JPS62169612A - Method and device for electromagnetic induction heating injection molding - Google Patents

Abstract

PURPOSE:To effect the injection molding operation of material resin efficiently by a method wherein a flow path for passing the material resin is formed so as to be an annular flow path and high-frequency electromagnetic induction heating system is employed as a heating means to heat quickly respective mechanisms necessary for runner process, resin splitting process and plasticating process, whereby the thin material resin in the annular flow path is heated and molten instantaneously and efficiently. CONSTITUTION:A runner mechanism B, communicating with a gate A, and a plasticating mechanism D are heated rapidly to a necessary temperature by a high-frequency electromagnetic induction heating mechanism Q and material resin, passing through an annular pipe type flow path P, can be melted effectively while the necessary amount of molten resin is injected into a cavity 6 through the gate A by the operation of an injection mechanism F and a molding operation can be effected. Especially, when a high-frequency electromagnetic induction coil (q1), wound around the runner mechanism B, is conducted intermittently at every molding operation, the melting by heating as well as the solidifying by cooling of a small amount of resin in the gate A can be effected very effectively and quickly, whereby the opening and closing operation of the gate can be effected surely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electromagnetic induction heating injection molding method and an apparatus therefor used, for example, in runnerless synthetic resin injection molding.

[Conventional technology]

Conventionally, this type of electromagnetic induction heating injection molding method and apparatus include those disclosed in, for example, Japanese Patent Application Laid-open No. 180811/1983.

This will be explained with reference to FIG.

1 is a chip incorporated in the mold 2; 3 is a high-frequency electromagnetic induction heating coil wound near the tip of the chip 1; 4 is a gate hole that communicates with the hole 5 opened at the tip of the chip 1; It communicates with 6. Reference numeral 7 indicates a resin inflow portion that contacts a nozzle (not shown) of an injection molding machine, 8 indicates a manifold, and each of the divided resin flow paths 9 has an opening lO opened at the rear end of each chip l. is connected to.

The chip 1 has a pipe structure with a circulation hole 11 passing through the center, and constitutes the heated material of the wound high-frequency electromagnetic induction heating coil 3, and a shield cover 12 is disposed around the outer periphery of the chip 1. At the same time, a temperature sensor 13 that can sense and measure the temperature of the chip 1 is embedded in the tip of the chip 1.

This injection molding method and apparatus is characterized by the use of a high-frequency electromagnetic induction heating coil 3 instead of the commonly known heater method using Joule heat.
The purpose is to accurately control the resin temperature near the gate hole 4. Specifically, the difference between the temperature measured by the temperature sensor 13 and the set temperature is supplied to the highly responsive high-frequency electromagnetic induction heating coil 3 by changing the high-frequency oscillation frequency, so that temperature fluctuations at the tip of the tip 1 can be constantly adjusted to the optimum molding temperature. Holds conditions. In addition, problems such as stringiness, separation, and gate clogging that occur from the gate hole can be solved by high frequency control of the resin temperature near the gate hole, without using mechanical valves or complicated mechanisms such as intermittent temperature control to open and close the gate. This is avoided by maintaining a good gate balance using a highly accurate control method called electromagnetic induction heating.

[Problem that the invention seeks to solve]

By the way, in such a conventional injection molding method and apparatus, the gate hole 4 is provided separately from the hole 5 of the chip 1, and the necessary length to communicate with the cavity 4 is essential, so that the gate hole 4 is different from the conventional injection molding method and apparatus. Even if a highly responsive heating means such as high-frequency electromagnetic induction heating, which has to be long, is used, it is difficult to control subtle changes in the raw resin phase, such as softening, solidification, or melting of a small amount of resin in the gate hole 4. It is extremely difficult to avoid inconveniences such as stringing, sagging, or gate clogging, making it difficult to achieve the intended purpose.

However, since the chip 1 that communicates with the gate hole 4 has a pipe-like shape, if the amount of channel resin is increased, the flow hole 11
If the hole diameter is increased, the high-frequency electromagnetic induction coil will also have to increase the number of windings, the thickness of the coil itself, and the high-frequency oscillation device, but in general, The magnetic heating effect is caused by the tip l.
Since it acts only on the surface layer of the pipe-shaped chip 1, the heating effect on the raw material resin at the center of the pipe-shaped chip 1 is gradually reduced.On the other hand, as the size of the pipe-shaped chip 1 increases, the overall heat capacity also increases, so temperature control inevitably becomes less responsive. This results in a decrease in the cutting angle of 1. Even if a heat generating means with excellent responsiveness using a high frequency electromagnetic induction coil is used, there is a disadvantage that it can only be used for small and small quantity injection molding means.

