JP2002347074A - Injection nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably perform molding by sufficiently suppressing the generation of stringing, sagging or the like. SOLUTION: The injection nozzle has the cylindrical main body 50 arranged to the front end of a heating cylinder and is equipped with a resin flow channel 50a and the nozzle heater 13 arranged to the outer periphery of the main body 50 to heat the resin in the resin flow channel 50a. A plurality of heat conduction preventing means are formed to the front end of the main body 50 so as to leave a predetermined interval in an axial direction. In this case, since a plurality of the heat conduction preventing means are formed so as to leave the predetermined interval in the axial direction, the heat transmitted to the main body 50 from the nozzle heater 13 is transmitted to the resin in the resin flow channel 50a in large quantities, and the quantity of heat transmitted to a fixed mold 15 is reduced. The viscosity of the resin at the front end of the injection nozzle 11 can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection nozzle.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is injected, filled into a cavity space of a mold apparatus, and cooled in the cavity space. A molded product is obtained by solidification.

For this purpose, the injection molding machine has a mold clamping device and an injection device, and the mold clamping device includes a fixed platen and a movable platen, and the movable platen is moved forward and backward by a mold clamping cylinder to form a mold device. Close, close and open the mold. The mold apparatus includes a fixed mold and a movable mold, and a cavity space is formed between the fixed mold and the movable mold as the mold is closed.

On the other hand, the injection device includes a heating cylinder for heating and melting the resin supplied from the hopper, and an injection nozzle for injecting the melted resin, wherein a screw is rotatable in the heating cylinder. And it is arranged so that it can move forward and backward. Then, the resin is injected from the injection nozzle by advancing the screw by the drive source, and is rotated by the drive source, and is then retracted to measure the resin.

Next, the injection nozzle will be described.

FIG. 2 is a sectional view of a conventional injection nozzle.

In FIG. 1, reference numeral 11 denotes a cylindrical injection nozzle. The injection nozzle 11 has a cylindrical main body 5 having a resin flow path 50a opened at a front end (left end in the figure).
0, and a nozzle heater 13 disposed on the outer periphery of the main body 50. By energizing the nozzle heater 13, a resin (not shown) in the resin flow path 50a can be heated. The injection nozzle 11 is attached to a front end of a heating cylinder (not shown), and a resin flow path in the heating cylinder communicates with the resin flow path 50a.

In the injection step, the injection nozzle 11 is pressed against a fixed mold 15 of a mold apparatus, and when a screw in the heating cylinder is advanced by driving a drive source (not shown), the injection nozzle 11 is stored in front of the screw. Resin is injected from the injection nozzle 11 and the fixed mold 1
The cavity is filled with a sprue 16 formed in the cavity 5.

Thereafter, when the mold device is cooled, the resin filled in the cavity space is cooled and solidified to form a molded product, and the mold device is opened to remove the molded product. It is. Further, with the cooling of the mold apparatus, the resin in the sprue 16 and the resin in the reverse tapered portion 20 are solidified integrally with the molded product to form a sprue portion. The sprue portion is taken out together with the molded product when the mold opening is performed.

A tapered portion 19 and a reverse tapered portion 20 are formed at the front end (left end in the figure) of the resin flow path 50a, and the boundary between the tapered portion 19 and the reverse tapered portion 20 has the smallest diameter. A separation point Q1 is formed. Therefore, when the sprue portion is taken out together with the molded product, it is cut at the separation point Q1. Since the diameter of the reverse tapered portion 20 decreases as the distance from the nozzle hole 51 to the separation point Q1 decreases, the sprue portion has a shape that can be easily removed from the fixed mold 15 and the injection nozzle 11.

Next, the temperature distribution of the injection nozzle 11 will be described.

FIG. 3 is a temperature distribution diagram of a conventional injection nozzle. In the figure, the horizontal axis indicates the injection nozzle 11 (FIG. 2).
, The temperature in the resin flow path 50a is plotted on the vertical axis. A nozzle heater 13 is provided at a predetermined distance from the front end of the injection nozzle 11.

When the front end of the injection nozzle 11 is brought into contact with the fixed mold 15 with a predetermined nozzle touch force, as shown in the figure, the temperature of the resin is set at the contact portion where the injection nozzle 11 and the fixed mold 15 are in contact. O is θ1 and becomes higher as the distance from the contact portion O increases.

When a resin having a low viscosity in the molten state is used, or when it is necessary to increase the diameter of the nozzle hole 51 at the front end of the injection nozzle 11, the heating cylinder is retracted in the measuring step. If the injection nozzle 11 is separated from the fixed die 15, stringing, drooling, etc. may occur at the front end of the injection nozzle 11.

