JP4174403B2 - Injection molding equipment - Google Patents

Description

The present invention relates to an injection molding apparatus for preventing entrainment of air and gas into a molded product by injection molding of a resin or a metal such as magnesium or aluminum.

When resin or metal is injection molded, air in the cavity, or gas generated from the resin or metal is involved during molding, which may cause appearance defects or internal defects in the molded product. In order to eliminate such defects, there are methods for venting a mold, such as providing a labyrinth structure vent around the cavity or embedding a porous ceramic. Also, a method is known in which after mold clamping, the air in the cavity is sucked by means such as a vacuum pump and then injected. In the latter method, a mechanism for opening and closing the suction passage is necessary, and a mechanism for sealing air and molten material so as not to be sucked from the cavity inlet side, that is, the runner and the molding machine nozzle, becomes a problem during suction. In order to solve this problem, a method has been proposed in which a hot runner mold is closed with a pin so that the molten material at the tip of the hot runner nozzle is not sucked (see, for example, Patent Document 1).

JP 2002-86257 A

However, this method has a problem that the mold structure is complicated.
By the way, the applicant of the present invention provides a hot nozzle at the tip of a heating cylinder for heating a material in a molten state or a semi-molten state as one embodiment of a molten metal material injection device, and controls the gate temperature of the hot nozzle. As a result, a molten metal material injection device configured to block the communication with the mold cavity by setting the material of the outlet channel in a solidified state was developed (Japanese Patent Application Laid-Open No. 2000-254664 and Japanese Patent Application No. 2002-318613) .
This invention uses a molten metallic material injection apparatus, such as its, by solidifying the molten material in a hot nozzle of the injection device, without providing a special mechanism in the mold, to prevent ingestion of the molten material An object of the present invention is to provide an injection molding apparatus that can perform the above-described process.

An injection molding apparatus according to the present invention includes a mold provided with a nozzle insertion hole communicating with a cavity and an air suction port, a vacuum pump communicating with the suction port via an on-off valve, and injecting a molten material into the cavity. An injection device. The injection device includes a heating cylinder that heats a resin or metal material in a molten state or a semi-molten state, and a hot part having a gate portion attached to the tip of the heating cylinder and connected to the inside of the heating cylinder. A nozzle and a control device for controlling the temperature of the gate portion of the hot nozzle to melt or solidify the material of the gate portion, and insert the tip of the hot nozzle into the nozzle insertion hole of the mold to hot the cavity The passage of the molten material of the nozzle is communicated. When the control device opens the on-off valve and sucks air in the cavity, the control device controls the temperature of the gate part of the hot nozzle to a temperature at which the material solidifies, and the inside of the cavity is in a vacuum state to close the on-off valve. In this case, the temperature of the gate part of the hot nozzle is controlled to a temperature at which the material melts, so that the molten material can be injected into the cavity.

According to the injection molding apparatus of the present invention , the hot nozzle is inserted into the mold and the mold is closed, and the resin in the gate part of the hot nozzle and the metal are solidified, the on-off valve is opened and the air in the cavity is discharged. After vacuuming or vacuuming, the on-off valve is closed and the material is injected into the cavity for injection molding. Thereby, it is possible to obtain a high-quality molded product without gas entrainment.

  According to the present invention, the gate portion temperature control of the hot nozzle of the injection device melts or solidifies the gate portion so that the material can be opened and closed, so the air in the cavity is sucked without sucking the molten material. It is possible to obtain a molded article of good quality that is free from gas entrainment and exhibits an extremely excellent effect.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
1 is configured to move back and forth with respect to a molding machine main body (not shown), and the figure shows that after the fixed mold 2 is attached to the fixed base 13, The state where the injection device 10 is advanced and the hot nozzle 19 is inserted into the nozzle insertion hole 6 of the fixed mold 2 is shown.
The heating cylinder 11 of the injection apparatus 10 is heated by the outer heater 12, and the material inside the melting path 11A is maintained in a molten state or a semi-molten state.
A hot nozzle 19 is attached to the tip of the heating cylinder 11, and the hot nozzle 19 is formed with a small-diameter outlet passage 20 that communicates with the melting passage 11A and forms a passage for the molten material. Further, the temperature of the gate portion 20a at the distal end of the outlet path 20 is controlled by supplying power through the power line 16 from a control device (not shown).

In this embodiment, the communicating part from the melting path 11A of the heating cylinder 11 to the outlet path 20 of the hot nozzle 19 has a shape in which the upper side is the same surface and the lower side is gradually reduced in diameter toward the upper side. With this shape, it is possible to prevent the gas generated from the molten material in the melting path 11A from being accumulated in the upper portion.

  The mold 1 has a general structure composed of a fixed mold 2 and a movable mold 3, and a detailed description of the structure is omitted. A cavity 4 is a space surrounded by the fixed mold 2 and the movable mold 3 with the mold 1 closed. The injection device 10 advances into the nozzle insertion hole 6 of the fixed mold 2 and the outer periphery of the tip of the hot nozzle 19 is mated in an airtight state.

