JP3253551B2 - Valve nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a valve nozzle used for injection molding of a synthetic resin.

[0002]

2. Description of the Related Art As a valve nozzle, a flow path is opened and closed by bringing a tip of a shut-off pin into contact with a gate at a tip of a nozzle head. The shut-off pin is gated by a coil spring built in a closed chamber. Japanese Patent Application Laid-Open No. 57-163542 discloses a configuration in which when the pressure of the resin exceeds a certain value and overcomes the urging force of the coil spring, the resin moves toward the closed chamber and the gate is opened. Have been.

In addition, a ring having a circular hole is arranged in the internal space of the nozzle head, and the leading end of the spool is engaged with the circular hole to close the flow path. When the resin pressure exceeds a certain value and overcomes the urging force of the coil spring, the spool moves in the gate direction and a groove is prepared in a part of the spool head. A structure in which a flow path is formed between a ring and a hole is disclosed in
-290021.

[0004]

Problems to be Solved by the Invention
The thing of this system shown in 163542 gazettes is:
A sealed chamber to which the pressure of the resin does not directly reach is required, and if the resin enters the sealed chamber from the part that slidably supports the shut-off pin, it becomes inoperable, so only high precision is required for manufacturing. In addition, it is impossible to completely prevent the intrusion of the resin, and it becomes inoperable due to the intrusion of the resin, deterioration or decomposition of the intruded resin, and thus has a drawback that the life is short.

In order to overcome such difficulties, there has been proposed a configuration disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-290021. In this method, the pressure difference of the resin applied to the spool, that is, the gate direction pressure of the resin calculated by adding the cross-sectional area of the protrusion attached to the rear part of the spool and the cross-sectional area of the shaft, and the cross-sectional integral of the shaft Because the spool slightly overcomes the biasing force of the coil spring and moves in the gate direction to form a flow path due to the difference from the anti-gate pressure of the resin calculated by the amount obtained by subtracting
Unlike the configuration disclosed in JP-A-163542, the coil spring does not need to be housed in a closed chamber, so that the precision required for manufacturing is moderate and that the resin does not stay in the nozzle head. Is an advantage.

However, according to this method, a flow path is formed by a small groove formed in the head portion of the spool, and the resin that passes through the coil spring portion has a portion that quickly passes and a portion that stagnates, that is, a branch flow. This has been found to cause so-called resin burning and discoloration.

In order to solve the above, the present applicant has proposed an improved valve nozzle shown in FIG. 5 in Japanese Patent Application No. Hei 6-3317.
No. 73 (Japanese Unexamined Patent Publication No. 8-15625).
This valve nozzle was one in which the entire amount was quickly discharged without any stagnation of the resin inside the valve nozzle, and there was no burning or discoloration of the resin.However, there was a problem with the movement of the spool. There was found. That is, in the structure shown in FIG. 5, the valve is closed when the head portion of the spool is in the circular hole portion of the ring, and when the head portion moves to the gate side and is located in the concave portion, the circular hole of the ring The resin flow path is formed in the part and the valve is opened, but in the valve open state, the axial position of the head part of the spool is restricted only around the arrow-shaped projection, and the spool The following inventor's research has revealed that the accurate linear reciprocating motion may not be performed when the actuator is returned, and the actuator may be shaken, and that the return operation may be delayed or the valve may not be completely closed. Turned out by.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned difficulties, to make the spool perform an accurate linear reciprocating motion, and to reduce the maintenance load.

[0009]

The above object of the present invention is achieved by the following constitution. 1. A spool having a circular cross-section head portion, a circular cross-section shaft portion having a smaller diameter than the diameter of the head portion, and an arrow blade-like projection is provided in the internal space of the nozzle head. A cylindrical core having a contacting circular hole and a coil spring for urging the spool in the direction opposite to the gate are arranged, and when the pressure of the resin is below a certain value, the spool is attached in the direction opposite to the gate by the coil spring. The resin flow path between the head part of the spool and the circular hole of the ring is closed, and when the pressure of the resin exceeds a certain value, the spool overcomes the urging force of the coil spring and the spool moves in the gate direction. Moved, an annular resin flow path is formed between the outer periphery of the shaft portion of the spool and the circular hole of the ring, the flow path of the resin is opened, and the resin is spiraled by the coil spring. In the valve nozzle, the guide is provided outside the circular hole of the cylindrical core so as to guide the linear reciprocating motion of the head portion of the spool. A valve nozzle, characterized in that a notch is provided at the rear end of the spool to control the movement of the spool by engaging the arrow-shaped projection of the spool.

