JP2001269963A - Injection unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection unit with a new structure, bring inert gas to contact with molten resin stably under approximately certain conditions for the purpose of dissolving the inert gas and making it possible to stably obtain the modification effect of the resin by the inert gas. SOLUTION: In the injection unit adopting a preplasticization type structure provided jointly with a screw device 14 and a plunger device 20, the region where a steady resin flow is kept a flow path shape of the molten resin unchangeable with time is formed in the resin passage from the inside of a plasticization cylinder 10 of the screw device 14 to the plunger device 20. A gas inlet 70 is made to open into the above region for the inert gas to be injected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding technique for a gas-dissolved resin in which an inert gas such as carbon dioxide is dissolved in a heat-melted resin material and then the molten resin material is injection-molded. The present invention relates to an injection device having a novel structure capable of stably dissolving an inert gas in a molten resin material.

[0002]

2. Description of the Related Art Conventionally, a synthetic resin material that has been heated and melted is injected into a molding cavity, and then cooled and solidified to produce a molded product having a desired shape. 2. Description of the Related Art There is known an injection molding method of a gas-dissolved resin in which a molded article having a fine foamed structure is obtained by dissolving an active gas in a molten resin. Also, in recent years, dissolving such an inert gas, particularly carbon dioxide gas, in a molten resin has made it possible to lower the viscosity of the resin, thereby lowering the melting temperature and the injection pressure, thereby improving moldability. It has been found that improvement and the like can be achieved, and that foaming is effective for promoting crystallization and modifying the resin material by molecular orientation and the like.

When performing injection molding of such a gas-dissolved resin, a large amount of inert gas must be rapidly dissolved in the molten resin. Attempts have been made to bring the resin into contact with a resin, and an injection device for that purpose is disclosed in, for example, US Pat. No. 5,158,986. In the injection device disclosed in this U.S. Patent, a screw is inserted and arranged so as to be rotatable around a central axis and movably in an axial direction with respect to a heating cylinder having a nozzle portion at a tip, and is provided at a rear portion of the heating cylinder. While the resin material supplied from the provided material supply port is fed forward by the rotation of the screw and melted by heating, the screw is displaced axially rearward to store the molten resin in the screw front while heating. An inert gas supply port is provided near the tip of the cylinder, and the inert gas is supplied from the supply port into the heating cylinder.
After the molten resin stored in the distal end portion of the heating cylinder is brought into contact with and melted, the screw is moved axially forward to inject the resin material from the nozzle portion.

However, such an injection device having a conventional structure has an in-line screw type injection device as a basic structure, and is inserted and arranged in a heating cylinder during a series of injection steps such as heating, melting, measuring and injection of a resin material. Since the screw is reciprocally displaced in the axial direction, it is inevitable that the relative position of the inert gas supply port formed at a predetermined position of the heating cylinder with respect to the screw changes. As a result, the contact state of the inert gas discharged into the heating cylinder with the molten resin material guided through the heating cylinder changes with time, and the dissolved state of the inert gas in the molten resin material is changed. That is, in some cases, it is difficult to obtain a sufficiently stable effect of modifying the molten resin material by the inert gas, and furthermore, obtaining the material of the molded article to be manufactured.

[0005]

Here, the present invention has been made in view of the above-described circumstances, and a problem to be solved is that a change in a flow state of a molten resin material at a discharge portion of an inert gas is detected. By avoiding and stabilizing the contact state of the inert gas with the molten resin material, the intended effect of modifying the molten resin material by the inert gas and, consequently, the material of the target molded product can be stably maintained. It is an object of the present invention to provide a gas melting resin injection device having a novel structure which can be obtained.

[0006]

An embodiment of the present invention which has been made to solve such a problem will be described below. The components employed in each of the embodiments described below can be employed in any combination as possible. In addition, aspects or technical features of the present invention are not limited to those described below, but are described in the entire specification and drawings, or based on the invention ideas that can be understood by those skilled in the art from the descriptions. It should be understood that it is recognized on the basis of.

