JP7442159B2 - Injection nozzle and nozzle heater - Google Patents

Description

The present invention relates to an injection nozzle and a nozzle heater used in an injection molding apparatus.

In an injection molding apparatus, in order to pour the molten resin into a mold, it is necessary to heat or keep the flow path of the molten resin at a high temperature. The same applies to the injection nozzle portion, and nozzle heaters for heating or keeping this portion warm are conventionally known.

It is known that if the molten resin is not kept at an appropriate temperature using this nozzle heater, the resin will deteriorate due to thermal changes, which will adversely affect the finish of the plastic molded product.

Conventionally, known nozzle heaters include coil heaters in which a heat transfer wire is wrapped around the injection nozzle, band heaters (cylindrical heaters) that concentrically surround the injection nozzle, and cartridge heaters in which a rod-shaped heater is installed in parallel with the injection nozzle. There is.

For example, the technology described in Patent Document 1 has a configuration in which a coil-shaped heater (H) is wound around the injection nozzle (gate nozzle 8) to heat or keep the injection nozzle warm (see FIGS. 1 to 2 in Patent Document 1). reference.).

Further, for example, the technique described in Patent Document 2 covers a predetermined range of the outer peripheral surface of the injection nozzle (12) with heater members (2A, 2B) formed into a cylindrical body by winding a sheathed heater wire into a coil shape. This is a nozzle heater (1A) that is installed in the same condition.

All of these techniques have a configuration in which a coil-shaped heater is wound around the outer peripheral surface of the body of the injection nozzle, and the injection nozzle can be efficiently heated.

However, the techniques disclosed in Patent Documents 1 and 2 have a problem in that a temperature difference occurs between the front portion and the rear portion of the injection nozzle, or between these portions and other portions.

Recently, there has been a desire to develop injection molding equipment and injection nozzles that can be used for super engineering plastics (abbreviation: super engineering plastics), but super engineering plastics are easily deteriorated by thermal changes in the molten state, High temperature stability is also required in each part of the nozzle.

Patent No. 4221056 Utility model registration No. 3142778

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an injection nozzle that has high temperature stability by preventing or keeping the temperature difference between each part of the injection nozzle, particularly between the front and rear parts of the injection nozzle, to a small range, and to provide an injection nozzle that has high temperature stability. An object of the present invention is to provide a nozzle heater used for.

The above object of the present invention is achieved by the following means.

1. In an injection nozzle used in an injection molding device and consisting of at least a body, a flange main body, and a flange collar,
A nozzle heater is provided to heat or keep warm the molten resin injected from the injection nozzle,
The nozzle heater includes a front heater part that heats or keeps warm the front part of the injection nozzle, and a rear heater part that heats or keeps warm the rear part of the injection nozzle.
The injection nozzle is characterized in that the rear heater section is installed in contact with an inner surface of a flange collar.

2. The injection nozzle according to claim 1, wherein the rear heater section is installed without contacting the outer surface of the rear portion of the body.

3. 3. The injection nozzle according to claim 1, wherein the front heater part is installed in contact with the outer surface of the front part of the body.

4. The injection nozzle according to claim 1, wherein the nozzle heater is a coil heater.

5. 5. The injection nozzle according to claim 1, wherein the front heater section and the rear heater section are separate bodies, and their temperatures can be controlled separately.

6. A nozzle heater installed in an injection nozzle for an injection molding device consisting of at least a body, a flange main body, and a flange collar, and heating or keeping warm the molten resin injected from the injection nozzle,
It consists of a front heater part that heats or keeps warm the front part of the injection nozzle, and a rear heater part that heats or keeps warm the rear part of the injection nozzle,
The nozzle heater is characterized in that the rear heater section is installed in contact with an inner surface of the flange collar.

7. The nozzle heater according to claim 6, wherein the nozzle heater is installed without contacting the outer surface of the rear portion of the body.