[0010] 2. Wherein the cylindrical core is sandwiched between the front step of the nozzle head and the rear step of the nozzle holder by screw connection of the nozzle head to the nozzle holder. The described valve nozzle.

[0011]

[0012]

Next, the present invention will be described in more detail with reference to the accompanying drawings. 1 to 4 show one embodiment of a valve nozzle according to the present invention. FIG.
FIG. 2 shows an open state.

In FIG. 1, the nozzle head 10 has a gate 11 at the center of the tip, and is detachably attached to the tip of a nozzle holder 15 by a screw mechanism. Reference numeral 20 denotes a spool, which is a head portion 21 at an end and an intermediate shaft portion 22.
-Consists of arrow-shaped projections 23 (see FIG. 3) arranged at the rear end. At least the vicinity of the head portion 21 of the head portion 21 and the shaft portion 22 is formed in a circular cross section.

Reference numeral 30 denotes a cylindrical core in which the above-described spool 20, coil spring 40, and washer 41 are housed. A circular hole 31 with which the outer periphery of the head portion 21 of the spool 20 abuts is provided on the distal end side (the side of the gate 11) of the cylindrical core 30. A plurality of guide portions 32 having the same inner diameter as the holes 31 are provided. Also, on the rear end side of the cylindrical core 30,
Notch 33 into which arrow-shaped projection 23 of spool 20 is fitted
Is prepared.

As shown in FIG. 3, the arrow blade-like projections 23 of the spool 20 have a three-spring configuration, but may have two or four springs or more.
However, in these cases, it is required that the configuration be such that the function of extruding while rotating the resin is not hindered.

A notch 33 formed at the rear end of the cylindrical core 30 and the arrow-shaped projection 23 of the spool 20 engaged with the notch 33
The notch 33 can be given a function as a guide for causing the spool 20 to perform an accurate linear reciprocating motion by increasing the manufacturing accuracy of the spool.

The coil spring 40 has a cylindrical core 3 at the front.
0 at the bottom, the back is through a washer 41 and the
3, the spool 20 is urged in the direction opposite to the gate, and the end of the arrow-shaped projection 23 of the spool 20 contacts the rear step 13 of the space formed inside the nozzle head 10. Have been.

The coil spring 40 may be formed of a plate material having a rectangular cross section, a circular cross section, or another cross sectional shape as long as the coil spring 40 does not hinder the function of extruding while rotating the resin.

In the state shown in FIG. 1, the outer periphery of the head portion 21 of the spool 20 seals the circular hole 31 of the cylindrical core 30, so that the resin flow path is closed. This state is a state in which the urging force of the coil spring 40 overcomes the pressure of the resin.

When the pressure of the resin exceeds a certain value, among the pressure components of the resin applied to the spool 20, the gate direction pressure and the anti-gate direction pressure are larger than the gate direction pressure by the sectional integral of the shaft portion 22. Therefore, if the pressure difference is set to be larger than the urging force of the coil spring 40, the spool 20 is moved in the direction of the gate 11 so that the front end of the arrow-like projection 23 is at the end of the cutout 33 of the cylindrical core 30. It will move to the position where it contacts the part. This is the head part 2 of the spool 20
In the following description, the head portion 21 of the spool 20 will be described.
Moves along a guide 32 provided outside the circular hole 31 of the cylindrical core 31 and is pushed out toward the concave portion 14 prepared near the gate 11, as shown in FIG. Then, a resin flow path is formed in an annular shape in the circular hole 31 of the cylindrical core 30. Therefore, the resin flows in from the side of the arrow feather-shaped projection 23 and advances while turning according to the spiral formed by the coil spring 40, and the flow path of the circular hole 31 portion, the outer periphery of the head portion 21 of the spool 20, the concave portion 14, It is injected from the gate 11 after passing through an annular flow path formed between them.

When the pressure of the resin is reduced below a certain value, the spool 20 returns to the state shown in FIG. 1 and the flow path is closed. At this time, since the outer peripheral portion of the head portion 21 of the spool 20 moves along the guide 32 which is provided so as to extend outside the circular hole 31, the circular hole 3 has no obstacle.
It is possible to return to one part.

FIG. 4 is a perspective view showing one example of the cylindrical core 30. As described above, the cylindrical core 30
A circular hole 31 with which the head portion 21 of the spool 20 is engaged, a guide 32 is formed to extend to the circular hole 31 at the front end side, and an arrow blade-like projection 23 of the spool 20 is engaged with the rear end side. A notch 33 is provided.