Therefore, in order to suppress the occurrence of stringing, dripping of the nose, and the like, a mechanical valve such as a needle valve or a rotary valve is disposed in the injection nozzle 11, and when the heating cylinder is retracted, a mechanical valve is used. An injection nozzle with a closed valve is provided. However, in this case, as the mechanical valve is closed, the resin stays and the deteriorated resin is mixed into the molded product, thereby deteriorating the quality of the molded product. Further, when the heating cylinder is retracted with the mechanical valve closed, the sprue portion and the melted resin cannot be stably separated at a certain place, and the melted resin is melted from the inside of the injection nozzle 11. The discharged resin is drawn out to the sprue 16 side, or solidified resin is left inside the injection nozzle 11.

Therefore, an injection nozzle in which an adiabatic slit is formed near the front end of the injection nozzle 11 is conceivable.

FIG. 4 is a sectional view of another conventional injection nozzle, and FIG. 5 is a temperature distribution diagram of another conventional injection nozzle. In addition,
In FIG. 5, the horizontal axis represents the position of the injection nozzle 11 in the axial direction, and the vertical axis represents the temperature of the resin in the resin flow path 50a.

In this case, an annular heat insulating slit 61 is formed at a portion corresponding to the separation point Q1 on the outer periphery of the main body 50. The heat insulating slit 61 is formed of an annular groove formed at a predetermined depth from the outer peripheral surface of the main body 50,
To the front (left in FIG. 4).

When the front end (the left end in FIG. 4) of the injection nozzle 11 is brought into contact with the fixed mold 15 with a predetermined nozzle touch force, as shown in FIG.
It is θ1 at a contact portion O where the injection nozzle 11 and the fixed mold 15 are in contact, and becomes higher as the distance from the contact portion O increases,
It rises discontinuously at the position where the adiabatic slit 61 is formed, that is, at the slit position S1, and further increases as the distance from the slit position S1 increases.

That is, since the heat insulating slit 61 is formed in the main body 50 at the slit position S1, most of the heat transmitted from the nozzle heater 13 to the main body 50 is transmitted to the resin in the resin flow path 50a and fixed. The amount of heat transferred to the mold 15 is reduced. Therefore, the temperature of the resin between the contact portion O and the slit position S1 can be lowered, so that the viscosity of the resin at the front end of the injection nozzle 11 can be increased. As a result, stringing, drooling, and the like can be suppressed.

Incidentally, 16 is a sprue, 19 is a tapered portion,
Reference numeral 20 denotes an inverted tapered portion, and reference numeral 51 denotes a nozzle hole.

[0022]

However, in the above-mentioned conventional injection nozzle, a resin having a low viscosity in a molten state, for example, polyamide (PA), polybutylene terephthalate (PBT), liquid crystal polymer (LCP), etc. When a resin is used, stringing, drooling, and the like cannot be sufficiently suppressed.

The present invention solves the above-described problems of the conventional injection nozzle, and can sufficiently suppress the occurrence of stringing, drooling, and the like, and provide an injection nozzle capable of performing stable molding. The purpose is to provide.

[0024]

For this purpose, in the injection nozzle of the present invention, the injection nozzle is disposed at the front end of the heating cylinder,
It has a cylindrical main body having a resin flow path opened at the front end, and a nozzle heater disposed on the outer periphery of the main body and heating the resin in the resin flow path.

At the front end of the main body, a plurality of heat conduction preventing means are formed at predetermined intervals in the axial direction.

In another injection nozzle of the present invention, a tapered portion and a reverse tapered portion are formed at the front end of the resin flow path.

The heat conduction preventing means is formed forward and rearward of a boundary between the tapered portion and the reverse tapered portion.

In still another injection nozzle of the present invention,
Further, each of the heat conduction preventing means is a heat insulating slit formed at a predetermined depth from the outer peripheral surface of the main body.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of an injection nozzle according to a first embodiment of the present invention, FIG. 6 is a schematic view of an injection device according to the first embodiment of the present invention, and FIG. FIG. 4 is a temperature distribution diagram of an injection nozzle in the embodiment. In addition,
7, the horizontal axis represents the position of the injection nozzle 11 in the axial direction, and the vertical axis represents the temperature of the resin in the resin flow path 50a.

In FIG. 6, reference numeral 12 denotes a heating cylinder as a cylinder member. An injection nozzle 11 is attached to a front end (left end in FIG. 6) of the heating cylinder 12, and a nozzle heater 13 is provided on an outer periphery of the injection nozzle 11. Will be arranged. In the heating cylinder 12, a screw 22 as an injection member is disposed rotatably and freely retractable.

