip 1.

The swing valve 3 consists of a conical head and a cylindrical body, and eight rail grooves 3a are carved along the circumference of the body on the outer peripheral wall of the body parallel to the axis, through which the molten raw material passes. ing. The nozzle tip 1, nozzle body 2 and swing valve 3 are made of stainless steel or other heat-resistant metal alloy.

Next, the operation of the nozzle shown in this embodiment will be explained. When a molten raw material, such as styrene, is supplied from a raw material supply source at a predetermined pressure, the styrene is introduced from the supply end of the nozzle body 2 into the supply passage inside the nozzle, and its fluid pressure presses the swing valve 3, causing the swing valve to open. 3 is brought into contact with the inner wall of the valve chamber 4 on the nozzle tip side against the urging force of the spring 5. In this state, the styrene advances to the rail groove 3a of the swing valve 3 through the gap formed between the swing valve 3 and the inner wall on the supply end side of the valve chamber, passes through the rail groove 3a, and enters the nozzle tip. Styrofoam is injected into the mold from the nozzle opening end 1a of No. 1. When the injection of styrene into the mold is completed, the necessary pressure is applied from the supply system to the inside of the mold through the styrene, and then the styrene is poured from the supply system. At this moment when the pressure is zero, the back pressure from inside the mold and the spring 5 press the swinging valve 3 directly or through the styrene, and the swinging valve 3 presses against the supply end side of the valve chamber 4. Touches the inner wall. Therefore, the styrene from the supply end and the swing valve 3
Since the styrene located in the rail groove 3a is blocked by the abutted inner wall, the initial pressure of the styrene in the mold is maintained as it is. In this state, the styrene in the mold is solidified to form a molded product, while the styrene in the nozzle is heated by the heating element 6, so the styrene remains in a molten state. When the molding in the mold is completed, the nozzle is separated from the sprue bush of the mold, connected to another mold, and the same casting operation as described above is repeated.

As described above, the necessary injection pressure of the molten raw material into the mold is maintained by the action of the swing valve 30, and a molded product free of casting defects such as cavities can be obtained.

FIG. 5 is a sectional view of the nozzle section of an injection molding machine showing another embodiment of the present invention. In the figure, the same reference numerals as in FIGS. 1 to 4 indicate the same contents, and the explanation will be omitted.

In this embodiment, the rail groove 3a and the spring 5 in the swing valve 3 are
The position of is reversed, and its operating principle is the same as that of the previous embodiment.

As explained in detail above, according to the present invention, it is possible to apply the necessary injection pressure to the molten raw material injected into the mold with a very simple structure, and it is also easy to manufacture and miniaturized. The benefits in implementation are significant.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram of an injection molding machine nozzle section showing one embodiment of the present invention. FIG. 2 is a sectional view showing the structure of the nozzle chip 1. FIG. FIG. 3 is a sectional view showing the structure of the nozzle body 2. FIG. 4(5), (B), and (C) are a left side view, a front view, and a right side view showing the structure of the swing valve 3, respectively. FIG. 5 is a cross-sectional configuration diagram of the nozzle part of an injection molding machine showing another embodiment of the present invention. 6 Heating element agent Patent attorney Aihiko Fukushi Tokukaiichi A58-84741 (3)

Claims (1)

[Claims] 1. An injection port connected to the mold, a supply port for supplying the molten material, a supply passage for the molten material connecting the supply port and the injection port, and a supply passage for the molten material interposed in the supply passage. A swing valve that swings in accordance with the pressure direction of the swing valve, a molten material passage groove formed in communication with the swing valve, and a valve chamber that accommodates the swing valve, The feeding groove is opened when supplying the molten material,
A nozzle structure for an injection molding machine, characterized in that when supply is stopped, the swing valve is closed by contact between the swing valve and an inner wall of the valve chamber due to reverse pressure from the mold.