JPH04223118A - Valve type nozzle - Google Patents

Abstract

PURPOSE:To provide a valve type nozzle for injection molder, in which the leakage of molten resin is prevented from occurring through a nozzle hole without increasing injection resistance and injection power loss by a simple means. CONSTITUTION:In a valve type nozzle for an injection molder, in which resin is injected by applying resin pressure to surpass the pressure of the spring of a pressing mechanism for pressing a needle 18 so as to retreat the needle 18 to the direction in order to part from a nozzle hole 22, the pressing mechanism consists of a first and a second pressing mechanisms 31 and 32. In addition, a releasing means, which releases the engagement between a spring and the needle, is provided in the second pressing mechanism 32. Thus, in an injection standing-by stage, both the first and the second pressing mechanisms are put into action so as to completely block the nozzle hole 22 in order to check the leakage through the nozzle hole 22. In an injection stage, the releasing means is put into action so as to inactivate the pressing force of the second pressing mechanism 32, neither injection resistance nor injection power loss are increased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a valve type nozzle for resin injection used in an injection device of an injection molding machine.

0002

[Prior Art] With the trend toward more complex and higher quality injection molded products, and the trend toward applying the injection molding method to the molding of crystalline resins, molten resin from the nozzle tip due to high back pressure during plasticization is increasing. Recently, valve-type nozzles have been used as nozzles in injection devices in order to prevent resin leakage from the tip of the nozzle during standby time and to maintain a constant injection amount.

As shown in FIG. 2, a conventional valve type nozzle 10 basically consists of a hollow conical section 12 forming a chamber for storing molten resin, and a nozzle body 14 connected to the conical section. ing. The valve type nozzle 10 is
A long hole 16 provided along the longitudinal centerline of the nozzle body and communicating with the chamber, a needle 18 that freely slides back and forth in the long hole 16, and a conical cone communicating with the chamber and having an opening outward. A nozzle hole 22 provided at the tip 20 of the section 12, and a pressing mechanism that propels the needle 18 toward the nozzle hole 22 by a spring force and presses the needle against the peripheral wall of the nozzle hole inlet to close the nozzle hole 22. 2
4. The pressing mechanism 24 includes at least one spring 26 and an arm 28 that transmits spring force to the needle 18. When the injection device moves forward toward the mold attached to the mold clamping device and the nozzle reaches a predetermined position, resin pressure that overcomes the spring force of the pressing mechanism is applied to the needle to move the needle away from the nozzle hole. to inject the resin.

In such conventional valve type nozzles, in order to seal the nozzle hole to prevent molten resin from leaking from the nozzle hole during the injection standby stage, a strong spring is used to move the needle into the nozzle hole. It is necessary to firmly adhere to the entrance peripheral wall. However, if a spring with a strong pressing force is used in a valve-type nozzle, it is necessary to apply a force to the needle that moves the needle backward against the strong spring force at the stage of opening the nozzle hole and injecting the resin. Therefore, the resin pressure acting on the needle must be increased. Therefore, there was a drawback that injection resistance and injection power loss were increased. Furthermore, it has become necessary to change the injection molding conditions, which may make it difficult to maintain the quality of the molded product.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a valve type valve system having a simple means for preventing leakage of molten resin from a nozzle hole during an injection standby stage without increasing injection resistance or injection power loss. Our goal is to provide nozzles.

[0006]

[Means for Solving the Problems] The above object is achieved by a configuration according to the present invention having the following features. The configuration is that the pressing mechanism includes a first and a second pressing mechanism, and the first pressing mechanism includes at least one first spring that applies a pressing force in a direction parallel to the longitudinal centerline. , a first intermediate member having one end of the first spring fixed and movable in the parallel direction; and a first intermediate member extending in a direction perpendicular to the center line and abutting the end of the needle farther from the nozzle hole. a first arm in the parallel direction;
The second pressing mechanism abuts and engages the intermediate member and is movable together with the needle in that direction, and the second pressing mechanism includes at least one other second spring that applies a pressing force in the parallel direction; 2. One end of the second spring is fixed, the second intermediate member is releasably engaged with the arm in the parallel direction, and is movable in the parallel direction, and the tip of the nozzle is connected to the injection molding machine. The second mold moves forward to the mold attached to the
and a release means for releasing the engagement between the intermediate member and the arm.

