JPH0811161A - Nozzle for injection molding - Google Patents

Abstract

PURPOSE:To suppress the stringing phenomenon generated in the retreat process of a nozzle from a nozzle touch part after the injection of a resin by forming a nozzle injection orifice into an almost cylindrical hollow part over the total length thereof and making the diameter thereof larger than the inlet caliber of the sprue of a mold part. CONSTITUTION:When the flow of a molten resin is once stopped after the completion of an injection process, the molten resin is released from restriction at a stroke and the curing thereof is started in an axial direction. In a stage beginning to advance in the curing of the molten resin up to the part being the passage of the molten resin, a nozzle 1 is separated from a sprue 31. Especially, the resin at the part in the vicinity of a nozzle touch part in the molten resin left in a state of communicating with the hollow part of a fine pipe of which the diameter is larger than the inlet caliber of the sprue being the injection orifice of the nozzle 1 from the interior of the sprue 31 is placed under environment where a tendency losing viscosity becomes especially marked and no 'stringing' phenomenon is generated.

Description

Detailed Description of the Invention

[0001]

SUMMARY OF THE INVENTION The present invention relates to an injection molding machine which is one of plastics product manufacturing apparatuses, and a predetermined amount of resin (molding material) which has been plasticized by heating in a cylinder is passed through a cavity of a mold through a cavity of a mold. The nozzle that has the function of reliably injecting and injecting into the inside is intended to provide a nozzle with an improved structure that can suppress the "stringing" phenomenon that occurs in the process of retracting after resin injection from the nozzle touch. is there.

[0002]

2. Description of the Related Art Because of its many advantages such as good moldability, lightweight and beautiful finish, mass production with large labor saving in the production process, cost reduction, etc. Even the parts that weren't there have been replaced with more and more plastics materials, and not only home appliances but daily sundries, office equipment, automobiles, and almost every other product that surrounds us now uses plastics materials. I'm changing so much that I can't think without it. Such alternative phenomena have been created by the development of a wide variety of new plastic materials with impact resistance, toughness, dimensional stability and other physical properties comparable to metals, and products comparable to metal product processing. It can be said that the development of new technology that enables the realization of precision has come one after another and has been implemented.

In particular, the injection molding method using a thermoplastic resin as a molding material has good moldability, high productivity, easy filling, high fluidity, suitable for thin-walled products, and low cost. It is a molding method that can demonstrate the typical characteristics of plastics, which makes it possible to make a great contribution to the popularization of plastics products. The equipment, the injection molding machine, heats and pelletizes the pellets,
It consists of a mechanism of injecting fluidized resin into a closed mold, cooling and solidifying, and in order to make this process efficient and increase productivity, FMC (Flexible Mol)
DingCell) method and FMS (Flexible)
The Manufacturing System) system has been developed, and further, an automatic take-out robot is combined and controlled by a computer.

As a result, it has become possible to produce high-quality plastic products even more efficiently, but even in these advanced injection molding machines, the nozzle-touch "stringing (dripping)" is performed. Regarding the phenomenon, there is no definitive countermeasure, and most of them still rely on the intuition of on-site engineers to continue manufacturing. Not only will this happen, but the worst case of damaging the die and shortening its life can also be caused.

In order to prevent the "stringing (dripping)" phenomenon, some proposals have been made and some of them have been adopted. The simplest means proposed is to create a molding material that does not cause "threading", but this requires extremely craftsmanship and lacks versatility. Therefore, there is proposed a means to bite the washer when the nozzle is touched on the spool inlet side, a means to optionally attach a shut-off nozzle (nozzle with check valve) to the tip of the cylinder, or a tip of the nozzle injection hole. In addition, it is a means of attaching a washer in advance.

[0006] However, although the means for biting the washer at the time of touching the nozzle certainly has a certain effect, there is a drawback that the technical fee is consumed and the parts which are not cheap are consumed every day. By means of adopting a shut-off nozzle as an attachment,
Not only the economical problem that it is expensive, but also the leakage of the molding material structurally easily occurs, and the previous color remains when changing the color of the molding material, and maintenance that takes time to remove it It has the above-mentioned drawbacks and is not practical,
In addition, the washer is not bitten when touching the nozzle, but rather shallow at the nozzle tip (usually twice the washer thickness, about 5
Although the "thread trimming" effect is recognized by means of cutting the washer mounting hole (with a depth of about mm) and mounting the washer, the molding material remains burned in the washer mounting hole and becomes dust, which is not expected. It is not reliable because it accidentally jumps out and mixes in when it is not done, resulting in an impaired quality, and in the end, none of the proposals is necessarily sufficient.

