JPH05261780A - Injection molding device and injection molding method - Google Patents

Abstract

PURPOSE:To shorten the time of one molding cycle by starting a measuring process during a dwell process. CONSTITUTION:For conducting dwelling after an injection process, a hydraulic cylinder device 42 is provided in a mold 1. As a nozzle 20 of a molding machine 2, a shut-off nozzle is used. In a dwelling process, a pressurizing rod 44 is pressed by the hydraulic cylinder device 42. A pressure toward a cavity 8 is applied to a resin contained in a resin path 9 of the mold 1 by the pressurizing rod 44.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus and an injection molding method, and more particularly, to holding pressure after an injection process.

[0002]

2. Description of the Related Art An injection molding machine includes, for example, a fixed side platen to which a fixed die of a die is attached, and a movable side to which a movable die of the die is attached to and moved away from the fixed side platen. A platen, a heating cylinder provided on the fixed side platen side, a screw built in the heating cylinder, and a screw drive mechanism including a hydraulic cylinder device and a servo motor that rotate the screw and move the screw in the axial direction. Is equipped with. The heating cylinder is provided with a heater on the outer periphery, a nozzle connected to a fixed sprue at the tip, and a hopper into which a resin pallet is charged is connected to the upper side. The mold has a product-shaped cavity formed between the fixed mold and the movable mold, which opens and closes when the fixed platen and the movable platen of the injection molding machine separate or approach each other, when the mold is clamped. In addition, a sprue or a runner for communicating a nozzle of an injection molding machine with the cavity is provided in, for example, a fixed mold.

In the conventional molding, the heating cylinder, the screw and the driving mechanism of the molding machine are repeatedly subjected to the measuring step, the injection step and the pressure holding step.
First, in the measuring step, the screw is rotated by the drive of the motor, the resin is sent from the hopper into the heating cylinder, and further, in this heating cylinder,
The resin is sent to the nozzle side while the screw retreats in the direction away from the nozzle. Meanwhile, the resin is melted by the external heating by the heater provided on the outer circumference of the heating cylinder and the shearing force generated in the resin itself as the screw rotates. In this way, a predetermined amount of molten resin is stored in the nozzle side tip of the heating cylinder. Next, in the injection step, the screw is advanced toward the nozzle by driving the hydraulic cylinder device, and the molten resin in the heating cylinder is injected from the nozzle. Next, in the pressure holding process, the hydraulic cylinder device applies a lower pressure to the screw in the forward direction than in the injection process.
Then, before the injection process, the fixed mold and the movable mold are clamped,
In the injection step, the molten resin injected from the nozzle is filled into the cavity between the fixed mold and the movable mold via the sprue and runner in the fixed mold. In the subsequent pressure-holding step, a certain amount of pressure is applied to the screw to prevent backflow of the molten resin from the cavity and to reduce the amount of resin contracted by cooling the molten resin in the cavity. It is replenished in the cavity. As a result, the product made of the resin filled in the cavity has a prescribed shape in conformity with the cavity. Then, after the resin filled in the cavity is sufficiently cooled and solidified, the fixed mold and the movable mold are opened, and the molded product is taken out. Then, the mold is clamped again, and the above molding cycle is repeated.

[0004]

As described above, in the past, since the pressure was held by the screw which also measures and injects on the injection molding machine side, the measuring step should be performed only after the pressure holding step is completed. Since it could not be started, the time for one molding cycle was long, and there was a problem of poor productivity.

The present invention is intended to solve such a problem, and the measuring step can be started in the middle of the pressure holding step, the time of one molding cycle can be shortened, and the productivity can be improved. An object of the present invention is to provide an injection molding apparatus and an injection molding method which can be performed.

[0006]

In order to achieve the above object, an injection molding apparatus of the present invention comprises a mold and a molding machine to which the mold is attached. The mold is openable and closable. While having a plurality of mold members that form a cavity inside when tightening, and having a resin passage leading from the cavity to the outside of the mold, the molding machine measures the amount of resin and the resin into the resin passage of the mold. And a resin holding mechanism for applying a pressure to the resin in the resin passage in the direction toward the cavity.

In order to achieve the above object, the injection molding method of the present invention uses the injection molding apparatus to measure a resin by a resin metering injection mechanism of a molding machine, and after the measuring step, After the injection step of injecting the resin into the resin passage of the mold by the resin measuring / injection mechanism, the pressure in the direction toward the cavity is applied to the resin in the resin passage of the mold by the pressure holding mechanism of the die after this injection step. And a pressure-holding step for applying, and the measuring step is started in the middle of the pressure-holding step.

