JP3227199U - Screw injection device and injection molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a high-strength and lightweight micro-foam molded article that does not contain coarse bubbles due to water or residual monomer in a screw injection device. A screw injection device (10) has a vent hole (11a) for discharging steam from the inside of a plasticizing cylinder (11) and a reinforcing material supply hole (11b) for supplying a predetermined reinforcing material into the cylinder. A supercritical fluid supply hole 11c for supplying a predetermined supercritical fluid into the cylinder is formed on the tip side of these holes. [Selection diagram] Figure 1

Description

The present invention relates to improvements in a screw injection device and an injection molding device configured using the same.

Conventionally, a fine foam molding method using a supercritical fluid as a foaming gas is known as a technique capable of reducing the weight of an injection molded product. By using this method, a lightweight molded product can be obtained by containing a large number of fine foams inside. However, the molded product thus obtained tends to have lower strength than the conventional molded product that does not involve fine foaming.

On the other hand, for example, in the following patent documents, a reinforcing fiber is obtained by using a resin composition in which reinforcing fibers are kneaded in advance, and then molding the resin by injecting a supercritical fluid of a foaming gas into the resin. It is described that a fine foamed molded product having a better impact resistance than that of a conventional molded product which does not contain the above can be obtained.

JP 2012-192630 A

If the resin before molding contains water or a volatile residual monomer, bubbles may occur in the molded product. In particular, in the case of fine foam molding, when coarse bubbles are generated due to moisture or residual monomer, the strength is significantly reduced at that portion, which becomes a problem. Conventionally, as a measure against such a problem, it has been general to dry resin pellets in advance. However, the water and the residual monomer contained in the resin cannot be completely removed only by drying, and the water and the residual monomer adversely affect the strength of the fine foam molded article.

The present invention has been made in view of this problem, and it is possible to reliably remove water and residual monomers, and to inject a resin containing a reinforcing fiber and a foaming gas to produce a high-strength and lightweight micro-foam molding. An object of the present invention is to provide a screw injection device capable of manufacturing a product and an injection molding device using the same.

The screw injection device according to the present invention has a plasticizing cylinder in which a screw is inserted. The plasticizing cylinder has a vent hole in the middle thereof for discharging steam from the cylinder and a predetermined reinforcing material in the cylinder. Reinforcing material supply holes for supplying the, and the tip side of these holes, characterized in that a supercritical fluid supply hole for supplying a predetermined supercritical fluid into the cylinder is formed To do.

Also, the injection molding apparatus according to the present invention comprises a combination of the screw injection apparatus and a molding die.

According to the present invention, the plasticized resin is vented to remove impurities such as water and residual monomers, and the reinforcing fiber and the foaming gas used as a supercritical fluid are supplied to the resin. It is possible to manufacture a high-strength, lightweight micro-foam molded article that does not contain coarse bubbles due to residual monomers.

It is a longitudinal section showing the schematic structure of an example of an embodiment. It is a phase diagram regarding temperature and pressure of a general substance. It is a longitudinal cross-sectional view which shows the schematic structure of the modification of embodiment. It is a longitudinal section showing a schematic structure of other modification of an embodiment. It is a longitudinal cross-sectional view which shows the schematic structure of the further modified example of embodiment. It is a longitudinal cross-sectional view which shows the schematic structure of the further modified example of embodiment. (A)-(e) is a side view of a specific example of the tip device mounted on a screw, a vertical cross-sectional view, a cross-sectional view when the tip side is viewed, a cross-sectional view when the rear side is viewed, and It is a front view of the valve body accommodated in a tip device. (A), (b) is a side view of a specific example of a tip device explaining a state when a valve element moves back and forth. (A) is a side view of another example of the tip device, and (b) and (c) are transverse sectional views for explaining the operation of the tip device. 1 is a vertical sectional view showing a schematic configuration of an injection molding device according to the present invention. (A)-(d) is a series of sectional drawings explaining an operation of an injection molding device in time series. (A) is a simple cross-sectional view for explaining the progress of the resin in the mold, and (b) is a simple cross-sectional view of the solidified work.

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of an injection device as an example of the embodiment.
As described in detail below, the injection device 10 removes impurities such as water and residual monomers from a plasticized resin by a vent, and the reinforcing fiber (reinforcing material) F and a supercritical fluid are added to the resin. Since it is configured to supply the foaming gas S described above, it is possible to manufacture a high-strength, lightweight micro-foam molded article that does not contain coarse bubbles due to water or residual monomer.
PLA (polylactic acid), PA (polyamide), PET (polyethylene terephthalate), PP (polypropylene), and the like are suitable as the resin, but the resin is not limited to these.