According to the invention shown in 1 above, by configuring the rear heater section to be installed in contact with the inner surface of the flange collar, temperature differences between various parts within the injection nozzle, particularly between the front part and the rear part of the injection nozzle, can be prevented or It is possible to provide an injection nozzle that can be accommodated within a small range and has high temperature stability.

The details of these effects are as follows.
In the conventional technology, the rear heater section was installed in contact with the outer surface of the body. Therefore, even if the body is heated or kept warm, the heat is not only radiated to the flange body and flange collar that are in contact with the body, but also to the mold etc. through the flange collar, etc., and the body (especially the resin flow path) There was a problem in that the temperature at the rear of the injection nozzle was unstable.

In contrast, in the invention shown in 1 above, the position of the rear heater section is different from that of the conventional technology, and the rear heater section is installed in contact with the inner surface of the flange collar. That is, in the present invention, the flange collar is heated and kept warm by the nozzle heater, and this heat is transferred to the body (especially the resin flow path) via the flange collar and the flange body in contact with the flange collar.

By adopting such a new configuration, the flange collar and the flange body are also heated and kept warm, so it is possible to suppress heat radiation to these locations. Furthermore, since the flange collar and the flange body are heated and kept warm, it is possible to suppress heat radiation to the mold, etc. in contact with the flange collar and the flange body. Due to these effects, heat radiation is suppressed and high temperature stability can be achieved even in the rear part of the body, where the temperature was not stable due to heat radiation in the past.

Further, according to the invention shown in 1 above, since the rear heater part is housed in the inner surface of the flange collar, the injection nozzle is thicker than when it is installed in other places such as the outer surface of the flange collar. It is possible to keep the size (diameter) small, and it is possible to reduce the installation interval between a plurality of injection nozzles.

According to the invention shown in 2 above, since the rear heater part is installed without contacting the outer surface of the rear part of the body, heating and heat retention to the body is performed through the flange collar and the flange main body. Limited to heating and heat retention, temperature stability can be improved.

According to the invention shown in 3 above, since the front heater part is installed in contact with the outer surface of the front part of the body, the front part of the injection nozzle can be stably heated and kept warm. In combination with configurations 1 and 2 above, it is possible to keep the temperature of the front part and the rear part of the injection nozzle constant, thereby improving the temperature stability of the injection nozzle as a whole.

According to the invention shown in 4 above, by adopting a coil type heater as the structure of the nozzle heater, it is possible to adjust the number of turns of the coil in response to changes in various conditions such as the length and diameter of the injection nozzle. We can respond.

According to the invention set forth in item 5 above, the front heater section and the rear heater section are separate bodies, and the temperature can be controlled separately, so that precise temperature control is possible for each part, The temperature stability of the injection nozzle as a whole can be further improved.
In addition, it is possible to flexibly respond to temperature changes in a portion of the injection nozzle without having to adjust the number of turns of the coil in response to changes in various conditions such as the length and diameter of the injection nozzle. can.

According to the inventions shown in 6 and 7 above, by configuring the rear heater part to be installed in contact with the inner surface of the flange collar, each part in the injection nozzle, especially the injection It is possible to provide a nozzle heater for an injection nozzle that can prevent or keep the temperature difference between the front part and the rear part of the nozzle within a small range and has high temperature stability.

A schematic side view showing an embodiment of the injection nozzle according to the present invention (integrated type) A schematic side view showing an embodiment of the injection nozzle according to the present invention (integrated type) A schematic side view showing another embodiment of the injection nozzle according to the present invention (individually controlled type) A schematic side view showing another embodiment of the injection nozzle according to the present invention (individually controlled type) Experimental data comparing temperature distribution at the injection nozzle

An injection nozzle and a nozzle heater according to the present invention will be explained according to the drawings.

As shown in FIG. 1, the injection nozzle 1 includes a body 2, a flange main body 3, a flange collar 4, a cap 5, a gate tip 6, and a nozzle heater 7.

