JP2006035846A - Injection molding machine and resin material supply method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding machine capable of injecting a resin material in a mold in a state held under vacuum and simple in constitution for supplying the resin material to a material supply part from an external tank, and a resin material supply method using it. <P>SOLUTION: The material supply part 20 is equipped with the material suction pipe 23c which communicates with the inside of the external tank 3 for storing the resin material, a material supply tank 25 receiving the supply of the resin material from the external tank 3, the material holding part 27 communicating with the material supply tank 25 on its upper end side and communicating with a cylinder 11 on its lower end side, a first supply valve 23 for partitioning the material suction pipe 23c and the material supply tank 25 in an openable and closable manner and a second supply valve 26 for partitioning the material supply tank 25 and the material holding part 27 in an openable and closable manner. The material supply tank 25 is connected to a vacuum exhaust means 90 and this vacuum exhaust means 90 can suck the resin material into the material supply tank 25 from the external tank 3 through the material suction pipe 23c. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an injection molding apparatus and a method for supplying a resin material, and in particular, an injection molding apparatus that can inject a resin material into a mold while keeping the resin material under vacuum, and a resin material supply using the injection molding apparatus. Regarding the method.

  2. Description of the Related Art Conventionally, an injection molding apparatus is known in which a resin material is plasticized while being held under vacuum and injected into a cavity in a mold (see, for example, Patent Document 1). In the resin material supply device described in Patent Literature 1, a first storage unit, a second storage unit, and a third storage unit that are connected to a storage unit of a resin material via a pipe are sequentially connected, Are configured to be opened and closed by a first shutter and a second shutter, respectively. The third accommodating portion is connected to the cylinder and configured to supply the resin material to the heated cylinder.

  Moreover, the inside of the 2nd accommodating part and the 3rd accommodating part can be exhausted with a vacuum pump. With such a configuration, the supply device of Patent Document 1 supplies the resin material from the storage unit to the second storage unit via the first storage unit in a state where the second shutter is closed and the third storage unit is exhausted, Thereafter, the first shutter is closed, the second housing portion is exhausted, and the second shutter is opened, so that the resin material is supplied to the third housing portion while keeping the third housing portion facing the cylinder in a vacuum state. Is possible.

  Moreover, in the supply apparatus of patent document 1, the air blower and the filter are arrange | positioned by piping which connects the storage part and 1st accommodating part of a resin material, and resin material is operated from a storage part by operating a fan. It is pumped through the piping to the first housing part.

JP 2002-192557 A (pages 3 to 4, FIGS. 1 to 7)

  However, since the supply device of Patent Document 1 needs to separately provide a blower and a filter in the piping in order to supply the resin material from the resin material storage unit to the first housing unit, the configuration and wiring of the device are complicated. There was the inconvenience of becoming.

  The present invention has been made in view of the above problems, and an object of the present invention is to inject a resin material into a mold while keeping the resin material under vacuum and to supply a material from an external tank that stores the resin material. It is an object of the present invention to provide an injection molding apparatus having a simple configuration for supplying a resin material to a resin and a method for supplying a resin material using the injection molding apparatus.

  According to the present invention, there is provided an injection molding apparatus for melting a resin material supplied from a material supply unit in an injection unit and injecting molten resin into a mold by the injection unit to form a resin molded product. The material supply unit includes a material suction pipe that communicates with an external tank that stores the resin material, a material supply tank that is supplied with the resin material from the external tank via the material suction pipe, and the material supply tank A material holding part that communicates with the upper end side and communicates with the lower end side within the injection part to supply a resin material to the injection part, and a first supply valve that opens and closes between the material suction pipe and the material supply tank. A second supply valve that opens and closes between the material supply tank and the material holding portion, and the material supply tank is connected to a vacuum exhaust means capable of exhausting the inside of the material supply tank, The vacuum exhaust means In a state where the first supply valve is opened, is solved by a resin material by sucking is retractable within the material supply tank from outside the tank through said material inlet pipe.