The injection device 10 is of an in-line screw type and has a plasticizing cylinder 11 into which a screw 12 is inserted.

The cylinder 11 is a cylindrical body made of magnetic metal such as ordinary steel. The cylinder 11 is provided with an injection nozzle 13 at its front end and is opened at its rear end to extend the screw 12 rearward. Further, the cylinder 11 has a vent hole 11a for releasing water vapor of the residual monomer from the inside of the cylinder 11 and a reinforcing material supply hole 11b for supplying a predetermined reinforcing fiber F into the cylinder 11 in an intermediate portion thereof. Further, a supercritical fluid supply hole 11c for supplying the supercritical fluid S of the foaming gas into the cylinder 11 is formed on the tip side of these holes. A resin pellet supply hole 11d for supplying the resin pellet PP into the cylinder 11 is formed at the rear end of the cylinder 11, and a hopper 14 for storing the resin pellet PP is provided above the resin pellet supply hole 11d. ..

The cylinder 11 has an induction heating coil 15 wound around its peripheral wall surface. A power supply device or the like for supplying an alternating current to the coil 15 is not shown. A heat insulating material 16 is arranged in a tubular shape so as to cover the coil winding portion of the cylinder 11. The type of the heat insulating material 16 is not particularly limited.
The induction heating of the cylinder 11 will be briefly described. An alternating current is applied to the coil 15 to generate an alternating magnetic field in the axial direction of the cylinder 11. Since the cylinder 11 is made of a magnetic metal exhibiting a high magnetic permeability, most of its magnetic field passes through the wall surface of the cylinder 11. Then, an eddy current is induced in the wall surface of the cylinder 11 in the direction canceling the change of the magnetic field, that is, in the circumferential direction. The cylinder 11 is heated by the Joule heat generated by this eddy current. By using such induction heating, the heating device for the cylinder 11 becomes compact and the efficiency becomes high.

The injection nozzle 13 is of a shut-off type, is formed in a substantially conical shape so as to be automatically aligned with the nozzle receiving portion of the molding die, and has a resin injection port 13a at the tip thereof. The valve mechanism 13b can control opening and closing.

The screw 12 is a rod body made of ordinary steel or various alloys, and has a series of spiral grooves formed over substantially the entire length except for the tip portion. The screw 12 has a different shaft diameter or groove shape for each part, so that the supply region 12b, the measuring region 12c, the vent region 12d, and the mixing region 12e are set in order from the rear end to the front end. The volume per pitch of the metering region 12c is set so that the resin feed amount per rotation of the screw 12 becomes a predetermined value. The volume per pitch of the supply region 12b and the vent region 12d is set larger than that of the metering region 12c. In the mixing region 12e, protrusions, ridges, etc. having a special shape are regularly arranged, and the reinforcing fibers F and the supercritical fluid S supplied into the cylinder 11 are uniformly mixed with the resin P. ing.

When the screw 12 is rotated with an alternating current flowing through the coil 15, the resin pellets PP dropped from the hopper 14 to the supply region 12b in the cylinder 11 are transported to the tip side of the cylinder 11 and pressed in the measuring region 12c. , Plasticized. The plasticized resin P is temporarily depressurized in the vent region 12d. Therefore, by disposing the vent hole 11a and the reinforcing material supply hole 11b in the depressurized vent region 12d, the resin ejection phenomenon (vent up phenomenon) can be suppressed. Since the plasticized resin P is at a high temperature, moisture and residual monomer vapor are easily released from the vent hole 11a opened to the outside, and as a result, the resin P is not exposed to moisture and water on the tip side of the vent hole 11a. It becomes a high-purity product in which residual monomers are almost completely removed. Thereafter, the resin P is mixed with the reinforcing fiber F from the reinforcing material supply hole 11b and further injected with the supercritical fluid S from the supercritical fluid supply hole 11c, and the reinforcing fiber F and the supercritical fluid S are mixed in the mixing region 12e. Is kneaded with the resin P.

The rear end of the screw 12 is connected to a motor device 18 through a power cylinder device 17. Here, the motor device 18 is a power source for rotating the screw 12, and the power cylinder device 17 is a power source for moving the screw 12 back and forth.

The power cylinder device 17 includes a hydraulic cylinder, an electric cylinder, and the like. Here, the basic structure of the hydraulic cylinder is shown as an example. The screw 12 is moved back and forth by adjusting the hydraulic pressure applied to the illustrated chambers A and B. When the screw 12 moves forward, the resin P accumulated at the tip of the cylinder 11 is injected from the injection nozzle 13.