The body 2 has a cylindrical shape in which a resin flow path 21 is provided, and the gate pin 8 is inserted into the resin flow path 21 . The molten resin flows from the manifold 9, passes through the resin flow path 21, and is injected toward the mold or stopped by opening and closing with the gate pin 8.

The body 2 is required to have a certain level of strength and thermal conductivity to transmit the heat generated from the nozzle heater 7. There are no specific limitations on the material, and any publicly known material can be used for the body used in the injection nozzle without any particular limitations. Examples include iron-based metals and iron-based alloys.

The flange main body 3 and the flange collar 4 are parts for attaching the injection nozzle 1 to the mold K. The injection nozzle 1 is fixed to the mold K using the flange main body 3 and the cap 5, which will be described later, as a reference for positioning.

As shown in FIG. 2, the flange main body 3 is attached to the rear of the body 2, and the other side is attached in contact with the manifold 9.
The flange main body 3 has a flange-like form, but the specific form is not limited.

The flange body 3 is subjected to mold clamping force during molding, stress due to injection, stress due to thermal expansion, etc., and therefore requires sufficient strength. There are no specific limitations on the material, and any publicly known material can be used as the flange used in the injection nozzle without any particular limitations. Examples include iron-based metals, iron-based alloys, titanium alloys, and the like.

As shown in FIGS. 1 and 2, the flange collar 4 has a cylindrical shape that partially surrounds the body 2, and is attached in contact with the flange main body 3, but not in contact with the body 2. . There are no limitations on the specific form, diameter, or range surrounding the body 2, that is, the length of the flange collar 4 in the longitudinal direction.

The flange collar 4 can be provided with an insertion hole or opening as appropriate in order to pass a heater wiring 73 of a nozzle heater 7 to be described later.

The flange collar 4 is required to have a certain level of strength and thermal conductivity for transmitting heat from the nozzle heater 7. There are no specific limitations on the material, and any publicly known material can be used as the flange collar used in the injection nozzle without any particular limitations. Examples include iron-based metals, iron-based alloys, titanium alloys, and the like.

The cap 5 is a component for attaching a gate chip 6, which will be described later, to the body 2. Further, together with the flange main body 3, it serves as a reference for positioning when fixing the injection nozzle 1 to the mold K.

The cap 5 is attached to the tip of the body 2, as shown in FIG. 2, etc., and plays the role of supporting and fixing the gate chip 6.
There are no limitations on the material for forming the cap 5, and any publicly known material can be used as a cap for use in an injection nozzle without any particular limitations. Examples include iron-based metals, iron-based alloys, titanium alloys, and the like.

The gate chip 6 is a component that is provided at the tip of the body 2 and has the role of transmitting heat from the nozzle heater 7 to the tip of the injection nozzle 1. Further, the gate G is opened and closed by the piston movement of the gate pin 8, and the injection or stop of injection of the molten resin is controlled, and when the gate G is opened and closed by the tip of the gate pin 8, axial wobbling of the gate pin 8 is suppressed. play a role.
Note that the injection nozzle 1 of the embodiment shown in FIGS. 1 to 4 has a so-called topless shape (a configuration in which the gate is directly provided in the mold or its cavity), so the gate G is located in the hole (opening) of the mold K. ) However, the present invention can be applied to any known and publicly used injection nozzle shape in addition to this topless shape injection nozzle without any particular limitation. For example, it is also applicable to a full-top injection nozzle.

The gate chip 6 is required to have sufficient strength and durability in order to suppress axial wobbling of the gate pin 8, and is also required to be made of a material with good thermal conductivity in order to transmit heat to the tip of the injection nozzle 1. Ru. There are no specific limitations on the material, and any publicly known material can be used as the gate chip used in the injection nozzle without any particular limitations. Examples include iron-based metals, iron-based alloys, copper alloys, and cemented carbide.
Although the gate chip 6 and the mold K are shown as being in contact with each other in FIGS. 2 and 4, in reality, a gap is provided for heat insulation and they are not placed in contact with each other.