  As described above, in the present invention, the material supply unit includes the material suction pipe, the material supply tank, and the material holding part communicating with the external tank, and the first supply valve is provided between the material suction pipe and the material supply tank. The material supply tank and the material holding part are partitioned to be opened and closed by a second supply valve. Since the material supply tank is connected to a vacuum exhaust means, by closing the first supply valve, the inside of the material supply tank, the material holding part and the injection part are exhausted by the vacuum exhaust means to be in a vacuum state. Can be held.

  Further, in a state where the inside of the material supply tank and the inside of the material holding portion are held under vacuum, the second supply valve is closed and the first supply valve is opened, so that the vacuum exhausting means allows the external tank to pass through the material suction pipe The resin material can be sucked into the material supply tank. As described above, in the present invention, the inside of the material supply unit can be exhausted by the vacuum exhaust unit, and the resin material can be sucked into the material supply unit. As a result, it is not necessary to separately provide a means for supplying the resin material to the material supply unit, so that the configuration of the entire apparatus can be made compact.

  In the injection molding apparatus of the present invention, after the resin material is sucked into the material supply tank, the first supply valve is closed, the material supply tank is evacuated to a vacuum state, and the second supply valve is opened, thereby holding the material. The resin material can be supplied from the material supply tank to the material holding part while keeping the inside of the part and the inside of the injection part in a vacuum state. As described above, in the present invention, it is possible to supply the resin material while the material holding portion and the injection portion are always kept in a vacuum state.

  In the present invention, an on-off valve is provided between the vacuum exhaust means and the material supply tank, and the amount of the resin material drawn into the material supply tank is determined by the opening time of the on-off valve or the first It can be configured to be controlled by the opening time of one supply valve.

  Further, it is preferable that the vacuum evacuation means is further used for evacuating the inside of the cavity of the mold. When configured in this way, it is possible to perform exhaust in the material supply unit, transfer of the resin material from the external tank into the material supply unit, and exhaust in the mold cavity by one vacuum exhaust unit. It can be simplified.

  In addition, by using the resin molding apparatus of the present invention, the material holding unit is evacuated to a predetermined vacuum state and the first supply valve is opened with the second supply valve closed, and the material supply is performed. A vacuum exhaust means capable of exhausting the inside of the tank sucks and draws the resin material from the external tank into the material supply tank through the material suction pipe, closes the first supply valve, and then closes the inside of the material supply tank. Is evacuated to a predetermined vacuum state by the vacuum evacuation means, the second supply valve is opened, the resin material drawn into the resin supply tank is discharged to the material holding portion, and the resin material is discharged into the injection portion. Can be supplied.

  According to the injection molding apparatus of the present invention, the material supply part for supplying the resin material into the injection part is configured to be partitioned by the first supply valve and the second supply valve that can be opened and closed, and the inside of the material supply part is provided by the vacuum exhaust device. It can be evacuated to a vacuum state. In the injection molding apparatus of the present invention, the resin material can be supplied from the external tank to the material holding portion while the material holding portion communicating directly with the injection portion is always kept in a vacuum state.

  Further, the vacuum exhaust means not only exhausts the inside of the material supply unit, but also can suck the resin material into the material supply unit through a material suction pipe communicating with an external tank that stores the resin material, Since there is no need to separately provide a means for supplying the resin material to the material supply unit, the overall configuration of the apparatus can be made compact.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that members, arrangements, and the like described below do not limit the present invention, and it goes without saying that various modifications can be made in accordance with the spirit of the present invention.

  1 to 7 relate to an embodiment of the present invention, FIG. 1 is an explanatory view of an injection molding apparatus, FIG. 2 is an explanatory view of a mold, FIG. 3 is an explanatory view of a control means, and FIG. FIG. 5 is an explanatory diagram of the vent cover of the material supply unit, FIG. 6 is a timing chart of the material supply unit, and FIG. 7 is a timing chart of the mold vacuum valve.

