JP2004130554A - Nozzle for injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the nozzle for an injection molding machine which individually controls the temperatures of two kinds of resins at the time of sandwich molding using the resins. <P>SOLUTION: The tip of an outer nozzle 12 is connected to a mold and an inner nozzle 11 is connected to the rear of the outer nozzle 12. A cavity part is formed in the outer nozzle 12 and the first half part of the inner nozzle 11 is housed in the cavity part, and the latter half part thereof is exposed to the outside. A first flow channel 15 pierces the inner nozzle 11 axially and a second annular flow channel 16 is formed between the outer peripheral surface of the inner nozzle 11 and the inner peripheral surface of the outer nozzle 12. The first and second flow channels 15 and 16 meet with each other in front of the inner nozzle 11 to be connected to a discharge port 13. A first heater 21 is attached to the outer periphery of the latter half part of the inner nozzle 11 and a second heater 22 is attached to the outer periphery of the outer nozzle 12. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a nozzle for an injection molding machine, in particular, a nozzle used in so-called sandwich molding using two types of resins, forming a skin layer with one resin and a core layer with the other resin. It is related to the structure of.
[0002]
[Prior art]
FIG. 4 shows an outline of the structure of a conventional nozzle used in sandwich molding.
[0003]
This nozzle is composed of a nozzle body 60 and first and second needle valves 61, 62 which are double-built in the nozzle body. A discharge port 63 is provided at the tip of the nozzle body 60. The tip of the nozzle body 60 is connected to a gate 10 a provided on the back of the mold 10. The first needle valve 61 is incorporated inside the second needle valve 62, and a discharge port 64 is provided at the tip of the second needle valve 62.
[0004]
A first flow path 65 is formed between the outer peripheral surface of the first needle valve 61 and the inner peripheral surface of the second needle valve 62. Similarly, a second flow path 66 is formed between the outer peripheral surface of the second needle valve 62 and the inner peripheral surface of the nozzle body 60. A first port 67 and a second port 68 for introducing molten resin are provided on a side surface near the rear end of the nozzle body 60. The first port 67 is connected to the discharge port 63 via a through hole 69 provided on a side surface of the second needle valve 62, the first flow path 65, and the discharge port 64. The second port 68 is connected to the discharge port 63 via the second flow path 66. The main injection device 71 is connected to the first port 67. The secondary injection device 72 is connected to the second port 68.
[0005]
The opening and closing of the first flow path 65 is performed in front of the discharge port 64 by moving the first needle valve 61 in the second needle valve 62 in the axial direction. Similarly, the opening and closing of the second flow path 66 is performed before the discharge port 63 by moving the second needle valve 62 in the nozzle body 60 in the axial direction.
[0006]
When the sandwich molding is performed, the skin resin is supplied from the sub-injection device 72, passes through the second port 68 and the second flow path 66 in order, and is injected into the mold 10 from the discharge port 63. On the other hand, the core resin is supplied from the main injection device 71, passes through the first port 67, the through hole 69, the first flow path 65, and the discharge port 64 in order, and is injected into the mold 10 from the discharge port 63.
[0007]
(Problems with conventional injection molding machine nozzles)
When sandwich molding is performed using a conventional nozzle, when the melting temperatures of the resin for the core and the resin for the skin are significantly different, the following problem occurs. That is, the temperature of the flow path from the main injection device 71 to the first port 67 and the flow path from the sub injection device 72 to the second port 68 can be individually controlled according to the type of resin. . However, regarding the heating of the nozzle portion, there is no practical method other than attaching a heater to the outer periphery of the nozzle body 60, so that the first flow path 65 and the second flow path 66 cannot be controlled at different temperatures. Was.
[0008]
[Problems to be solved by the invention]
The present invention has been made in order to solve the problems with the conventional nozzle for sandwich molding as described above, and an object of the present invention is to use a resin for skin and a resin for core whose melting temperatures are significantly different. It is an object of the present invention to provide a sandwich molding nozzle capable of individually controlling the temperatures of these two resins when performing sandwich molding.
[0009]
[Means for Solving the Problems]
The injection molding machine nozzle of the present invention,
An inner nozzle having an opening at the front end, a first port at the rear end, and a first flow path connecting the opening and the first port formed therein,
A discharge port connected to the front of the inner nozzle and connected to the mold at the tip, a cavity in which the first half of the inner nozzle is housed, and a second part connected to the cavity near the rear end. An outer nozzle comprising a port, forming an annular second flow path connecting the discharge port and the second port between the inner peripheral surface of the hollow portion and the outer peripheral surface of the inner nozzle,
A first heater attached around the rear half of the inner nozzle exposed behind the outer nozzle,
A second heater mounted around the outer nozzle,
A first supply path for leading a first molten resin to the first port,
A second supply path for guiding a second molten resin to the second port,
It is characterized by having.