A first aspect of the present invention is provided with a plasticizing cylinder in which a screw is inserted and arranged, and a resin material supplied from a rear portion of the plasticizing cylinder is moved forward of the plasticizing cylinder by rotation of the screw. A screw device that feeds and heats and melts, and discharges from a discharge nozzle hole at the tip of the plasticizing cylinder; and an injection cylinder in which a plunger is inserted and disposed, and injects the molten resin material discharged from the screw device. A plunger device that guides and stores it in a cylinder, and injects through an injection nozzle hole at the tip of the injection cylinder by advancement of the plunger.
In the pre-plasticization type injection device configured to include the inside of the plasticizing cylinder in the screw device and the inside of the connection passage for guiding the molten resin material discharged from the screw device to the injection cylinder of the plunger device. A gas supply path for supplying an inert gas from the outside is provided for at least one of them, and the inert gas is dissolved in the molten resin.

[0008] In the injection device having the structure according to this aspect, the injection device for the gas-dissolved resin is constituted by using the pre-plasticization type injection device as a basic structure, so that the screw is fixed in the plasticizing cylinder in the axial direction. Position, the flow path of the molten resin material from the plasticizing cylinder to the injection cylinder through the connection passage could be formed in a constant shape that does not change with time, and the fixed shape was adopted. Since the inert gas is supplied by opening the gas supply path on the flow path of the molten resin material, for example, the inert gas is stabilized with respect to the molten resin material over the entire operation time of the measuring step of the resin material. The contact can be made under substantially constant conditions.

Therefore, in such an injection device, the molten resin material which is heated and melted by the plasticizing cylinder and guided to the injection cylinder is brought into contact with the inert gas substantially uniformly over the whole thereof to be dissolved. As a result, as a result, it is possible to substantially uniformly and stably exert the reforming effect of the target inert gas on the entire molten resin material, and thus, the quality of the material of the molded article to be manufactured can be improved. Improvement and stabilization can be achieved.

It is desirable that the inert gas is brought into contact with the molten resin in a supercritical state.
The effect of modifying the intended resin material is more effectively achieved. In that case, the inert gas is sufficient if it is in a supercritical state when it is supplied into the heating cylinder and brought into contact with the molten resin, for example, by supplying a fluid (liquid or gas) having a critical temperature or less, It is also possible to bring the supercritical state in the heating cylinder by raising the temperature in contact with the molten resin.

According to a second aspect of the present invention, in the injection device having the structure according to the first aspect, a check valve is provided at a tip portion of the screw in the screw device, and the gas supply passage is provided. The opening of the passage of the molten resin material is closer to the screw tip than the check ring. In this embodiment, the backflow of the molten resin caused by the supply of the inert gas at a high pressure to the passage of the molten resin material is prevented by the check valve. By being prevented, the state of contact of the inert gas with the molten resin material, and further, the effect of modifying the molten resin material can be further stabilized. As the check valve, a conventionally known ring valve type (backflow ring type) or a ball check type provided on a screw may be used.
It is preferably adopted. The opening position of the inert gas may be selected, for example, from the screw head portion and the outer peripheral side wall surface of the screw tip in the plasticizing cylinder, as well as the discharge hole and the connection passage of the molten resin material.

Still further, according to a third aspect of the present invention, in the injection device having the structure according to the first or second aspect, the cross-sectional area of the passage of the molten resin is provided in the plasticizing cylinder of the screw device. Forming an enlarged decompression section, for such a decompression section, that the gas supply path was opened,
Features. In such an embodiment, by supplying the inert gas to the decompression portion in which the passage cross-sectional area is partially enlarged in the flow direction of the molten resin, the supply amount of the inert gas is increased, and The solubility of the inert gas in the molten resin material can be improved. In addition, such a decompression part can be formed in the longitudinal middle part of the plasticizing cylinder by forming a small-diameter part in the axial middle part of the screw like a screw in a conventional vent-type injection molding machine, for example. Yes, it is also possible to form the check valve at the screw tip by reducing the diameter of the screw front part of the check valve.