  FIG. 1 is an explanatory cross-sectional view of an injection molding apparatus S according to an embodiment of the present invention. As shown in FIG. 1, the injection molding apparatus S includes an injection unit 10, a mold 30, a mold clamping unit 80, a vacuum exhaust unit 90, and a control unit 100 as main components. The injection unit 10 and the mold clamping unit 80 are mounted on the gantry 1, and the mold 30 is mounted on the mold clamping unit 80.

  The injection means 10 of this example is a screw-in-line type injection machine, and includes a cylinder 11, a nozzle 13, a drive unit 14, and a material supply unit 20 for supplying resin material into the cylinder 11. Configured. The cylinder 11, the screw 12, the nozzle 13, and the drive unit 14 correspond to an injection unit.

  The drive unit 14 includes a rotation drive unit 14a including a motor and a speed reduction mechanism that rotate the screw 12 in the cylinder 11, an injection cylinder device 14b that extrudes the screw 12 and injects molten resin in the cylinder 11 into the mold 30, and a cylinder. 11 is provided with a shift cylinder that moves the nozzle 11 in the left-right direction to bring the nozzle 13 into contact with or retract from the sprue.

  In the cylinder 11 of this example, a vacuum seal 11a is disposed at a position behind the opening for communicating the material supply unit 20 and the cylinder 11 (right side in the figure), and a screw 12 is inserted into the vacuum seal 11a. It is slidable. The vacuum seal 11 a seals the inside of the cylinder 11 and the drive unit 14.

  The cylinder 11 is heated by a band heater 15. The resin material is supplied into the cylinder 11 through the material supply unit 20, plasticized and kneaded by the screw 12 that is rotationally driven by the rotation driving unit 14 a, and pushed forward. When the injection cylinder device 14b is operated in this state, the screw 12 is pushed out to the mold 30 side, and the front molten resin in the cylinder 11 is injected into the cavity 30a in the mold 30 through the nozzle 13.

  In addition, although the injection means 10 of this example is a screw-in-line type, it is not limited to this, and may be a plunger type or a pre-plastic type.

  As shown in FIGS. 1 and 2, the mold 30 is disposed relative to the fixed side mounting plate 33 </ b> A, the fixed side mold 31 attached to the fixed side mounting plate 33 </ b> A, and the fixed side mold 31. The movable mold 32, the back plate 34 that supports the movable mold 32 from the back side, the movable mounting plate 37A connected to the back plate 34 via the spacer block, the back plate 34, and the movable mounting plate. The main components are an ejector plate 35 movably disposed between 37A and an ejector pin 36A having a base fixed to the ejector plate 35. And the cavity 30a for shape | molding a molded article is formed by clamping the fixed side metal mold | die 31 and the movable side metal mold | die 32. FIG.

  An annular mold seal groove is formed around the cavity 30a on the parting surface of the fixed side mold 31 of this example, and the parting surface of the movable side mold 32 is fitted into the mold seal groove. A convex mold seal member made of silicon rubber is provided so as to be embedded. Then, when the inside of the cavity 30a is evacuated after the mold clamping, the mold seal member fitted in the mold seal groove is brought into close contact with the inner side wall of the mold seal groove to seal the inside and the outside of the cavity 30a. It is possible.

Further, the movable mold 32 of this example is formed with a sliding hole which is a through hole so as to communicate the cavity 30a and the outside (back plate 34) side. An ejector pin 36A as a moving member is slidable so as to be able to advance and retreat.
And in order to ensure the sealing performance in this sliding hole, the sliding seal part 60 is formed in the back plate 34 side of the movable mold 32. The sliding seal portion 60 extends the sliding hole from the outer end of the sliding hole to a predetermined depth, and a seal member made of silicon rubber and paste-like grease is disposed in the expanded space.

The fixed side mold 31 and the movable side mold 32 of this example are made of aluminum alloy. The aluminum alloy mold has a weight of about 1/3 as compared with, for example, a mold made of steel S55C, and the injection molding apparatus S of this example is reduced in weight and size as a whole.
In this example, although the aluminum alloy mold is used for the fixed mold 31 and the movable mold 32, a mold made of steel can also be used.

