JPH01257019A - Hot runner tip device - Google Patents

Abstract

PURPOSE:To contrive miniaturization and cost reduction of a controller by a method wherein a hot wire of a fine wire diameter is made of a metallic wire material which increases its resistance value in proportion to a temperature and possesses oxidation resistance, which is wound round in a coil-shaped state in the vicinity of a gate and keeps noncontacting with circulating resin. CONSTITUTION:A hot wire (a1) is formed of a platinum wire 1 having oxidation resistance and properties where a resistance value also increases when a temperature becomes high by winding round the same into a coil-shaped state with a wire diameter of not exceeding 0.6mm, for example, size of 0.15mm. The hot wire (a1) is provided with a conical external form 2 where the more it moves rearward from the tip of the coil the larger the diameter of the same is formed and fitted longitudinary to the inside of a tip case 4 of an acute heating unit 5 comprised of a body case 3 and the tip case 4. A plurality of insulators 9 are interposed and fixed with an insulating material 10 so that the filled hot wire (a1) is held under an insulation state due to noncontacting. When the hot wire (a1) is electrified, the external form 2 becomes red heat and a high-temperature, the chip case 4 is heated, the resin which is cooled and solidified at a gate pert is melted thermally and instantly and the gate is opened. when the electrification is suspended, the molten resin is cooled and solidified immediately and the gate is closed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hot runner tip device that can locally heat a narrow space in a gate portion of an injection molding device.

[Conventional technology]

This type of hot runner chip device includes, for example, Japanese Patent Laid-Open No. 61-58711 and Japanese Patent Laid-Open No. 62-1403.
No. 85 is known. The techniques disclosed in both publications were created by the inventor of the present invention, and are characterized in that a coil-shaped heater with a small wire diameter is fixed within the tip of a sharp heating element vertically mounted within a portion of the runner.

The technique disclosed in the former publication involves thermally welding one lead wire of a nichrome wire heater vertically mounted in a coil shape to the tip of a sharp heating element to form a wear-resistant alloy bending layer. In addition, the technology in the latter publication increases the thermal distance between the heating tip and the tapered circumferential surface over the entire range by changing the winding diameter of the coiled heater as much as possible or increasing the number of windings. This is a technical content that has been reduced over a period of time.

(Problems to be Solved by the Invention) In the above-mentioned conventional example, the heater is formed into a coil shape, and the wire diameter is reduced to reduce the vertical heating in the tapered part of the sharp heating element, which has an extremely small volume. Although characterized by cleft fixation,
The material of the heater itself is exclusively metal wire that is easily oxidized, such as nichrome wire.

Therefore, the smaller the wire is, the weaker the mechanical strength as well as the oxidation resistance becomes, and damage and oxidation disconnection are inevitable. Therefore, there was a limit to how much it could be reduced.

In addition, the above-mentioned embodiment has a problem in that it is limited to a sharp heating element that heats the gate internally, and cannot be applied to a so-called hot runner chip that heats from the outer periphery of the gate. .

[Means to solve the problem]

This invention was made by focusing on the points mentioned above, and it has oxidation resistance like platinum, has the property of increasing resistance value in proportion to temperature, and has further reduction workability. The above problem was solved by making a reduced diameter hot wire using a metal wire, and vertically disposing the stiffened wire inside or outside near the gate by winding it in a coil shape while maintaining non-contact with the circulating resin. did.

In addition, in order to solve the specific problem of this invention, a reduced diameter heating wire wound into a coil shape is arranged and fixed at the sharp end of a sharp heating element vertically arranged in a runner, and is fixed to a gate. On the other hand, it is characterized by being heated from the inside,
Furthermore, the reduced-diameter hot wire wound in a coil is wound around the outer periphery near the gate formed at the tip of the hot runner body with a central hole through which the molten resin flows. It is characterized in that it becomes more heated.

[Effect]

When the mold is in a closed state and the molding resin is accumulated in the gate, if a current is passed through the hot wire, the temperature will rise and the gate portion will reach the desired set temperature.

