JPH0453689B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a nozzle sealing valve for an injection device, particularly a nozzle sealing valve for an injection device used for injection molding a resin-bonded magnet. It is.

(b) Prior Art A conventional nozzle sealing valve for an injection device is disclosed in, for example, Japanese Utility Model Application No. 60-46217.
That is, in this system, a needle, which is a valve body, is supported by a valve housing, which is a valve body support member, so as to be able to move in the axial direction, and this needle is pressed against a valve seat in the inner diameter part of the nozzle by a spring force. It is shown. As a result, when the molten resin pressure in the injection device is low, the needle comes into close contact with the valve seat and the nozzle is closed, and when the molten resin pressure rises, the needle retreats and the nozzle is opened, allowing the molten resin to pass through the nozzle. Injected into the mold.

(C) Problems to be Solved by the Invention However, when the nozzle sealing valve of the conventional injection device as described above is used for injection molding of a resin bonded magnet, the valve body and the valve body support member are separated. Since magnetic particles enter the sliding part and the valve body does not move smoothly, there is a problem of malfunction, that is, insufficient sealing, resulting in leakage of molten resin. This type of problem occurs because when injection molding is performed in a magnetic field, leakage magnetic flux acts on the valve body and valve body support member, magnetizing them and making it easy for magnetic particles to adhere to them. be. If the valve element slides with magnetic particles in the raw material adhering to the valve element and the valve element support member, the magnetic particles will get caught in the sliding part, making the valve element's sliding movement less smooth. When resin leaks from the nozzle tip as described above, the leaked resin may be caught between the nozzle tip and the mold sprue, causing damage to the mold.
In addition, if the nozzle is arranged vertically, such as in a vertical injection molding machine, leaked resin may fall onto the mold dividing surface and damage the mold during mold clamping. There is. Furthermore, a portion of the leaked resin may enter the mold as it is, causing so-called cold flow molding defects. The present invention aims to solve these problems.

(d) Means for Solving the Problems The present invention solves the above problems by making the sliding part between the valve body and the valve body support member made of a non-magnetic material. That is, in the nozzle sealing valve of the injection device according to the present invention, the entire valve body and valve body support member or the surfaces of their sliding parts are made of a non-magnetic material.

(e) Effect When injection molding is performed in a magnetic field, the influence of leakage magnetic flux extends to the valve body and the valve body support member. However, since the valve body and the valve body support member are made of non-magnetic material, or at least their sliding parts are made of non-magnetic material,
The moving parts do not become magnetized. Therefore, the magnetic particles in the raw materials do not stick to each other due to magnetic force, and it is no longer easy for magnetic particles to enter the sliding parts compared to before, making it possible to prevent the smooth sliding movement of the valve body for a long period of time. can be held for a period of time.

(F) Example (First Example) FIG. 1 shows a first example of the present invention. A valve housing 12 is installed at the tip of the cylinder 10 of the injection device.
is installed, and this valve housing 1
A nozzle 14 is attached to 2. The valve housing 12 includes a chamber 16 inside the cylinder 10.
A flow path 20 is provided to send the molten resin to the chamber 18 in the inner diameter of the nozzle 14. Further, a hollow needle support fitting 22 (valve body support member) is attached to the center portion of the valve housing 12. The needle support fitting 22 is made of non-magnetic material. A needle 24 (valve body) is guided in the inner diameter portion of the needle support fitting 22 so as to be movable in the axial direction.
This needle 24 is also made of non-magnetic material. The tip of the needle 24 can be seated on a valve seat 26 of the nozzle 14 . Further, the rear end of the needle 24 is connected to a spring receiving fitting 2 disposed within the cavity of the valve housing 12.
In contact with 8. Spring holder 28 and cylinder 1
A spring 30 is provided between the spring holder 28 and the spring holder 28, thereby applying a predetermined pressing force to the spring receiver 28.

Next, the operation of this embodiment will be explained. When the molten resin in the chamber 16 of the cylinder 10 is not pressurized, the spring 30 is
The spring force acting on the needle 24 acts on the needle 24, and the tip of the needle 24 touches the valve seat 2 of the nozzle 14.
Closely attached to 6. In this state, the resin on the chamber 18 side will not flow out to the mold 32 side. In this state, the raw material is sent to the chamber 16 while being melted by the screw of the injection device. When a predetermined amount of molten resin has accumulated, the injection piston of the injection device is activated, and the molten resin in the chamber 16 is pressurized. This molten resin flows through channel 2
When the pressure of the molten resin in the chamber 18 rises to a predetermined value, the needle 24 is pushed to the right in FIG. 1 against the force of the spring 30, and the tip of the needle 24 The state of close contact with the valve seat 26 is released, and the molten resin is injected into the mold 32. Next, a pressure holding step is performed, and when the resin pressure in the chamber 16 decreases after a predetermined period of time, the needle 24 is moved forward again by the force of the spring 30 and is seated on the valve seat 26. This completes one injection and starts melting the raw material for the next injection.