  A mold vacuum valve 40 as an exhaust part is incorporated in the fixed mold 31. The fixed side mold 31 is provided with a recess 31e on the side surface in contact with the fixed side mounting plate 33A, and the mold vacuum valve 40 is attached to the recess 31e. The mold vacuum valve 40 is configured to be able to switch between communicating the gate of the fixed mold 31 to the nozzle 13 side or communicating to the vacuum exhaust means 90 side.

  Further, an electromagnetic valve 59b is disposed in a pipe 59 extending from the mold vacuum valve 40 to the vacuum tank 92 side of the vacuum exhaust means 90. The electromagnetic valve 59b includes the mold vacuum valve 40, the vacuum exhaust means 90, and the like. Can be communicated or closed.

  In the mold vacuum valve 40 of this example, the gate of the fixed mold 31 is normally communicated with the nozzle 13 side. However, when the electromagnetic valve 59b is opened, the gate is communicated with the evacuation means 90 side and the cavity 30a. The inside can be exhausted.

  A pipe 59 between the electromagnetic valve 59b and the mold vacuum valve 40 is provided with a vacuum sensor 59a and a digital vacuum meter 59c, and measures the atmospheric pressure in the pipe 59 and the cavity 30a communicated with the pipe 59. ing. The vacuum sensor 59a displays the internal atmospheric pressure on the display unit. The vacuum meter 59c sends a detection signal representing the internal atmospheric pressure value to the control means 100, and the control means 100 uses this detection signal for control and display.

  The mold clamping means 80 includes a fixed die plate 81 fixed to the end of the tie bar 83, a mold clamping mechanism 86, and a movable die plate 82 that can move forward and backward with respect to the fixed die plate 81 by the mold clamping mechanism 86. And a drive unit 87 for driving the mold clamping mechanism 86 and the like.

The fixed side die plate 81 supports the fixed side mounting plate 33A, and the movable side die plate 82 supports the movable side mounting plate 37A.
The mold clamping mechanism 86 is configured by a link mechanism or the like, and is configured so that the position of the movable mold 32 can be adjusted by being driven by the drive unit 87.

  The mold clamping means 80 is provided with a position detection switch 88 for detecting the position of the movable mold 32. The position detection switch 88 detects that the movable mold 32 is in the mold clamping position. The position detection signal is sent to the control means 100.

  Further, the drive unit 87 can move the ejector plate 35 forward and backward toward the movable mold 32 side. After the mold opening, when the drive unit 87 is driven and the ejector plate 35 advances to the movable mold 32 side, the molded product is removed from the mold surface of the movable mold 32 by the ejector pins 36A.

The vacuum exhaust means 90 is for evacuating the inside of the cavity 30a of the mold 30 and the material supply unit 20, and includes a vacuum pump 91 and a vacuum tank 92 as main components.
The pipe from the vacuum tank 92 branches into two pipes (28, 59) that go to the electromagnetic valve 28a and the electromagnetic valve 59b on the way. A vacuum sensor 90a and a digital vacuum meter 90b are attached to the piping between the vacuum tank 92, the electromagnetic valve 28a, and the electromagnetic valve 59b. The vacuum sensor 90a displays the internal atmospheric pressure on the display unit. The vacuum meter 90 b sends a detection signal obtained by measuring the internal atmospheric pressure to the control means 100. The control means 100 uses this detection signal for control and display.

  The vacuum pump 91 always exhausts the vacuum tank 92 so as to maintain a predetermined degree of vacuum. That is, the control means 100 monitors the degree of vacuum in the vacuum tank 92 based on the detection signal received from the vacuum meter 90b, and when it is determined that the vacuum tank 92 has become greater than a predetermined atmospheric pressure value, the vacuum pump 91 To evacuate the vacuum tank 92 to a predetermined degree of vacuum.

  Further, the control means 100 controls the electromagnetic valves 28a, 28b, 59b and the like so as to exhaust the inside of the cavity 30a and the material supply unit 20 at a predetermined timing.