The screw 22 has a screw head 25 at the front end, extends rearward (rightward in FIG. 6) inside the heating cylinder 12, and has a drive source (not shown) at the rear end (right end in FIG. 6). Be linked. A spiral (helical) flight 23 is formed on the outer periphery of the screw 22, and the flight 23 forms a groove 26.
Is formed.

A resin supply port 29 is formed at a predetermined position of the heating cylinder 12, and a hopper 30 is fixed to the resin supply port 29. The resin supply port 29 is located at a position corresponding to the rear end (the right end in FIG. 6) of the groove 26 when the screw 22 is located at the forefront (left side in FIG. 6) inside the heating cylinder 12. Formed.

In the measuring step, when the screw 22 is rotated by driving the drive source, the resin 33 in the hopper 30 falls, enters the heating cylinder 12, and advances in the heating cylinder 12 (see FIG. 6 to the left). Accordingly, the screw 22 is moved backward (moved to the right in FIG. 6).

A cylinder heater (not shown) is provided on the outer periphery of the heating cylinder 12 so that the heating cylinder 12 can be heated by the cylinder heater and the resin in the heating cylinder 12 can be melted. Has become. Therefore, when the screw 22 is retracted by a predetermined amount as the screw 22 is rotated, one shot of the melted resin is stored in front of the screw head 25.

Next, in the injection step, when the drive source is driven to advance the screw 22 without rotating, the resin stored in front of the screw head 25 is injected from the injection nozzle 11, It is filled into a cavity space (not shown) of the mold apparatus.

Next, the injection nozzle 11 will be described.

In FIG. 1, reference numeral 11 denotes a cylindrical injection nozzle, and the injection nozzle 11 has a front end (left end in FIG. 1).
A main body 50 having a resin flow path 50a opened at the front end thereof and having a nozzle hole 51 formed at a front end thereof;
Has a nozzle heater 13 disposed at a predetermined distance from the front end of the injection nozzle 11. When the nozzle heater 13 is energized, the resin flow path 50a
The resin inside can be heated. Then, the resin flow path in the heating cylinder 12 and the resin flow path 50a are communicated.

A tapered portion 19 and a reverse tapered portion 20 are formed at the front end (the left end in FIG. 1) of the resin flow path 50a. A small separation point Q1 is formed. The separation point Q1 represents a point that is cut when the sprue portion is taken out together with the molded product. Since the diameter of the reverse tapered portion 20 decreases as the distance from the nozzle hole 51 to the separation point Q1 decreases, the sprue portion has a shape that can be easily removed from the fixed mold 15 and the injection nozzle 11.

Further, a point on the outer periphery of the main body 50 slightly ahead of the portion corresponding to the separation point Q1 (left side in FIG. 1) and slightly behind the portion corresponding to the separation point Q1 (right side in FIG. 1). In this regard, in the present embodiment, a plurality of first and second heat insulating slits 62 and 63 as two heat conduction preventing means are formed at predetermined intervals in the axial direction. The first and second heat insulating slits 62, 6
3 is a predetermined depth d1 from the outer peripheral surface of the main body 50,
It consists of an annular groove formed by d2 (d1> d2), and prevents heat from being conducted from the rear to the front.

When the front end of the injection nozzle 11 is brought into contact with the fixed mold 15 with a predetermined nozzle touch force, as shown in FIG. It is θ1 at the contact portion O that makes contact, and becomes higher as the distance from the contact portion O increases.
2 rises discontinuously at the position where the slit 2 is formed, that is, at the slit position S1, becomes higher as the distance from the slit position S1, and becomes discontinuous again at the position where the second heat insulating slit 63 is formed, ie, the slit position S2. And rises further away from the slit position S2.

That is, at the slit positions S1 and S2, the first and second heat insulating slits 62 and 6 are formed in the main body 50.
3 is formed, the nozzle heater 13 is moved to the main body 50.
Most of the heat transmitted to the resin flow path 50a is transmitted to the resin in the resin flow path 50a, and the amount of heat transmitted to the fixed mold 15 is reduced.
Therefore, the temperature of the resin between the contact portion O and the slit position S1 can be lowered, so that the viscosity of the resin at the front end of the injection nozzle 11 can be increased. As a result, stringing, drooling, and the like can be suppressed.