On the other hand, the motor device 18 is composed of a motor unit such as a stepping motor, a brush motor, a brushless motor and a power transmission mechanism. When the motor device 18 rotates the screw 12, the resin pellet PP or the plasticized resin P is transported toward the tip of the cylinder 11 by the action of the spiral groove.

The reinforcing material supply device 20 is an element that supplies the reinforcing fibers F to be kneaded with the resin P. The reinforcing fiber F supplied to the reinforcing material supply hole 11b of the cylinder 11 is mixed with the resin P and automatically drawn into the cylinder 11. Therefore, the reinforcing material supply device 20 can be simply configured by, for example, a holding portion of a reel that supplies the reinforcing fiber F, a fiber yarn feeding guide, and the like as illustrated.

As the reinforcing fiber F, a carbon fiber filament yarn (long fiber), a carbon fiber tow (a bundle of several thousands to tens of thousands of filaments) and the like are suitable, but the reinforcing fiber F is not limited thereto. For example, a glass fiber filament may be used as another reinforcing fiber, or a carbon fiber filament and a glass fiber filament may be mixed and used. Alternatively, a chopped fiber in which the fiber tow is cut into a predetermined length in advance may be used.

The reinforcing material is not limited to a fibrous material, and a granular material can be used. For example, carbon, ceramic, glass powder and the like. It is considered that the fibrous reinforcing material mainly contributes to the tensile strength of the molded product, and the granular reinforcing material contributes to the compressive strength of the molded product.

The reinforcing fiber F supplied into the cylinder is cut into an appropriate length by the screw 12 in the vent region 12d. The chopped reinforcing fibers F are uniformly dispersed in the resin P by the mixing in the mixing region 12e.

The supercritical fluid supply device 21 is an element that pressurizes a foaming gas such as nitrogen or carbon dioxide and sends out the supercritical fluid S at a constant flow rate, and is composed of a tank, a heater, a pressure pump, a solenoid valve, and the like. It

The supercritical fluid injection device 22 is an element for receiving the supercritical fluid S from the supercritical fluid supply device 21, adjusting the pressure of the fluid, and injecting the fixed amount into the cylinder 11 from the supercritical fluid supply hole 11c. , Pressure sensor, solenoid valve, etc.

FIG. 2 is a phase diagram relating to temperature and pressure of a general substance. As shown in this phase diagram G, the substance has three phases: solid, liquid, and gas. Usually, when gas is compressed, it becomes liquid at a certain pressure. However, if the temperature exceeds a certain value at this time, it will not become liquid no matter how much pressure is applied. Such a value is called the critical temperature of the substance. Further, when the liquid is heated, it usually becomes a gas at a certain temperature. However, if the pressure exceeds a certain value at this time, it will not turn into a gas no matter how much it is heated. Such a value is called the critical pressure of the substance.
When both the temperature and the pressure of the substance exceed the critical temperature and the critical pressure, the substance is a fluid in a state where gas and liquid cannot be distinguished, that is, a supercritical fluid. Supercritical fluids are known to exhibit both high diffusivity of gases and high solubility of liquids.

The reason why the foaming gas is made into a supercritical fluid and injected into the cylinder is that a large amount of gas is injected, so it is necessary to make it high pressure, and as a result, it becomes a supercritical fluid. Is easy. Further, if the foaming gas is injected into the cylinder in a supercritical fluid state, it is considered that the diffusivity immediately after the injection is also improved.
Although the solubility of the foaming gas in the resin increases with the pressure of the resin, the supercritical fluid injection device controls the injection amount of the foaming gas so that the injection amount of the foaming gas is slightly lower than the saturation amount. Then, by sufficiently mixing the resin in which the foaming gas is injected, a single-phase resin in which bubbles of the foaming gas are not mixed is obtained. Further, the reinforcing material is appropriately cut by this mixing and is well dispersed in the resin. When such a resin is injected into the mold, the foaming gas is rapidly reduced in solubility due to the reduced pressure in the mold, and the foaming gas is vaporized to generate a large number of minute bubbles in the resin.
Further, after the resin is injected into the molding die, the injection pressure spreads it to the cavities and the like. However, since the resin in which a large number of minute bubbles are generated has a reduced viscosity and becomes soft, the injection pressure can be lowered. If the injection pressure is low, the pressure that the molding die receives from the resin is also small, so the mold clamping force can be small and the press machine can be downsized. For example, in the case of a resin pallet having an area of about 0.5 to 1 square meter, a mold clamping force of about 700 to 3000 tons was conventionally required, but this can be reduced to about 450 to 1000 tons. Further, since the decrease in strength of the molded product due to the minute foaming of the resin is compensated by the blending of the reinforcing fiber, it is possible to reduce the weight by about 10 to 30% while maintaining the strength of the molded product.