[Means for solving problems]

The electromagnetic induction heating injection molding method of the first invention includes forming an annular tubular flow path P at least in the runner process of the runner process following the gate A leading to the cavity 6, the resin dividing process, and the plasticizing process. The purpose is to provide a high-frequency electromagnetic induction heating means capable of heating this annular tubular flow path P, melt the raw resin, and intermittently perform injection molding.

Further, the electromagnetic induction heating injection molding method of the second invention includes, in addition to the above method, independently providing a high frequency electromagnetic induction heating means for heating the gate A in the gate step of injecting the molten resin into the cavity 6. By locally heating A)
The purpose is to melt the raw resin in A and intermittently injection mold it.

Furthermore, the electromagnetic induction heating injection molding apparatus of the third invention is an apparatus for implementing the methods of the first and second inventions, and includes a runner mechanism B, a manifold mechanism C, and a gate A leading to the cavity 6. Among the plasticizing mechanisms, sequentially from the side closer to the gate A, the flow path of the raw resin of at least one mechanism is formed as a ring tubular flow path P of a desired shape by arranging an inclusion X such as a core, Further, a high frequency electromagnetic induction heating mechanism Q is provided which can heat the mechanism and/or the inclusion X provided along the annular tubular flow path P as a material to be heated.

Note that the high frequency electromagnetic induction heating mechanism Q can freely change the frequency of the high frequency using a desired high frequency oscillation control circuit 18 to obtain the required temperature.

[Effect]

At least the cavity 6 in the flow path through which the raw material resin passes.
The runner process following A) has a ring tubular flow path P.
is formed, and has a heating mechanism Qttlt as a high-frequency electromagnetic induction heating means on its outer periphery, so that this heating mechanism Q, when energized, uses electromagnetic induction to remove inclusions X such as a core as a material to be heated and/or the runner process. The constituent runner mechanism B can generate heat to melt the raw resin in the annular tubular flow path P.

Furthermore, an inclusion X such as a core is disposed in one or both of the manifold mechanism C and the plasticizing mechanism that constitute the resin dividing process and the plasticizing process other than the runner process, respectively, and is connected to the annular tubular flow path P. Even if a communicating annular tubular channel P is formed, the respective mechanisms C, D and/or inclusions X act as heat-receiving materials in the same manner as described above, so a heat generating effect based on electromagnetic induction occurs, and the annular tubular channel P is formed. The raw resin in P can be melted.

In particular, a high frequency electromagnetic induction heating mechanism that can locally heat the gate A based on an electromagnetic induction effect independent of other processes such as the runner process is used in the gate process in which molten resin is injected into the cavity 6 from the tar) A. (not shown), by energizing this mechanism, the raw resin in gate A is rapidly heated and melted, and when the power is removed, the raw resin in gate A is rapidly cooled and solidified. So-called tar)
A can be turned on and off. Note that the heating temperature can be freely varied up and down by changing the frequency of the high-frequency oscillation control circuit.

〔Example〕

Below, a first embodiment of the method and apparatus according to the present invention will be described.
Explanation will be given based on the explanatory diagram of the figure and the partial structural sectional view of FIG. 2.

Reference numeral 6 denotes a cavity which can be opened and closed each time a molding operation is performed to take out a molded product, similar to the mold of a conventional injection molding apparatus, and has substantially the same structure as shown in FIG. 3. Reference numeral A denotes a gate which communicates with the cavity 6 and operates in a gate process in which a hole as small and short as possible is formed to inject the raw material resin in a semi-molten or molten state. B is a runner mechanism that operates during the runner process and constitutes the final stage in which the molten resin can be supplied to the gate A. C is a manifold mechanism that can maintain the raw material resin in a molten state and divide it into a required number of - or more (four locations in the figure) to carry out a so-called resin division process. Reference numeral D indicates a plasticizing mechanism, which is connected in communication with a raw material supply mechanism E that supplies a fixed amount of raw material, so that a plasticizing process and a raw material supply process can be performed together with this mechanism E. F is an injection mechanism composed of a desired type such as a plunger or an in-line screw, and is operable each time an injection operation is performed.