The solidified or softened resin in the gate portion is heated from the inside or outside and melts, so that the so-called gate becomes "open" and an injection molding operation can be performed.

After the injection molding operation has stopped, if the power to the hot wire is stopped, the temperature of the gate part will drop, the resin in the gate part will solidify or soften, the so-called gate will be "closed", and the molded product can be removed by opening the mold. becomes.

Next, the mold clamping operation brings the mold into the first clamping state, and the above-described series of operations is repeated.

Even if the heat wire is a shrinking wire, it is not oxidized by heat, so it can be used for a long time, and the resistance value increases in proportion to the rise in temperature, so the range of use of molding resin can be expanded.
Since the temperature range of the hot wire when energized is turned on and off is extremely wide, the gate section can be "opened" and "closed" with good sensitivity.

(Example〕 At the same time, embodiments of the present invention will be described with reference to the drawings.

First, the hot runner tip device shown in FIG. 1 is provided in a hot runner body having a sharp heating element structure capable of heating from the inside, and will be described below. - 1 indicates a platinum wire that has oxidation resistance and has the property that the resistance value increases proportionally as the temperature increases,
This platinum wire 1 has a wire diameter of 0.8 mm or less, for example 0.1 mm.
The hot wire a1 is formed by winding it into a coil with a size of 5 mm. Moreover, this hot wire a has a conical outer shape 2 with a coil diameter gradually increasing from the tip to the rear, and has a body case 3 and a tip case 4.
The tip case 4 of the sharp heating element 5 is vertically split.

That is, the hot wire a1 is loaded into the tip of the center hole 6 of the chip case 4 with the tip facing forward, and one conductor part 7 of the hot wire al passes through the center hole 6 and runs along the center axis of the body case 3. One electrode is led out to the outside, and the other conductive wire portion 8 is connected to the base of the chip case 4 by welding or the like along the outer periphery of the center hole 6 to be grounded to the body.

Then, a plurality of insulating insulators 9 are interposed and the whole is fixed with an insulating material 10 so that the loaded hot wire a1 can maintain a non-contact insulated state.

Although only a portion of the body case 3 is shown, it has a cylindrical shape as shown in the conventional example described above, and a body beater is built inside the body case 3 to heat the raw resin of a part of the runner. Of course, it is possible to maintain the molten state.

With the configuration described above, when the hot wire a is energized, the coiled conical outer shape 2 becomes red hot and reaches a high temperature, and the chip case 4 is heated.

Since this chip case 4 faces the gate section of the injection molding apparatus from the runner side, the resin that has been cooled and solidified at the gate section can be instantly melted by heat to open the gate.

Therefore, normal injection molding operations can be carried out.

Next, if the power to the hot wire a1 is stopped, the hot wire a1 will stop turning red, and the heating to the chip case 4 will stop, so the heating at the gate will stop, the temperature will drop, and the molten resin at the gate will cool down immediately. It can solidify and close the so-called gate.

By the way, the hot wire a uses platinum wire 1, and is 0.1
Because it is made of 5++on, a material with an extremely small wire diameter, wound into a coil, the conical outer diameter 2 of the coil can be made much smaller than conventional nichrome wire, and the number of windings can be increased. It has the advantage that it can be installed as close as possible to the conical tip of the case 4, and as a result, the thermal response to the gate can be significantly improved.

Moreover, since the platinum wire 1 does not oxidize, its durability is significantly improved, and in particular, as the temperature rises, the resistance value increases in proportion to the stiffness, so there is a temperature change from 0°C to 550°C, for example. In this case, the resistance value can be expected to be about three times as high and a high temperature can be obtained. Therefore, unlike conventional hot wires, it can be used as a hot runner chip device for almost any resin material.

In this embodiment, the hot wire a1 is wound in a coil shape and has a conical outer shape 2, but the number of windings in the coil shape is denser at the tip and becomes sparser toward the rear. Moreover, there is no problem even if it is vertically split into a cylindrical outer shape with the same diameter.