Further, in the present embodiment, since water and residual monomer are removed from the resin by the vent, it is not necessary to dry the resin pellets in advance, and since coarse air bubbles due to water and residual monomer are not generated in the molded product, the molded product It is possible to suppress the decrease in strength.

FIG. 3 is a vertical sectional view showing a schematic configuration of a modified example of the embodiment.
The major difference between this modification and the embodiment shown in FIG. 1 is that a reinforcing material supply amount adjusting device 23 that freely adjusts the supply amount of the reinforcing fiber F is provided.

The reinforcing material supply amount adjusting device 23 may be configured by combining a drive roller whose rotation speed is adjustable and a driven roller facing the drive roller. In such a case, if the rotation speed of the drive roller is adjusted with the reinforcing fiber F sandwiched between the driving roller and the driven roller, the supply amount of the reinforcing fiber F changes according to the rotation speed. By providing such a reinforcing material supply amount adjusting device 23, for example, it becomes possible to supply a larger amount or a smaller amount of the reinforcing fiber F than that which is automatically drawn into the cylinder 11, so that the strength of the molded product is improved. Can be adjusted freely. The reinforcing material supply amount adjusting device 23 may adjust the number (tow) of filament yarns. Further, the reinforcing material supply amount adjusting device 23 may be provided with a cutting means for automatically cutting the reinforcing fiber F into an appropriate length, and may always supply the reinforcing fiber F having a constant length to the reinforcing material supply hole 11b. (Not shown).

Further, in this modification, the vent hole 11a and the resin supply hole are formed as one common hole. If the vent hole 11a and the resin supply hole are formed as one common hole, there is an advantage that the manufacturing cost of the cylinder 11 can be suppressed.
Since other elements are common to the above-described embodiment, the common elements are designated by the same reference numerals and the description thereof will be omitted.

FIG. 3A is a vertical cross-sectional view showing a schematic configuration of another modified example of the embodiment. The elements common to the above-described embodiments are designated by the same reference numerals and the description thereof will be omitted.
The major difference between this modified example and the above-described embodiment is that it further comprises a heat treatment device 24 for supplying heat to the reinforcing fiber F before it is supplied to the reinforcement material supply hole 11b to generate heat, and further treats by the heat treatment device 24. That is, the reinforcing fiber F after being treated is provided with a surface treatment device 25 for performing a predetermined surface treatment.

The reinforcing fibers F are assumed to be carbon fiber filament yarns and tows. The filament yarn is a fiber bundle in which a large number of single fibers having a thickness of 5 to 10 μ are converged, and the tow is a fiber bundle in which a few thousand to tens of thousands of filament yarns are converged. These filament yarns and tows are coated with a resin such as an epoxy-based resin, a urethane-based resin, or a polyamide-based resin as a sizing agent for suppressing the fraying of the fiber bundle.

The reinforcing fiber F in the present invention is intended to reinforce a molded product, but important for that purpose are workability and dispersibility during injection molding and adhesion with a resin after curing. It is the strength (the resistance to the resin being pulled out). In general, the resin (matrix) and the sizing agent are compatible with each other, and when the compatibility is poor, satisfactory dispersion and strong adhesion with the resin cannot be achieved even if the reinforcing fiber F is kneaded. Can't get Therefore, it is desirable to remove the sizing agent having poor compatibility with the resin or the unknown sizing agent before the reinforcing fiber F is supplied to the reinforcing material supply hole 11b. The heat treatment apparatus 24 of the present modification is to remove the sizing agent by vaporizing and thermally decomposing the sizing agent by energizing the reinforcing fiber F to generate heat.

The heat treatment apparatus 24 is composed of metal grippers (clips) arranged at predetermined intervals as electrodes 24a connected to the reinforcing fibers F, and is connected to a power supply device 24b that supplies DC power or AC power to them. Since carbon fiber is a conductor, it heats itself when an electric current is passed through it. The opening and closing of the metal gripping tool may be performed automatically. If the metal gripping tool is used as the electrode 24a, the heat treatment device 24 heat-treats the reinforcing fiber F by a constant length, but the electrical connection with the reinforcing fiber F is ensured and abnormal heat generation occurs at the connecting portion. Etc. is less likely to occur.

