JPH0419007B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hot runner chip 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, JP-A-61-58711 and JP-A-62-58711.
Publication No. 140385 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 the runner section.

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 metal layer. The technology of the latter publication is to increase the thermal distance between the heating tip and the tapered circumferential surface 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 reduces the area over the entire area.

[Problem to be solved by the invention]

In the conventional example described above, the heater is formed into a coil shape,
In addition, the wire diameter is reduced and the wire is fixed vertically in an extremely small space such as the tapered part of the sharp heating element, but the heater itself is made of a material that is easily oxidized, such as nichrome wire. Intended for metal wires.

Therefore, the smaller the wire is, the weaker the mechanical strength and oxidation resistance become, and damage and oxidation breakage are unavoidable. Therefore, there was a limit to how small the size could be.

In addition, the above-mentioned embodiment has the problem 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, or that uses an external heating method. .

[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 fine workability. The above problem is solved by creating a small diameter hot wire using a metal wire and vertically disposing it by winding it in a coil shape inside or outside near the gate and keeping it out of contact with the circulating resin. did.

Furthermore, in order to solve the specific problem of this invention, a small diameter hot wire wound into a coil is arranged and fixed at the sharp end of a sharp heating element vertically arranged in a runner, and is attached to a gate. It is characterized by being heated from the inside, and furthermore, the small diameter hot wire wound into a coil is connected to a gate formed at the tip of the hot runner body, which has a central hole through which the molten resin flows. It is characterized in that it is wound in a coil shape around the outer periphery of the vicinity so that the gate is heated from the outside.

[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, a 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 thin wire, it is not oxidized by heat, so it can withstand long-term use.Moreover, the resistance value increases in proportion to the rise in temperature, so the range of use for molded resin can be expanded, and it is also possible to conduct electricity. Since the temperature range of the heating wire when turned on and off is extremely wide, the gate section can be "opened" and "closed" with high sensitivity.

〔Example〕

Next, embodiments of the invention will be described with reference to the drawings.

First, the hot runner chip device shown in FIG. 1 is installed 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.
For example, the hot wire _a1 is formed by winding it into a coil with a size of 0.15 mm. Moreover, this heat ray a ₁
has a conical outer shape 2 with a coil diameter gradually increasing from the tip to the rear, and is vertically mounted in the tip case 4 of a sharp heating element 5 consisting of a body case 3 and a tip case 4. be.

That is, the hot wire a 1 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 _{a 1 passes} through the center hole 6 and runs along the center axis of the body case 3. The conductive wire portion 8 is connected to the base of the chip case 4 along the outer periphery of the center hole 6 by welding or the like, and is 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, its shape is a cylinder as shown in the conventional example described above, and a body heater is built inside the body case 3 to heat and melt the raw material resin of the runner part. Of course, it is possible to maintain the state.

Since the configuration is as described above, if you energize hot wire _A1 ,
The coiled conical outer shape 2 becomes red hot and becomes high temperature.
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 instantaneously melted and the gate opened.

Therefore, normal injection molding operations can be carried out.

Next, when the power supply to the hot wire a ₁ is stopped, the hot wire a ₁ stops becoming red hot, and the heating to the chip case 4 is stopped, so the heating at the gate part stops, the temperature decreases, and the molten resin at the gate part is immediately discharged. The so-called gate can be closed by cooling and solidifying.

By the way, hot wire a ₁ uses platinum wire 1, and
Since the material with an extremely small wire diameter of 0.15 mm is 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 turns can be increased. It has the advantage that it can be installed as close as possible to the conical tip of the chip case 4, and as a result, the thermal response to the gate portion can be significantly improved.

Moreover, since the platinum wire 1 does not oxidize, its durability is significantly improved, and in particular, as the temperature increases, the resistance value increases in proportion to it, so for example, at 0°C
If there is a temperature change from
Therefore, unlike conventional hot wires, it can be used as a hot runner chip device for almost any resin material.

In this example, the hot wire a ₁ 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. It may also be configured as a cylindrical outer shape having the same diameter and may be mounted vertically.

Next, in the sharp heating element structure of this example, the temperature at the tip of the chip case 3 when intermittent temperature control is applied when using the platinum wire 1 and when using the conventional nichrome wire. The measurement results are shown in the graphs of FIGS. 5 and 6.

In this example, the wire diameter of platinum wire 1 is 0.15
mm, 12 turns, 27~24W, (6.9V, 3.9~3.5A),
On the other hand, the nichrome wire has a wire diameter of 0.6 mm and a power output of 40 W (5.0 V−
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, and show a configuration 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 made of the same material as in the previous embodiment, that is, the platinum wire 1, and the wire diameter is, for example, 0.15 mm, and is wound into a coil shape with the same diameter. Turn to form.