[0008]

In the injection molding apparatus of the present invention, a mold is attached to the molding machine at the time of molding, a plurality of mold members of this mold are clamped, and the resin measuring injection of the molding machine after the measurement of the resin is completed. The resin is injected from the mechanism into the resin passage of the mold. This resin is
A cavity formed between a plurality of mold members is filled through a resin passage in the mold. After that, the pressure in the direction toward the cavity is applied to the resin in the resin passage of the mold by the pressure holding mechanism provided in the mold. This prevents backflow of the molten resin from the cavity and replenishes the resin with shrinkage due to cooling of the molten resin in the cavity, so that the product made of the resin filled in the cavity conforms to the cavity. Make sure it has the specified shape. At this time, since the pressure-holding mechanism is provided on the mold, not on the molding machine, the resin metering injection mechanism of the molding machine measures the resin for the next molding during the holding pressure. Can start.

That is, in the injection molding method of the present invention, in the measuring step, the resin is measured by the resin measuring / injecting mechanism of the molding machine, and in the injection step after this measuring step, the resin is measured by the resin measuring / injecting mechanism. The resin is injected into the resin passage, and in the pressure-holding step after this injection step, the pressure in the direction of the cavity is applied to the resin in the resin passage of the die by the pressure-holding mechanism of the die. The time of one molding cycle is shortened by starting the measuring process from.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows an outline of an injection molding machine 2 to which a mold 1 is attached. The mold 1
Includes a fixed die 6 and a movable die 7 as die members. The fixed mold 6 and the movable mold 7 are opened and closed with each other to form a product-shaped cavity 8 inside during mold clamping. Further, in the fixed mold 6, a resin passage 9 is formed which communicates from the cavity 8 to the outside of the mold 1. On the other hand, the molding machine 2 has a fixed side platen 11 to which the fixed die 6 is detachably attached, and a movable side platen 12 to which the movable die 7 is detachably attached.
The movable platen 12 is connected to a mold clamping ram 13 driven by a hydraulic cylinder device (not shown),
The movable die 7 is moved with respect to the fixed die 6 by moving together with the die clamping ram 13 in a direction approaching and leaving the fixed side platen 11. In addition, the molding machine 2
Has a resin measuring / injecting mechanism 16 for measuring the resin and injecting the molten resin into the resin passage 9 of the mold 1. Here, the resin metering and injection mechanism 16 will be described. A heating cylinder 17 is provided with a hopper 18 for supplying a resin pallet into the heating cylinder 17, and a heater 19 on the outer peripheral side. A nozzle 20 connected to the resin passage 9 of the mold 1 is provided at the tip of the heating cylinder 17. A screw 21 is coaxially provided in the heating cylinder 17. A plunger 24 connected to a piston 23 of a hydraulic cylinder device 22 is connected to the screw 21, and is moved in the axial direction of the heating cylinder 17 by driving the hydraulic cylinder device 22. A gear 25 is supported by the plunger 24 so as to be movable in the axial direction and prevented from rotating. The gear 25 is rotationally driven by an electric servo motor 26 via the gear 27. In this way, the screw 21 is rotationally driven by the drive of the servo motor 26. A shut-off nozzle 20 is used as the nozzle 20. As shown in FIG. 2, for example, the shut-off nozzle 20 is formed by screwing a cap 29 onto the tip of a nozzle body 28, and resin passages 30 and 31 are formed through the cap 29 in the axial direction. .. A part of the resin passage 30 of the nozzle main body 28 is a large diameter portion 32, and the heating cylinder 17 of this large diameter portion 32.
The side has a tapered valve seat 33. Then, in the large-diameter portion 32, a ball valve 34 that comes in contact with and separates from the valve seat 33.
And a spring 35 for urging the ball valve 34 toward the heating cylinder 17. Thus, the ball valve 34
Normally, the resin 35 is abutted against the valve seat 33 by the urging force of the spring 35.
When the resin pressure above a predetermined level is received from the heating cylinder 17 side, it is separated from the valve seat 33 against the bias of the spring 35, and the resin passages 30 and 31 are opened. Further, the fixed die 6 of the mold 1 is provided with a pressure holding mechanism 41 for applying a pressure to the resin in the resin passage 9 in the direction toward the cavity 8. The pressure-holding mechanism 41 is composed of, for example, a hydraulic cylinder device 42, and a pressurizing rod 44 integrated with a piston 43 of the hydraulic cylinder device 42 is formed by communicating with the resin passage 9 in the fixed mold 6. It is slidably fitted in the resin reservoir 45.