The surface treatment device 25 performs a predetermined surface treatment on the reinforcing fiber F that has been treated by the heat treatment device 24, for example, a treatment such as coating a specific sizing agent or a chemical agent having excellent adhesiveness with a resin. is there. There is no particular limitation on the specific configuration of the surface treatment device 25. For example, a treatment tank (not shown) in which such a sizing agent or a chemical is stored may be provided in the transportation route of the reinforcing fiber F, and the reinforcing fiber F may be immersed in the sizing agent or the like therein. The surface treatment device 25 is connected to a chemical supply device 25a that supplies a sizing agent or the like. By thus re-coding the sizing agent or the like having good compatibility with the resin in the reinforcing fiber F, a sufficient reinforcing effect of the reinforcing fiber F can be obtained.

FIG. 3B is a modification of the heat treatment apparatus 24 of the modification shown in FIG. 3A. In the modification shown in FIG. 3B, the heat treatment device 24 includes metal rollers arranged at predetermined intervals as electrodes 24a connected to the reinforcing fibers F, and a power supply device 24b that supplies DC power or AC power to them. It is connected. The metal roller rotates in accordance with the movement of the reinforcing fiber F to maintain the electrical connection with the moving reinforcing fiber F. With such a configuration, since the reinforcing fiber F can be continuously heat-treated at a desired feed rate including stop, the effect of being able to follow the operation of the injection device without special control is obtained.

FIG. 3C is a vertical sectional view showing a schematic configuration of a further modified example of the embodiment.
The major difference between this modification and the embodiment shown in FIG. 1 is that the plasma processing apparatus 26 that applies surface plasma by applying atmospheric pressure plasma to the reinforcing fiber F before being supplied to the reinforcing material supply hole 11b. Be prepared.

Atmospheric pressure plasma is a technology that has received a great deal of attention in recent years. Briefly described, plasma (ionized gas) is generated under atmospheric pressure by corona discharge, dielectric barrier discharge, RF discharge and the like. Using the plasma, it is possible to perform various surface treatments such as reducing the oxide film by hydrogen radicals, decomposing and removing organic substances on the surface of the substance, coating the surface of the substance by mixing various liquids and gases with plasma, and imparting functional groups. Is. The atmospheric pressure plasma treatment has an advantage that it does not require a vacuum environment and can be continuously treated.

In this modification, the sizing agent coated on the reinforcing fiber F is removed by atmospheric pressure plasma. Further, at the same time, a specific sizing agent may be coated or a specific functional group may be provided. The surface treatment device 25 shown in FIG. 3A may be provided on the downstream side of the plasma treatment device 26 to recoat the reinforcing fiber F with a sizing agent or the like having excellent adhesiveness to the resin.

The configuration of the plasma processing device 26 is not particularly limited. For example, the plasma may be jetted from a jet nozzle guided from a plasma generation device (not shown), and the plasma may be directly blown to the reinforcing fiber F being transported. Alternatively, an electrode for plasma generation may be arranged in the transportation path of the reinforcing fiber F to generate plasma in the vicinity of the reinforcing fiber F. The illustrated plasma processing apparatus 26 includes a gas supply apparatus 26a for supplying a gas to be plasma and a power supply for supplying power to generate corona discharge, dielectric barrier discharge, RF discharge, etc. in the plasma processing apparatus 26. The device 26b is connected.

By the way, in the embodiment and its modification, the check valve is not provided at the tip of the screw, but if a tip device having a check valve function is attached to the tip of the screw, the injection pressure can be adjusted with high accuracy. Be in control. However, it is necessary to devise a method for suppressing the breakage of the reinforcing fiber F that tends to occur at the check valve portion.

3D(a) to 3D(e) are side views of a specific example of a tip device having a check valve function and in which breakage of the reinforcing fiber F is suppressed, a vertical cross-sectional view along the central axis, and the tip side is viewed. FIG. 4 is a horizontal cross-sectional view when viewed from above, a horizontal cross-sectional view when viewed from the rear side, and a front view of a spherical valve body housed in the tip device. The vertical cross-sectional view of FIG. 3D(b) is taken by cutting the tip device along a plane S including the center line thereof, and the cross-sectional views of FIGS. 3D(c) and 3(d) are all perpendicular to the center line of the tip device. It is cut at a plane T to be cut.

