JP3474795B2 - Gas injection and discharge method and device for injection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas charging / discharging method and apparatus for a heating cylinder of an injection device.

[0002]

2. Description of the Related Art Conventionally, in injection molding, it has been known to introduce an inert gas such as nitrogen gas into a heating cylinder from a material supply section of an injection device in order to prevent burning due to oxidation of a resin in a plasticizing process. (For example, Japanese Patent Laid-Open No. 1-1
54713 and Japanese Utility Model Publication 5-20511). According to these known techniques, the so-called inactive gas is provided in the material supply section at the rear of the heating cylinder (shown in JP-A-1-154713) and its vicinity (shown in JP-B-5-20511). It is introduced from the feed zone. This is because the resin material in the feed zone is still in a solid (pellet) state and it is easy to introduce an inert gas.
When the introduction port is provided in the compression zone in the front part of the feed zone, the resin material, which has been plasticized, flows out of the cylinder through the introduction port, which prevents such a situation.

However, in order to actually prevent the oxidation of the resin by the inert gas, it is effective to apply the resin material in a semi-molten state immediately after the start of melting in the compression zone of the heating cylinder. Further, even if an inert gas is introduced into the material supply section or in the vicinity thereof, it is difficult for the gas to reach the compression zone sufficiently and the desired effect may not be obtained.

On the other hand, the monomer gas and water generated by the plasticization of the resin in the injection device are normally supposed to be naturally discharged from the material dropping port of the material supply section at the rear of the heating cylinder. Etc. are generated in the compression zone of the heating cylinder, it is more effective to discharge them in the compression zone. Further, when the inert gas is introduced from the material dropping port as described above, it is difficult to discharge these monomer gases and the like.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention effectively supplies gas to the semi-molten resin material immediately after the start of melting in the compression zone of the heating cylinder, or effectively The present invention provides a method and an apparatus for introducing and discharging gas in an injection device capable of discharging gas.

[0006]

That is, the invention according to claim 1 is the compression zone or the filter in the heating cylinder.
Vent (20) provided in the cylindrical wall of Dozon, screw
(14) is in the melt initiation or Han溶 fusion state during rotation of the
The resin material is unevenly distributed on the front side of the mountain portion (15) of the screw.
The rear side (15R) of the screw mountain becomes the space (S).
In addition, the vent is opened only when the space is located in the vent (20), and gas is introduced into the heating cylinder or discharged from the heating cylinder through the vent. It relates to the gas input and discharge method of the device.

The invention of claim 2 is the same as that of claim 1.
Which is a device for realizing the gas input / exhaust method in a heating cylinder, which is a compression zone or a feed zone cylinder.
In the wall vent (20), the ridges of the screw (14) in the vent (15) ridges position detecting device for detecting the position (30), by the crest portion position detecting device
Based on the detected peak position detection signal, the ventilation port is closed.
The present invention relates to a gas charging / discharging device of an injection device, which comprises an opening / closing valve device (40) provided so as to be opened for a fixed time .

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the accompanying drawings. 1 is a schematic cross-sectional view of an injection device showing an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of an essential part thereof, FIG. 3 is a partial cross-sectional view schematically showing an example of a screw mountain position detecting device, FIG. 4 is a time chart showing the relationship between the screw mountain position detecting device of FIG. 3 and opening / closing of the vent, FIG. 5 is a schematic sectional view showing another example of the mountain position detecting device, and FIG. It is a schematic sectional drawing which shows the other example of a part position detection apparatus.

The illustrated injection device 10 relates to a gas charging / discharging method and device of the injection device of the present invention. In the drawing, reference numeral 11 is a heating cylinder, and a material supply having a material dropping port 13 at a rear end side thereof. A device 12 is provided. The material discharge port 13 is provided with an open gas discharge port 13a. Reference numeral 14 denotes a screw, which has a spiral mountain portion (flight) 15 on the outer peripheral surface, and is fitted in the heating cylinder 11 so as to be rotatable and axially movable. Injection device 1
The basic structure of 0 is the same as the conventional one, and the pellet-shaped resin material P supplied into the heating cylinder 11 from the material dropping port 13 of the resin material supply device 12 is heated by the screw 14 to the heating cylinder 1.
It is plasticized and stored while being rotationally moved forward in the inside of 1, and is ejected from a nozzle 17 into a mold (not shown) of a molding device by the forward movement of the screw 14. Reference numeral 16 is a heater.

The heating cylinder 11 constitutes a cylinder portion of the injection device 10, and in accordance with the plasticized state of the resin material P, a feed zone F for supplying the resin material P forward from the material dropping port 13 side of the rear portion, A compression zone C in which the resin material P is melted and compressed, and a metering zone M in which the completely melted resin material P is filled are distinguished.

