JP3566627B2 - Valve nozzle - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a valve nozzle used for a synthetic resin molding machine, and more particularly, to a valve nozzle and a shut-off nozzle used for hot runner molding.
[0002]
[Prior art]
The valve nozzle opens and closes the flow path by bringing the tip of the shut-off pin into contact with the gate at the tip of the nozzle head. The shut-off pin is urged in the gate direction by a coil spring built in the 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.
[0003]
The method disclosed in Japanese Patent Application Laid-Open No. 57-163542 has a problem that the residual stress near the gate is large when the resin flow path is closed, and the molded product is easily broken at this portion. Furthermore, when the resin flow path is opened and the resin is injected through the gate, the resin travels straight along the space of the gate, contacts the mold, and changes its flow in the lateral direction. Therefore, in this configuration, the flow of the resin near the gate is poor.
[0004]
Therefore, the present inventor has previously proposed Japanese Patent Application No. 9-209808 as a valve nozzle which improves the flow of resin near the gate and has a small residual stress near the gate.
Although the prior proposed technique could solve the problem of JP-A-57-163542, the temperature control was strictly controlled so that the flow of the resin near the gate was not deteriorated because the optimum temperature range of the resin was narrow. It has been found that it is necessary to perform the process, and that there is a point to be improved that a flow mark is easily attached to a molded product.
[0005]
[Problems to be solved by the invention]
The present inventor further researched and investigated the cause, and found that the resin flow path was only the cutout portion of the head portion, that is, since the resin flow was a partial flow, the heat balance of the resin near the gate was observed. Was found to be the cause.
[0006]
Therefore, an object of the present invention is to provide a valve nozzle capable of obtaining a molded product having a wide temperature control range and inconspicuous flow marks.
[0007]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following configurations.
1. A spool having, in the internal space of the nozzle head attached to the tip of the nozzle holder, a head portion having a circular cross section, a constricted portion formed continuously from the entire circumference of the head portion, a shaft portion, and an arrow-shaped projection; A collar disposed in the internal space of the nozzle head, slidably supporting the outer diameter of the shaft of the spool, serving as a guide for the spool, and extending the end so as to reach the vicinity of the gate; A gate opening / closing mechanism comprising a coil spring biasing in the gate direction is arranged, and when the pressure of the resin is lower than a certain value, the spool is biased in a direction opposite to the gate by the coil spring to have a circular cross section of the head portion of the spool. The entire circumference of the nozzle abuts against the inner wall of the gate of the nozzle head to close the resin flow path. When the pressure of the resin exceeds a certain value, it overcomes the urging force of the coil spring. Head portion of said spool Te is protruded outside the gate of the nozzle head, a resin passage is formed configurations resin flow path is opened between the constricted portion and the gate inner wall of the spool, said collar Wherein the spool shaft is supported by two to four points .
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in more detail with reference to the accompanying drawings.
1 to 3 show one embodiment of a valve nozzle according to the present invention. FIG. 1 is a closed state, FIG. 2 is an opened state, and FIG. 3 is an enlarged end view.
[0009]
In FIG. 1, a nozzle head 10 has a gate 11 formed of a circular hole at the center of the tip, and is detachably attached to a tip of a nozzle holder 12 by a screw mechanism. Reference numeral 20 denotes a spool, which is a head portion 21 at the front end, a constricted portion 22 formed continuously and narrowly from the entire circumference of the head portion 21, an intermediate shaft portion 23, and a feather-like shape arranged at the rear end. The projection 24 is formed. Reference numeral 30 denotes a collar, which is disposed in the internal space of the nozzle head 10 and slidably supports the outer diameter of the shaft portion 21 of the spool 20 to serve as a guide for the spool 20 so that the tip portion 31 reaches the vicinity of the gate 11. Is growing.
[0010]
As shown in FIG. 3C, the distal end portion 31 of the collar 30 has a three-point support configuration, but has a configuration that can slidably support the shaft portion 23 of the spool 20 and does not hinder the flow of resin. if any, it may be configured of a two-point support or four Ten支lifting.
[0011]
In the internal space of the nozzle head 10, the spool 20 slidably supported by the collar 30 is urged rightward in the drawing by a coil spring 40. Are stationary while in contact with the step 13 formed in the nozzle holder 12. Reference numeral 41 denotes a washer which is a member for suppressing the coil spring 40.
The arrow feather-like projection 24 of the spool 20 has a three-spring configuration, but may have two or four springs or more.
[0012]
As shown in FIG. 3, the vicinity of the tip of the head portion 21 of the spool 20 is circular in cross section, and a constricted portion 22 is formed so that the circular shape is gradually constricted.