According to a fourth aspect of the present invention, there is provided an injection device having a structure according to any one of the first to third aspects, wherein an outer peripheral surface is provided at a tip end portion of the screw in the screw device. A protruding stirring blade is provided, and the gas supply passage is opened on a rear side of a position where the stirring blade of the screw is provided in the plasticizing cylinder. In this embodiment,
The inert gas and the molten resin material supplied from the gas supply path are kneaded by the stirring blade, whereby the inert gas can be more uniformly and more dissolved in the molten resin material.

Further, a fifth aspect of the present invention is an injection apparatus having a structure according to any one of the first to fourth aspects, wherein the plunger apparatus communicates / blocks the injection nozzle hole. It is characterized in that an injection valve is provided. In this embodiment, the pressure accompanying the dissolution of the inert gas in the molten resin material guided to the plunger device is prevented from being inadvertently released through the injection nozzle hole. Can be supplied to and dissolved in the molten resin material at a higher pressure, and the material of the molten resin material in which the inert gas is dissolved can be stabilized.

According to a sixth aspect of the present invention, there is provided an injection apparatus having a structure according to any one of the first to fifth aspects, wherein a gas supply valve for communicating / blocking the gas supply path is provided. Is the feature. In such an embodiment, the supply of the inert gas to the molten resin material can be easily controlled by operating the gas supply valve, and the supply of the inert resin to the molten resin material in a state where the supply of the inert gas is stopped is performed. By preventing entry into the gas supply path, it is possible to avoid problems such as clogging of the gas supply path.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 shows an overall schematic view of an apparatus for injecting a gas-soluble resin as one embodiment of the present invention. Such an injection device includes a screw device 14 having a plasticizing cylinder 10 and a screw 12, and an injection cylinder 1
6 and a plunger device 20 having a plunger 18, and the screw devices 14
And the plunger device 20 are disposed and supported integrally on a base base (not shown) so as to be able to reciprocate, and are movable in the approaching / separating direction with respect to a molding die of a mold clamping device (not shown). I have. Then, the molten resin material heated and melted in the plasticizing cylinder 10 of the screw device 14 is guided into the injection cylinder 16 of the plunger device 20 and stored therein, and then is mounted on the mold clamping device. The molding cavity in the molding die is injection-filled.

More specifically, the screw device 14 includes a plasticizing cylinder 10 formed by attaching a discharge nozzle 24 to a distal end opening of a cylindrical cylinder 22 having a thick cylindrical shape. The cylinder hole 26 of the plasticizing cylinder 10 is open at the rear (right side in the figure), while the discharge nozzle 24 forms a small-diameter discharge nozzle hole 28 at the front. Also,
A material supply port 30 which opens vertically upward is formed near the rear end of the cylinder hole 26 in the cylinder body 22, and a resin material guided from a hopper 32 fixed above the material supply port 30 is used for material supply. The liquid is supplied from the port 30 to the cylinder hole 26. Note that a band heater 34 is wound around the outer peripheral surface of the plasticizing cylinder 10.

The screw 12 is connected to the tip (left side in FIG. 1) of a circular rod-shaped screw body 36.
A screw head 38 having a sharp tip is screwed and fixed. The screw main body 36 has an outer peripheral surface with a slight reverse taper that increases in diameter toward the distal end side in the axial direction (left side in the figure), and a spiral blade is integrally formed to protrude from the outer peripheral surface. ing. The screw head 38 has a straight circular outer peripheral surface. A resin passage 40 penetrates through the inside, and a ball check type check valve 42 is formed on the resin passage 40. The flow of the resin toward the front of the screw through the resin passage 40 is allowed, and the flow of the resin (backflow) toward the rear is prevented.