Even when a resin having a low viscosity in a molten state, for example, a resin such as polyamide, polybutylene terephthalate, or liquid crystal polymer, is used, it is possible to sufficiently suppress the occurrence of stringing, drooling, and the like. Molding can be performed stably.

The first and second heat insulating slits 62, 6
3 are formed adjacent to each other with the separation point Q1 interposed therebetween, so that the amount of heat flowing from the injection nozzle 11 to the mold apparatus, the amount of heat flowing from the nozzle heater 13 to the main body 50,
Of the separation point Q even if the set temperature of the
The change in the temperature gradient (gradient) around 1 can be reduced.

As a result, even when a resin having a low viscosity in a molten state, for example, a resin such as polyamide, polybutylene terephthalate, or liquid crystal polymer is used, stringing, drooling, and the like are more sufficiently suppressed. And molding can be performed more stably.

Next, a second embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol.

FIG. 8 is a sectional view of an injection nozzle according to the second embodiment of the present invention, and FIG. 9 is a temperature distribution diagram of the injection nozzle according to the second embodiment of the present invention. In FIG. 9, the horizontal axis represents the position of the injection nozzle 11 in the axial direction, and the vertical axis represents the temperature of the resin in the resin flow path 50a.

In this case, in the present embodiment, the first and second heat insulating slits 62 and 64 as the two heat conduction preventing means are respectively provided at predetermined depths d1 and d1 from the outer peripheral surface of the main body 50. d3 (d1 = d3), formed from an annular groove, from the rear (right side in FIG. 8) to the front (FIG. 8).
To the left). Therefore, the diameter a of the inner peripheral edge of the first heat insulating slit 62 and the diameter b of the inner peripheral edge of the second heat insulating slit 64 are made equal.

When the front end (the left end in FIG. 8) of the injection nozzle 11 is brought into contact with the fixed mold 15 with a predetermined nozzle touch force, as shown in FIG.
It is θ1 at a contact portion O where the injection nozzle 11 and the fixed mold 15 are in contact, and becomes higher as the distance from the contact portion O increases,
It rises discontinuously at the slit position S1, takes substantially the same value from the slit position S1 to the position where the second adiabatic slit 64 is formed, that is, the slit position S2, and again discontinuously at the slit position S2. It rises and becomes even higher as the distance from the slit position S2 increases. The temperature gradient between the slit positions S1 and S2 changes as the diameter b changes, and becomes smaller as the diameter b takes a value closer to the diameter a.

In this case, since the diameters a and b are equalized, the amount of heat flowing from the nozzle heater 13 into the main body 50 is reduced.
When the set temperature of the injection nozzle 11 changes, the change in the temperature gradient around the separation point Q1 can be further reduced.

As a result, even when a resin having a low viscosity in a molten state, for example, a resin such as polyamide, polybutylene terephthalate, or liquid crystal polymer is used, stringing, nasal dripping and the like are more sufficiently suppressed. And molding can be performed more stably.

Next, a third embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol.

FIG. 10 is a sectional view of an injection nozzle according to the third embodiment of the present invention, and FIG. 11 is a temperature distribution diagram of the injection nozzle according to the third embodiment of the present invention. In FIG. 11, the horizontal axis represents the position of the injection nozzle 11 in the axial direction, and the vertical axis represents the temperature of the resin in the resin flow path 50a.

In this case, a point on the outer periphery of the main body 50 slightly ahead of the portion corresponding to the separation point Q1 (left side in FIG. 10) and slightly behind the portion corresponding to the separation point Q1 (right side in FIG. 10). ), A plurality of first and second heat insulating slits 62 and 63 as heat conduction preventing means are formed, and a point slightly behind the point at which the second heat insulating slit 63 is formed. Third as blocking means
Is formed.

The first to third heat insulating slits 6
Reference numerals 2, 63, and 65 each comprise an annular groove formed at a predetermined depth d1, d2, and d4 (d1>d2> d4) from the outer peripheral surface of the main body 50, and heat is conducted from the rear to the front. To block.

An annular heater 66 is buried in the outer periphery of the sprue 16 in the fixed mold 15, and when the heater 66 is energized, the resin in the sprue 16 is heated.

When the front end (the left end in FIG. 10) of the injection nozzle 11 is brought into contact with the fixed mold 15 with a predetermined nozzle touch force, as shown in FIG. It is θ1 at the contact portion O where the fixed mold 15 contacts, becomes higher as the distance from the contact portion O increases, and rises discontinuously at the slit position S1,
The distance increases further away from the slit position S1, rises discontinuously again at the slit position S2, and further increases away from the slit position S2.
Rises discontinuously again at the position where the heat insulating slit 65 is formed, that is, at the slit position S3, and further increases as the distance from the slit position S3 increases.