The nozzle heater 7 is a heating element provided to heat or keep warm the injection nozzle 1, thereby heating or keeping warm the molten resin passing through or staying in the resin flow path 21.

Band heaters, cartridge heaters, and the like are known as heaters for heating or keeping the injection nozzle warm, but in the present invention, it is preferable to use a coil heater as the nozzle heater 7.

A coil heater is used by wrapping a coiled heater part around an object to be heated, and in the present invention, a coiled heater is used by wrapping it around each part of the injection nozzle 1. The advantage of coil heaters is that they can accommodate changes in the length of the injection nozzle by adjusting the length of the coil, and the heating temperature can also be adjusted by adjusting the number of turns. There is. Coil heaters are sometimes called hot springs.

There are no limitations on the specific structure or heater type of the nozzle heater 7 used in the present invention, and any publicly known heater can be used without any particular restrictions. As will be described later, the present invention is characterized by the position where the nozzle heater 7 is installed, and not by the specific structure or type of the nozzle heater 7.

The nozzle heater 7 includes a front heater part 71 that heats or keeps the front part 11 of the injection nozzle 1 warm, and a rear heater part 72 that heats or keeps the rear part 12 of the injection nozzle 1 warm. As will be described in detail later, these front heater section 71 and rear heater section 72 may be formed as one heater, or may be formed as two or more separate heaters, and their respective temperature controls are also integrated. It can be controlled separately or separately.

The front heater section 71 is a heater for heating and keeping warm the molten resin passing through and staying in the front part 71 of the injection nozzle 1, that is, near the cap 5 and the gate chip 6. Specifically, as shown in FIGS. 1 and 2, it is attached in contact with the body 2 of the front portion 11 of the injection nozzle 1. In other words, the front heater section 71 is wound around the outer surface (outer circumferential surface) of the body 2 in contact with it. A part of the front heater section 71 may come into contact with the cap 5 or the gate chip 6.

The rear heater section 72 is a heater for heating and keeping warm the molten resin passing through and staying in the rear part 72 of the injection nozzle 1, that is, in the vicinity of the flange main body 3 and the flange collar 4. Specifically, as shown in FIGS. 1 and 2, it is attached in contact with the inner surface (inner peripheral surface) of the flange collar 4. In other words, the outer surface (outer peripheral surface) of the rear heater portion 72 wound into a coil shape is installed in contact with the inner surface (inner peripheral surface) of the flange collar 4 . A portion of the rear heater section 72 may come into contact with the flange main body 3.

In the present invention, the flange collar 4 is heated and kept warm by the rear heater section 72 of the nozzle heater 7, and this heat is transferred to the body 2 (particularly the resin flow path 21) via the flange collar 4 and the flange body 3 in contact with the flange collar 4. The configuration is as follows.

It is preferable that the rear heater section 72 be attached without contacting the outer surface (outer peripheral surface) of the body 2 . As a result, the rear heater section 72 does not directly heat and keep the body 2 warm, but instead conducts heat through the flange collar 4 and the flange body 3 in contact with it, and the temperature of the resin flow path 21 at various locations in the injection nozzle 1 is kept constant. It can be done.

As described above, the nozzle heater 7 according to the present invention is composed of the front heater part 71 that is wrapped around the outer peripheral surface of the body 2, and the rear heater part 72 that is attached in contact with the inner peripheral surface of the flange collar 4. In other words, it can be said to be a two-stage diameter heater in which the diameters of the coiled portions of the front heater section 71 and the rear heater section 72 are different.

Temperature sensors are provided at the locations where the front heater section 71 and the rear heater section 72 are attached, and the temperature is managed and controlled thereby, but the temperature sensors are omitted in the drawings.