Next, an injection molding method using the injection molding apparatus will be described. For molding, molding machine 2
The fixed die 6 is attached to the fixed side platen 11 and the movable die 7 is attached to the movable side platen 12. Nozzle 20 of molding machine 2
Is connected to the resin passage 9 of the fixed mold 6. Then, during molding, in the resin measuring / injecting mechanism 16 of the molding machine 2, the measuring process and the injection process are repeated. In the weighing process,
The screw 21 is rotated by the drive of the motor 26, the resin is sent from the hopper 18 into the heating cylinder 17, and further, in the heating cylinder 17, while the screw 21 retreats in the direction away from the nozzle 20, the resin is discharged into the nozzle.
It is sent to the 20 side. Meanwhile, the external heating by the heater 19 provided on the outer periphery of the heating cylinder 17 and the screw 21
The resin is melted by the shearing force generated in the resin itself as the resin rotates. Thus, the nozzle 20 in the heating cylinder 17
A predetermined amount of molten resin is stored at the side tip portion. Next, in the injection step, the screw 21 advances toward the nozzle 20 by driving the hydraulic cylinder device 22, and the molten resin in the heating cylinder 17 is injected from the nozzle 20 into the resin passage 9 in the fixed mold 6. This nozzle 20 opens only during the injection process. Note that, as will be described later, in the molding machine 2 of this embodiment, the measuring step immediately follows the injection step.

Before the injection process, the movable platen 12
Approaches the fixed side platen 11, and the fixed mold 6 and the movable mold 7 are clamped, and in the injection process, the molten resin injected from the nozzle 20 passes through the resin passage 9 in the fixed mold 6 and A cavity 8 formed between 6 and the movable die 7 is filled. The pressure rod of the pressure-holding mechanism 41 is used until the injection process.
44 is located away from the resin passage 9. After the injection step, the pressure holding step is performed, and this pressure holding is performed by the pressure holding mechanism 41 in the mold 1. That is, the hydraulic cylinder device 42 pressurizes the pressurizing rod 44 toward the resin passage 9 in the fixed mold 6. At this time, the resin pressure in the resin passage 9 acts in the direction in which the nozzle 20 is closed, and the resin in the mold 1 does not return to the molding machine 2 side. Therefore, pressure is applied from the resin reservoir portion 45 to the resin in the resin passage 9 in the direction toward the cavity 8. As a result, backflow of the molten resin from the cavity 8 is prevented, and the resin contracted by the cooling of the molten resin in the cavity 8 is replenished from the resin passage 9 into the cavity 8. Thus, the product made of the resin filled in the cavity 8 is
It will be a prescribed shape according to. After the pressure-holding step, the pressurizing rod 44 moves in the direction away from the resin passage 9 by the drive of the hydraulic cylinder device 42, and returns to the original position. Then, after the resin filled in the cavity 8 is sufficiently cooled and solidified, the movable side platen 12 is separated from the fixed side platen 11, and the fixed mold 6 and the movable mold 7 are opened to form a molded product. Is taken out. After that, the fixed mold 6 and the movable mold 7 are clamped again, and the above molding cycle is repeated.

As described above, according to the configuration of the above-described embodiment, since the pressure holding mechanism 41 is provided in the mold 1 instead of the molding machine 2, the molding machine 2 side has the following structure from the start of the pressure holding process. The weighing process for molding can be started. Therefore, the time of one molding cycle can be shortened and the productivity can be improved.

Next, a second embodiment of the present invention will be described with reference to FIGS. 3 to 6. The mold 51 shown in these figures is also provided with a fixed mold 52 and a movable mold 53 as mold members that can also be opened and closed, and a cavity 54 is formed between the fixed mold 52 and the movable mold 53 during mold clamping. Is done. The fixed mold 52 is a fixed side mounting plate for mounting the fixed side mold plate 55 to the fixed side platen 11 of the molding machine 2 as shown in FIG. 1 via the fixed side receiving plate 56 and a spacer block (not shown). It is attached to 57. The movable die 53 is such that the movable die plate 58 is attached to a fixed side attachment plate (not shown) for attaching to the movable platen 12 of the molding machine 2. Further, the fixed side mounting plate 57 is provided with a nozzle receiver 59 to which the nozzle 20 of the molding machine 2 is attached, and the nozzle receiver 59, whose inside is a resin passage to the outside of the mold 51, is fixed. It communicates with a runner 61 which is a resin passage in a manifold 60 having a heater (not shown) provided between the side receiving plate 56 and the fixed side mounting plate 57.