According to the present invention, in view of the above situation,
As a result of repeated trial and error, we worked on the development and research of a nozzle that is more reliable in its "thread cutting" effect, and economically and practically advantageous. It succeeded in realizing an injection molding nozzle based on a technical idea. In the following, the present invention will be described in detail along with representative embodiments in order of its details.

[0008]

According to the present invention, the nozzle injection hole is basically regulated such that it has a substantially cylindrical hollow portion over its entire length, and the diameter thereof is larger than the inlet diameter of the die spool. An injection molding nozzle, which is characterized in that it is formed by the above, is the gist of the configuration. Further, more specifically, the nozzle injection hole becomes a substantially cylindrical hollow portion over the entire length thereof, and its diameter is 1.5 to 3 times, and optimally about 2 times, the inlet diameter of the mold spool. The gist of the structure of the injection molding nozzle can be summarized as follows:

Furthermore, to express the technical idea of the present invention in another way, the diaphragm continuous with the nozzle injection hole is formed by narrowing the inner part of the hollow portion of the plasticized resin pressure feed in the cylinder on the nozzle injection hole side in a substantially straight line. While being formed in the hollow part, the nozzle injection hole is a cylindrical hollow part having approximately the same diameter from the part continuous to the throttle hollow part to the tip, and the diameter is 1.5 to 3 times as large as the die part spool inlet diameter. It can also be expressed as an injection molding nozzle that is formed by restricting to the above. More specifically, by narrowing the inner part of the plasticized resin pressure feeding hollow part of the cylinder on the nozzle injection hole side into a substantially linear shape, While forming in the continuous throttle hollow part, the nozzle injection hole is a cylindrical hollow part of approximately the same diameter from the part continuous to the throttle hollow part to the tip, and the diameter is 1.5 times the die part spool inlet diameter. ~
The injection molding nozzle is formed to be 3 times, optimally about 2 times, and regulated so that the total length is at least 5 mm or more.

The nozzle injection hole is formed in advance in the size regulated by the present invention at the stage of the nozzle mounted on the cylinder of the injection molding machine. It also includes a material which is realized by cutting or the like so as to obtain a cylindrical hollow portion having an optimum diameter. And, the cylindrical hollow portion is completely different from the conventional one, and the entire hollow portion portion over the entire length thereof, that is, the entire portion from the nozzle tip to the portion connected to the cylinder hollow portion has a predetermined diameter size, that is, 1.5. ~
3 times (usually the most commonly used spool inlet diameter is 2.5 to 2.8 mm, so 3.7 to 8.
4mm) diameter, and optimally, it should be controlled so that the hollow space is about twice as large.

The cylindrical hollow portion is formed by cutting the nozzle itself to directly form the regulated cylindrical hollow portion into an injection hole, and is equivalent to the size of the cylindrical hollow portion. A metal or plastic thin tube excellent in heat conduction having a regulated hollow cross section is fitted to the full length of the cylindrical hollow portion, and is used as an injection hole (hence, the nozzle 1). The cutting diameter can be made larger than that of the cylindrical hollow portion by an amount corresponding to the thin wall thickness of the thin tube. In the case of this configuration, the temperature is easily changed, and the technique of the present invention is used. It is particularly advantageous in realizing the physical idea.

The cylinder hollow portion connected to the innermost portion of the nozzle injection hole, when viewed from the side of the cylindrical hollow portion of the regulated size of the nozzle injection hole, is a screw for mixing the molding material of the cylinder hollow portion and pressure feeding. Or, towards the hollow part where the topid that functions to uniformly heat and melt the molding material is arranged, rather than the outward curved shape as before, it is a substantially straight end spreading shape (when viewed from the cylinder side The resin melted by being plasticized so that it is formed in a narrowed hollow portion which becomes a substantially linear shape toward the nozzle injection hole, and the plasticized and melted resin is the innermost portion of the cylindrical hollow portion of the nozzle injection hole. It is desirable to form the structure such that the entrance thereof to the cylindrical hollow portion when viewed from the flow of the molten resin does not receive any resistance. Hereinafter, representative examples shown in the drawings will be explained to help understanding of the technical idea constituting the present invention.

