JP3312014B2 - Injection device and injection nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine for molding a molded product by injecting a molding material such as a resin or glass, a molding material heated and melted in a heating cylinder is injected at a high pressure to form a mold. Filling cavity space inside
Then, it is cooled and solidified in the cavity space to form a molded product.

[0003] The injection molding machine has a mold, a mold clamping device and an injection device. The mold includes a fixed mold unit and a movable mold unit, and the mold closing device moves the movable mold unit back and forth, thereby closing, clamping and opening the mold. Further, the injection device includes a heating cylinder and a screw rotatably and advancing and retracting in the heating cylinder. And by advancing the screw,
A molding material is injected from an injection nozzle formed at the front end of the heating cylinder, and is filled in a cavity space in a mold.

[0004] The injection device moves the injection nozzle forward and backward by driving a drive source, and connects a nozzle port formed at the front end of the injection nozzle to a molding material inflow port of a fixed platen of the fixed mold unit. Can be separated.
The filling of the molding material is performed in a state where the nozzle port is in contact with the molding material inflow port.

FIG. 2 is a view for explaining the stringing phenomenon of a molding material in the first conventional injection device.

In the drawing, reference numeral 11 denotes an injection nozzle formed at the front end of a heating cylinder, 12 denotes a heater disposed around the injection nozzle 11, and 13 denotes a front end (left end in the figure) of the injection nozzle 11. The nozzle opening, 15 is a fixed-side mold unit of the mold, and 16 is a sprue. The fixed mold unit 15 includes a fixed platen and a fixed mold attached to the fixed platen.

[0007] Then, the mold is clamped by a mold clamping device (not shown). Subsequently, when the molten molding material is injected from the injection nozzle 11, the molding material passes through the sprue 16. The cavity space (not shown) in the mold is filled. Subsequently, by cooling the mold, the molding material in the cavity space is cooled and solidified to form a molded product. The molding material remaining in the sprue 16 is similarly cooled and solidified to form the sprue portion 17.

Next, the mold is opened, and the molded product and the sprue portion 17 are retracted as the movable mold unit (not shown) is retracted. Subsequently, an ejector pin provided in the movable mold unit is advanced, and the molded product and the sprue portion 17 are pushed down and taken out.

By the way, the temperature of the injection nozzle 11 is maintained at a temperature equal to or higher than the melting point of the molding material while the mold is opened, and the molding material in the injection nozzle 11 is kept in a molten state. Therefore, as the molded product and the sprue portion 17 are retracted, a stringing phenomenon occurs, and as shown in the figure, the molten molding material in the injection nozzle 11 is pulled by the sprue portion 17, A thread-shaped molding material (hereinafter referred to as a “filament”) 18 is formed between the tip (the right end in the drawing) of the sprue portion 17 and the molding material in the injection nozzle 11. When the thread 18 becomes 10 mm or more, the thread 18 may be pinched between the movable mold unit and the fixed mold unit 15 when removing the molded product and the sprue portion 17. is there. In that case, since the mold is damaged, the mold protection device is activated, the operation of the injection molding machine is interrupted, and the molding is not performed.

Therefore, there has been provided an injection apparatus in which the temperature of the injection nozzle 11 is lowered to suppress the occurrence of the stringing phenomenon.

FIG. 3 is a longitudinal sectional view of a main part of an injection nozzle in a second conventional injection device, and FIG. 4 is a sectional view taken along line XX of FIG.

In the drawing, reference numeral 21 denotes an injection nozzle formed at the front end of a metal heating cylinder;
Nozzle port formed at the front end (left end in FIG. 3) of 1
Reference numeral 3 denotes a cooling member disposed near the front end in the injection nozzle 21. The cooling member 23 has a disk-shaped portion 26 having a circular flow path hole 25 through which molding material flows at four locations in the circumferential direction, and from the center of the disk-shaped portion 26 toward the front end of the injection nozzle 21. It has a protruding needle portion 27.
After the filling of the molding material into the cavity is completed, the cooling member 23 transfers the heat of the molding material around the cooling member 23 to the fixed mold unit 1 via the injection nozzle 21.
5 (FIG. 2).