Examples of the nozzle heater 7 include an "integrated type" in which the front heater part 71 and rear heater part 72 are integrated, and "integral type" in which the front heater part 71 and rear heater part 72 are separate bodies and the temperature can be controlled individually. "individual control type" can be mentioned.

The integrated type has a configuration in which the front heater section 71 and the rear heater section 72 are integrally formed as one coil heater, as shown in FIGS. 1 and 2. In other words, there is one coil section which is a heat generating section, and this coil section is attached to the front heater section 71 and the rear heater section 72 with the number of turns adjusted respectively.

In the integrated type, since there is only one coil, there is also one controller that performs temperature control, and it is not possible to perform separate temperature control for the front heater section 71 and the rear heater section 72. On the other hand, by adjusting the number of windings in the front heater section 71 and the rear heater section 72, it is possible to make the temperature constant in the front part 11 and the rear part 12 of the injection nozzle 1. The number of turns varies depending on the length and diameter of the injection nozzle 1, and the number of turns is adjusted according to customer orders and the mold used.
The integrated type requires only one heater and the number of temperature controls can be kept to a small number, so it is possible to reduce component costs and work costs during manufacturing.

The individual control type has a configuration in which the front heater section 71 and the rear heater section 72 are formed as separate coil heaters, as shown in FIGS. 3 and 4.

In the individual control type, the front heater section 71 and the rear heater section 72 have separate coils, and since there are two coils, each is connected to a controller that controls the temperature separately, and the temperature is also controlled separately. be able to. With this configuration, the temperature can be individually and precisely controlled without adjusting the number of turns of the coil portion according to various conditions such as the length of the injection nozzle. It can be said to be highly versatile because there is no need to adjust the number of turns in the coil part according to the customer's order or the mold used.

Next, the results of a verification experiment conducted to confirm the effects of the present invention will be explained.
This verification experiment was conducted using a conventional configuration (a configuration in which the rear heater part is wrapped around the body in contact with the rear part of the injection nozzle. The front heater part is the same as the present invention), the present invention (integrated type), and the present invention (integrated type). The temperature distributions are compared for the three inventions (individual control type).

The results of the verification experiment are shown in FIG.
The length (mm) shown on the horizontal axis indicates the temperature measurement position in the injection nozzle 1, where 0 mm is the tip of the injection nozzle 2 (near the tip of the gate tip 6), and the length is in the range of 0 mm to 40 mm. corresponds to the front portion 11, 40 to 80 mm corresponds to the area between the front portion 11 and the rear portion 12 (hereinafter referred to as the “intermediate portion”), and the range from 80 to 120 mm corresponds to the rear portion 12. The injection nozzle 1 used in this verification experiment has a length of about 120 mm.
The numerical values shown on the vertical axis are temperatures indicated by a plurality of temperature sensors provided in the injection nozzle 2.

According to the results shown in Fig. 5, for any of the conventional configuration, the present invention (integrated type), or the present invention (individual control type), the temperature is significantly lower in the area from 0 to 15 mm compared to other locations. There is. This is because the molten resin injected from the injection nozzle 1 needs to be cooled and solidified, so no heater is provided in this area. Therefore, temperature changes within this range are not a problem.

First, consider the conventional configuration.
According to the results shown in Figure 5, in the conventional configuration, the temperature in the front part is around 330°C, but in the middle part it increases to 340-360°C, and in the rear part it increases from 320°C to 300°C. It is rapidly declining. The maximum temperature difference from the front part to the rear part was about 60°C.

Next, the present invention (integrated type) will be considered.
According to the results shown in FIG. 5, in the present invention (integrated type), the front part showed a temperature of 330 to 340 degrees Celsius, the middle part showed a slight temperature increase to slightly over 340 degrees, and the rear part The temperature drop has stopped at around 330 degrees. The maximum temperature difference from the front part to the rear part was about 20°C.