The screw 12 is inserted into the cylinder hole 26 of the plasticizing cylinder 10 from the rear opening, and is disposed so as to be rotatable around the central axis and immovable in the central axis direction. I have. An output shaft of a hydraulic motor 44 is connected to the rear end of the screw 12 projecting rearward from the plasticizing cylinder 10 so as to be relatively immovable. The screw 12 is rotated around the central axis by the hydraulic motor 44. It has become so. Then, by rotating the screw 12 in the cylinder hole 26 of the plasticizing cylinder 10, the resin material supplied from the material supply port 30 is heated and plasticized and sent forward, and the plasticized molten resin material is discharged. The liquid is discharged forward through the discharge nozzle hole 28 of the nozzle 24.

The screw device 14 including the plasticizing cylinder 10 and the hydraulic motor 44 is fixed and supported by a moving base 46 which is reciprocally supported by a base base (not shown). Such a moving base 4
Reference numeral 6 is disposed on the base base so as to be movable in the direction of approaching / separating from the mold clamping device, and is reciprocated by a base moving hydraulic cylinder mechanism (not shown).

On the other hand, the plunger device 20 is provided with an injection cylinder 16 in which a connection block 48 and a discharge nozzle 24 are attached to a distal end opening of a cylinder body 47 having a thick cylindrical shape. The cylinder hole 55 of the injection cylinder 16 is open at the rear (right side in the figure), while the injection nozzle 50 forms a small-diameter injection nozzle hole 52 at the front. The plunger device 20 is located vertically below the screw device 14 and has the injection cylinder 16 and the plasticizing cylinder 1.
0 are arranged in a state of being superposed at a predetermined distance from each other so as to be parallel to each other, and are fixedly supported by the moving base 46, and are integrally formed with the plasticizing cylinder 10. Above, it can be moved in the direction of approach / separation with respect to the mold clamping device. A band heater 53 is wound around the outer peripheral surface of the injection cylinder 16.

The connecting block 48 extends vertically upward from the tip of the injection cylinder 16, and the upper end thereof is fixed to the tip of the discharge nozzle 24 of the plasticizing cylinder 10 of the screw device 14. . As a result, the connecting block 48 straddles between the screw device 14 and the plunger device 20, and is disposed in a state where the two devices 14, 20 are fixedly connected to each other. Also,
A connecting resin passage 54 extending in the vertical direction is formed in the connecting block 48, and the upper end of the connecting resin passage 54 is connected to the discharge nozzle hole 28 of the plasticizing cylinder 10, while the lower end is connected to the injection cylinder. 16 injection nozzle holes 5
2 are connected to the intermediate portion in the longitudinal direction. This allows
The discharge nozzle hole 28 and the injection nozzle hole 52 are connected to each other by a connection resin passage 54.
The molten resin material discharged from the nozzle is guided to the injection nozzle hole 52 through the connection resin passage 54.

Further, the plunger 18 is inserted into the injection cylinder hole 55 of the injection cylinder 16. The plunger 18 has a circular rod shape,
A large diameter piston 5 for the front end (left end in the figure)
6 are integrally formed. And this plunger 18
With respect to the injection cylinder hole 55 of the injection cylinder 16
It is inserted from the rear opening, and is arranged movably in the direction of the central axis. An output shaft of a hydraulic cylinder 57 for injection is fixedly connected to a rear end of the plunger 18 projecting rearward from the injection cylinder 16, and the hydraulic cylinder 57 for injection causes the plunger 18 to reciprocate in the axial direction. It is designed to be driven. The molten resin material guided from the plasticizing cylinder 10 through the connection resin passage 54 by the backward movement of the plunger 18 in the injection cylinder hole 55 of the injection cylinder 16 is stored in the injection cylinder hole 55 of the injection cylinder 16. At the same time, the amount of stored resin is measured by the amount of retreat of the plunger 18. Further, after the amount of the stored resin in the injection cylinder hole 55 of the injection cylinder 16 reaches a predetermined constant amount, the plunger 18 is moved forward so that the stored molten resin material is discharged through the injection nozzle hole 52. The mold is injected forward and injected into a molding cavity of a mold (not shown).