Therefore, the molding material in the injection nozzle 21 is injected from the nozzle port 22 through the passage hole 25.
At this time, the molding material is cooled by the cooling member 23 and solidification is promoted, so that the thread 18 is easily cut. As a result, the occurrence of the stringing phenomenon can be suppressed.

[0014]

However, in the above-mentioned conventional injection apparatus, not only the pressure loss at the time of injection becomes large, but also a resin or the like that leaves an optical mark at the merging position is used as a molding material. When used, a molding defect occurs.

For example, when molding is performed using a resin having a structure in which only carbon and hydrogen are bonded to a pentagonal nucleus and each molecule is three-dimensionally arranged as a molding material, Since air is contained between the molecules, the thermal conductivity is low. Therefore, the molding material cannot be sufficiently cooled by the cooling member 23, so that the occurrence of the stringing phenomenon cannot be sufficiently suppressed. In addition, the position where the filament 18 is cut fluctuates, and the length of the filament 18 becomes unstable.

The molding material in the injection nozzle 21 is diverted once (temporarily) when passing through the flow passage hole 25, and then merged. In the molten state, the resin melts from the core to the blades. The carbon that extends is entangled with
If they are merged after being split in the cooling member 23, the resin cannot be sufficiently mixed at the joint. Therefore, streaks remain on the molded product, and the quality of the molded product is degraded. In particular, when the molded product is an optical product, for example, a lens, the optical characteristics deteriorate.

The present invention solves the above-mentioned problems of the conventional injection device, can sufficiently suppress the occurrence of the stringing phenomenon, can stabilize the length of the filament, and can mold the molded product. It is an object of the present invention to provide an injection device and an injection nozzle capable of improving the quality of a product.

[0018]

For this purpose, in the injection apparatus of the present invention, a cylinder member having an injection nozzle at a front end, an injection member disposed to be able to advance and retreat in the cylinder member, and an injection member are provided. And driving means for moving back and forth.

The nozzle opening formed at the front end of the injection nozzle has a projection formed at a predetermined position so as to protrude radially inward and to be annularly formed along the circumferential direction. .

In another injection apparatus according to the present invention, the nozzle port has a tapered portion. The protrusion is formed at a rear end of the tapered portion.

[0021]

In still another injection device of the present invention, a round portion is further formed between the tapered portion and the projection.

According to still another injection device of the present invention, there is further provided a backflow prevention device for preventing the molding material stored in front of the injection member from flowing back during the injection step, and Suckback control means for retracting the injection member by a predetermined distance.

In the injection nozzle of the present invention, the injection nozzle is arranged at the front end of the cylinder member. The nozzle port formed at the front end of the injection nozzle has a projection at a predetermined position, which protrudes radially inward and is formed annularly along the circumferential direction.

In another injection nozzle of the present invention, the nozzle port further has a tapered portion. The protrusion is formed at a rear end of the tapered portion.

[0026]

In still another injection nozzle of the present invention,
Further, a round portion is formed between the tapered portion and the projection.

[0028]

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

FIG. 5 is a schematic view of a main part of an injection molding machine according to the first embodiment of the present invention.

In the figure, reference numeral 32 denotes a heating cylinder as a cylinder member. The heating cylinder 32 has an injection nozzle 33 at a front end (left end in the figure). The injection nozzle 33 is formed separately from the main body 34 of the heating cylinder 32 and is fixed to the main body 34 by bolts or the like (not shown). Note that the injection nozzle 33 may be formed integrally with the main body 34. On the outer periphery of the main body 34, the main body 3
In order to prevent the molten molding material in the injection nozzle 33 from being solidified, a heater 35 is provided to melt the molding material such as resin and glass in the injection nozzle 33. A heater 36 is provided. A nozzle port 38 is formed at the front end of the injection nozzle 33 so as to communicate with the inside of the heating cylinder 32. In addition, 91 and 92 are temperature sensors.