In the first embodiment , the cavity 4 has a cup shape in which the solid mold 2 side is concave and the movable mold 3 side is convex, and the valve hole 7 is open from the outer surface of the fixed mold 2 toward the inner peripheral surface of the cavity 4. Yes. The valve hole 7 has a stepped shape including a mating hole 7a, a tapered surface 7b, and a relief hole 7c from the tip, and an opening to the inner peripheral surface of the cavity 4 serves as a suction port 8. The cavity 4 does not have a hole communicating with the outside other than the suction port 8.

  A reciprocating cylinder 31 driven by pneumatic pressure is attached to the valve hole 7 via a sleeve 35. When the port of the reciprocating cylinder 31 is switched by the electromagnetic valve 33, the air pressure from the air source 34 is supplied to either the closed side supply hose 32a or the open side supply hose 32b, and the piston 21 reciprocates. The reciprocating cylinder may be driven by hydraulic pressure, electricity, or the like.

The on-off valve 24 connected to the piston 21 of the reciprocating cylinder 31 has a stepped shape of a mating portion 24a, a tapered portion 24b, and a shaft portion 24c from the tip, and when the on-off valve 24 moves forward, it is shown in FIG. Thus, the mating portion 24a of the on-off valve 24 mates with the mating hole 7a of the valve hole 7, the taper portion 24b contacts the tapered surface 7b, closes the suction port 8, and the on-off valve 24 is in the closed state. Become. At this time, an annular path 23 is formed between the clearance hole 7 c of the valve hole 7 and the shaft portion 24 c of the on-off valve 24.
When the on-off valve 24 moves backward, as shown in FIG. 2, the mating portion 24a is separated from the mating hole 7a of the valve hole 7, and the tapered portion 24b is separated from the tapered surface 7b. 23 communicates, and the on-off valve 24 is opened.

  In the sleeve 35, a communication port 35 a communicating with the annular path 23 is formed orthogonal to the shaft portion 24 c of the on-off valve 24. The communication port 35 a is connected to the vacuum pump 36 and the negative pressure gauge 37 by a hose 38. In other places, the circular path 23 and the outside are kept airtight.

Next, the operation of the first embodiment will be described.
When the mold 1 is open, the temperature of the gate portion 20a of the hot nozzle 19 is controlled to a lower temperature at which the material solidifies and is closed by the solidified material.
Next, when the mold 1 is closed, the electromagnetic valve 33 is operated, the on-off valve 24 is opened, and the suction port 8 and the annular path 23 are communicated, the air in the cavity 4 is passed through the annular path 23 and the communication port 35a. The vacuum pump 36 is sucked through the hose 38. Accordingly, the negative pressure gauge 37 indicates a vacuum state of approximately minus 1 atmosphere (about −0.1 MPa).
At this time, since the gate portion 20a of the hot nozzle 19 remains solidified, the molten material is not sucked together.

When a certain time (for example, 5 seconds) has elapsed after opening the on-off valve 24 and the inside of the cavity is in a vacuum state, the on-off valve 24 is closed and the suction port 8 is closed. The time is determined by the volume of the cavity 4, the capacity of the vacuum pump 36, and the like.
In this state, electric power is supplied to the hot nozzle 19, and the temperature of the gate portion 20a is heated to a higher temperature at which the material melts, so that the internal material is melted and ready for injection. In this state, when the material inside the melting path 11A is pushed in by pressing means comprising a cylinder and a piston (not shown) at the rear of the heating cylinder 11, the material is injected from the outlet path 20 of the hot nozzle 19 through the gate portion 20a. And filled into the cavity 4.
When the injection is completed, the temperature of the hot nozzle 19 is again controlled to a lower temperature at which the material solidifies, and the material in the gate portion 20a is solidified. Further, after the molded product in the cavity 4 is cooled and solidified, the mold 1 is opened, the molded product is taken out, and a release agent is sprayed.

  In this way, by controlling the temperature of the hot nozzle 19, it is possible to inject the material while keeping the cavity 4 in a vacuum state while preventing the molten material from being sucked. It is possible to prevent the product from being caught and to obtain a molded product with good quality.

In addition, in this embodiment, as described above, the shape of the communication part from the melting path 11A of the heating cylinder 11 to the outlet path 20 of the hot nozzle 19 is the same surface, and the lower side is temporarily small in diameter toward the upper side. By adopting the shape as described above, it is possible to prevent the gas generated from the molten material in the melting path 11A from accumulating in the upper part, and to make the inside of the heating cylinder 11 in a vacuum state. .
Even if the mold cavity is in a vacuum state, if the molten material to be injected contains gas, entrainment of gas will occur in the molded product. As a result, the quality of the molded product can be further improved.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment , since the cavity 44 has a shallow dish shape, a space for installing the opening / closing valve in the fixed mold 2 parallel to the mold dividing surface 5 cannot be taken. Therefore, the opening / closing valve 54 is installed in the direction perpendicular to the mold dividing surface 5 from the movable mold 3 side.
In this case, the movable mold 3 includes a movable mold plate 45 and a receiving plate 46. The movable mold plate 45 has a valve hole 47 from the receiving plate 46 side toward the mold dividing surface 5. The valve hole 47 has a stepped shape including a mating hole 47a, a tapered surface 47b, a relief hole 47c, a spring seat surface 47d, and a flange mating hole 47e from the tip, and an opening to the cavity 44 is a suction port. 8
Further, the suction hole 49 communicates with the inner side surface of the relief hole 47 c of the valve hole 47 from the side surface of the movable mold plate 45. A hose nipple 39 is attached to the inlet of the suction hole 49 and is connected to the vacuum pump 36 and the negative pressure gauge 37 through the hose 38 as in the first embodiment.
The receiving plate 46 is engraved with a storage groove 46a for storing an eccentric cam shaft 53 described later.