The injection nozzle 52 of the injection cylinder 16
Is provided with an injection valve 58. The injection valve 58 has a needle disposed in the injection nozzle hole 52 and facing the nozzle opening. The needle is moved in the axial direction by the opening / closing hydraulic cylinder 60 to open / close the nozzle opening. By closing, the injection nozzle hole 52 is communicated / blocked. Then, the molten resin supplied from the plasticizing cylinder 10 is injected into the injection cylinder 16.
In the step of storing and metering, the injection nozzle hole 52 is shut off to prevent the escape of the pressure of the molten resin, and after the measurement, the injection nozzle hole 52 is connected to allow the injection of the molten resin from the injection nozzle hole 52. Is being done.
The needle is driven by the opening / closing hydraulic cylinder 60 through a swing arm 64 driven by an output rod 62 of the opening / closing hydraulic cylinder 60.

Further, the connection resin passage 54 formed in the connection block 48 is connected to the injection nozzle hole 5 of the injection cylinder 16.
2 and a vertical hole 66a branching at a right angle from the injection nozzle hole 52 and rising upward from the injection nozzle hole 52.
And a horizontal hole 68b extending horizontally from the discharge nozzle hole 28 and connected to the vertical hole 66a. In this case, particularly in the present embodiment, the vertical holes 66
a is extended to the upper end surface of the connection block 48 and is opened, and at the opening of the vertical hole 66a,
A gas inlet 70 is formed. An external conduit 72 is fluid-tightly connected to the gas inlet 70, and an inert gas such as carbon dioxide is supplied through the external conduit 72. In the present embodiment, the carbon dioxide supplied from the gas cylinder 74 is supplied in a supercritical state from the gas inlet 70 through the pressure increasing means 78 by opening the opening / closing valve 76 as a gas supply valve. Has become.

In manufacturing an intended resin product by the injection molding machine having the above-described structure, first, the moving base 46 supporting both the screw device 14 and the plunger device 20 is moved closer to the mold clamping device. The injection nozzle 50 is fixed to the fixed mold clamped in the mold clamping device.
Nozzle touch. Further, in the plunger device 20, the injection nozzle 58 is closed by the injection valve 58, and the plunger 18 is positioned at the forward end position. The plunger 1 in the plunger device 20
The position of 8 can be confirmed by a position sensor using an encoder or the like. In this state, the screw device 14 is operated, and the resin material is supplied to the plasticizing cylinder 10 while the screw 12 is driven to rotate.
While being transferred forward by the rotation of 2, the heater is heated and plasticized by the heating of the heater and the rotation of the screw, and while being kneaded, the molten resin material is discharged from the discharge nozzle hole 28 to the connection resin passage 54, and the injection of the plunger device 20 is performed. Send to cylinder 16.

At this time, it is preferable that the open / close valve 76 is always opened and the inert gas in a supercritical state is supplied at all times in the entire process in which the screw 12 of the screw device 14 is rotated. An inert gas is pumped from the gas inlet 70 to the connecting resin passage 54. This allows
For the molten resin continuously guided from the plasticizing cylinder 10 of the screw device 14 to the injection cylinder 16 of the plunger device 20 via the connecting resin passage 54, the connecting resin passage 54
Above, the inert gas discharged from the gas inlet 70 is brought into contact, and the inert gas is dissolved in the molten resin.

Then, the molten resin in which the inert gas is dissolved is continuously sent to the tip of the injection cylinder 16 in the plunger device 20 through the connecting resin passage 54, and the plunger 18 is moved backward. The molten resin material is stored and measured in the injection cylinder 16.
Thereafter, the plunger 18 is moved forward to inject a predetermined amount of the molten resin material into the molding cavity of the mold (not shown) from the injection nozzle hole 52, thereby obtaining a desired resin molded product. .