Alternatively, although an inclusion corresponding to a core is shown in which the runner mechanism B, the manifold mechanism C, and the plasticizing mechanism are integrally configured, only the runner mechanism B or the runner mechanism It may be configured to include only two mechanisms, B and manifold mechanism C, and this configuration may be provided at least in runner mechanism B (not shown).

P is a ring tubular flow path formed between the inclusion or each of the mechanisms, and serves as a passage through which the raw resin can be transferred. The annular tubular flow path P shown in FIGS. 1 and 2 has an annular shape based on a double structure, but is not necessarily limited to the shape shown in the figures. 1
For example, it is possible to have a desired shape such as an ellipse, a triangle, or a square, and this annular tubular flow path P has the smallest diameter in the runner mechanism B closest to each cavity 6.
The diameter can be increased as the manifold mechanism C1 and the plasticizing mechanism are gradually separated from the cavity 6 to accommodate the production of a large number of molded products or the size of the capacity.

To explain the annular tubular channel P having the same double structure as shown in FIG. However, as the radius r increases, the cross-sectional area S increases. In short, it can be seen that the cross-sectional area S of the annular tubular channel P having the same wall thickness increases or decreases as the square of the radius r.

Therefore, the amount of raw material resin can be heated, melted and transferred very effectively while the wall thickness of the annular tubular flow path P is maintained in a thin layer.

Moreover, this relationship is maintained in exactly the same way no matter what shape the annular tubular flow path P has. Q indicates a high frequency electromagnetic induction heating coil, and a high frequency electromagnetic induction coil ql is wound around any one of the mechanisms B to D provided with the annular tubular flow path P or the required number of mechanisms.

q2. Similarly, although not shown, a high frequency electromagnetic induction coil can also be wound around ter)A if necessary. In this high-frequency electromagnetic induction coil, the number of windings, the wire diameter, and the frequency to be applied can be varied depending on the size and wall thickness of the annular flow path P. In the figure, the high frequency electromagnetic induction coils q1. Q2. (Although 13 is a winding mechanism, it may be provided independently for each mechanism, or only runner mechanism B or runner mechanism B) A and runner mechanism B
In addition to heating the other parts, a conventional cartridge heater or the like may be used to heat the other parts.

By the way, this high frequency electromagnetic induction coil q1. q2, q3
In the high frequency electromagnetic induction heating mechanism Q based on It is possible.

When the heat-receiving material is a magnetic material, hysteresis loss also works synergistically to provide a good heat-generating effect, but non-magnetic materials such as ceramics may also be used.

Although the high-frequency oscillation control circuit 18 for operating the high-frequency electromagnetic induction heating mechanism Q is shown as a block circuit in FIG. 1, this circuit 18 can be operated on each mechanism simultaneously or separately.

In Fig. 2, a slanted cross-sectional view is shown for effectively incorporating the inclusions X into each mechanism B, C, and D to form the annular tubular flow path P, but the inclusions , at least two or more split molds 14 and 15 having circular heat similar to the shape of this inclusion X are formed, and the circular heat is generated in both molds 14 and 15.
The length corresponding to the wall thickness of the annular tubular flow path P is added to the diameter r of the inclusion X, and the inclusion X is provided with a small protrusion 16 so that the inclusion X is It can be formed by holding it by both molds 14 and 15 while supporting it in the middle of the two heats, and by winding the tightening metal wire 17, or by an appropriate means such as fixing with screws (not shown). It is something. In addition, high frequency electromagnetic induction coil q+
Although (q2, q3) are wrapped around each other, a shield case (not shown) for shielding may be placed on the outer periphery.

Although not shown in the figure, the inclusion Cooling means can also be provided.

By the way, although not explicitly shown, the mold structure may be integrated over the entire area from the gate A to the injection mechanism F, or it is also possible to separate the necessary mechanisms.

With the configuration described above, the runner mechanism B or plasticizing mechanism leading to the gate A is rapidly heated to the required temperature by the action of the high frequency electromagnetic induction heating mechanism Q, and the raw resin passing through the annular tubular flow path P is heated. Not only can the resin be effectively melted, but also the necessary amount of molten resin can be injected into the cavity 6 through the t-A by the function of the injection mechanism F to perform the molding operation.