In the heating cylinder 32, a screw 44 as an injection member is rotatably arranged and movable forward and backward. The screw 44 includes a flight part 45 and a screw head 46 attached to a front end of the flight part 45, and extends inside the heating cylinder 32 from the front (left in the figure) to the rear (right in the figure), At the rear end (right end in the figure), it is connected to a driving unit (not shown) as driving means. The drive unit includes, for example, a weighing motor and an injection motor.
The flight part 45 includes a screw main body 47 and a spiral flight 48 formed around the screw main body 47.
9 is formed. The injection device is constituted by the heating cylinder 32, the screw 44, the driving unit, and the like.

By the way, the mold 5 is opposed to the injection device.
1 is provided, and the injection nozzle 33 is
Are provided so as to be freely contactable and detachable. The mold 51 includes a fixed platen, a fixed mold unit 52 including a fixed mold attached to the fixed platen, a movable platen, and a movable mold including a movable mold attached to the movable platen. A sprue 54 is formed in the fixed mold unit 52, and a runner 56, a gate 57 and a cavity space 5 are provided between the fixed mold and the movable mold.
8 are formed.

The injection device is moved forward and backward by driving a driving means (not shown) different from the driving unit, and selectively takes a forward position and a backward position. Then, in the measuring step, the injection step, and the pressure holding step, the injection device is placed at the forward position, and the injection nozzle 33 comes into contact with the fixed mold unit 52 to perform nozzle touch.

Next, the operation of the injection device will be described.

First, a weighing step is started. In the weighing step, a weighing control means of a control device (not shown) drives the weighing motor to drive the screw 4.
Rotate 4. As a result, the molding material in the hopper (not shown) falls, enters the heating cylinder 32, advances (moves leftward in the drawing) in the heating cylinder 32 along the groove 49, and is heated by the heater 35. Melted. The molten molding material is stored in front of the screw 44, that is, in front of the screw head 46, and the screw 44 is retreated (moved to the right in the drawing) accordingly.

When the measuring step is completed, the suck-back control means of the control device performs suck-back. For this purpose, suckback control means stops the weighing motor and stops the screw 44 in the rotational direction,
By driving the injection motor in the reverse direction, the screw 44 is retracted by a predetermined distance. as a result,
The pressure of the molding material in front of the screw head 46 is reduced.

Subsequently, the injection control means of the control device comprises:
The injection process is started, and the screw 44 is moved forward by driving the injection motor in the forward direction. Accordingly, the molding material stored in front of the screw head 46 is injected from the injection nozzle 33, and is filled into the cavity space 58 through the sprue 54, the runner 56, and the gate 57.

Subsequently, a pressure holding step is started. In the pressure holding step, the pressure of the molding material in the cavity space 58 is maintained at a predetermined value. Then, a cooling step is started. In the cooling step, the fixed mold and the movable mold are cooled, and the molding material in the cavity space 58 is cooled and solidified to form a molded product. The molding material remaining in the sprue 54 is similarly cooled and solidified to form a sprue portion.

On the other hand, in the mold 51, before the injection step is started, the mold is closed by a mold clamping device (not shown), and the movable mold unit 53 moves forward (moves rightward in the figure). After that, the mold is clamped, and the cavity space 58 is formed between the fixed mold and the movable mold.

When the cavity space 58 is filled with a molding material and the molding material is cooled and solidified to form a molded product, the mold is opened and the movable mold unit 53 is opened.
Is moved backward (moves to the left in the drawing), the molded product and the sprue portion are moved backward. At this time, an ejector pin (not shown) provided in the movable mold unit 53 is advanced, and the molded product and the sprue portion are pushed down and taken out.