[0010]
According to the nozzle for an injection molding machine of the present invention, a first molten resin (for example, a resin for a core) is introduced into an inner nozzle through a first supply path and a first port, and is provided with a first flow path and the opening. Through the part, it is injected into the mold from the discharge port. On the other hand, the second molten resin (for example, skin resin) is introduced into the outer nozzle via the second supply path and the second port, and is formed into an annular shape formed between the outer nozzle and the inner nozzle. The liquid is injected into the mold from the discharge port through the second flow path. By appropriately adjusting the timing of supplying the first molten resin and the second molten resin, sandwich molding can be performed.
[0011]
By appropriately adjusting the supply timing of each molten resin, the resin for the skin is passed through the first flow path and the resin for the core is passed through the second flow path in the mold, as opposed to the above example. Can also be injected.
[0012]
According to the injection molding machine nozzle of the present invention, the type of the molten resin to be injected into the mold can be switched by controlling the injection operation of the first molten resin and the second molten resin, The internal structure of the nozzle body can be simplified as compared with a conventional nozzle.
[0013]
Furthermore, according to the nozzle for an injection molding machine of the present invention, since the rear half of the inner nozzle is exposed behind the outer nozzle, a heater (first heater) can be easily attached around this part. Therefore, by individually controlling the outputs of the first heater and the second heater attached around the outer nozzle, the temperatures of the first molten resin and the second molten resin can be individually controlled. Therefore, it is possible to perform sandwich molding using a combination of a resin for the skin and a resin for the core having greatly different melting temperatures. For example, it is possible to use a heat-resistant embra having a high melting temperature for the skin resin and to use POM or PVC having poor thermal stability for the core resin, thereby greatly expanding the application range of the sandwich molding.
[0014]
Preferably, the inner nozzle is made of a material having a higher thermal conductivity than the outer nozzle.
[0015]
Since the inner nozzle has a first heater mounted around the latter half thereof, in order to ensure controllability of the temperature with respect to the first molten resin, as described above, the inner nozzle is connected to the outer nozzle. It is preferable to use a material having a higher heat conductivity than that of the material.
[0016]
For example, when the outer nozzle is made of carbon steel or alloy steel, the inner nozzle is made of copper, a copper alloy, an aluminum alloy, or the like.
[0017]
Preferably, a heat pipe is embedded inside the inner nozzle along the first flow path.
[0018]
In this way, by embedding the heat pipe inside the inner nozzle, the heat generated by the first heater attached around the latter half can be efficiently transmitted to the tip side of the inner nozzle. .
[0019]
In order to enhance the controllability of the temperature of the molten resin, the inner nozzle may be provided with a cooling means such as a cooling jacket or a cooling internal flow path in addition to the first heater.
[0020]
Similarly, in order to enhance the controllability of the temperature with respect to the molten resin, the outer nozzle may be provided with a cooling means such as a cooling jacket or a cooling internal flow path in addition to the second heater.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an example of a nozzle for an injection molding machine according to the present invention.
[0022]
In the figure, 11 is an inner nozzle, 12 is an outer nozzle, 13 is a discharge port, 14 is an opening, 15 is a first flow path, 16 is a second flow path, 17 is a first port, 18 is a second port, 21 is The first heater, 22 indicates a second heater, 31 indicates a first supply path, and 42 indicates a second supply path.
[0023]
This injection molding nozzle includes an outer nozzle 12, an inner nozzle 11, a first connection block 30, and a second connection block 40.
[0024]
A discharge port 13 is provided at a tip of the outer nozzle 12. The tip of the outer nozzle 12 is connected to a gate provided on the back of a mold (not shown). Behind the outer nozzle 12, the inner nozzle 11 is connected. Inside the outer nozzle 12, a hollow portion is formed in a cylindrical shape from the rear end face, and the front half of the inner nozzle 11 is fitted into the hollow portion. The latter part of the inner nozzle 11 is a part whose diameter is enlarged like a flange, and this latter part is exposed to the rear of the outer nozzle 12.
[0025]
At the center of the inner nozzle 11, a through hole 15 (hereinafter, referred to as a first flow path) is formed in the axial direction. An annular flow path 16 (hereinafter, referred to as a second flow path) is formed between the outer peripheral surface of the inner nozzle 11 and the inner peripheral surface of the hollow portion of the outer nozzle 12. The first flow path 15 and the second flow path 16 are connected to the discharge port 13 after merging in front of the inner nozzle 11.