In the illustrated embodiment, three guides 32 are provided at equal intervals, and the inner surface of each is formed with a circular hole 31.
It has the same inner diameter as. The number of the guides 32 is not limited to three, and a configuration having a linear shape may be employed in addition to a configuration having a predetermined width as illustrated.

Further, according to the valve nozzle of the present invention, the nozzle head 10 is a replacement part having a difference in the curvature of the tip, the shape and size of the gate 11 and the concave portion 14, and the spool 20, the cylindrical shape Core 30, coil spring 4
By using the washer 41 and the washer 41 as common parts, there is also an advantage that it can be provided at a low cost for various types of molding machines, especially for injection molding machines.

[0025]

According to the valve nozzle of the present invention, the flow path formed between the circular hole 31 of the cylindrical core 30 and the spool 20, and the outer periphery and the recess of the head portion 21 of the spool 20 14 are both annular, and unlike the configuration shown in the above-mentioned JP-A-61-290021, the channels are not unevenly distributed.
In particular, there is no shunt in the flow of the resin in the coil spring 40 portion, and therefore, it is possible to effectively prevent the resin from staying in this portion and causing so-called burning or discoloration. In addition, according to the valve nozzle of the present invention, since the flow path in the nozzle head 10 is annular, the portion where the coil spring 40 exists rotates while following the spiral formed by the coil spring 40, and the resin swirls. The pushing is continued without being hindered by the cylindrical core 30 or the flow path portion of the concave portion 14 even after the gate 11. For this reason, the resin in the flow path is extruded while the inside and the outside are mixed, so that burning and discoloration of the resin are more effectively prevented.

Further, according to the valve nozzle of the present invention, by performing a linear reciprocating motion of the head portion 21 of the spool 20, an annular resin flow path is formed in the circular hole 31 of the cylindrical core 30. However, since the guide 32 is provided to extend outside the circular hole 31, the spool 2
Since the zero head portion 21 moves while being restricted by the guide 32, the moving axis does not fluctuate, and the linear reciprocating motion can be accurately performed, and the head portion 21 can return to the circular hole 31 without any obstacle. Can be. When such a guide 32 does not exist, the movement axis tends to fluctuate,
Compared to the possibility that the nozzle cannot be closed, it is possible to remarkably improve the operation efficiency.

In the valve nozzle according to the present invention, the cylindrical core 30 is connected to the front step 12 of the nozzle head 10 and the rear step 13 of the nozzle holder 15 by screwing the nozzle head 10 to the nozzle holder 15. Since the resin is sandwiched between them, it is possible to prevent the resin from flowing around the cylindrical core 30 and flowing backward.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a sectional view showing one embodiment of the present invention.

FIG. 3 is a sectional view showing an embodiment of the spool.

FIG. 4 is a perspective view showing one embodiment of a cylindrical core.

FIG. 5 is a sectional view showing a conventional example.

[Explanation of symbols]

 Reference Signs List 10-Nozzle head 11-Gate 12-Front step 13-Rear step 14-Recess 15-Nozzle holder 20-Spool 21-Spool head part 22-Spool shaft part 23-Spool arrow blade projection 30-Cylinder Core 31-circular hole 32-guide 33-notch 40-coil spring 41-washer

Claims (2)

(57) [Claims] A spool having, in an internal space of the nozzle head, a head part having a circular cross section, a shaft part having a circular cross section having a diameter smaller than the diameter of the head part, and an arrow blade-like projection; A cylindrical core having a circular hole in contact with the outer periphery of the portion, and a coil spring for urging the spool in the anti-gate direction are arranged, and when the pressure of the resin is below a certain value, the spool is moved by the coil spring. The resin flow path between the head portion of the spool and the circular hole of the ring is closed by being biased in the anti-gate direction, and when the pressure of the resin exceeds a certain value, it overcomes the biasing force of the coil spring and The spool is moved toward the gate,
A valve nozzle having a configuration in which an annular resin flow path is formed between the outer circumference of the shaft portion of the spool and the circular hole of the ring, the flow path of the resin is opened, and the resin is extruded while turning according to the spiral by the coil spring. , A guide for guiding the linear reciprocating motion of the head portion of the spool is provided outside the circular hole of the cylindrical core, and the feather of the spool is provided at the rear end side of the cylindrical core. A valve nozzle provided with a notch for engaging a projection and restricting movement of a spool. 2. A structure in which a cylindrical core is sandwiched between a front step of the nozzle head and a rear step of the nozzle holder by screw connection of the nozzle head to the nozzle holder. The valve nozzle according to claim 1, wherein