A backflow prevention device is provided to prevent the molding material stored in front of the screw head 46 from flowing backward during the injection step. The backflow prevention device,
It comprises a screw head 46, an annular check ring 64 and a seal ring 65. The screw head 46 has a conical (conical) head body 60 at a front portion (left portion in the drawing), a small diameter portion 61 at a center portion, and a screw portion (not shown) at a rear portion (right portion in the drawing). Have. The thread extends through the seal ring 65 into the screw body 47 and is screwed into a screw hole (not shown) formed in the screw body 47.

The check ring 64 is disposed on the outer periphery of the small diameter portion 61, and a first molding material flow path is formed between the small diameter portion 61 and the check ring 64. At the front end of the flight section 45, a seal ring 65 is disposed so as to be able to freely contact and separate from the rear end of the check ring 64. The dimensions of the small diameter portion 61 and the check ring 64 are set so that the check ring 64 can move relative to the screw head 46 by the seal stroke S. The check ring 64 has a non-corotating structure so as not to rotate in conjunction with rotation of the screw 44.

Therefore, when the screw 44 is rotated during the measuring step, the molding material advanced along the groove 49 passes between the check ring 64 and the seal ring 65 and then the first And is stored in front of the screw head 46 through a second molding material flow path between the head body 60 and the check ring 64. Also, when the screw 44 is advanced during the injection step, the molding material stored in front of the screw head 46 tends to flow backward and move backward.
The check ring 64 is moved rearward relative to the screw 44 by the pressure of the molding material, and the check ring 6
Since the rear end of the seal 4 contacts the seal ring 65 to perform sealing, the molding material stored in front of the screw head 46 can be prevented from flowing backward.

By the way, the temperature of the injection nozzle 33 is maintained at a temperature equal to or higher than the melting point of the molding material while the mold is opened, and the molding material in the injection nozzle 33 is kept in a molten state. Therefore, as the molded product and the sprue portion are retracted, a stringing phenomenon occurs, and the molten molding material in the injection nozzle 33 is pulled by the sprue portion. The filament 18 (see FIG. 2) is formed between the material and the molding material. When the filament 18 becomes 10 mm or more, the filament 18 may be pinched between the movable mold unit 53 and the fixed mold unit 52 when removing the molded product and the sprue portion. is there. In that case, the mold will be damaged,
The mold protection device is activated, the operation of the injection molding machine is interrupted,
Molding will not be performed.

Therefore, in order to suppress the occurrence of the stringing phenomenon, a break is formed in the molding material at the rear end of the nozzle opening 38.

FIG. 1 is a sectional view of a main part of an injection nozzle according to a first embodiment of the present invention, and FIG. 6 is a front view of the injection nozzle according to the first embodiment of the present invention.

In the drawing, reference numeral 33 denotes an injection nozzle, which comprises a cylindrical portion 71 and a conical portion 72, and the cylindrical portion 71 and the conical portion 72 have substantially the same thickness. The flow path 70 in the nozzle is formed. And, as described above, the injection nozzle 33 includes the nozzle port 38, and the nozzle port 38 is formed by penetrating the center of the conical portion 72. The nozzle opening 38 has a tapered portion 73 having a diameter gradually reduced from a front end (left end in FIG. 1) to a rear end (right end in FIG. 1), and the tapered portion 7.
At the rear end of the nozzle 3, that is, at the rear end of the nozzle port 38, there is provided an annular projection 74 as a break point forming means formed to protrude radially inward. Then, a radius R is formed between the tapered portion 73 and the projection 74 with a predetermined curvature.

Therefore, at the rear end of the nozzle opening 38, a break is formed in the molding material by the projection 74, and the yarn and the sprue are retracted during the mold opening as the molded product and the sprue portion are retracted. When the pull phenomenon occurs,
Irrespective of the type of molding material, it can be sufficiently suppressed, and the length of the filament 18 (see FIG. 2) can be stabilized. Moreover, since break points can be formed in the molding material over the entire area in the circumferential direction, it is possible to reliably suppress the occurrence of the stringing phenomenon.