The tip device 27 is a rod-shaped body made of ordinary steel or various alloys and having a taper portion 27a on the tip side, and a screw portion 27b for fixing to the screw 12 at the rear end portion. Further, the tip device 27 has a cylinder sliding contact portion 27c that slidably contacts the inner wall surface of the cylinder 11. The cylinder sliding contact portion 27c separates the space V at the tip of the cylinder 11 for storing the resin before injection from the space W at the rear side for melting and kneading the resin. Inside the tip device 27, a valve body accommodating sinus 27d for accommodating the spherical valve body 28 so as to be movable back and forth is formed.

The spherical valve body 28 is a spherical body made of ordinary steel or various alloys. The valve body accommodating sinus 27d has a cocoon shape in which a spherical body having substantially the same size as the spherical valve body 28 is divided into two and a cylindrical body is sandwiched therebetween. With such a shape, the spherical valve body 28 can smoothly move back and forth inside the valve body housing cavity 27d.

An opening 27e serving as a resin inlet is arranged on an outer wall surface rearward of the cylinder sliding contact portion 27c of the tip device 27, and an opening 27f serving as a resin outlet is arranged on the wall surface forward of the cylinder sliding contact portion 27c. A fluid passage 27g that connects these openings 27e and 27f is formed in combination with the valve body accommodating sinus 27d. The structure of the fluid passage 27g is as follows. The opening 27e, which serves as an inlet for the resin, is communicated with the rear wall surface of the valve body accommodating sinus 27d which comes into contact when the spherical valve body 28 moves rearward. The communication port 27h is opened when the spherical valve body 28 is on the front side, but when the spherical valve body 28 moves to the rear side, the communication port 27h is closed by the spherical valve body 28.

Then, a resin guide groove 27i is formed starting from the vicinity of the front side of the communication port 27h and ending at an appropriate position on the front wall surface of the valve body accommodating sinus 27d which comes into contact when the spherical valve body 28 moves to the front side. There is. The resin guide groove 27i serves as a path for the resin to move around the spherical valve body 28.
Further, an opening 27f serving as a resin outlet is arranged on the outer wall surface in front of the cylinder sliding contact portion 27c of the tip device 27, and the opening 27f communicates with the bottom surface near the end point of the resin guide groove 27i. Since the communication port 27j is located on the bottom surface of the resin guide groove 27i, the spherical valve body 28 is always open regardless of the position on the front side or the rear side.

3E(a) and 3E(b) are side views of a specific example of the tip device for explaining the state when the spherical valve body moves back and forth. In these figures, the movement of the resin P is shown by the gray arrow.
The spherical valve body 28 melts the resin and moves back and forth in the valve body accommodating sinus 27d due to the difference between the pressure of the resin in the space W on the rear side of the cylinder 11 and the pressure of the resin in the space V at the tip of the cylinder 11. That is, when the tip device 27 (screw 12) retracts, the pressure of the resin P in the space W on the rear side of the cylinder 11 increases, and the spherical valve body 28 receives a reaction force from the resin P and moves to the front side. As a result, the fluid passage 27g is opened. On the other hand, when the tip device 27 (screw 12) advances, the pressure of the resin P in the space V at the tip of the cylinder 11 increases, and the spherical valve body 28 receives a reaction force in the opposite direction from the resin P from the resin P. Move to the rear side. As a result, the fluid passage 27g is closed.

In short, the spherical valve element 28 receives the reaction force of the fluid P associated with the backward movement or forward movement of the tip device 27 in the cylinder 11 to move back and forth to open and close the fluid passage 27g. As a result, the tip device 27 exerts a check valve function. At this time, the spherical valve body 28 moves back and forth with only the outer peripheral portion in contact with the wall surface of the valve body accommodating sinus 27d, and the sliding area at that time is small. Fracture at the sliding surface is also extremely reduced.

FIG. 3F(a) is a side view of another example of the tip device, and FIGS. 3F(b) and 3C are transverse sectional views for explaining the operation of the tip device. In FIGS. 3F(b) and 3F(c), the movement of the resin P is indicated by gray arrows. The same elements as those in the above example are designated by the same reference numerals and the description thereof will be omitted.

The tip device 27 is different from the above example in the shape of the valve body accommodating sinus 27d. That is, the valve body accommodating cavity 27d has a shape in which a cylindrical portion 27d1 having a smaller diameter than the spherical valve body 28 and a cylindrical portion 27d2 having a large diameter are coaxially connected, and the spherical valve 28 body is accommodated in the large diameter cylindrical portion 27d2. Has been done. On the inner peripheral surface of the large-diameter cylindrical portion 27d2, a plurality of guide protrusions 27d3 for preventing rattling of the spherical valve body 28 are formed in the front-rear direction, and the spherical valve body 28 is guided by the guide protrusion 27d3. It moves back and forth on the axis of the large diameter cylinder 27d2.