  As shown in FIG. 3, the control unit 100 includes a control unit 101, a display unit 102, and an operation unit 103 as main components. The control unit 101 stores a control program and receives an operation signal from the operation unit 103, a position signal from a solenoid valve, a sensor, a limit switch, a vacuum meter, a detection signal, and the like, The operation signal is sent to etc. The display unit 102 displays the operating status of each device such as the open / close status of each electromagnetic valve and the atmospheric pressure value measured by a vacuum meter.

  Next, the material supply unit 20 of this example will be described with reference to FIG. The material supply unit 20 of this example is configured such that the material supply tank 25 and the material holding unit 27 that supply the resin material to the cylinder 11 can be maintained in a vacuum state.

The material supply unit 20 includes a material suction pipe 23c that communicates with one end side in the external tank 3 that stores the granular resin material, a first supply valve 23 that has the other end of the material suction pipe 23c connected to the top, and a first supply valve 23c. A cylindrical material supply tank 25 connected to the lower part of the supply valve 23, a second supply valve 26 connected to the lower part of the material supply tank 25, and the material supply tank 25 via the second supply valve 26. The cylindrical material holding portion 27 is configured as a main component.
The material suction pipe 23c only needs to be able to suck the resin material from the external tank 3, and one end thereof may be inserted into the external tank 3, or one end thereof is connected to the lower opening of the external tank 3. Also good.

  The first supply valve 23 includes a valve body 23a having a valve for opening and closing an internal passage in an airtight manner, and a valve switch 23b to which a hose for compressed air from the compressed air supply source 4 is connected. The valve switch 23 b supplies compressed air to the valve body 23 a based on the drive signal from the control means 100 to open and close the valve, and detects the open / closed state of the valve and sends an open / close position signal to the control means 100. To do.

  The material supply tank 25 is formed in a substantially cylindrical shape, and a pipe 28 is connected to the center of the side surface. In addition, a vacuum sensor 25 a that measures the atmospheric pressure in the material supply tank 25 and a digital vacuum meter 25 c are attached to the outside of the material supply tank 25. The vacuum sensor 25a displays the internal atmospheric pressure on the display unit. The vacuum meter 25c sends a detection signal obtained by measuring the internal atmospheric pressure to the control means 100, and the control means 100 uses this detection signal for control and display.

  The pipe 28 is connected to a filter 28e on the way, and is branched in two directions on the downstream side of the filter 28e. One of the branches is connected to a vacuum tank 92 via an electromagnetic valve 28a, and the other is connected to an electromagnetic valve 28b and a silencer 28f for opening to the atmosphere. A pipe 59 is joined to the pipe 28 between the electromagnetic valve 28 a and the vacuum tank 92.

  A hand valve 28c is connected between the vacuum tank 92 and the electromagnetic valve 28a, and an operator can open and close between the vacuum tank 92 and the electromagnetic valve 28a by the hand valve 28c. The hand valve 28c is normally open. Further, the pipe 28 is further branched in two directions on the downstream side of the hand valve 28c, and a vacuum tank 92 is connected to one side, and a hand valve 28d is connected to the other side. The hand valve 28d is normally closed. When the hand valve 28d is opened, the vacuum tank 92 is opened to the atmosphere.

  The electromagnetic valves 28 a and 28 b are opened and closed in response to a drive signal from the control means 100, and send an open / close position signal to the control means 100. The hand valves 28c and 28d can be manually opened and closed by an operator.

  A vent hole cover 25b having a large number of through holes as shown in FIG. 5A is attached to the connecting portion between the material supply tank 25 and the pipe. The vent hole cover 25b is formed by forming a large number of small holes having a diameter smaller than that of a resin material on a circular thin plate made of metal or synthetic resin.

When the inside of the material supply tank 25 is evacuated by the vacuum evacuation means 90, the vent hole cover 25b prevents the resin material from flowing out to the vacuum evacuation means 90 side. Further, the resin material crushed into a powder is recovered by the filter 28e.
As the vent cover 25b, a net-like member made of metal or synthetic resin as shown in FIG. 5B may be used.