When the molded product and the sprue portion are taken out, the thread 18 is not caught between the movable mold unit 53 (FIG. 5) and the fixed mold unit 52. Will not be damaged. Therefore, the quality of the molded product can be improved. Also,
Since it is not necessary to stop the operation of the injection molding machine and remove the filament 18, the cost of the molded product can be reduced.

Since the radius R is formed between the tapered portion 73 and the projection 74, the tip of the projection 74 has an acute angle. Therefore, the occurrence of the stringing phenomenon can be more sufficiently suppressed, and the length of the filament 18 can be further stabilized. In the present embodiment, the rounded portion R is formed between the tapered portion 73 and the protrusion 74, but the space between the tapered portion 73 and the protrusion 74 is made vertical or inclined. can do.

By the way, since the projection 74 is formed at the rear end of the nozzle port 38, the molding material passing through the projection 74 forms a turbulent flow near the tapered surface of the tapered portion 73 while passing through the nozzle port 38. It flows forward (to the left in FIG. 1). Therefore, the molding material does not stay at the front of the protrusion 74, so that the molding material can be prevented from adhering to the tapered surface. In this case, during molding, the molding material attached to the tapered surface does not peel off and mix with the molding material, so that the quality of the molded product can be improved. Further, since the molding material does not stay, burning of the molding material does not occur.

Since the stringing phenomenon can be suppressed without cooling the molding material, the molding material is, for example, a molecule having a structure in which only carbon and hydrogen are bonded to a pentagonal core. And a resin having a low thermal conductivity, such as a resin in which each molecule is three-dimensionally arranged.

Further, since it is not necessary to join the molding materials after they are separated, no trace of streaks remains on the molded product.
Therefore, the quality of the molded product can be improved.
In particular, when the molded product is an optical product, for example, a lens, the optical characteristics can be improved.

By the way, usually, in the case of a small injection device,
The seal stroke S is set to 2-3 mm,
In the present embodiment, the distance is set to about 1 [mm]. In this case, since the seal stroke S is short, the head main body 60 and the check ring 64 can be brought into close contact with each other by slightly moving the screw 44 when suckback is performed after the measurement process is completed. Therefore, since the pressure of the molding material in front of the screw head 46 can be sufficiently reduced, the molding material includes, for example, a molecule having a structure in which only carbon and hydrogen are bonded to a pentagonal core, and Even if a resin in which molecules are arranged three-dimensionally is used, it is possible to suppress carbon entanglement. As a result, the occurrence of the stringing phenomenon can be more sufficiently suppressed, and the length of the thread 18 can be further stabilized.

Next, a second embodiment of the present invention will be described.

FIG. 7 is a front view of a main part of an injection nozzle according to a second embodiment of the present invention.

In the drawing, reference numeral 38 denotes a nozzle port. The nozzle port 38 has a tapered portion 73 formed so as to gradually decrease in diameter from the front end to the rear end, and the nozzle port 38.
At the rear end, there is provided at least one arc-shaped projection 81 as a break point forming means formed so as to protrude radially inward. The tapered portion 73 and each projection 8
1 and R are formed with a predetermined curvature.

In this case, since the projections 81 are formed so as to be scattered in the circumferential direction, the molding material passing through the projections 81 forms a strong turbulent flow near the tapered surface of the tapered portion 73 while forming the nozzle opening. It flows forward in 38. Therefore, it is possible to further prevent the molding material from adhering to the tapered surface in front of the projection 81.

Next, a third embodiment of the present invention will be described.