The opening 27e provided behind the cylinder sliding contact portion 27c communicates with the end of the small diameter cylindrical portion 27d1. On the other hand, the opening 27f provided in front of the cylinder sliding contact portion 27c communicates with the end of the large diameter cylindrical portion 27d2. At this time, the fluid passage 27g that connects the openings 27e and 27f is configured by the small diameter cylindrical portion 27d1 and the vicinity of the inner peripheral surface of the large diameter cylindrical portion 27d2 (the gap between the spherical valve body and the inner peripheral surface). Become. Further, the small-diameter cylindrical portion 27d1, the large-diameter cylindrical portion 27d2, and the edge of the connecting portion are chamfered so that they can come into contact with the spherical valve body 28 without a gap. Therefore, the connecting portion will be closed by the spherical valve body 28 when the spherical valve body 28 is retracted.

The mechanism for back and forth movement of the spherical valve body 28 is similar to the above, and the tip device 27 exerts a check valve function by opening and closing the fluid passage 27g. Further, since the spherical valve element 28 moves back and forth in contact with only the guide protrusion 27d3, and the sliding area at that time is small, the reinforcing fiber F is broken at the sliding surface. Is also very low. Further, in this example, since the passage width of the fluid passage 27g can be sufficiently secured, the fluid can be smoothly passed.

Next, an injection molding device in which a molding die is combined with the screw injection device will be described.
FIG. 4 is a vertical sectional view showing a schematic configuration of the injection molding apparatus.

In the figure, a part of a cylinder 11 that constitutes the injection device 10 and a molding die 31 are shown as main parts of the injection molding device 30, and a frame portion and the like for holding them are not shown. Although a three-plate type mold is used here, it is not limited to the three-plate type.

The molding die 31 is composed of first to third dies 31a to 31c.
The first mold 31a is fixed to the movable side mounting plate 32. The second and third molds 31b and 31c are attached to the fixed-side attachment plate 33 so as to be able to move forward and backward. A nozzle receiving portion 33 a that receives the injection nozzle 13 of the injection device 10 is formed on the fixed side mounting plate 33.
A cavity 31d is formed on the surface of the first die 31a, and a core 31e housed in the cavity 31d is formed on the second die 31b. The cavity 31d and the core 31e form a work of a molded product.
The third mold 31c is provided with a runner cavity 31f. A runner is formed by the back surface of the second mold 31b and the runner cavity 31f of the third mold 31c. The runner cavity 31f is connected to the surface of the core 31e through a thin gate, and is connected to the injection nozzle 13 of the resin injection cylinder 22 through a spool.
Further, the protruding pin 34 penetrates from the back surface of the third mold 31c to the front surface of the core 31e. The projecting pin 34 is capable of advancing and retracting with respect to the third mold 31c, and can push the molded work from the core 31e.
The resin P injected from the cylinder 11 expands into the cavity 31d while generating minute bubbles of the foaming gas by depressurization and growing the bubbles. Since the bulk of the resin P increases due to the growth of bubbles, the gate connecting the cavity 31d and the runner cavity 31f is provided in the thin portion of the work, whereby the resin P is the thin portion of the work. It is thought that it is desirable to proceed from the above to the thick part.

5A to 5D are a series of cross-sectional views for explaining the operation of the injection molding apparatus in time series.

In FIG. 5A, the mold 31 is closed and the protruding pin 34 is in the retracted position. The injection nozzle 13 of the cylinder 11 is communicated with the runner cavity 31f of the third mold 31c via the fixed-side mounting plate 33. In this state, the molten resin P is injected from the cylinder 11 into the mold 31 to mold the work. The temperature of the mold 31 is appropriately controlled in each step of resin injection and curing. The injection device 10 holds the resin for a predetermined time after the injection of the resin.

In FIG. 5B, the molding of the work 2 is completed and the first and second molds 31a and 31b are opened. At this time, the runner 2a is separated from the resin injection cylinder 22 by retracting the cylinder 11. At this time, the work 2 is in a state of being fitted into the core 31e.

In FIG. 5C, the protruding pin 34 is advanced. As a result, the work 2 is removed from the core 31e, and the work 2 and the runner 2a are automatically cut and separated at the gate portion. The work 2 separated from the runner 2 a is taken out of the mold 31 by the work take-out device 40.

In FIG. 5D, the second mold 31b is separated from the third mold 31c. This makes it possible to remove the runner 2a from the third mold 31c.

Finally, the structural features of the workpiece manufactured by the injection molding apparatus will be described with reference to FIGS. 6(a) and 6(b).