Further, a bush 62 is assembled in the fixed side mold plate 55 and the fixed side receiving plate 56, and a through hole 63 whose axial direction is the vertical direction in the drawing is formed in the bush 62. .. The through-hole 63 is directly connected to a gate 64 that opens to the cavity 54 and has an axial direction in the vertical direction in the drawing. A tubular valve guide 65 is slidably fitted in the upper part of the through hole 63 in the vertical direction in the drawing, and a pin-shaped valve for opening and closing the gate 64 is provided inside the valve guide 65. 66 is slidably fitted and supported in the vertical direction in the drawing, and the gap between the valve 66 and the peripheral surface of the through hole 63 forms a gate passage 67 which is a resin passage. Further, a manifold passage 68, which is a resin passage, is formed in the bush 62, and one end of the manifold passage 68 is opened above the peripheral surface of the gate passage 67. The valve guide 65 is movable between a position where the opening 68a of the manifold passage 68 to the gate passage 67 is fully opened and a position where the opening 68a is fully closed. On the other hand, the other end of the manifold passage 68 communicates with the runner 61 of the manifold 60 that communicates with the nozzle 20 of the molding machine 2. Further, the manifold 60 is provided on the rear side of the fixed side mounting plate 57.
A hydraulic cylinder device 69 for moving the valve 66 penetrating through the valve 60 in the vertical direction in the figure is provided, and a hydraulic cylinder device 70 for moving the valve guide 65 penetrating the manifold 60 in the vertical direction in the figure is provided separately from the hydraulic cylinder device 69. Has been. The valve guide 65 and the hydraulic cylinder device 70 make the cavity 54 against the resin in the gate passage 67.
A pressure-holding mechanism 71 that applies a pressure in a direction toward is configured.

Before the injection process, as shown in FIG. 3, the valve 66 is in the lower position shown in the figure, and the lower end of the valve 66 shown in the figure fits into the gate 64 to close the gate 64. .. On the other hand, the valve guide 65 is in the rising position in the figure, and the opening 68a of the manifold passage 68 is fully opened. And
During the injection process, as shown in FIG. 4, first, the valve 66 is raised by driving the hydraulic cylinder device 69, the valve 66 is separated from the gate 64, and the gate 64 is opened. On the other hand, the valve guide 65 remains in the raised position in the drawing, and the opening 68a of the manifold passage 68 is fully opened. Then, the molten resin injected from the nozzle 20 of the molding machine 2 by the pressing of the screw 21 of the molding machine 2 passes through the runner 61 of the manifold 60, and as shown by the arrow, an opening to the manifold passage 68 and its gate passage 67. 68a, bush 62
Cavity 54 through gate passage 67 and gate 64 in
It is injected into. When the injection process is completed, the pressure-holding process is started. At the time of the pressure-holding process, as shown in FIG. 5, first, the valve guide 65 is pushed toward the gate 64 with an appropriate pressure by driving the hydraulic cylinder device 70, and is lowered in the drawing. However, the valve guide 65 closes the opening 68a of the manifold passage 68 at least halfway. In this way, the valve guide 65 pushed toward the gate 64 applies a pressure to the molten resin in the gate passage 67 as shown by an arrow to maintain the pressure. At this time, since the opening 68a of the manifold passage 68 is at least half closed, the pressure applied to the gate passage 67 has almost no effect on the molding machine 2 side even if the nozzle 20 is not a shut-off nozzle. Instead, it will be added to the gate 64 side. On the other hand, from the start of the pressure-holding step, the molding machine starts measuring the resin for the next molding with the screw 21. Then, when the pressure-holding step is completed, as shown in FIG. 6, the valve 66 is lowered by driving the hydraulic cylinder device 69 to close the gate 64.

Also according to the configuration of the second embodiment,
By providing the pressure-holding mechanism 71 on the mold 51 side, the pressure-holding process can be omitted on the molding machine 2 side, and the measuring process can be started on the molding machine 2 side from the start of the pressure-holding process on the mold 51 side. Therefore, the time of one molding cycle can be shortened.

7 and 8 show a third embodiment of the present invention. In the third embodiment, the cylindrical valve guide 76, which guides the valve 66 and constitutes the pressure holding mechanism, is not only movable in the axial direction but also rotatable in the cylindrical through hole 63 of the bush 62. And a drive device (not shown) for the valve guide 76 also moves the valve guide 76 in the axial direction and rotates the valve guide 76. The lower end surface of the valve guide 76 that moves up and down in the drawing is the gate passage of the manifold passage 68.
It is always located below the opening 68a to 67 in the figure. Along with this, a spiral groove 77 is formed on the outer peripheral surface of the valve guide 76, and the lower end of the spiral groove 77 shown in the drawing is pulled out to the lower end surface of the valve guide 76 shown in the drawing, and opens into the gate passage 67 leading to the gate. ing. With such a configuration, the spiral groove 77 is formed so that the opening 68 of the manifold passage 68 is formed.
When it overlaps a, the opening 68a is fully opened and communicates with the gate passage 67, and when the portion of the outer peripheral surface of the valve guide 76 without the spiral groove 77 overlaps the opening 68a of the manifold passage 68, this opening 68a is opened. Completely shut off from.