[0026]
A first port 17 for introducing the first molten resin is provided on a rear end surface of the inner nozzle 11. The first port 17 is connected to the discharge port 13 via the first channel 15 and the opening 14. A second port 18 for introducing the second molten resin is provided on a side surface near the rear end of the outer nozzle 12. The second port 18 is connected to the discharge port 13 via the second flow path 16.
[0027]
A first heater 21 is attached to the outer periphery of the rear half of the inner nozzle 11. A second heater 22 is attached to the outer periphery of the outer nozzle 12.
[0028]
The inner nozzle 11 is connected to the main injection device 51 via the first connection block 30 at the rear end face. A first supply path 31 is formed inside the first connection block 30. The first supply path 31 is connected to the main injection device 51 on the upstream side, and is connected to the first port 17 on the downstream side. Around the first connection block 30, a heater 36 for temperature adjustment is attached.
[0029]
Similarly, the outer nozzle 12 is connected to the sub-injection device 52 via the second connection block 40 on the side surface near the rear end. A second supply path 42 is formed inside the second connection block 40. The second supply path 42 is connected to the sub injection device 52 on the upstream side and to the second port 18 on the downstream side. A heater 46 for temperature adjustment is also mounted around the second connection block 40.
[0030]
Switching the type of the molten resin injected through the discharge port 13 between the first molten resin and the second molten resin by controlling the injection operation of the first molten resin and the second molten resin. Can be. Further, two kinds of resins can be simultaneously injected through the discharge port 13.
[0031]
When performing the sandwich molding, usually, the skin resin is supplied from the sub-injection device 52, passes through the second supply path 42, the second port 18, and the second flow path 16 in order, and enters the mold from the discharge port 13. Injected. On the other hand, the core resin is supplied from the main injection device 51, and is sequentially injected through the first supply path 31, the first port 17, and the first flow path 15 into the mold from the discharge port 13.
[0032]
According to the nozzle having the above structure, the temperature of the molten resin (first molten resin) flowing in the first flow path 15 is controlled by controlling the temperature of the inner nozzle 11 using the first heater 21. Can be controlled. Similarly, by controlling the temperature of the outer nozzle 12 using the second heater 22, the temperature of the molten resin (second molten resin) flowing in the second flow path 16 can be controlled. As described above, since the temperatures of the first molten resin and the second molten resin can be individually controlled, the sandwich molding is performed using a combination of the resin for the skin and the resin for the core having greatly different melting temperatures. be able to.
[0033]
If a cooling jacket is attached to the inner nozzle 11 in addition to the first heater (or if an internal cooling passage is provided), more accurate temperature control of the inner nozzle 11 becomes possible. Similarly, if a cooling jacket is attached to the outer nozzle 12 in addition to the second heater (or if an internal cooling passage is provided), more accurate temperature control of the outer nozzle 12 can be performed. . In particular, when molding a resin that is easily decomposed, a rapid cooling operation for preventing decomposition can be performed.
[0034]
When carbon steel or alloy steel is used as a material of the outer nozzle 12, the first connection block 30, and the second connection block 40, the inner nozzle 11 has a thermal conductivity of beryllium copper, an aluminum alloy, or the like. When a high material is used, the controllability of the temperature of the molten resin flowing in the first flow path 15 can be improved.
[0035]
(Example 2)
FIG. 2 shows another example of a nozzle for an injection molding machine according to the present invention.
[0036]
In this example, a heat pipe 25 is embedded along the first flow path 15 inside the rear half of the inner nozzle 11. Other configurations are the same as those shown in FIG.
[0037]
By burying the heat pipe 25 inside the inner nozzle 11 in this manner, the heat generated by the first heater 21 attached to the rear half of the inner nozzle 11 can be efficiently transmitted to the tip side of the inner nozzle 11. Can be.
[0038]
(Example 3)
FIG. 3 shows still another example of a nozzle for an injection molding machine according to the present invention.
[0039]
In this example, the shapes of the inner nozzle 11 and the outer nozzle 12 are changed from the example shown in FIG. 1 (FIG. 1). It is modified to be a flow path. Therefore, in the embodiment of FIG. 1, while the first molten resin supplied from the main injection device 51 flows inside and the second molten resin supplied from the sub-injection device 52 flows outside, In the embodiment shown in FIG. 3, the first molten resin supplied from the main injection device 51 flows outside, and the second molten resin supplied from the sub-injection device 52 flows inside.
[0040]
【The invention's effect】
According to the injection molding machine nozzle of the present invention, by individually controlling the output of the first heater attached to the inner nozzle and the second heater attached to the outer nozzle, the first molten resin and the second The temperature of the molten resin can be individually controlled. Therefore, it is possible to perform sandwich molding using a combination of a resin for the skin and a resin for the core having greatly different melting temperatures.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a nozzle for an injection molding machine according to the present invention.