Finally, the present invention (individual control type) will be considered.
According to the results shown in Fig. 5, in the present invention (individual control type), the temperature in the front part is around 330 to 330°C, the middle part is slightly over 330°C, and the rear part is 330°C. The temperature has only dropped to a slightly lower level. The maximum temperature difference from the front part to the rear part was about 10°C.

To summarize these results, the present invention (individually controlled type) has the best temperature stability in each part of the injection nozzle 1, followed by the present invention (integrated type), and lastly the conventional configuration. .
This verification experiment was conducted under the same conditions for the number of turns of the front heater section and the number of turns of the rear heater section. Therefore, in the present invention (integrated type), if the number of windings of the rear heater section 72 is optimally adjusted, it is possible to improve the temperature change to a range comparable to that of the present invention (individual control type). be.

These results demonstrate that by adopting the configuration of the present invention, that is, the configuration in which the rear heater section 72 is installed in contact with the inner surface of the flange collar 4, the temperature stability in each part of the injection nozzle 2 is excellent. Ta.

BACKGROUND ART Recently, there has been a desire to develop an injection molding apparatus compatible with super engineering plastics (abbreviation: super engineering plastics) or an injection nozzle used therein.
Super engineering plastics are susceptible to deterioration due to thermal changes in the molten resin state during injection molding, so they need to be stabilized at high temperatures. Specifically, in the state of molten resin, it is ideal to stabilize the temperature at a high temperature of around 400°C and a low temperature of around 300°C, with high temperature stability such that the temperature difference is within 10°C or 20°C. is required.
The molding temperature for super engineering plastics varies greatly depending on the type of resin, and as mentioned above, the high molding temperature is around 400°C and the low molding temperature is around 300°C, but in the verification experiment whose results are shown in Figure 5, The molding temperature was about 330°C.

With the injection nozzle 1 and nozzle heater 7 according to the present invention, it is possible to maintain a high temperature of approximately 330°C (the molding temperature of the resin used in the verification experiment) at various locations within the injection nozzle 1, and the temperature change is also 10°C. It was found that it is possible to keep the temperature within ℃. By changing the set temperature of the nozzle heater 7, it is possible to maintain a temperature other than the above-mentioned 330°C, such as 300°C or 400°C.
Therefore, the present invention can be used as an injection molding apparatus compatible with super engineering plastics, and an injection nozzle or nozzle heater used therein.

1 Injection nozzle 11 Front part 12 Rear part 2 Body 21 Resin flow path 3 Flange body 4 Flange collar 5 Cap 6 Gate chip 7 Nozzle heater 71 Front heater part 72 Rear heater part 73 Heater wiring 8 Gate pin 9 Manifold K Mold G Gate

Claims (5)

In an injection nozzle used in an injection molding device and consisting of at least a body, a flange main body, and a flange collar,
A nozzle heater is provided to heat or keep warm the molten resin injected from the injection nozzle,
The nozzle heater includes a front heater part that heats or keeps warm the front part of the injection nozzle, and a rear heater part that heats or keeps warm the rear part of the injection nozzle.
The injection nozzle is characterized in that the rear heater portion is installed in contact with an inner surface of a flange collar , and is installed without contacting an outer surface of a rear portion of the body . The injection nozzle according to claim 1 , wherein the front heater part is installed in contact with the outer surface of the front part of the body. The injection nozzle according to claim 1 or 2 , wherein the nozzle heater is a coil heater. 4. The injection nozzle according to claim 1 , wherein the front heater section and the rear heater section are separate bodies, and their temperatures can be controlled separately. A nozzle heater installed in an injection nozzle for an injection molding device consisting of at least a body, a flange main body, and a flange collar, the nozzle heater heating or keeping warm the molten resin injected from the injection nozzle,
It consists of a front heater part that heats or keeps warm the front part of the injection nozzle, and a rear heater part that heats or keeps warm the rear part of the injection nozzle,
The nozzle heater is characterized in that the rear heater section is installed in contact with an inner surface of the flange collar , and is installed without contacting an outer surface of the rear portion of the body .