JPS6233930B2 - - 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 inlet hole 5, and guides it to the valve chambers 6a and 6b. It is injected from 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 a result of the resin flowing as indicated by the arrows in FIG. This residence A and B
This can be alleviated to some extent depending on the shape of the needle valve 8 and the inlet hole 5, but it 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, it is difficult for the resin pressures in the valve chambers to 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 that does not cause stagnation, can open and close the nozzle simultaneously, and can adjust its pressing force.

Next, an embodiment of the present invention will be explained with reference to FIGS. 5 to 10, 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.

Reference numeral 13 denotes a multi-valve nozzle to which the tip of the heating cylinder 11 is attached.
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 are normally pushed by one end of a lever 23 behind the needle valves 18a and 18b to open the nozzle holes 17a and 1.
7b respectively, but the resin pressure in the valve chambers 16a and 16b closes the needle valves 18a and 18b.
When the pressure becomes larger than the pressure applied from behind, the needle valves 18a and 18b move back by a predetermined amount (move to the right in the figure) against the pressure, open the nozzle holes 17a and 17b, and perform injection. It's summery. 20a and 20b are bushes provided coaxially with the needle valves 18a and 18b;
a and 18b.

Reference numeral 22 denotes an adjustment bolt, which is provided on one side of the lever 23 as shown in FIG. This is a pressure adjustment mechanism designed to adjust the pressure. The lever 23 has one side in contact with the opposite nozzle hole end of the needle valve 18 as described above, and the other side connected to the piston rod 25 of the hydraulic cylinder 24, and swings around a fulcrum 26 in the center, so that the needle valve This controls the opening and closing of 18.

Here, instead of the adjustment bolt 22 which is the pressing force adjustment mechanism, it is also possible to adjust the pressing force using a spring 27 as shown in FIG.

The inflow hole 15 is machined radially from the outer surface toward the connection hole 14.
Plugs 21a and 21b having rounded portions that smoothly connect with the inner wall surface of the inlet hole 15 are provided so that the molten resin passing through them does not leak out or stagnate. As shown in FIG.
It is arranged to be in contact with the outer diameter surface of b. Further, as shown in FIG. 7, since the outer peripheral surface of the inflow hole 15 passes through the axes of the needle valves 18a and 18b, the axis B of the inflow hole 15 and the axis C of the needle valves 18a and 18b are different. It has become a different plane. Therefore, the eighth
As shown in Figures and Figure 9, the molten resin flows through the inflow hole 1
5 to the valve chambers 16a and 16b from only 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 20a that supports the resin 8 is made to protrude into the valve chamber 16, and the corner portion D relative to 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, and there is no variation in the opening/closing operation of the needle valve. By providing a pressing device having the above, it is possible to perform the opening and closing operations 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 the "A" part 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 diagram showing a case where the outer periphery of the inflow hole is in contact with the outer diameter of the needle valve in the cross section shown in FIG. 5. FIG. 7 is a diagram showing another embodiment of the present invention, in which the outer periphery of the inlet hole passes through the axis of the needle valve. 8 and 9 are explanatory diagrams according to the implementation of the present invention, and FIG. 8 is a detailed diagram of the communication part between the inflow hole and the valve chamber, and "H" in FIG.
Detailed view of the part. FIG. 9 is a detailed view of the "N" part of FIG. 5. FIG. 10 is a cross-sectional view taken from FIG. 5 and is a detailed explanatory diagram of the lever portion. FIG. 11 is a diagram showing another embodiment of the pressing force adjustment mechanism. 14... Connection hole, 15... Inflow hole, 16a, 1
6b... Valve chamber, 17a, 17b... Nozzle hole, 1
8a, 18b...needle valve, 20a, 20b...bush, 22...adjustment bolt, 23...lever, 24
...hydraulic cylinder, 27...spring.

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, so that the molten resin flows around the outer periphery of the needle valve only from one side and flows in a spiral shape. An inflow hole communicated 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 one side contacting the opposite end of the nozzle hole of the two or more needle valves, and one side on the other side. The hydraulic cylinder is rotatably mounted around a central portion connected to a piston rod of the hydraulic cylinder, and the hydraulic cylinder moves the two or more needle valves simultaneously in the axial direction to open and close the nozzle hole, A multi-valve nozzle for an injection molding machine comprising a pressing device equipped with a lever having a pressing force adjustment mechanism capable of adjusting the pressing force for pressing the nozzle hole. 2. The device according to claim 1, wherein the pressing force adjustment mechanism is located at a portion of the lever that comes into contact with the needle valve, and the length of the projection from the lever is adjusted by pushing and pulling a screw. Multi-valve nozzle for injection molding machine. 3. The injection mechanism according to claim 1, wherein the pressing force adjustment mechanism is located at a contact portion between one side of the lever and an end opposite to the nozzle hole of the needle valve, and adjusts the pressing force by a spring. Multi-valve nozzle for molding machine. 4. In the valve according to any one of 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 A multi-valve nozzle for an injection molding machine, which projects into a valve chamber and has a smooth sloped surface against the flow of resin from an inflow hole.