In particular, the high-frequency electromagnetic induction coil q1 wound around the runner mechanism B or the high-frequency electromagnetic induction coil wound around the runner mechanism A is intermittently energized every time the molding operation is performed.
, when turning OFF, the small amount of resin in the gate A portion can be heated and melted and cooled and solidified very effectively and quickly, so that the so-called opening and closing operation of the gate can be performed reliably.

〔Effect of the invention〕

In this invention, the flow path through which the raw material resin passes is a ring-tubular flow path, and a high-frequency electromagnetic induction heating method is used as the heating means, and the necessary mechanisms of the runner process, resin dividing process, and plasticizing process are operated by energization. As a result, the thin-walled raw material resin in the ring-tubular flow path can be instantly and extremely efficiently heated and melted, making it possible to perform injection molding operations of the raw material resin efficiently. Become.

In addition, the flow path of the raw material resin is a ring tubular flow path, and even if the wall thickness is made thin, the cross-sectional area of the ring tubular flow path can be freely changed by varying the diameter. Therefore, even if the diameter of the annular flow path becomes large, the heating effect of the raw material resin is not lost and the raw material resin can be effectively heated and melted simply by increasing the winding diameter of the high-frequency electromagnetic induction coil. This has the effect that not only small-sized molding but also large-sized molding is possible.

Furthermore, by providing a high-frequency electromagnetic induction heating means in the gate or runner mechanism and intermittently turning on and off the power to the high-frequency electromagnetic induction coil each time injection molding is performed, the raw resin in the gate part is repeatedly melted and solidified. This allows the gate to be opened and closed using the same method, making so-called high-precision molding possible.

When a high-frequency electromagnetic induction coil is wound around the gate and the gate portion is intermittently heated during the gate process, it can work effectively even if the gate itself is long.

Generally, when the gate is short, the runner mechanism and the high frequency electromagnetic induction heating means are turned on intermittently during the runner process.
, the gate can be opened and closed effectively by the OFF operation.

Note that the annular tubular flow path can be formed by incorporating it into the members constituting each mechanism using an inclusion such as a core, but the shape,
The size is free, and it has the effect that any uneven heat can be applied to the place where it is formed, except for the runner mechanism.

Furthermore, since the flow path is annular and tubular, the bent portion does not have an acute angle as in the conventional case, and therefore the bended portion is as large as possible, which eliminates the accumulation of uneven heat in the raw material resin, resulting in smooth injection molding. It has the effect of causing an operation to be performed.

[Brief explanation of drawings]

FIG. 1 is a principle explanatory diagram showing an embodiment of the electromagnetic induction heating injection molding method and apparatus according to the present invention; FIG. FIG. 3 is an explanatory enlarged sectional view of the same as the above, and FIG. 4 is an explanatory sectional view of the main part of the conventional example. 6... Cavity A... Gate B... Runner mechanism C... Manifold mechanism D... Plasticizing mechanism E...・Raw material supply mechanism F...Injection mechanism Figure 4 Procedural Amendment Document March 28, 1986 Director General of the Patent Office Mr. Michibe Uga 1, Indication of Case Patent Application No. 11036 of 1988 3
, Relationship with the case of the person making the amendment Patent applicant name: Sanri Co., Ltd. 4, agent address: 3-3-14-5 Shinbashi, Minato-ku, Tokyo, date of amendment order: Voluntary 6, subject of amendment: Specification ( (Detailed Description of the Invention) 7. Contents of the Amendment (1) ``...'' in the third line from the bottom of page 15 of the specification
, and the inclusion X and the small protrusion 16 are r...
・And, for the inclusion X, correct a small protrusion 16 of your choice, such as a triangular cross-section or a spline shape as shown in the figure, as 1. (2) Since the annular tubular flow path P is formed between the seventh and eighth lines of page 16 of the same book by two or more split molds 14 and 15, the gas during injection molding is The removal is carried out effectively and there is no problem of resin leakage. ” is inserted. (3) On the 11th line of the same page of the same book, it says, "It is also possible to...", but "...it is also possible to use high-frequency electromagnetic induction to heat the annular tubular flow path P. It is also possible to incorporate a coil or other heating element (not shown).'' Procedural amendment July 24, 1988 Commissioner of the Patent Office Black 1) Akio Yu 1, Indication of case Patent Application No. 11036 of 1988 2, Title of invention Electromagnetic induction heating injection molding method and apparatus 3, Amendment Name of patent applicant: Sanri Co., Ltd. 4, Agent address: 3-3-14-5 Shinbashi, Minato-ku, Tokyo, Date of amendment order: Voluntary 6, Subject of amendment: Specification 7, Amendment Contents (1) In the second line of page 16 of the specification, between "...screwed, not shown" and "etc.," or material 1 that shrinks when heated, such as carbon fiber. Insert and correct.

