JPS6233054B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a needle valve type multi-valve nozzle for an injection molding machine.

This type of conventional device will be explained with reference to FIGS. 1 to 4. Reference numeral 1 denotes a heating cylinder, and a screw 2 is rotatably and axially slidably inserted into the inner diameter surface of the heating cylinder. 3 is a multi-valve nozzle attached to the tip of the heating cylinder 1, which introduces the molten resin from the heating cylinder 1 through the connecting hole 4, passes through the inflow hole 5, and guides it into the valve chambers 6a and 6b, and then enters the nozzle hole 7a. and 7b. The nozzle holes 7a and 7b are provided with needle valves 8a and 8b, respectively, and the needle valves 8a and 8b are normally provided.
The valve chamber 6a is closed by springs 9a and 9b pressing from behind the valve chamber 6a and 8b.
When the resin pressure of the springs 9a and 6b exceeds the pressing force of the springs 9a and 9b, they open and injection is performed.

However, the inflow hole 5 and needle valves 8a and 8b
are arranged so that they are on the same plane, so the third
Retentions A and B occur as shown in FIG. These retentions A and B can be alleviated to some extent by the shapes of the needle valve 8a and the inlet hole 5, but they cannot be completely eliminated.

Further, the needle valves that open and close the nozzle holes 7a and 7b must operate simultaneously, but due to the current situation as described above, the resin pressures in the valve chambers do not reach the same value at the same time. Therefore, the opening and closing operations of the needle valves were not performed simultaneously, which was inconvenient.

The object of the present invention is to eliminate the above-mentioned drawbacks and provide a needle valve type multi-valve nozzle in which stagnation does not occur and the nozzles can be opened and closed simultaneously.

Next, referring to FIGS. 5 and 6, one embodiment of the present invention will be explained by taking the case of two nozzle holes as an example. Reference numeral 11 denotes a heating cylinder, and the screw 12 is rotatable and slidable in the axial direction. is inserted into its inner diameter surface.

13 is a multi-valve nozzle attached to the tip of the heating cylinder 11;
The molten resin is introduced through the connection hole 14, guided through the inflow hole 15 to the valve chambers 16a and 16b, and injected from the nozzle holes 17a and 17b. The valve chambers 16a and 16b are provided with needle valves 18a and 18b, respectively, and normally a hydraulic plunger 1 behind the needle valves 18a and 18b is provided.
The nozzle holes 17a and 17 are pushed by the liquid pressure acting on the nozzle holes 9a and 19b as shown by arrow A.
Although the valve chambers 16a and 1
6b is applied to the plungers 19a and 1.
When the pressing force becomes larger than the pressing force due to the hydraulic pressure acting on the needle valves 18a and 18b, the needle valves 18a and 18b resist the pressing force.
is moved back by a predetermined amount (to the right in the figure), the nozzle holes 17a and 17b are opened, and injection is performed. 20a and 20b are the needle valves 1;
A bushing is provided coaxially with 8a and 18b, and supports the needle valves 18a and 18b.

The pressing force acting behind the needle valves 18a and 18b is not limited to hydraulic pressure such as oil pressure as described above, but may also be pneumatic pressure such as air, or a spring may be used as explained in the conventional example. It is self-evident that it is okay to do so.

Further, the inflow hole 15 is connected to the connection hole 1 from the outer surface.
The holes are machined radially toward the inflow hole 15, and the R portion smoothly connects to the inner wall surface of the inflow hole 15 so that the molten resin passing through the inflow hole 15 does not leak out of the machine or accumulate. stoppers 21a and 21 with
b is provided. As shown in FIG. 6, the inflow hole 15 is arranged such that the outer circumferential surface of the inflow hole 15 is in contact with the outer diameter surfaces of the needle valves 18a and 18b. In addition, as shown in FIG. 7, the outer peripheral surface of the inflow hole 15 is
The plane is different from the axis C of a and 18b. Therefore, as shown in FIGS. 8 and 9, the molten resin flows from the inlet hole 15 to the valve chambers 16a and 1.
It wraps around to 6b only from one side, forming a spiral flow to prevent stagnation.