Next, in the sharp heating element structure of this example,
Figures 5 and 6 show the results of measuring the temperature at the tip of the chip case 3 when intermittent temperature control was applied when using platinum AT and when using conventional nichrome wire.
Shown in the graph of figure.

In this example, the wire diameter of the platinum wire 1 is 0.15 mm.
, 12 times winding, 27-24W, (6.9V, 3.
9-3.5A), while for nichrome wire, the wire diameter is 0.6 m.
m, 40W (5, OV-8A).

Comparing the two, it is clear that the example using the platinum wire 1 has a larger temperature difference than the nichrome wire, and requires less voltage and current.

In particular, the wide temperature difference indicates that the method can be applied to a wide variety of resins without specifying the resin used, and that it is extremely sensitive.

Next, another embodiment of the present invention will be described with reference to FIGS. 2 to 4.

These embodiments are so-called external heating methods,
A configuration is shown in which the heating means for the runner and the gate section heats the runner and the gate section from outside.

Each figure will be explained.

The hot wire a2 that heats the gate part 11 is
Using the same material as in the example, that is, platinum wire 1, the wire diameter is, for example, 0.15 mm, and is wound into a coil shape with the same diameter.

And gate 12. Gate section 11 and runner 13
The gate part of the cylindrical hot runner body 14 arranged on the same axis as the center hole! On the outer circumference of 1, there is a heat line a
2 is insulated with an insulating material 15 such as ceramics, and then wound and fixed.

By the way, one conductor of the hot wire a2 is body grounded to the hot runner body 14, and the other conductor 16 passes through the outer periphery of the cage portion 11, further passes through the outer periphery of the hot runner body 14, and is insulated by an insulating material 15 such as ceramics. Processed and externalized.

Further, in the hot runner body 14, a body heater 17 for heating the runner 13 is wrapped in a cylinder 18 which is insulated by the ceramic material 15 and is covered with the outer periphery of the hot runner body 14. The resin flowing through the runner 13 is kept warm and melted. Further, the tip of the cylindrical body 18 is provided with a circular hook-shaped cap portion 19, and a space portion 20 is formed at the tip of the hot runner body 14 to provide an air gap for heat insulation.

Also, reference numeral 21 denotes a manifold which is disposed so as to come into contact with the bulge 22 at the rear end of the hot runner body 14 so that the circulation hole 23 and the runner 13 can communicate with each other, and 24 denotes a manifold in which the hot runner body 14 is also connected. The mold section 25 is a required number of cooling holes bored in the mold section 24, and 26 is an annular holder for mounting the hot runner body 14 on the mold section 24.

By the way, in FIG. 3, the mold part 24 is divided into two parts, front and rear, and a conical bushing 27 is attached to the member on the gate side, and the outer periphery is extended from the tip of the hot runner body 14 to the front part. In addition, as shown in FIG. 4, a cylindrical body 28 is further provided on the outer periphery of the hot runner body 14 to protect the gate part 11 from cooling medium such as cooling air. Introduction hole 29. A discharge hole 30 extending outward from the gate portion 11 is slowly bored, so that the raw resin facing the gate portion 11 can be forcibly cooled.

Furthermore, the outer periphery of the gate portion 11 is bored with an annular protrusion 31 for effective circulation of the cooling medium.

Further, a pipe body 32 such as a tube is connected to the holes 29 and 30 of the hole 29 through the mold part 24.

33 indicates the body temperature sensor line.

The action will be explained in the above structure.

In the embodiment shown in each figure, a hot wire a2 of a reduced diameter made of platinum wire 1 is wound in a coil shape near the gate 12, that is, around the outer periphery of the gate portion 11.
2, the assimilated resin in the gate part 11 is immediately heated and melted, so that the so-called gate 12 is opened, and the injection molding operation is performed.