In the method defined as the invention of claim 1, the cylinder wall 11 of the compression zone C in the heating cylinder 11 is used.
a is provided with a vent 20 to melt and open during rotation of the screw 14.
The resin material P in the initial or semi-molten state is unevenly distributed on the front side of the screw ridges 15 and the rear side 1 of the screw ridges 1
The air vent 20 is opened only when the space S where the 5R becomes the space S is located in the air vent 20, and gas is introduced into the heating cylinder through the air vent or inside the heating cylinder. It is characterized by discharging the gas.

As well understood from the drawings, the ventilation port 20 is formed through the cylinder wall 11 a between the compression zone C of the heating cylinder 11 and the material dropping port 13.
As described above, since the compression zone C is a portion that is particularly likely to be oxidized in the plasticizing step of the resin material P and that gas or the like is easily generated, the ventilation port 20
Are preferably formed in the compression zone C. Of course, the resin material P may be provided in the feed zone F depending on the molten state of the resin material P or the molding conditions.

In the method of the present invention, the vent hole 20 is formed as shown in FIG.
As shown in FIG. 5, the vent 20 is opened only when the screw 14 is located at the rear position from the position of the mountain portion 15 with respect to the vent 20. This is because the resin material P is not yet completely melted between the compression zone C and the material dropping port 13, and at most the compression zone C
In the state in which the resin material P has started to be melted or is in a semi-molten state, the resin material P is
Is unevenly distributed on the front side 15F of the mountain portion (flight) 15, and is therefore rotated on the rear side 15R of the mountain portion 15 of the screw 14.
Is a space S. In this invention, this space S
The heating cylinder 11 that effectively heats gas from the vent 20 by using
The gas in the heating cylinder 11 is effectively discharged to the outside.

Next, a more detailed description will be given together with the device defined as the invention of claim 2. An apparatus according to the invention of claim 2 realizes the gas charging / discharging method of claim 1.
An apparatus, the vent port 20 provided in the cylindrical wall 11a of the compression zone C in the heating cylinder 11, the mountain portion position detecting device for detecting the peak portion 15 the position of the screw 14 in the through <br/> outlet port 20 30 and the mountain portion position detection device 30
An on-off valve device 4 provided so as to open the vent hole 20 for a certain period of time based on the peak position detection signal detected by
It consists of 0 and. The configuration of the vent hole 20 is as described above with respect to the invention of claim 1.

FIG. 1 shows an example of a crest position detecting device 30 that detects the position of the crest 15 of the screw 14 in the vent 20. As shown in FIG. 3, the mountain portion position detecting device 30A of this example has a mountain portion of the same pitch corresponding to the mountain portion (flight) 15 of the screw body on the rear base end portion 14A of the screw 14 as shown in FIG. A position detecting crest 17 is provided, and the position of the crest 15 of the screw 14 main body is detected by detecting the crest position of the detecting crest 17 by, for example, a reflection type laser photoelectric sensor 31. Is.

The peak position detection signal detected by the peak position detecting device 30A is transmitted to the controller 32, and is transmitted from the controller 32 to the opening / closing valve device 40 as a signal for controlling opening / closing of the vent 20. As described above, since the vent hole 20 is opened in a certain region on the rear side 15R of the mountain portion 15 of the screw 14 where the space S is exposed in the screw 14, the mountain portion position detecting device 30A A certain time t after the detection of the position of the part is the timing for opening the vent 40. Although FIG. 4 is a time chart for performing this control, such control can be easily performed by a known method such as timer setting by the controller 32.
It should be noted that the time t for opening the ventilation port 20 is the same as the ventilation port 20.
It can be appropriately set according to the state of the resin material P corresponding to the installation position of.

Explaining the on-off valve device 40, the on-off valve device 40 of the embodiment shown in FIG. 3 comprises an air cylinder 41 having a piston rod 42.
The electromagnetic valve 33 of the air circuit 45 is switched by a signal from the controller 32, and the piston rod 42 reciprocates to open and close the vent hole 20. Although the state shown in the drawing is a state in which the ventilation port 20 is closed, it is desirable that the tip of the piston rod 42 be flush with the inner wall surface of the heating cylinder 11 when the ventilation port 20 is closed as shown in the figure. . In the figure, reference numeral 36 is an air pressure source, and 37 is a pressure reducing valve.