In the injection device having the above-described structure, a pre-plasticization type injection device structure including a screw device 14 and a plunger device 20 is used. The screw 12 is disposed at a fixed position in the axial direction, so that the molten resin passage from the plasticizing cylinder 10 to the plunger device 20 via the connecting resin passage 54 does not change during the entire injection molding process. Formed with shape,
The flow of the molten resin is generated stably. Then, since the discharge port of the inert gas is set on the molten resin passage formed with this constant shape, the inert gas is almost uniformly contacted with the molten resin to be flown, Since a stable amount of dissolution is realized, the effect of modifying the target resin material by the inert gas is stably exhibited, and the material of the molded product can be stabilized.

In particular, in the present embodiment, the gas inlet 70 for the inert gas is provided on the connection resin passage 54 in the connection resin passage 5.
4 is opened on the extension of the connecting resin passage 5.
Since the inert gas is injected in the flow direction of the molten resin in the inside 4, the inert gas is more uniformly and uniformly supplied to the entirety of the molten resin sequentially sent through the connection resin passage 54. The contact is smooth.

In this embodiment, the screw device 14
Even if the gas pressure of the inert gas injected from the gas injection port 70 becomes larger than the pressure of the molten resin fed by the screw 12, since the check valve 42 is disposed on the screw head 38 of FIG. The backflow of the resin and the escape of the gas pressure are prevented, so that the solubility of the inert gas in the molten resin and the fluidity of the molten resin can be further stabilized.

Further, in the present embodiment, an injection valve 58 for opening and closing the injection nozzle hole 52 of the plunger device 20 is provided, and the escape of the pressure through the injection nozzle hole 52 is prevented. The molten resin in which the gas is dissolved at a high pressure can be stably stored in the injection cylinder 16 of the plunger device 20,
Thereby, the modification of the resin material with the target inert gas and the improvement of the material of the molded product can be more advantageously achieved.

Next, FIG. 2 shows an injection device according to a second embodiment of the present invention. Note that, in the present embodiment, only a portion having a structure different from that of the first embodiment is shown in an enlarged manner, and in such drawings, a member having a structure similar to that of the first embodiment and The parts are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof will be omitted.

That is, in the injection device of the present embodiment, a screw head 80 having a structure different from that of the first embodiment is attached to the tip of the screw 12 in the screw device 14. Such a screw head 80
As in the first embodiment, a check valve 42 is provided, but the tip of the check valve 42 is further extended axially forward from the check valve 42. A number of projections and depressions are provided on the cylindrical outer peripheral surface of the extended portion, and the convex portion protrudes so as to be in sliding contact with the inner peripheral surface of the plasticizing cylinder 10. A plurality of mixing heads 82 are provided in the axial direction and in the circumferential direction so as to form a concave portion that forms a flow path of the molten resin between the inner surface of the plasticizing cylinder 10 and the inner surface of the plasticizing cylinder 10.

In the injection device of the present embodiment,
Gas inlet 70 for supplying an inert gas to the molten resin passage
Are formed to penetrate the cylinder wall of the cylinder cylinder 22 of the plasticizing cylinder 10, and the mixing head 8
A gas inlet 70 is opened near the base end of the valve 0, in other words, near the check valve 42 and the mixing head 80.

In the injection device of this embodiment having such a structure, the screw 12 is rotated and the molten resin is continuously fed forward in the plasticizing cylinder 10 so that the connection resin passage is discharged from the discharge nozzle hole 28. In leading to 54,
An inert gas is supplied to the outer peripheral portion of the screw head 80 through the gas injection port 70. Further, the molten resin in which the inert gas is dissolved passes through the mixing head portion 82 to the discharge nozzle hole 28. Will be led.

In this regard, in the injection device of the present embodiment, the use of the pre-plasticization type injection device makes it possible to prevent the molten resin passage shape from being kept substantially constant without changing over time. Therefore, an inert gas can be supplied and dissolved in the molten resin, and therefore,
As in the first embodiment, effects such as modification of the molten resin by the inert gas and stabilization of the material of the molded product can be effectively exhibited.