Injection molding is performed by the function of

Then, when the power to the hot wire a2 is removed, the hot wire a2 stops generating heat, the temperature inside the gate portion 11 decreases, and the molten resin is immediately cooled and solidified. That is, the gate 12 is closed.

In the embodiment shown in FIG. 4, if the heating wire a2 is kept in the energized heating state and the cooling medium is supplied from the introduction hole 29 to the annular disciple 31 on the outer periphery of the gate part 11, this part can be locally heated. Since it can be forcibly cooled, the resin in the chain part cools and solidifies, and the gate 12 closes and exhibits the same effect. Furthermore, when the flow of the cooling medium is stopped, the chain portion 11 is heated and melted by the heating action of the hot wire a2, and the gate 12 is opened again.

By the way, the coiled hot wire a2 wound and fixed to the gate part 11 is a platinum wire! Therefore, it has oxidation resistance and does not oxidize, so it has a long life, and the resistance value also increases in proportion to the rise in temperature, so high temperatures can be obtained. By using this platinum wire 1, a coiled hot wire a2 with a reduced wire diameter can be obtained, so the coil pitch can be significantly narrowed, and a long wire can be wound with a small volume. It can be turned.

Moreover, the mutual temperature control of the hot wire a2 and the body heater 17 can be controlled independently, and both of them can be controlled at a low current.
Since the voltage is low, the cost of the controller can be reduced and the size can be reduced compared to the case of conventional nichrome wire.

Although the platinum wire 1 is used in the embodiments of the present invention, it goes without saying that a metal having the same effect as the platinum wire 1 may be used in place of the platinum wire 1.

〔Effect of the invention〕

As mentioned above, this invention uses a metal such as platinum wire, which has excellent oxidation resistance and whose resistance value increases in proportion to the rise in temperature, as the hot wire material, so it has a long life and has an extremely small diameter. It is possible to use a coiled hot wire with a wire diameter of Since there is no need for heat insulating material or the like, the structure can be simplified, and intermittent heating control can maintain a large temperature difference, so it can be used to open and close gates for all kinds of resins.

Moreover, it is easy to use it in combination with a forced cooling method, and it is also possible to control both the body and chip heat sources in one circuit.

Furthermore, since the wire diameter can be reduced, the number of turns can be increased, and the high temperature can be controlled as desired.In addition, the wire can be locally heated from the inside or outside. .

[Brief explanation of the drawing]

FIG. 1 is an enlarged vertical cross-sectional view of the main structure of a hot runner chip device according to an embodiment of the present invention, and FIGS. 2 to 4 show other embodiments of the present invention in use. FIG. 5 is a temperature change graph obtained by intermittent temperature control of the hot runner-chip device according to the present invention having the configuration shown in FIG. FIG. 7, which is a temperature change graph obtained by intermittent temperature control, is an enlarged cross-sectional view of a main part showing the state in which the coiled heating wire of each of the embodiments shown in FIGS. 2 to 4 is attached. 1...Platinum wire aI+ a2...Hot wire 3...Body case 4...Chip case 6...Center hole 11... ... Gate part 12 ... Gate 13 ... Runner 14 ... Hot runner body 15 ... Insulating material 17 such as ceramics ...
... Body heater 29 ... Cooling medium introduction hole 30 - ... Discharge hole

Claims (3)

[Claims] (1) Using a metal wire whose resistance value increases in proportion to temperature, which has high precision machinability and oxidation resistance, create a hot wire with a small diameter and place it near the gate. A hot runner chip device characterized in that it is wound into a coil and arranged vertically so as to maintain non-contact with circulating resin. (2) A small-diameter hot wire wound into a coil shape is arranged and fixed at the sharp end of a sharp heating element vertically arranged in the runner,
2. The hot runner chip device according to claim 1, wherein the gate is heated from inside. (3) A small-diameter hot wire wound in a coil shape is wound around the outer periphery near the gate formed at the tip of the hot runner body with a central hole through which molten resin flows, and is connected to the gate. 2. The hot runner chip device according to claim 1, wherein the hot runner chip device is heated from the outside.