FIG. 6A is a simple cross-sectional view for explaining the progress of the resin P in the mold 31. In the figure, the white arrow indicates the traveling direction of the resin P. It is considered that the traveling speed of the resin P is faster in the central portion than in the interface portion with the mold 31, and therefore, more bubbles B are generated in the central portion.
Further, the resin P progresses while vigorously bursting and evaporating the foaming gas from the interface with the space at the tip of the traveling direction, so that the interface with the space in which the bubbles B are reduced is made by the resin P coming later from the mold. It is considered that a new interface portion with the die 31 is formed by being pushed toward the boundary with the mold 31. As a result, the resin P fat is solidified with a small amount of bubbles B at the interface with the mold 31 and a large amount of bubbles B at the center. The foaming gas evaporated from the resin P into the space inside the mold 31 is discharged to the outside from a vent portion provided at an appropriate position of the mold 31.

FIG. 6B is a simple sectional view of the solidified work. As shown in the drawing, the work 2 has a multi-layer structure in which the skin layer SL containing almost no bubbles B is formed in the surface layer portion and the core layer CL containing many bubbles B is formed in the center portion of the thickness. Although the reinforcing fibers F are uniformly dispersed in the resin P, the skin layer SL has a smaller number of bubbles B and a higher density than the core layer CL, and therefore the skin layer SL has a higher density than the core layer CL. The reinforcing fibers F are mixed in high density. Therefore, the skin layer SL becomes tougher than the core layer CL.
As described above, according to the present embodiment, the reinforcing fiber F is dispersed in the resin, and the molded product does not contain coarse bubbles (500 microns or more) and contains a large amount of fine bubbles B (5 to 50 microns). Is obtained.

10 Screw Injection Device 11 Plasticizing Cylinder 11a Vent Hole 11b Reinforcing Material Supply Hole 11c Supercritical Fluid Supply Hole 12 Screw 15 Induction Heating Coil 20 Reinforcing Material Supply Device 21 Supercritical Fluid Supply Device 23 Reinforcing Material Supply Amount Control Device 24 Heat Treatment Device 25 Surface Treatment Device 26 Plasma Treatment Device 27 Tip Device 27c Cylinder Sliding Contact Area 27d Valve Body Housing Cave 27e, 27f Opening 27g Fluid Passage

Claims (9)

In a screw injection device having a plasticizing cylinder with a screw inserted,
The plasticizing cylinder is provided with a vent hole for discharging steam from the inside of the cylinder and a reinforcing material supply hole for supplying a predetermined reinforcing material into the cylinder, and the tip side of these holes. A screw injection device, characterized in that a supercritical fluid supply hole for supplying a predetermined supercritical fluid is formed in the cylinder. The screw injection device according to claim 1,
An induction heating coil is wound around a peripheral wall surface of the plasticizing cylinder. The screw injection device according to claim 1 or 2,
A reinforcing material supply device for supplying carbon fibers to the reinforcing material supply hole,
A screw ejection device comprising: a supercritical fluid supply device for supplying a supercritical nitrogen fluid to the supercritical fluid supply hole. The screw injection device according to claim 3,
The screw injection device further comprising a reinforcing material supply amount adjusting device for freely adjusting the supply amount of the carbon fibers. The screw injection device according to claim 3,
The screw injection device further comprising a heat treatment device that heats the carbon fibers before they are supplied to the reinforcing material supply holes by supplying electricity. The screw injection device according to claim 5,
The screw injection device further comprising a surface treatment device for subjecting the carbon fiber after being treated by the heat treatment device to a predetermined surface treatment. The screw injection device according to claim 3,
The screw injection device further comprising a plasma processing device that applies atmospheric pressure plasma to the carbon fibers before being supplied to the reinforcing material supply holes to perform surface treatment. The screw injection device according to any one of claims 1 to 7,
The screw is equipped with a tip device having a check valve function,
The tip device is
It has a cylinder sliding contact portion that slidably contacts the inner wall surface of the plasticizing cylinder,
A valve body accommodating sinus for accommodating a spherical valve body so as to be movable back and forth is formed inside, and an opening arranged on an outer wall surface rearward of the cylinder sliding contact portion and an opening arranged on a front outer wall surface. A fluid passage communicating with the valve body accommodating sinus is formed,
The screw injection device, wherein the spherical valve body moves back and forth by receiving a reaction force from a fluid accompanying the movement of the screw in the cylinder to open and close the fluid passage. An injection molding apparatus comprising a screw injection apparatus according to any one of claims 1 to 8 and a molding die.

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