In the present embodiment, the mixing head 82 is used for the molten resin in which the inert gas is dissolved.
Is added, the contact of the inert gas with the molten resin becomes more uniform, and the modification of the molten resin by dissolution of the inert gas and the stabilization thereof can be improved. As is apparent from this, in the present embodiment, a pressure reducing section is formed in the area where the mixing head section 82 is provided in the plasticizing cylinder 10.

Furthermore, in the present embodiment, the cross-sectional area of the passage of the molten resin in the plasticizing cylinder 10 is slightly enlarged in the mixing head portion 82, although it is not always clear in the drawings. As a result, the pressure of the molten resin that is caused to flow in the plasticizing cylinder 10 is slightly reduced by the mixing head portion 82, and an inert gas is supplied thereto at a high pressure.
The solubility of the inert gas in the molten resin is improved.

FIG. 3 shows an injection apparatus according to a third embodiment of the present invention. Note that, in the present embodiment, members and portions having the same structure as the first embodiment are denoted by the same reference numerals as those in the first embodiment in the drawings, and their details are described. Detailed description is omitted.

That is, in the injection device of this embodiment, the screw 12 in the screw device 14
In the region from the rear end in the axial direction to the substantially central portion in the axial direction, a reverse tapered outer peripheral surface that gradually increases in diameter toward the front is attached, and one end is reduced in diameter in the substantially central portion in the axial direction. A reverse tapered outer peripheral surface which gradually increases in diameter again from the front to the front end in the axial direction is provided. In short, in the present embodiment, the screw main body 36 has a shape similar to that of a vent-type screw in a conventional in-line screw-type injection device.

The plasticizing cylinder 10 of the screw device 14 is formed with a gas inlet 70 penetrating inward and outward at a substantially central portion in the axial direction thereof. The opening is located on the outer peripheral surface of the small diameter portion formed at the axially intermediate portion.

In the injection device of this embodiment having such a structure, the screw 12 is rotated and the molten resin is continuously fed forward in the plasticizing cylinder 10 so that the connection resin passage is discharged from the discharge nozzle hole 28. In leading to 54,
An inert gas is supplied to a substantially central portion in the axial direction in the plasticizing cylinder 10 through the gas injection port 70, and the molten resin in which the inert gas is dissolved is further supplied by the spiral blade of the screw 12. The mixture is fed to the front of the screw 12 while being kneaded, and is guided to the discharge nozzle hole 28.

In the injection device of the present embodiment, the use of the pre-plasticization type injection device also makes it possible to prevent the molten resin passage shape from being kept substantially constant without changing over time. Therefore, an inert gas can be supplied and dissolved in the molten resin, and therefore,
As in the first embodiment, effects such as modification of the molten resin by the inert gas and stabilization of the material of the molded product can be effectively exhibited. As is apparent from this, in the present embodiment, the pressure reducing portion is formed on the outer peripheral side of the small diameter portion formed substantially at the center of the screw 12 in the axial direction.

Further, in this embodiment, in particular, the cross-sectional area of the passage of the molten resin in the plasticizing cylinder 10 is enlarged at a substantially central portion in the axial direction of the plasticizing cylinder 10, whereby the flow in the plasticizing cylinder 10 is increased. When the pressure of the molten resin is reduced, the gas injection port 70 is opened.
Thus, the inert gas is supplied from the nozzle, and therefore, as in the second embodiment, the solubility of the inert gas in the molten resin is improved.

Although the embodiments of the present invention have been described in detail above, these are merely examples, and the present invention
The description of these embodiments should not be construed as limiting in any way.

For example, in the injection apparatus of the above embodiment, in the resin injection step, the injection pressure is applied by closing the open / close valve 76 provided on the external pipe 72 for supplying the inert gas. The resulting molten resin may be prevented from entering the gas injection port 70.

In the injection device shown in the first embodiment, a check valve is provided on the connecting resin passage 54 for guiding the molten resin from the plasticizing cylinder 10 to the injection cylinder 16 so that the injection valve can be used for injection. It is also possible to prevent the backflow of the resin material in the above.