In the third embodiment, during the injection process, as shown in FIG. 7, the spiral groove of the valve guide 76 is formed.
77 overlaps the opening 68a of the manifold passage 68, and the molten resin flows out to the gate passage 67 through the manifold passage 68, the fully opened opening 68a, and the spiral groove 77 as shown by the arrow. On the other hand, during the pressure-holding step, as shown by the arrow in FIG. 8, the valve guide 76 is pushed toward the gate (downward in the drawing) in the axial direction, and the valve guide 76 rotates to rotate the spiral groove 77 on the outer peripheral surface thereof. The open area overlaps the opening 68a in the manifold passage 68, and this opening 68a
Is fully closed.

By the way, when the valve guide is simply pushed toward the gate in the axial direction during the pressure holding step, the amount of movement of the valve guide does not always become sufficiently large due to the pressure from the molten resin in the gate passage. Therefore, the opening of the manifold passage to the gate passage may not be completely closed. However, in the third embodiment, the lower end surface of the valve guide 76 shown in the drawing is connected to the manifold passage 68.
This opening is always located below the opening 68a in the figure.
68a communicates with the gate passage 67 through the spiral groove 77 of the valve guide 76, and not only moves the valve guide 76 in its axial direction but also rotates it to completely open the opening 68a of the manifold passage 68 during the pressure-holding process. Can be occluded.

The present invention is not limited to the above embodiment, but various modifications can be made. For example,
In the above embodiment, the molding machine was of the in-line screw type, but the molding machine may be of the plunger type or the like. Further, the drive source of the pressure holding mechanisms 41, 71 is not limited to the hydraulic cylinder devices 42, 70, and pneumatic cylinder devices and the like are also possible.

[0022]

According to the injection molding apparatus of the present invention, a resin measuring / injecting mechanism for measuring resin and injecting the resin into the resin passage of the mold is provided in the molding machine. Since the pressure-holding mechanism that applies a pressure to the resin in the passage in the direction toward the cavity is provided in the mold, the measuring step can be started during the pressure-holding step, for example, when the pressure-holding step is started.

Then, like the injection molding method of the present invention,
By starting the measuring process from the middle of the pressure holding process, 1
The time of one molding cycle can be shortened and therefore productivity can be improved.

[Brief description of drawings]

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

FIG. 2 is a sectional view of the same nozzle.

FIG. 3 is a partial cross-sectional view of a mold showing a second embodiment of the present invention, showing a state before an injection step.

FIG. 4 is a sectional view of the same injection step.

FIG. 5 is a sectional view of the same pressure holding step.

FIG. 6 is a cross-sectional view after the above pressure holding step.

FIG. 7 is a partial cross-sectional view of a mold showing a third embodiment of the present invention, showing an injection step.

FIG. 8 is a sectional view of the same pressure holding step.

[Explanation of symbols] 1 mold 2 molding machine 6 fixed mold (mold member) 7 movable mold (mold member) 8 cavity 9 resin passage 16 resin metering and injection mechanism 41 pressure holding mechanism 51 mold 52 fixed mold (mold Member) 53 Movable mold (mold member) 54 Cavity 61 Runner (resin passage) 67 Gate passage (resin passage) 68 Manifold passage (resin passage) 71 Pressure holding mechanism 76 Valve guide (pressure holding mechanism)

Claims (2)

[Claims] 1. A mold and a molding machine to which the mold is attached, the mold having a plurality of mold members capable of opening and closing and forming a cavity therein when the mold is clamped. Having a resin passage leading to the outside of the mold, the molding machine has a resin measuring injection mechanism for measuring the resin and injecting the resin into the resin passage of the mold, the mold,
An injection molding apparatus comprising a pressure holding mechanism for applying a pressure to a resin in the resin passage in a direction toward the cavity. 2. An injection molding method using the injection molding device according to claim 1, wherein the resin measuring injection mechanism of the molding machine measures the resin, and the resin measuring injection mechanism after the measuring step measures the resin. An injection step of injecting into the resin passage of the mold, and a pressure holding step of applying pressure in the direction toward the cavity to the resin in the resin passage of the mold by the pressure holding mechanism of the mold after this injection step. An injection molding method, characterized in that the measuring step is started in the middle of the pressure holding step.