[0007]

[Operation] With the above configuration, when the tip of the nozzle has not reached a predetermined position with respect to the mold installed in the injection molding machine, that is, when the release means is not activated, the first spring A pressing force is applied to the first intermediate member, and the pressing force received by the first intermediate member is transmitted to the needle via the arm with which the first intermediate member is abuttingly engaged. In addition, like the first spring, the second spring exerts a pressing force on the second intermediate member, and transmits the pressing force received by the second intermediate member to the needle via the arm in abutting engagement. Therefore, in the resin plasticization stage of the injection cycle, which corresponds to the above-mentioned stage, for example,
Both the first and second springs act on the needle to force the tip of the needle into strong contact with the peripheral wall of the nozzle hole inlet, sealing the nozzle hole and preventing leakage of molten resin from the nozzle hole. Note that the second spring is preferably selected so that the pressing force of the second spring is stronger than the pressing force of the first spring. This is because the configuration of the first spring and the second spring more effectively achieves the object of the present invention, as will be clear from the following description.

[0008] In the injection stage, the injection device moves forward and immediately before the nozzle tip contacts the injection port of the mold, a strong second
A release means for releasing the pressing force of the spring operates to release the abutting engagement between the second intermediate member and the arm, so that the pressing force of the second spring does not act on the needle. As a release means for releasing the pressure of the spring, for example, a rod member having one end fixed to the second intermediate member and extending from there toward the nozzle hole parallel to the longitudinal center line of the nozzle is provided. By making the tip of the rod member slightly protrude toward the mold from the tip of the nozzle, the rod member contacts the mold immediately before the tip of the nozzle contacts the injection port of the mold. The abutted rod member remains stationary at that position, and therefore the second rod member fixed to the rod member is
The intermediate member is moved relatively backward to release the engagement with the arm and cut off the transmission of the pressing force of the second spring to the needle. Furthermore, depending on the positional relationship between the other party that the tip of the bar member comes into contact with, the injection port of the mold, and the tip of the nozzle, the positional relationship will determine whether the tip of the bar member will protrude or be retracted from the tip of the nozzle. is determined. Note that the above-mentioned release means is just an example, and any suitable release means may be provided depending on the relationship between the valve type nozzle and the mold clamping device. At the point when the nozzle contacts the injection port of the mold and the resin is injected, the needle is
It is only pressed by the first spring with a weak pressing force. Therefore, by adjusting the pressing force of the first spring, the injection resistance can be made smaller than that of the conventional valve type nozzle. Hereinafter, the present invention will be explained in more detail based on examples and with reference to the accompanying drawings.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a valve type nozzle 30 according to the present invention taken along a plane including the longitudinal centerline. The valve type nozzle 30 according to the present invention basically has the same structure as the conventional valve type nozzle except for the pressing mechanism. That is, the valve-type nozzle 30 includes a conical part 12 consisting of a hollow conical part that forms a chamber for storing molten resin and a cylindrical part that has a threaded wall inside that forms a connection part with the nozzle body; The cylindrical nozzle body 14 is screwed into the cylindrical portion of the section 12 and connected so that the longitudinal center lines thereof coincide with each other.

The valve type nozzle 30 includes a long hole 16 provided along the longitudinal center line of the nozzle body 14 and communicating with the chamber, a needle 18 that freely slides back and forth within the long hole 16, and a chamber. A nozzle hole 22 provided at the tip 20 of the conical portion 12 that communicates with the outside and has an opening, and the end of the needle 18 remote from the nozzle hole is propelled toward the nozzle hole 22 by a spring force, and A pressing mechanism that presses the needle 18 against the peripheral wall of the nozzle hole inlet to close the nozzle hole 22 is provided.