Claims (8)

[Claims] (1) A raw material supply process that supplies the desired raw material resin, a plasticization process that can soften and melt the raw resin, a resin division process that can divide the molten resin into one or more required numbers, and a molding process in which the molten resin that leads to the cavity is molded. It consists of a runner process in which accumulation occurs each time an operation is performed, and at least in the runner process of the processes, a ring tubular flow path heated by high frequency electromagnetic induction heating means is provided to melt the raw resin and transfer the molten resin to the ring. An electromagnetic induction heating injection molding method comprising intermittently injecting into a cavity via a gate by a desired injection means through a tubular flow path. (2) The high-frequency electromagnetic induction heating means is disposed so as to be able to operate continuously or separately in the resin dividing step and the plasticizing step following the runner step, and each step is provided with a ring-tubular flow through which the raw material resin passes. A passage is formed, and the raw material resin passing through the annular flow passage is intermittently injected into the cavity through a gate by a desired injection means that softens and melts the raw resin. The electromagnetic induction heating injection molding method according to scope 1. (3) The high-frequency electromagnetic induction means, which operates at least in the runner process, is operated intermittently during each molding operation to soften and melt a small amount of solidified raw material resin that mainly accumulates in the gate area. 2. The electromagnetic induction heating injection molding method according to claim 1, wherein a gate is opened to enable injection. (4) A raw material supply process that supplies the desired raw material resin, a plasticization process that can soften and melt the raw resin, a resin division process that can divide the molten resin into one or more required numbers, and a molding process in which the molten resin that leads to the cavity is molded. It consists of a runner process in which molten resin accumulates each time the operation is performed, and a gate process in which molten resin is injected into a cavity. Of the above processes, the gate process is provided with high-frequency electromagnetic induction heating means for heating the gate, and at least the runner process In this method, a ring tubular flow path heated by a high frequency electromagnetic induction heating means that is continuous or independent of the heating means is provided to melt the raw resin, and the molten resin is intermittently introduced into the cavity through the gate and the ring tubular flow path. An electromagnetic induction heating injection molding method characterized by performing an injection operation within the interior. (5) The high-frequency electromagnetic induction heating means, at least the one that operates in the gate process, is operated intermittently during each molding operation to soften and melt a small amount of solidified raw material resin that mainly accumulates in the gate area. 5. The electromagnetic induction heating injection molding method according to claim 4, wherein the gate is opened to enable injection. (6) a raw material supply mechanism that supplies a fixed amount of the desired raw material resin;
An injection molding device comprising a plasticizing mechanism, a manifold mechanism having one or more divided flow paths, and a runner mechanism communicating with a gate, and capable of injecting raw resin to be melted by a desired injection mechanism into a cavity through the gate. , among the runner mechanism following the gate, the manifold mechanism, and the plasticizing mechanism, the flow path for the raw material resin of at least one of the mechanisms, starting from the side closer to the gate, is formed by an annular tube shape formed by arranging an inclusion such as a core. An electromagnetic induction heating injection molding apparatus characterized in that a high frequency electromagnetic induction heating mechanism is disposed in a flow path and a mechanism along the annular tubular flow path. (7) The electromagnetic induction according to claim 6, characterized in that the high-frequency electromagnetic induction heating mechanism disposed at least in the runner mechanism is configured to control opening and closing of an electric circuit in conjunction with an injection molding operation. Heated injection molding equipment. (8) The high frequency electromagnetic induction heating mechanism disposed in the runner mechanism is divided into a high frequency electromagnetic induction heating mechanism for gates that can locally heat the gate and a mechanism that can heat the annular tubular flow path of the runner mechanism. 7. The electromagnetic induction heating injection molding apparatus according to claim 6, wherein the high frequency electromagnetic induction heating mechanism is configured to control opening and closing of an electric circuit in conjunction with an injection molding operation.