The gate portion 11 of a cylindrical hot runner body 14 is arranged on the same axis with the gate 12, the gate portion 11, and the runner 13 as a center hole.
The hot wire a ₂ is insulated and wound and fixed together with an insulating material 15 such as ceramics around the outer periphery of the heat wire a 2 .

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 gate portion 11, further passes through the outer periphery of the hot runner body 14, is insulated with an insulating material 15 such as ceramics, and is led out to the outside.

Further, in the hot runner body 14, a body heater 17 for heating the runner 13 is wound in a cylindrical body 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. Furthermore, a conical cap 19 is provided at the tip of the cylinder 18, and a space 20 is formed at the tip of the hot runner body 14 to provide an air gap for heat insulation.

Also, reference numeral 21 indicates the hot runner body 14.
A manifold is disposed so as to be in contact with the bulging portion 22 at the rear end so that the flow hole 23 and the runner 13 can communicate with each other, 24 is a mold part to which the hot runner body 14 is also mounted, and 25 is this mold. The required number of cooling holes 26 are formed in the portion 24 and serve as an annular holder for attaching the hot runner body 14 to the mold portion 24.

By the way, in the case of FIG. 3, the mold part 24 is divided into two parts, front and rear, and a conical bushing 27 is attached to the gate side member to attach the hot runner body 14.
In addition, in FIG.
A cooling medium introduction hole 29 through which cooling air or the like can act toward the gate part 11 and a discharge hole 30 facing outside from the gate part 11 are bored respectively, so that the raw resin facing the gate part 11 is forcibly drained. It has a configuration that allows for cooling.

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

In addition, a mold part 24 is provided in each hole 29, 30.
A pipe body 32 such as a tube is connected through the pipe.

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 a ₂ of a small 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 _. When energized and heated, the fixed resin of the gate portion 11 is immediately heated and melted, the so-called gate 12 is opened, and injection molding is performed by the injection molding operation.

Then, when the power supply to the hot wire a ₂ is stopped, the hot wire a ₂ stops generating heat, the temperature inside the gate portion 11 decreases, and the molten resin is immediately cooled and solidified. That is,
Gate 12 is closed.

However, in the embodiment shown in _FIG .
If the resin is supplied from 9 to the annular recess 31 on the outer periphery of the gate part 11, this part can be forcibly cooled locally, so that the resin in the part is cooled and solidified, and the gate 12 is closed and exhibits the same effect. Further, when the flow of the cooling medium is stopped, the 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, since the coiled hot wire A ₂ wound and fixed around the gate part 11 is made of platinum wire 1, 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. Therefore, high temperatures can be obtained. By using this platinum wire 1, a coiled hot wire _a2 with a small diameter can be obtained, so the coil pitch can be made extremely narrow.
Long wires can be wound in a small volume.

In addition, the mutual temperature control of the hot wire a ₂ and the body heater 17 can be controlled independently, and since both have low current and power outage, the cost of the controller is lower than in the case of conventional nichrome wires.
It becomes possible to downsize.

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
There is no need for a heat insulator or the like in the gate part, which simplifies the configuration.Furthermore, intermittent heating control allows 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 in combination with the forced cooling method.
It also becomes possible to control both the body and chip heat sources in one circuit.

Furthermore, since the wire diameter can be made smaller, the number of turns can be increased, and the high temperature can be controlled as desired, as well as being able to locally heat the gate from the inside or outside. .

[Brief explanation of drawings]

FIG. 1 is an enlarged vertical cross-sectional view of the main components 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 a state of use. 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. 2, and FIG. 6 is a temperature change graph of the conventional hot runner chip device. The temperature change graph obtained by intermittent temperature control, Figure 7, is similar to Figures 2 to 4.
FIG. 2 is an enlarged sectional view of a main part showing a state in which a hot wire wound into a coil in each embodiment shown in the figures is attached. 1...Platinum wire, _a1 , _a2 ...Heat wire, 3...Body case, 4...Chip case, 6...Center hole, 1
1... Gate portion, 12... Gate, 13... Runner, 14... Hot runner body, 15... Insulating material such as ceramics, 17... Body heater, 29... Cooling medium introduction hole, 30... Discharge Hole.

Claims (1)

[Claims] 1. A hot wire with a small wire diameter is made by using a metal wire material whose resistance value increases in proportion to temperature, which has high fine workability and is oxidation resistant. A hot runner chip device characterized in that the hot runner chip is vertically arranged by winding it into a coil near the gate and maintaining non-contact with the circulating resin. 2. A small-diameter heating wire wound into a coil is fixed to the sharp end of a sharp heating element installed vertically in the runner, and heats the gate from the inside. 2. A hot runner chip device according to claim 1. 3 A small-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, which has a central hole through which molten resin flows, and is connected to the gate from the outside. 2. The hot runner chip device according to claim 1, wherein the hot runner chip device is configured to heat the hot runner chip. 4. Claim 1, wherein the metal wire material for making the hot wire is platinum wire.
4. The hot runner chip device according to any one of items 3 to 3.