A rotary actuator 61 that is driven by air pressure and rotates 180 ° is attached to a side surface of the receiving plate 46 via a support 62. A rotary shaft 51 of the rotary actuator 61 is connected to an eccentric cam shaft 53 via a connecting rod 52. The eccentric cam shaft 53 includes a small-diameter shaft portion 53a and a large-diameter cam portion 53b, and 53a and 53b are eccentric by a half of a stroke of an on-off valve 54 described later. Further, bearings 55 and 56 are inserted into the receiving plate 46 so that the connecting rod 52 and the eccentric cam shaft 53 rotate along the axis of the rotary actuator 61.
The rotary actuator 61 is driven by air pressure in the same manner as the reciprocating cylinder 31 of the first embodiment. Further, it may be driven by hydraulic pressure, electricity or the like.

The opening / closing valve 54 has a stepped shape including a mating portion 54 a, a tapered portion 54 b, a shaft portion 54 c, and a flange portion 54 d from the tip, and the spring 57 is connected to the flange portion 54 d and the spring seat surface 47 d of the valve hole 47. It is inserted between. When the eccentric cam shaft 53 rotates, the cam portion 53b hits the end surface of the flange portion 54d and reciprocates the on-off valve 54 against the urging force of the spring 57. When the on-off valve 54 moves forward in the direction of the cavity 44, as shown in FIG. 3, the engaging portion 54a of the on-off valve 54 engages with the engaging hole 47a of the valve hole 47, and the tapered portion 54b abuts on the tapered surface 47b. Thus, the suction port 8 is closed, and the on-off valve 54 is closed . A circular path 48 is formed between the clearance hole 47c and the shaft portion 54c.
In addition, since the outer diameter of the flange portion 54d is a size that engages and seals with the flange engagement hole 47e, the airtightness between the circular path 48 and the outside is maintained except through the suction hole 49. .
When the on-off valve 54 moves backward, as shown in FIG. 4, the mating portion 54a is separated from the mating hole 47a of the valve hole 47, the tapered portion 54b is separated from the tapered surface 47b, and the suction port 8 and the circular path 48 are connected. As a result, the on-off valve 54 is opened .

Next, since the operation of the second embodiment of the present invention is basically the same as that of the first embodiment , a description thereof will be omitted.
In the first embodiment , since the on-off valve 24 and the reciprocating cylinder 31 are directly connected, there is a problem that the heat of the cavity 4 is easily transmitted to the reciprocating cylinder 31. In the second embodiment , the on-off valve 54 and Since the rotary actuator 61 is not directly connected, there is an advantage that heat is not easily transmitted to the rotary actuator 61 and the durability of the apparatus is increased as compared with the first embodiment .
Moreover, the form of the on-off valve is not limited to these, and any form may be used as long as the suction port can be opened and closed.

It is sectional drawing when the on-off valve which shows the structure of the injection molding apparatus which is 1st Example of this invention is a closed state . It is sectional drawing when the on-off valve which shows the structure of the injection molding apparatus which is 1st Example of this invention is an open state . It is sectional drawing when the on-off valve which shows the structure of the injection molding apparatus which is 2nd Example of this invention is a closed state . It is sectional drawing when the on-off valve which shows the structure of the injection molding apparatus which is 2nd Example of this invention is an open state .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 4,44 Cavity 8 Suction port 10 Injection apparatus 11 Heating cylinder 19 Hot nozzle 20 Outlet path 20a Gate part 24, 54 On-off valve

Claims (1)

A mold provided with a nozzle insertion hole communicating with the cavity and an air suction port, a vacuum pump communicated with the suction port via an on-off valve, and an injection device for injecting molten material into the cavity, The injection device includes a heating cylinder that heats a resin or metal material to be in a molten state or a semi-molten state, and an outlet path and an outlet for a molten material that are attached to the tip of the heating cylinder and communicate with a melting path inside the heating cylinder A hot nozzle having a gate portion at the end of the path, and a control device for controlling the temperature of the gate portion of the hot nozzle to melt or solidify the material of the gate portion, and the nozzle insertion hole of the mold includes a hot nozzle The front end of the nozzle is inserted and mated in an airtight state so that the outlet path of the hot nozzle communicates with the cavity. The control device opens the on-off valve to allow the air in the cavity to flow. The temperature of the gate part of the hot nozzle is controlled to a temperature at which the material solidifies, and the temperature of the gate part of the hot nozzle is melted when the on-off valve is closed due to the vacuum inside the cavity. This is an injection molding device that can be controlled to inject molten material into the cavity .

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