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

In the drawing, reference numeral 38 denotes a nozzle port. The nozzle port 38 has a tapered portion 82 formed so that its diameter gradually decreases from the front end (left end in the figure) to the rear (right side in the figure). At the rear end (the right end in the figure) of the tapered portion 82, an annular projection 83 is formed as a break point forming means and formed to protrude inward in the radial direction, and the rear end of the nozzle port 38 from the projection 83 And an inverted tapered portion 84 formed so that the diameter gradually increases toward.

In this case, the breaking point of the molding material can be formed without reducing the strength of the conical portion 72. Since the thread 18 (see FIG. 2) can be cut at the breaking point, the thread 18 can be shortened. The projection 83 can be formed at any position between the front end and the rear end of the nozzle port 38.

Next, a fourth embodiment of the present invention will be described.

FIG. 9 is a sectional view of a main part of an injection nozzle according to a fourth embodiment of the present invention.

In the drawing, reference numeral 38 denotes a nozzle port, and the nozzle port 38 comprises a tapered portion 86 formed so that its diameter gradually decreases from the front end (left end in the drawing) to the rear end (right end in the drawing). Pins 87 are provided at a plurality of positions in the circumferential direction so as to penetrate the conical portion 72, and a tip 88 as a break forming means is provided at the nozzle port 3
8 to the rear end. The pin 87 is fitted (contained) on the conical portion 72 and then welded, and the tip 88 forms a projection. Note that the pin 87 and the conical portion 72 can be screwed together.

In this case, at the rear end of the nozzle port 38,
Since a break point is formed in the molding material by the tip 88, it is possible to sufficiently suppress the occurrence of a stringing phenomenon as the molded product and the sprue portion (not shown) are retracted while the mold is opened. Thus, the length of the filament 18 (see FIG. 2) can be stabilized.

Then, the pins 87 are formed to form the projections.
Only needs to be inserted from the outside of the conical portion 72, and no processing is required. Therefore, not only can the operation be simplified, but also the cost of the injection device can be reduced.

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.

[0069]

As described above in detail, according to the present invention, in the injection device, the cylinder member provided with the injection nozzle at the front end, and the injection member disposed to be able to advance and retreat within the cylinder member are provided. And driving means for moving the injection member forward and backward.

The nozzle opening formed at the front end of the injection nozzle is provided with a projection formed at a predetermined position so as to protrude inward in the radial direction and formed annularly along the circumferential direction. .

In this case, since the breaks are formed in the molding material by the projections, the occurrence of the stringing phenomenon as the molded product and the sprue portion are retracted while the mold is opened is considered as follows. Irrespective of the type of the molding material, it can be sufficiently suppressed, and the length of the filament can be stabilized.

When the molded article and the sprue portion are taken out, the thread is not caught between the movable mold unit and the fixed mold unit, so that the mold is not damaged. Therefore, the quality of the molded product can be improved.

Further, since there is no need to stop the operation of the injection molding machine to remove the thread, the cost of the molded product can be reduced.

Since the stringing phenomenon can be suppressed without cooling the molding material, the molding material is, for example, a molecule having a structure in which only carbon and hydrogen are bonded to a pentagonal core. And a resin having a low thermal conductivity, such as a resin in which each molecule is three-dimensionally arranged.

Further, since it is not necessary to merge the molding materials after they are separated, no trace of streaks remains on the molded product.
Therefore, the quality of the molded product can be improved.
In particular, when the molded product is an optical product, for example, a lens, the optical characteristics can be improved. Further, since the protrusion is formed in a ring shape along the circumferential direction of the nozzle port, it is possible to form a break in the molding material over the entire area in the circumferential direction, and to surely prevent the occurrence of the stringing phenomenon. Can be suppressed.

In another injection apparatus of the present invention, the nozzle port further includes a tapered portion, and the projection is formed at a rear end of the tapered portion.

In this case, since the projection is formed at the rear end of the tapered portion, the molding material having passed through the projection flows forward in the nozzle opening while forming a turbulent flow near the tapered surface of the tapered portion. Therefore, since the molding material does not stay in front of the protrusion, it is possible to prevent the molding material from adhering to the tapered surface. Then, during the molding, the molding material attached to the tapered surface does not come off and mix with the molding material, so that the quality of the molded product can be improved. Further, since the molding material does not stay, burning of the molding material does not occur.