FIG. 5 shows another example of the mountain portion position detecting device 30. This device 30 B is a rear base end portion 14 of the screw 14.
Instead of the detection peak portion (flight) 17 of the above-described embodiment, a reflected light type tape 18 is spirally wound around A in accordance with the peak portion 15 of the screw body. The detection of the screw mountain portion position is performed on the basis of the reflected light by the laser photoelectric sensor 31 as described above. In the case of using the reflection type tape 18 as described above, if necessary, the tape width can be adjusted so that a signal for directly opening and closing the on-off valve device 40 can be issued in response to an optical signal from the tape.

Further, as shown in FIG. 6, a laser photoelectric sensor 31 is arranged on the inner wall surface behind the material dropping port 13 of the resin material supply device 12, and a detection mountain portion (flight) 19 behind the material dropping port 13 is arranged. You may make it detect the mountain part position of. According to this, it is not necessary to particularly lengthen the rear portion of the screw 14 as described above.

According to the present invention, for example, when the inert gas is introduced into the heating cylinder 11, the inert gas supply device 50 is connected to the ventilation port 20 as shown in FIG. The open / close valve device is provided only when the screw 14 is in the position of the rear side 15R from the position of the mountain portion 15 with respect to the ventilation port 20 by a signal from the mountain portion position detection device 30 accompanying the rotation of the screw 14. The piston rod 42 of 40 rises and the vent 20 is opened, and the inert gas is introduced into the heating cylinder 11. As described above, between the compression zone C of the heating cylinder 11 and the material dropping port 13, the resin material P is unevenly distributed on the front side 15F of the mountain portion 15 of the screw 14 as the screw 14 rotates. The rear side 15R of the mountain portion 15 of the screw 14 is a space S, and if the vent 20 is opened corresponding to this space S, the resin material P does not jump out of the vent 20. The inert gas can be effectively introduced into the heating cylinder 11.

When the inert gas is introduced into the heating cylinder 11 when the molding operation by the molding apparatus is interrupted or stopped and the screw 14 stops its rotation,
It goes without saying that the space S of the screw 14 is stopped so as to come to a position corresponding to the ventilation port 20.

Further, when discharging the monomer gas or the like from the heating cylinder 11, an air suction device 55 may be connected to the ventilation port 20 as illustrated in FIG. The opening / closing of the ventilation port 20 by the opening / closing valve device 40 is performed in the same manner as in the case of introducing the inert gas. In this case, the inert gas may be introduced from the material supply unit and discharged from the ventilation port of the compression zone C, as in the above-described conventional device. The circulation of the inert gas is improved, and the monomer gas and the like can be discharged smoothly.

Further, as shown by the broken line in FIG. 1, the inert gas supply device 50 and the air suction device 55 are connected to each other by a switching valve V.
You may make it selectively connect with the ventilation port 20 via. It is possible to alternately insert the inert gas into the heating cylinder 11 and discharge the gas, and it is possible to perform more effective and efficient molding.

[0024]

As shown and described above, according to the present invention, gas is effectively introduced into the semi-molten resin material immediately after the start of melting in the compression zone of the heating cylinder, or effectively. A gas charging / discharging method and device of an injection device capable of discharging gas can be provided.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an injection device showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a partial cross-sectional view schematically showing an example of a mountain portion position detecting device of a screw.

FIG. 4 is a time chart showing the relationship between the screw mountain position detecting device of FIG. 3 and opening / closing of a vent.

FIG. 5 is a schematic sectional view showing another example of the peak position detecting device.

FIG. 6 is a schematic sectional view showing another example of the mountain portion position detecting device.

[Explanation of symbols]

10 Injection Device 11 Heating Cylinder 13 Material Drop Port 14 Screw 15 Crest 20 Vent 30 Crest Position Detection Device 40 Open / Close Valve Device 50 Inert Gas Supply Device C Compression Zone S Space Section

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 45/00-45/84 B29C 47/00-47/96

Claims (2)

(57) [Claims] 1. A compression zone in a heating cylinder
Or, provide a ventilation port (20) on the cylinder wall of the feed zone ,
Melting started or semi-molten state during rotation of the cru (14)
The resin material on the front side of the ridge (15) of the screw.
The rear side (15R) of the unevenly distributed mountain portion of the screw is the space portion (S)
The air vent is opened only when the space portion is located at the air vent (20), and gas is introduced into the heating cylinder or discharged from the heating cylinder through the vent. Gas injection and discharge method of injection device. 2.The gas charging / discharging method according to claim 1 is implemented.
A device that appears,Compression in the heating cylinder
zoneOr the cylinder wall of the feed zoneVent provided on the
(20)When,The aboveScrew in vent(14)Mountain
Department(15)Mountain position detector for detecting position(30)
With the mountain position detecting deviceDetected mountain position
Based on detection signalThe ventA certain timeSet to open
On-off valve device(40)Characterized by consisting of
Gas injection and discharge device for injection device.