When the nozzle is closed, the outer periphery of the circular section in the vicinity of the tip of the head portion 21 is in contact with the inner wall of the circular hole of the gate 11 to close the resin flow path.
[0013]
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 23 of the spool 20. Therefore, if the pressure difference is set to be larger than the urging force of the coil spring 40, as shown in FIG. (Formed on the collar 30). In this state, as shown in FIGS. 3A and 3B, a resin flow path is formed between the circular hole of the gate 11 and the constricted portion 22 of the spool 20.
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.
[0014]
As described above, since the spool 20 is slidably supported by the collar 30 (see FIG. 3D), the collar 30 serves as a guide when the spool 20 is moved. On the other hand, the linear reciprocating motion can be accurately performed without causing a positional shift. When the resin flow path is in an open state, as shown in FIG. 2, the head portion 21 of the spool 20 projects outside the gate 11, and is located between the inner peripheral portion of the gate 11 and the constricted portion 22. A resin flow path will be formed.
[0015]
As is apparent from FIG. 3B, the resin flow path is formed on the entire circumference of the constricted portion 22, so that the presence of the coil spring 40, coupled with the effect that the resin turns toward the gate 11 while turning, causes the head to move. Not only is the resin flow better than in the prior proposed technology in which only the cutout portion is formed, but the resin is injected in all directions at 360 degrees, so that a good molded product is obtained and the flow mark of the molded product is significantly reduced. be able to. The improved flow of the resin provided a good heat balance and significantly widened the temperature control range as compared with the prior art.
[0016]
Further, since the distal end portion 31 of the collar 30 extends so as to reach the vicinity of the gate 11, the heat transmitted through the collar 30 reaches the resin in the vicinity of the gate 11, so that there is an additional effect that the fluidity is always good. Have.
[0017]
In the valve nozzle of the present invention, the tip of the head portion 21 of the spool 20 protrudes outside the gate 11. It is preferable to form a concave portion in a corresponding mold.
[0018]
【The invention's effect】
According to the valve nozzle according to the present invention, the resin flow path is formed on the entire circumference between the circular hole of the gate 11 and the constricted portion 22 of the spool 20, so that the flow of the resin is good and 360 degrees in all directions. The resin can be injected, a good molded product can be obtained, and the flow mark of the molded product can be significantly reduced. Further, since the flow of the resin in the gate 11 is good, the heat balance is good, and the temperature control range is significantly wider than that of the prior art. Therefore, the problem described above can be solved.
[0019]
Since the tip 31 of the collar 30 slidably supporting the shaft 23 of the spool 20 extends so as to reach the vicinity of the gate 11, heat is transmitted to the resin near the gate 11, so that the fluidity is always good. Can also be expected.
[0020]
More specifically, since the injected resin flows evenly and radially in all directions without going straight, the flow near the gate 11 is good, and the molecular orientation of the resin and the orientation of the filler are weakened. Not only the residual stress is small, but also there is no precision sliding part and no resin leakage unlike the prior art, so that the effect of smooth reciprocating motion of the shaft part 23 and smooth resin flow can be exhibited.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing one embodiment of the present invention. FIG. 2 is a cross-sectional view showing one embodiment of the present invention. FIG. 3 is an enlarged end view showing one embodiment of the present invention.
10-Nozzle Head 11-Gate 12-Nozzle Holder 13-Step 20-Spool 21-Spool Head 22-Spool Neck 23-Spool Shaft 24-Spool Arrow Feather 30-Collar 31-Collar Tip 40-coil spring 41-washer

Claims (1)

A spool having, in the internal space of the nozzle head attached to the tip of the nozzle holder, a head portion having a circular cross section, a constricted portion formed continuously from the entire circumference of the head portion, a shaft portion, and an arrow-shaped projection; A collar disposed in the internal space of the nozzle head, slidably supporting the outer diameter of the shaft of the spool, serving as a guide for the spool, and extending the end so as to reach the vicinity of the gate; A gate opening / closing mechanism comprising a coil spring biasing in the gate direction is arranged, and when the pressure of the resin is lower than a certain value, the spool is biased in a direction opposite to the gate by the coil spring to have a circular cross section of the head portion of the spool. The entire circumference of the nozzle abuts against the inner wall of the gate of the nozzle head to close the resin flow path. When the pressure of the resin exceeds a certain value, it overcomes the urging force of the coil spring. Head portion of said spool Te is protruded outside the gate of the nozzle head, a resin passage is formed configurations resin flow path is opened between the constricted portion and the gate inner wall of the spool, said collar Wherein the spool shaft is supported by two to four points .

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