[0078]

[0079]

In still another injection device of the present invention, a round portion is further formed between the tapered portion and the projection.

In this case, since a round portion is formed between the tapered portion and the projection, the tip of the projection has an acute angle. Therefore, the occurrence of the stringing phenomenon can be more sufficiently suppressed, and the length of the thread can be further stabilized.

[0082] In still another injection device of the present invention, a backflow prevention device for preventing the molding material stored in front of the injection member from flowing back during the injection process, and a backflow prevention device after the measurement process is completed. Suckback control means for retracting the injection member by a predetermined distance.

In this case, since the pressure of the molding material in front of the injection member can be sufficiently reduced, the molding material may be, for example, a molecule having a structure in which only carbon and hydrogen are bonded to a pentagonal core, In addition, even when a resin in which each molecule is three-dimensionally arranged is used, it is possible to suppress carbon entanglement. Therefore, the occurrence of the stringing phenomenon can be more sufficiently suppressed, and the length of the thread can be further stabilized.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a stringing phenomenon of a molding material in a conventional first injection device.

FIG. 3 is a longitudinal sectional view of a main part of an injection nozzle in a second conventional injection device.

FIG. 4 is a sectional view taken along line XX of FIG. 3;

FIG. 5 is a schematic view of a main part of the injection molding machine according to the first embodiment of the present invention.

FIG. 6 is a front view of the injection nozzle according to the first embodiment of the present invention.

FIG. 7 is a front view of a main part of an injection nozzle according to a second embodiment of the present invention.

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

FIG. 9 is a sectional view of a main part of an injection nozzle according to a fourth embodiment of the present invention.

[Explanation of symbols]

 32 Heating cylinder 33 Injection nozzle 38 Nozzle port 44 Screw 46 Screw head 64 Check ring 65 Seal ring 73, 82, 86 Tapered part 74, 81, 83 Projection 88 Tip R radius

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-341814 (JP, A) JP-A-5-177663 (JP, A) JP-A-5-104597 (JP, A) JP-A-10-104 86181 (JP, A) JP-A-10-217282 (JP, A) JP-A-5-84782 (JP, A) JP-A-5-91821 (JP, U) (58) Fields investigated (Int. ⁷ , DB name) B29C 45/00-45/84

Claims (7)

(57) [Claims] (A) a cylinder member having an injection nozzle at a front end; (b) an injection member arranged to be able to advance and retreat within the cylinder member; and (c) a driving means for moving the injection member forward and backward. And (d) a nozzle port formed at the front end of the injection nozzle,
At a predetermined position, protruding radially inward , and
An injection device comprising a projection formed in a ring shape along a circumferential direction . 2. The injection device according to claim 1, wherein (a) the nozzle port has a tapered portion, and (b) the projection is formed at a rear end of the tapered portion . Injection device according to claim 1, rounded portion is formed between the wherein the front Symbol tapered portion and the protrusion. (A) a backflow prevention device for preventing a molding material stored in front of the injection member from flowing backward during the injection step; and (b) a predetermined amount of the injection member after the measurement step is completed. 2. The injection device according to claim 1, further comprising suck-back control means for retracting by a distance of. 5. An injection nozzle disposed at a front end of a cylinder member, wherein a nozzle port formed at a front end of the injection nozzle is projected at a predetermined position radially inward , and has a circular shape. Circumferential direction
An injection nozzle comprising a projection formed in an annular shape along the line . 6. The injection nozzle according to claim 5 , wherein (a) the nozzle port has a tapered portion, and (b) the projection is formed at a rear end of the tapered portion . Injection nozzle according to claim 5, rounded portion is formed between 7. and front Symbol tapered portion and the protrusion.