Further, the specific shape of the mixing head portion 82 in the screw device shown in the second embodiment is not particularly limited, but may be any of various projection shapes effective for stirring the molten resin. Can be adopted.

Further, the injection position of the inert gas into the passage of the molten resin does not have to be one, and the inert gas can be injected simultaneously or selectively into a plurality of positions of the molten resin passage. Is also possible.

Further, the material of the resin material to which the present invention is applied is not limited at all, and the present invention is applicable to any known injection apparatus for injection molding various resin materials. Obtaining is, of course.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, various changes, modifications, improvements, and the like can be made, and unless such embodiments depart from the spirit of the present invention.
Both are included in the scope of the present invention,
Needless to say.

[0054]

As is apparent from the above description, in the injection device having the structure according to the present invention, the plasticization of the screw device is achieved by adopting the pre-plasticization type structure including the screw device and the injection device. In a region from the cylinder to the connection passage, a resin passage is formed in which a steady flow is generated without a temporal change in the passage cross-sectional area, and an inert gas is injected into the resin passage. The contact state with the molten resin is stabilized, and the effect of modifying the resin material by dissolving the inert gas into the molten resin can be exhibited stably.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing the overall schematic structure of an injection device as a first embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional view showing a main part of an injection device according to a second embodiment of the present invention.

FIG. 3 is an explanatory longitudinal sectional view showing an overall schematic structure of an injection device as a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Plasticizing cylinder 12 Screw 14 Screw device 16 Injection cylinder 18 Plunger 20 Plunger device 28 Discharge nozzle hole 52 Injection nozzle hole 54 Connection resin passage 72 External pipeline

Continuing from the front page (72) Inventor Hirotaka Okamoto 41, Chukumi Yokomichi, Oku-cho, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside the Toyota Central R & D Laboratories Co., Ltd. No. 1 Inside Toyota Central Research Laboratories Co., Ltd. (72) Inventor Norio Sato 41-cho, Yokomichi, Oku-cho, Nagakute-cho, Aichi-gun, Aichi Prefecture No. 1 Inside Toyota Central Research Laboratories Co., Ltd. (72) Inventor Mitsumasa Matsushita 41, Yokomichi 41

Claims (6)

[Claims] 1. A plasticizing cylinder in which a screw is inserted and arranged, and a resin material supplied from a rear part of the plasticizing cylinder is fed to the front of the plasticizing cylinder by rotation of the screw to be heated and melted, A screw device that discharges from a discharge nozzle hole at the tip of the plasticizing cylinder, and an injection cylinder in which a plunger is inserted and arranged,
A plunger device configured to guide and store the molten resin material discharged from the screw device into the injection cylinder, and to inject the molten resin material through an injection nozzle hole at the tip of the injection cylinder as the plunger advances. In the chemical injection device, at least one of the inside of the plasticizing cylinder in the screw device and the inside of a connection passage for guiding the molten resin material discharged from the screw device to the injection cylinder of the plunger device. A gas supply path for supplying an inert gas from the outside to dissolve the inert gas in the molten resin. 2. The screw device according to claim 1, wherein a check valve is provided at a tip portion of the screw, and the gas supply path is opened in the passage of the molten resin material closer to the screw tip than the check valve. 2. The injection device according to 1. 3. A pressure reducing section having an enlarged passage cross-sectional area of a molten resin is formed in the plasticizing cylinder of the screw device, and the gas supply path is opened to the pressure reducing section. 3. The injection device according to 2. 4. An agitating blade protruding from an outer peripheral surface is provided at a tip end portion of the screw in the screw device, and the gas supply passage is provided rearward of a position where the agitating blade of the screw is provided in the plasticizing cylinder. The injection device according to any one of claims 1 to 3, wherein an opening is provided. 5. The plunger device according to claim 1, further comprising an injection valve for communicating / blocking the injection nozzle hole.
The injection device according to any one of claims 1 to 4. 6. The injection device according to claim 1, further comprising a gas supply valve that connects / disconnects the gas supply path.