The pressing mechanism of the valve type nozzle according to the present invention is composed of a first pressing mechanism 31 and a second pressing mechanism 32. The first pressing mechanism 31 is arranged symmetrically from the longitudinal center line on the outside of the nozzle body 14, and has a weak pressing force that applies a pressing force in a direction parallel to the longitudinal center line.
a spring 34, and a first intermediate member which is provided so as to surround the nozzle body 14 and has two parallel surfaces facing each other perpendicular to the longitudinal center line, and which is movable in the longitudinal direction. It is comprised of an annular plate 38 and an arm 40, one end of which abuts the end of the needle 18 remote from the nozzle hole 22, is longitudinally movable, and extends radially outward. The first spring 34 is held between a first protrusion 42 that protrudes radially outward from the nozzle cylindrical portion 14 and a first annular plate 38 . The arm 40 abuts and engages with a part of the surface of the first annular plate 38 that is closer to the nozzle hole 22 . With this configuration, the first pressing mechanism always applies the pressing force of the first spring 34 to the arm 40 through the annular plate 38.
The via needle 18 can be acted upon.

The second pressing mechanism 32 is arranged symmetrically with respect to the longitudinal center line of the nozzle body 14 on the outside of the first spring, and has a strong pressing force that applies a pressing force in a direction parallel to the longitudinal center line. 2 springs 44, and a second intermediate member having two parallel surfaces facing each other perpendicular to the longitudinal center line and surrounding the nozzle body 14 from the outside of the first annular plate 38. , and a second annular plate 48 that is movable in the longitudinal direction, and a second annular plate 48 as a release means.
A rod-shaped member 5 has one end fixed to the nozzle body 14, extends parallel to the longitudinal center line of the nozzle body 14, and has the other free end 50 slightly protruding from the tip 20 of the conical part 12.
2. The second spring 44 is held between a second projection 54 that projects radially outward from the nozzle body 14 and is fixed, and a second annular plate 48 that is movable in the longitudinal direction. A part of the surface of the second annular plate 48 closer to the nozzle hole 22 abuts and engages with the arm 40 near the end opposite to the side of the arm 40 that contacts the needle 18 . With this configuration, the nozzle advances toward the mold clamping device, the free end 50 of the rod member 52 comes into contact with something, pushes the annular plate 48 backward, and does not release the engagement between the annular plate 48 and the arm 40. As far as possible, the second pressing mechanism can apply the pressing force of the second spring 44 to the needle 18 via the arm 40 via the annular plate 48 in addition to the pressing force of the first pressing mechanism. Although coil springs are shown as examples of the first and second springs, leaf springs or the like may be used as necessary.

[0013] At the stage where the tip of the nozzle has not reached a predetermined position relative to the mold, that is, at the stage when the bar member 52 is not in contact with the mold, the free end 50 of the bar member 52 is free. The release means is not working. At this stage,
For example, in the resin plasticizing stage of the injection cycle corresponding to this, the weak first spring 34 of the first pressing mechanism 31 is
The pressing force of the second pressing mechanism 32 and the strong second spring 44
Both of the pressing forces are transmitted to the end of the needle 18 via the arm 40 through the first annular plate 38 and the second annular plate 48, respectively, and bring the needle 18 into close contact with the inlet peripheral wall of the nozzle hole 22. The nozzle hole 22 is sealed. This prevents the molten resin from leaking from the nozzle hole.

Similar to the conventional valve type nozzle, the molten resin is press-fitted into the chamber inside the conical portion 12 via a plurality of resin passages 60 provided outside the elongated hole 16 of the nozzle body 14. The resin passage 60 is a resin press-fitting part of an injection device,
For example, the chamber in which the tip of a resin press-fitting screw (not shown) moves forward and backward communicates with the chamber of the conical portion 12 .