[0013]

[Embodiment 1] As can be understood from the longitudinal cross-sectional view of the main part of FIG. 1, the spool 31 is incorporated into the mold clamping part of the injection molding machine, the female mold 3 which is one mold attached to the fixed platen 5. Is
The inlet 31a for receiving the molten resin from the tip of the nozzle of the present invention is in a state of being opened at the innermost portion of the nozzle touch portion formed in the semi-spherical concave portion so that the nozzle is surely touched. The configuration of the mold clamping part side including the mold is the same as that of the injection molding machine until now, and no change is required when adopting the nozzle of the present invention. Therefore, the male and female dies 3 and 4 are used to form cavities as before, and the predetermined amount of the molten resin P pressure-fed through the spool 31 is fed into the cavities via the runner and the gate as before, and the cooling water is supplied. The mechanism for releasing the male die 4 by the operation of the movable plate 6 after being cooled and solidified by is adopted as it is.

On the other hand, on the plasticizing injection side of the injection molding machine, the nozzle 1 has its injection hole 11 larger than the diameter of the inlet 31a of the spool 31 as shown in the figure. The inlet 31a and the cylindrical hollow portion of the injection hole 11 are formed in such a relationship that the central axes thereof are regulated and the nozzle is touched, and the injection hole 11 is It must be formed to have a structure in which the innermost portion of the cylindrical hollow portion reaches the narrowed hollow portion 21 of the cylinder 2 and has a continuous structure with substantially the same diameter. The embodiment is an example in which the injection hole 11 is realized by a thin tube made of engineering plastic containing fine metal powder, and is incorporated in the nozzle 1 so that the end of the thin tube reaches the narrowed hollow portion.

The diameter of the hollow portion of the thin tube which becomes the injection hole 11 of the nozzle 1 is formed as an example of a size which is the most ideal size within the range regulated by the present invention and which is approximately twice the size of the spool 31. Therefore, when viewed from the inlet 31a side of the spool 31, the nozzle injection hole 11 has a diameter larger than that of the spool inlet 31a by about 0.5 times outward from each axis. The resin P that has been plasticized and melted flows according to the diameter of the hollow portion of the thin tube to the portion where the nozzle is touched, is extruded from the cylinder 2 at a predetermined pressure, and reaches the spool inlet 31a.

The injection hole 11 of the nozzle 1 has a cylindrical hollow portion of substantially the same diameter as that of the cylinder 2 from the tip thereof, that is, the portion where the molten resin is ejected by touching the inlet 31a of the spool 31 with a predetermined pressure. The most important constituent element of the present invention is arranged so as to communicate with the narrowed hollow portion 21, while the hollow portion of the cylinder 2, that is, the molding material is kneaded and melted, and then a predetermined pressure is applied. As for the shape of the space portion for sending out, the structure of the portion reaching the innermost portion of the injection hole 11 is formed in the diaphragm hollow portion 21 that narrows in a substantially linear shape as shown in the figure, The molten resin pressed to a predetermined pressure in the cylinder 2 is
1 is a case in which a more desirable structure of the present invention is adopted in which the flow resistance can be alleviated in the vicinity of the boundary between 1 and the innermost portion of the injection hole 11.

[0017]

[Operation] The injection molding nozzle of the present invention having the above-described configuration is preliminarily processed and incorporated into a predetermined structure as a nozzle of an injection molding machine, or a plastic product processing plant or the like has already been manufactured. In the case of an injection molding machine installed in the above, only the nozzle part is separately processed and adopted, and after the processing step is started, the nozzle 1
The nozzle touches the concave portion of the inlet 31a of the spool 31 arranged in the female die 3 of the mold, and reaches the posture of FIG.