In this case, the third heat insulating slit 6 is provided at a point slightly behind the point where the second heat insulating slit 63 is formed.
5 is formed, the nozzle heater 13 is moved to the main body 50.
When the amount of heat flowing into the nozzle, the set temperature of the injection nozzle 11, and the like change, the change in the temperature gradient around the separation point Q1 can be further reduced.

Further, since the heater 66 is provided in the fixed mold 15, a change in the temperature gradient around the separation point Q1 when the temperature of the mold apparatus changes can be further reduced.

As a result, even when a resin having a low viscosity in a molten state, for example, a resin such as polyamide, polybutylene terephthalate, or liquid crystal polymer is used, stringing, drooling, and the like are more sufficiently suppressed. And molding can be performed more stably.

In each of the above embodiments, a heat insulating slit is formed as a heat conduction preventing means, but an annular heat insulating material may be embedded instead of the heat insulating slit.

The present invention is not limited to the above embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0063]

As described above in detail, according to the present invention, in the injection nozzle, a cylindrical main body having a resin flow path which is disposed at the front end of the heating cylinder and is open at the front end is provided. A nozzle heater disposed on the outer periphery of the main body for heating the resin in the resin flow path;

Further, a plurality of heat conduction preventing means are formed at predetermined intervals in the axial direction at the front end of the main body.

In this case, since a plurality of heat conduction preventing means are formed at predetermined intervals in the axial direction, most of the heat transmitted from the nozzle heater to the main body is transmitted to the resin in the resin flow path. The amount of heat transferred to the stationary mold is reduced. Therefore, since the temperature of the resin between the contact portion between the injection nozzle and the fixed mold and the position where the heat conduction preventing means is formed can be reduced, the viscosity of the resin at the front end of the injection nozzle can be increased. Can be. As a result, stringing, drooling, and the like can be suppressed.

Since a plurality of heat conduction preventing means are formed, the amount of heat flowing out of the injection nozzle to the mold apparatus, the amount of heat flowing from the nozzle heater to the main body, the set temperature of the injection nozzle, the mold temperature, Even if the temperature or the like of the apparatus changes, the change in the temperature gradient around the separation point corresponding to the point where the sprue portion is cut when the sprue portion is taken out together with the molded product can be reduced.

As a result, even when a resin having a low viscosity in a molten state, for example, a resin such as polyamide, polybutylene terephthalate, or liquid crystal polymer is used, stringing, drooling, and the like are suppressed more sufficiently. And molding can be performed more stably.

[Brief description of the drawings]

FIG. 1 is a sectional view of an injection nozzle according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a conventional injection nozzle.

FIG. 3 is a temperature distribution diagram of a conventional injection nozzle.

FIG. 4 is a cross-sectional view of another conventional injection nozzle.

FIG. 5 is a temperature distribution diagram of another conventional injection nozzle.

FIG. 6 is a schematic diagram of an injection device according to the first embodiment of the present invention.

FIG. 7 is a temperature distribution diagram of an injection nozzle according to the first embodiment of the present invention.

FIG. 8 is a sectional view of an injection nozzle according to a second embodiment of the present invention.

FIG. 9 is a temperature distribution diagram of an injection nozzle according to a second embodiment of the present invention.

FIG. 10 is a sectional view of an injection nozzle according to a third embodiment of the present invention.

FIG. 11 is a temperature distribution diagram of an injection nozzle according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Injection nozzle 12 Heating cylinder 13 Nozzle heater 19 Taper part 20 Reverse taper part 33 Resin 50 Main body 50a Resin channel 62 First heat insulating slit 63, 64 Second heat insulating slit 65 Third heat insulating slit

Claims (3)

[Claims] 1. (a) disposed at a front end of a heating cylinder;
A cylindrical main body having a resin flow path opened at a front end thereof, and (b) a nozzle heater disposed on an outer periphery of the main body and heating a resin in the resin flow path,
(C) An injection nozzle, wherein a plurality of heat conduction preventing means are formed at predetermined intervals in an axial direction at a front end of the main body. (A) a tapered portion and a reverse tapered portion are formed at a front end of the resin flow path; and (b) the heat conduction preventing means is located forward of a boundary between the tapered portion and the reverse tapered portion. The injection nozzle according to claim 1, wherein the injection nozzle is formed rearward. 3. The injection nozzle according to claim 1, wherein each of the heat conduction preventing means is an adiabatic slit formed at a predetermined depth from an outer peripheral surface of the main body.