FIG. 2 is a view showing another example of a nozzle for an injection molding machine according to the present invention.
FIG. 3 is a view showing another example of a nozzle for an injection molding machine according to the present invention.
FIG. 4 is a view showing an example of a conventional nozzle for an injection molding machine for sandwich molding.
[Explanation of symbols]
10 ... mold,
10a ... gate,
11 ... inner nozzle,
12 ・ ・ ・ Outer nozzle,
13, 63, 64 ... discharge port,
14 ... opening,
15, 65 ... first flow path,
16, 66 ... second flow path,
17, 67 ... first port,
18, 68 ... second port,
21 ... first heater,
22 ... second heater,
25 ... heat pipe,
30 first connection block,
31 ... first supply path,
36, 46 ... heater,
40 ... second connecting block,
42 ... second supply path,
51, 71 ... main injection device,
52, 72 ... sub-injection device,
60 ... nozzle body,
61 ... first needle valve,
62 ... second needle valve,
69 ... through-hole.

Claims (9)

An inner nozzle having an opening at the front end, a first port at the rear end, and a first flow path connecting the opening and the first port formed therein,
A discharge port connected to the front of the inner nozzle and connected to the mold at the tip, a cavity in which the first half of the inner nozzle is housed, and a second part connected to the cavity near the rear end. An outer nozzle comprising a port, forming an annular second flow path connecting the discharge port and the second port between the inner peripheral surface of the hollow portion and the outer peripheral surface of the inner nozzle,
A first heater attached around the rear half of the inner nozzle exposed behind the outer nozzle,
A second heater mounted around the outer nozzle,
A first supply path for leading a first molten resin to the first port,
A second supply path for guiding a second molten resin to the second port,
A nozzle for an injection molding machine, comprising: The nozzle for an injection molding machine according to claim 1, wherein the inner nozzle is made of a material having a higher thermal conductivity than the outer nozzle. The outer nozzle is made of carbon steel or alloy steel,
The nozzle for an injection molding machine according to claim 2, wherein the inner nozzle is made of one of copper, a copper alloy, and an aluminum alloy. The nozzle for an injection molding machine according to claim 1, wherein a heat pipe is embedded inside the inner nozzle along the first flow path. The nozzle for an injection molding machine according to claim 1, wherein a cooling unit is provided in the inner nozzle in addition to the first heater. The nozzle for an injection molding machine according to claim 1, wherein a cooling unit is provided in the outer nozzle in addition to the second heater. An injection molding machine comprising the nozzle for an injection molding machine according to any one of claims 1 to 6. A surface layer portion is formed of a resin for the skin, the inside of which is a sandwich molding method for manufacturing an injection molded article formed of the resin for the core,
An inner nozzle having an opening at the front end, a first port at the rear end, and a first flow path connecting the opening and the first port formed therein,
A discharge port connected to the front of the inner nozzle and connected to the mold at the tip, a cavity in which the first half of the inner nozzle is housed, and a second part connected to the cavity near the rear end. An outer nozzle comprising a port, forming an annular second flow path connecting the discharge port and the second port between the inner peripheral surface of the hollow portion and the outer peripheral surface of the inner nozzle,
A first heater attached around the rear half of the inner nozzle exposed behind the outer nozzle,
A second heater mounted around the outer nozzle,
A first supply path for leading a first molten resin to the first port,
A second supply path for guiding a second molten resin to the second port,
Using a nozzle for an injection molding machine equipped with
Core resin is introduced into the mold via the first supply path and the first flow path,
A sandwich molding method, wherein a skin resin is introduced into a mold via the second supply path and the second flow path. A surface layer portion is formed of a resin for the skin, the inside of which is a sandwich molding method for manufacturing an injection molded article formed of the resin for the core,
An inner nozzle having an opening at the front end, a first port at the rear end, and a first flow path connecting the opening and the first port formed therein,
A discharge port connected to the front of the inner nozzle and connected to the mold at the tip, a cavity in which the first half of the inner nozzle is housed, and a second part connected to the cavity near the rear end. An outer nozzle comprising a port, forming an annular second flow path connecting the discharge port and the second port between the inner peripheral surface of the hollow portion and the outer peripheral surface of the inner nozzle,
A first heater attached around the rear half of the inner nozzle exposed behind the outer nozzle,
A second heater mounted around the outer nozzle,
A first supply path for leading a first molten resin to the first port,
A second supply path for guiding a second molten resin to the second port,
Using a nozzle for an injection molding machine equipped with
Introducing the skin resin into the mold through the first supply path and the first flow path, and introducing the core resin into the mold through the second supply path and the second flow path. Characteristic sandwich molding method.

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