Then, until then, the heating heater 2 of the cylinder 2 is separated from the mold clamping portion and becomes independent, and on the plasticizing injection portion side.
Although the temperature inside the injection hole 11 of the nozzle 1 is in a heating state of about 180 to 200 ° C., which can hold the resin in a molten state by receiving heat from the nozzle 2, the mold clamping part side at the moment of touching the nozzle. Influenced by the temperature of the female mold 3, usually around 50 to 70 ° C., the temperature of the inner surface of the thin tube from the tip of the nozzle 1 tends to decrease. In addition, the injection hole 11 of the nozzle 1 has the structure unique to the present invention,
Since it is formed to be considerably larger than the diameter of the inlet 31a of No. 1, the narrow hollow portion 21 of the cylinder 2 fills the wide hollow portion of the narrow tube of the injection hole 11 and is pumped to reach the spool inlet 31a. The molten resin P has a portion that comes into direct contact with the surface of the spool 31 having a low temperature around the inlet 31a (a ring-shaped surface corresponding to 0.5 times the diameter of the spool inlet 31a in the embodiment), and that portion is However, it is directly affected by the low temperature on the die side.

As a result, as shown in the enlarged cross-sectional view of the main part of FIG. 3, the molten resin P in the portion touched by the nozzle is
Due to the above-mentioned two causes, the resin P1 portion that is semi-cured around the spool inlet 31a and is semi-cured is
The nozzle 1 has a state like a part of the nozzle 1 and narrows the tip diameter of the injection hole 11 that should have been originally formed in a cross section larger than the spool inlet 31a. In a state that is almost the same as the injection state realized by the conventional nozzle,
The molten resin P is vigorously pumped through the sprawl 31 into the cavity.

On the other hand, when the injection of the predetermined amount of the molten resin P is completed, the male die 4 side supported by the movable plate 6 is automatically retracted (separated) from the female die 3 supported by the fixed platen 5. Since the plasticizing injection part side is also interlocked with the operation of separating from the mold clamping part side at the same time (the state of the cross-sectional view of the main part of FIG. 2), the nozzle 1 also naturally has its tip at the spool 31. However, in this operation process, the molten resin P left in the cylindrical hollow portion in the injection hole 11 of the nozzle 1 from the inside of the spool 31 in the operation process until now is Since it is still in a molten state, it gradually expands thinly like when the rice cake is stretched, it is exposed to the air and solidifies and remains in the form of thin threads, so-called "threading" phenomenon (Or also called the "dripping" phenomenon) Then, when the nozzle is touched in the next step as it is, the "stringing" resin is present between the spool 31 and the tip of the nozzle 1 to cause a defective product due to insufficient injection pressure due to contact failure. It is customary for the spool 31 to be damaged, resulting in an unexpected situation in which the work must be stopped for its replacement.

However, in the nozzle 1 of the present invention, the injection hole 11 is formed to have a larger cross section than the spool inlet 31a, and as described above, the tip of the injection hole 11 and the cylinder are already formed in the resin injection process after the nozzle is touched. In the state where the semi-cured resin P1 portion has been formed on the inner surface of the hollow portion of the hollow portion, and the molten resin P is injected at high pressure and flows, the pressure of the molten resin P is lost by the pressure to cure in the axial direction. Although the situation is unavoidable in which the phenomenon cannot be progressed, but once the injection process is finished and the flow of the molten resin P is stopped, the restrictions are uniformly released and the shaft core is released. The nozzle 1 is separated from the spool 31 at the stage when the curing in the direction is started and the curing is starting to proceed to the portion that has been the flow path of the molten resin P until then. Melt is left in a state that led to the hollow portion of the thin tube is an injection hole 11 of the nozzle 1 resin P
Among them, especially the resin of the part bordering the nozzle touch part,
It is placed in an environment where the tendency to lose viscosity is particularly strong, and while the tendency to grow like rice cake is weakening, it is exposed to air immediately after releasing the nozzle touch and further strengthens that tendency, so the resin in that part is easy It's cut into pieces, so-called "string drawing"
The phenomenon will be stopped.