Also, the valve chambers 16 at the tips of the plugs 21a and 21b
The portions of a and 16b that are in contact with the hole diameter surface are rounded along the same hole diameter surface, and further, as shown in FIG. 9, the needle valve 1
If the bushing 20 that supports the resin 8 is made to protrude into the valve chamber 16, and the corner portion D facing the inlet hole 15 is made a smooth sloped surface against the resin flow to prevent stagnation, the corner portion will be smooth and the stagnation will be further reduced. It becomes harder to get up, and the spiral flow becomes more effective.

Furthermore, as mentioned above, there is no accumulation of resin flowing into the valve chamber, so there is no difference in the resin pressure depending on each nozzle, there is no variation in the opening/closing operation of the needle valve, and there is an independent pressing mechanism for each needle valve. By providing this, opening and closing operations can be performed even more simultaneously.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a conventional device. FIG. 2 is a cross-sectional view of FIG. 1. 3 and 4 are diagrams explaining the flow state of the resin in the nozzle, and FIG. 3 is a detailed view of "A" in FIG. 2. FIG. 4 is a detailed view of the "b" part in FIG. 1. FIG. 5 is a diagram showing one embodiment according to the present invention. FIG. 6 is a cross-sectional view of FIG. 5. 7th
The figure shows another embodiment of the present invention, in which the outer periphery of the inflow hole passes through the axis of the needle valve. Figures 8 and 9
The figures are explanatory diagrams according to the implementation of the present invention, and FIG. 8 is a detailed view of the communication portion between the inflow hole and the valve chamber, and the "C" detailed view of FIG. 6. FIG. 9 is a detailed view of the "N" part of FIG. 5. 14... Connection hole, 15... Inflow hole, 16a, 1
6b... Valve chamber, 17a, 17b... Nozzle hole, 1
8a, 18b...needle valve, 20a, 20b...bush.

Claims (1)

[Scope of Claims] 1. When the resin melted and measured in the heating cylinder of an injection molding machine flows into a mold having two or more gates, the heating cylinder and the mold opening are communicated. 2. In a multi-valve nozzle in which the opening and closing of at least one gate and the same number of nozzle holes are controlled by a needle valve, one gate is provided coaxially with the heating cylinder on an extension of the outlet of the molten resin at the tip of the heating cylinder. A connecting hole, a number of valve chambers having the same axis as the needle valve and having a nozzle hole at the tip, the same number as the two or more gates, and communicating radially between the connecting hole and the valve chamber, and The molten resin has its axis on a plane different from the plane connecting the center of the connection hole and the axis of the needle valve, and the molten resin flows around the outer periphery of the needle valve only from one side and flows in a spiral shape, so that the outer periphery is an inflow hole that communicates with the needle valve in a range from a position touching the outer periphery of the needle valve to a position coinciding with the axis of the needle valve; and an inlet hole provided at an end opposite to the nozzle hole of the needle valve to push and pull the needle valve to open the nozzle hole. A multi-valve nozzle for an injection molding machine comprising a pressing mechanism independently provided for closing two or more nozzle holes. 2. The multi-valve nozzle for an injection molding machine according to claim 1, wherein the pressing mechanism is a hydraulic cylinder or a pneumatic cylinder. 3. A multi-valve nozzle for an injection molding machine according to claim 1, wherein the pressing mechanism is a spring. 4. In any one of the valves according to claims 1 to 3, in the communication portion between the inflow hole and the valve chamber, the end surface of the bushing supporting the needle valve facing the valve chamber is inserted into the valve chamber. A multi-valve nozzle for an injection molding machine, characterized in that it protrudes and forms a smooth sloped surface against the flow of resin from an inflow hole.