Immediately before the injection process and during the pressure holding process as described above, the mold 32 is
A predetermined magnetic field acts on. This allows the magnetic particles in the molten resin to be oriented. The influence of the magnetic field applied to the mold 32 is on the nozzle 14, the valve housing 12, the needle support fitting 22, and the needle 2.
4 etc. However, the needle support fitting 22
Since the needles 24 and 24 are made of non-magnetic material, they will not become magnetized. Therefore, the magnetic particles in the molten resin can cause the needle support fitting 22 and the needle 24 to
It does not stick to the surface by magnetic force. Therefore, the magnetic particles around the needle 24 are easily removed without being caught when the needle 24 moves along the inner diameter of the needle support fitting 22. Therefore, the needle 24 relative to the needle support fitting 22
The sliding movement is always performed smoothly, and the valve can be opened and closed reliably. This ensures that the tip of the needle 24 is in close contact with the valve seat 26, and molten resin is prevented from leaking. Therefore, it is possible to prevent problems such as breakage of the mold due to leaked molten resin and molding defects due to so-called cold flow. In addition, in this embodiment, the needle support fitting 22 and the needle 24
Although the entire structure is made of a non-magnetic material, only the outer diameter portions of the needle support fitting 22 and the needle 24, that is, only the sliding portions, may be covered with a coating made of a non-magnetic material.

(Second Embodiment) FIGS. 3 and 4 show a second embodiment of the present invention. In this second embodiment, the present invention is applied to a rotary sealing valve. That is, nozzle housing 1
A valve body support fitting 52 (valve body support member) is provided in the middle of the flow path 20 of No. 2, and a valve body 54 is provided on the inner diameter portion of the valve body support fitting 52 so as to be movable in the rotational direction. Both the valve body support fitting 52 and the valve seat 54 are provided with holes 52a and 54a that penetrate in the radial direction, and the holes 52a and 54a communicate with each other at a predetermined position in the rotation direction of the valve body 54. When the valve body 54 is rotated to the rotational direction position, the flow path 20 is cut off. The valve body 54 can be rotationally driven by a hydraulic cylinder 60 via a lever 56 and a link 58. Both the valve element support fitting 52 and the valve seat 54 are made of non-magnetic material. In the case of this second embodiment as well, by making the valve body support fitting 52 and the valve body 54 made of non-magnetic material, adhesion of magnetic particles is prevented, and the smooth rotation direction of the valve body 54 and the valve body support fitting 52 is prevented. The rolling motion can be sustained for a long period of time. This second
In the embodiment, only the surface of the sliding part may be made of non-magnetic material.

(Third Embodiment) FIGS. 5 and 6 show a third embodiment of the present invention. In this third embodiment, the present invention is applied to a reciprocating type nozzle sealing valve. That is, a valve body 74 that is movable in the axial direction is provided in a valve body support fitting 72 provided in the middle of the flow path 20 of the nozzle housing 12, and the valve body 74 is positioned at a predetermined position with respect to the valve body support fitting 72. At the axial position, a passage is formed to communicate the flow passages 20, and at other positions, the passages 20 are blocked. The valve body is driven axially by a hydraulic cylinder 80 via links 76 and 78. The valve body support fitting 72 and the valve body 74 are made of non-magnetic material. In this third embodiment, the same functions and effects as in the first and second embodiments described above can be obtained.

(G) Effects of the Invention As explained above, according to the present invention, the entire valve body and valve body support member of the nozzle sealing valve of the injection device, or at least the sliding parts of both, are made of non-magnetic material. Therefore, the valve body and the valve body supporting member are not magnetized by leakage magnetic flux during injection molding in a magnetic field, and adhesion of magnetic particles is prevented. This allows for smooth movement between the valve body and the valve body support member, making it possible to reliably seal the molten resin, thereby preventing defects such as mold damage and molding defects due to molten resin leakage. Occurrence can be prevented.

[Brief explanation of the drawing]

Fig. 1 shows the first embodiment of the present invention, Fig. 2 shows the injection molding process in a magnetic field, Fig. 3 shows the second embodiment, and Fig. 4 shows the third embodiment. Figure 5 is a diagram showing the third embodiment, Figure 6 is a diagram seen in the direction of the arrow.
The figure is a view seen in the direction of the arrow in FIG. 10...Cylinder, 12...Valve housing, 14...Nozzle, 22...Needle support fitting (valve body support member), 24...Needle (valve body), 2
6...Valentine seat.

Claims (1)

[Claims] 1. A nozzle sealing valve for an injection device that opens and closes a nozzle by sliding or rotating the valve body relative to the valve body support member, including: the entirety of the valve body and the valve body support member; Or a nozzle sealing valve for an injection device, characterized in that the surface of these sliding parts is made of a non-magnetic material.