In this way, the nozzle 1 that has been separated without causing the "threading" phenomenon is completely affected by the mold until it moves to the next step (the state of FIG. 1 where the nozzle touches again). It is cut off by this and is heated by the heat from the heater 22 of the cylinder 2, and the tip of the nozzle 1 that had been lowered in temperature immediately after the nozzle is touched is almost returned to the original state, and the temperature in the injection hole 11 also rises. As a result,
The resin in the hollow part of the thin tube, which had conveniently solidified to prevent the "stringing" phenomenon, was plasticized to a state suitable for injection again and returned to a state where it did not hinder the next injection process. Waiting for the next manufacturing cycle. Hereinafter, only this step is repeated, and the favorable injection molding is continuously continued without being affected by the "stringing" phenomenon as before.

[0023]

[Effects] The injection molding nozzle of the present invention having the above-described structure has the unpredictable measures for preventing the "stringing" phenomenon up to that point, for example, uncertain factors such as examining the molding material. In addition, there is no need to repeat daily work such as through a washer, and it is not necessary to stop the device to clean the part, and it is possible to extremely reliably prevent the "stringing" phenomenon and The injection pressure from is also an excellent invention that realizes a structure that enables smooth and stable injection molding by directly applying pressure to the nozzle tip through the hollow portion of the cylinder.
Moreover, it is a very principle invention, and since it adopts a configuration that has been overlooked without being noticed, it is very easy to implement, and the cost required for its adoption is much more economical. Besides, it is easy to maintain after that, and the subsequent manufacturing process smoothness,
Considering advantages such as quality assurance and yield effect, it is possible to achieve excellent economic effects.

In particular, in the one shown in the embodiment, a thin tube having excellent heat conductivity is adopted for the injection hole 11 to realize a structure more easily affected by heat from the other side, and its inner surface is Compared with the one in which the nozzle 1 itself is cut into a cylindrical hollow portion, it is easy to realize the smoothness of the inner surface of the hollow portion, and it should be noted that it is possible to realize smooth injection molding. The nozzle 1 has a substantially ideal structure as the nozzle 1 realized by the basic technical idea of the present invention. As described above, the injection molding nozzle of the present invention is capable of reliably achieving the intended purpose based on its excellent technical idea, and is expected to intensify competition. The benefits to the product manufacturing industry, especially its subcontractors, are expected to be immeasurable.

[Brief description of drawings]

The drawings are based on a representative embodiment of the invention.

FIG. 1 is a cross-sectional view of a main part in a nozzle touch state.

FIG. 2 is a cross-sectional view of an essential part showing a state after the nozzle touch is released.

FIG. 3 is an enlarged sectional view of an essential part of a nozzle touch portion.

[Explanation of symbols]

 1 Nozzle 11 Same injection hole 2 Cylinder 21 Same throttle hollow part 22 Same heater 3 Female type 31 Same spool 31a Same inlet 4 Male type 5 Fixed plate 6 Movable plate

Claims (4)

[Claims] 1. A nozzle injection hole is formed so as to become a substantially cylindrical hollow portion over the entire length thereof, and the diameter thereof is regulated so as to be larger than the die portion spool entrance diameter. Characteristic injection molding nozzle. 2. The nozzle injection hole becomes a substantially cylindrical hollow portion over the entire length thereof, and the diameter thereof is 1.5 to 3 times, and optimally about 2 times, the entrance diameter of the die spool. An injection molding nozzle characterized in that it is formed so as to be regulated as described above. 3. The plastic injection molding hollow part of the cylinder in which the plastic injection resin hollow part is narrowed substantially linearly to form a narrowed hollow part continuous with the nozzle injection hole, while the nozzle injection hole is formed in the hollow part. A nozzle for injection molding, which is a cylindrical hollow portion having substantially the same diameter from the portion continuous with the portion to the tip, and the diameter of which is regulated to 1.5 to 3 times the inlet diameter of the die spool. 4. The plastic injection molding hollow portion of the cylinder in the nozzle injection hole side is squeezed in a substantially linear manner to form a squeezed hollow portion continuous with the nozzle injection hole, while the nozzle injection hole is formed in the squeezed hollow portion. From the part continuous to the tip to the tip, it is a cylindrical hollow part of approximately the same diameter, whose diameter is 1.5 to 3 times the spool inlet diameter of the mold part, optimally about 2 times, and the total length is at least 5 mm or more. An injection molding nozzle that is formed so as to be restricted.