In the injection process, when the injection device advances toward the mold mounted on the mold clamping device, a rod-shaped member 52 slightly protruding from the tip 20 of the nozzle toward the mold is inserted. The free end 50 abuts the mold just before the tip 20 of the nozzle reaches the inlet of the mold, and the nozzle continues to advance and thus the second annular plate 48 relative to the arm 40.
is moved backward to release the abutted state of engagement between the second annular plate 48 and the arm 40. This makes the second spring 4 stronger.
The pressing force of 4 no longer acts on the needle 18. Therefore, since only the weak pressing force of the spring 34 acts on the needle 18, a small force is sufficient to retract the needle 18 and open the nozzle hole 22, and the injection resistance or injection loss is reduced accordingly. can do.

As the injection process is completed and the injection device retreats from the mold clamping device, the abutting engagement between the rod member 52 and the mold is released. Once the free end 50 of the bar member 52 is free,
The strong pressing force of the second spring 44 acts in the direction of the nozzle hole, moves the second annular plate 48 in the direction of the nozzle hole, and moves the arm 4.
0 to abut and engage. As a result, the pressing force of the second spring acts on the needle 18 in addition to the pressing force of the first spring, which is always acting, and the needle 18 moves into the nozzle hole 2.
The nozzle hole 22 is quickly moved forward toward the nozzle hole 22, comes into contact with the peripheral wall of the nozzle hole entrance, and is pressed, thereby closing the nozzle hole 22. Therefore, since the nozzle hole is rapidly closed after the injection process, the outflow of molten resin during that time is also reduced.

[0017]

[Effects of the Invention] As can be seen from the above explanation, the valve type nozzle according to the present invention uses a simple means to prevent molten resin from leaking from the nozzle hole even when high back pressure is applied, and also reduces injection resistance during injection. Since the valve-type nozzle is quickly blocked after the injection process, the present invention
Contributes to improving the work efficiency of injection molding machines and improving the quality of injection molded products.

[Brief explanation of the drawing]

1 is a sectional view in a plane including the longitudinal axis of a valve-type nozzle according to the invention; FIG.

FIG. 2 is a cross-sectional view of a plane including the longitudinal axis of a conventional valve-type nozzle.

[Explanation of symbols]

10 Conventional valve type nozzle 12 Cone part 14 Nozzle body 16 Long hole 18 Needle 20 Tip 22 Nozzle hole 24 Pressing mechanism 26 Spring 28 Arm 30 Valve type nozzle according to the present invention 31 First pressing mechanism 32 Second pressing mechanism 34 First spring 38 First annular plate 40 Arm 42 First protrusion 44 Second spring 48 Second annular plate 50 Free end 52 Rod member 54 Second protrusion 60 Resin passage

Claims (1)

[Claims] 1. A nozzle comprising a hollow conical part forming a chamber for storing molten resin, and a nozzle body connected to the conical part, and having a length extending along the longitudinal center line of the nozzle body and communicating with the chamber. a hole, a needle that freely slides back and forth in the elongated hole, a nozzle hole provided at the tip of the conical portion that communicates with the chamber and has an opening outward, and a pressing mechanism that propels the needle by a spring force and presses the needle against a peripheral wall at the entrance of the nozzle hole to close the nozzle hole, and applies resin pressure to the needle that overcomes the spring force of the pressing mechanism. In the valve-type nozzle provided in an injection device of an injection molding machine, the needle is retreated in a direction away from the nozzle hole to inject resin, wherein the pressing mechanism includes a first and a second pressing mechanism; 1 pressing mechanism includes at least one first spring that applies a pressing force in a direction parallel to the longitudinal centerline;
a first intermediate member having one end of a spring fixed and movable in the parallel direction; and an arm extending in a direction perpendicular to the center line and abutting the end of the needle farther from the nozzle hole. the arm is in contact engagement with the first intermediate member in the parallel direction and is movable integrally with the needle in that direction, and the second pressing mechanism applies a pressing force in the parallel direction. at least one other second spring that acts; one end of the second spring is fixed, releasably engages with the arm in the parallel direction, and is movable in the parallel direction; a second intermediate member, and a release that releases the engagement between the second intermediate member and the arm immediately before the tip of the nozzle moves forward relative to a mold mounted on an injection molding machine and reaches a predetermined position; A valve-type nozzle comprising: means.