A pipe 18 is connected to the side surface of the material supply tank 25. The pipe 18 extends to the nozzle 13 side, and is connected to a heat cover 16 provided in the cylinder 11 via an electromagnetic valve 19. The electromagnetic valve 19 is opened and closed by a drive signal from the control means 100 and sends an open / close position signal to the control means 100.
A vent hole cover 25d similar to the vent hole cover 25b is disposed at the connection portion between the material supply tank 25 and the pipe 18.

  A heat cover 16 is disposed on the outer periphery of the cylinder 11 so as to cover a band heater 15 that is a heating means for heating the cylinder 11. The heat cover 16 is provided with a suction port 16a and a discharge port 16b, and a pipe 18 is connected to the discharge port 16b. Further, a fan 17 for sending air in the heat cover 16 to the material supply unit 20 side is disposed near the discharge port 16b. The heat cover 16, the fan 17, the pipe 18, and the electromagnetic valve 19 correspond to a drying unit.

When the band heater 15 is activated, the surrounding air is heated and the temperature of the air in the heat cover 16 rises.
When the electromagnetic valve 19 is opened, the inside of the heat cover 16 and the inside of the material supply tank 25 are communicated via the pipe 18. In a state where the material supply tank 25 is opened to the atmosphere, the hot air in the heat cover 16 is sent into the material supply tank 25 through the pipe 18 by the operation of the fan 17.

  The resin material is dried and heated by the hot air sent into the material supply tank 25. Thus, in this example, the resin material is dried and heated by reusing the heat generated from the band heater 15. As described above, in this example, the heat generated from the band heater 15 is reused without securing any other dedicated heat source for drying and heating the resin material, thereby saving energy. be able to.

  The second supply valve 26 connected to the lower part of the material supply tank 25 has the same configuration as the first supply valve 23. The second supply valve 26 includes a valve body 26a having a valve therein and a valve switch 26b to which a hose for compressed air is connected. The valve switch 26 b supplies compressed air to the valve body 26 a based on the drive signal from the control means 100 to open and close the valve, and detects the open / closed state of the valve and sends an open / close position signal to the control means 100. To do.

  The material holding unit 27 is provided with a sensor 27a. The sensor 27a detects whether or not a predetermined amount of resin material is held in the material holding unit 27 and outputs a detection signal to the control means 100. Sending out. In this example, a photoelectric tube is used for the sensor 27a.

  When the sensor 27a detects the resin material, the sensor 27a sends a signal (filling signal) indicating that a predetermined amount of the resin material is stored to the control means 100. A signal indicating that a fixed amount of resin material is not stored (unfilled detection signal) is sent to the control means 100.

  In this example, when the sensor 27a detects that a predetermined amount of resin material is not stored, it is set so that the resin material corresponding to several injection amounts remains in the material holding unit 27. . And in the injection molding apparatus S of this example, the supply process of the new resin material mentioned later is performed before the resin material which remains in the material holding | maintenance part 27 does not run out.

  Further, a pipe 29 is connected to the lower part of the material holding part 27, one being opened to the atmosphere via a hand valve 29b, and the other being a hand valve 29c, a material recovery pipe 29e and a hand. It is connected to the vacuum tank 92 side through a valve 29d. The hand valves 29b, 29c, 29d are normally kept closed.

  The material recovery pipe 29e is for discharging the resin material from the material holding portion 27 to the outside when the resin material is replaced. The material recovery pipe 29e is detachably attached to the pipe 29, and a cover 29f having a large number of small-diameter holes such as the vent hole cover 25b is attached to the vacuum tank 92 side.

  In order to recover the resin material from the material holding unit 27, the hand valves 29b, 29c, and 29d are opened after the molding process is completed, and the vacuum pump 91 is operated. Accordingly, the resin material in the material holding unit 27 is collected in the material recovery pipe 29e through the pipe 29. If the hand valves 29b, 29c, 29d are closed again and the material recovery pipe 29e is removed from the pipe 29, the resin material collected inside can be taken out from the material recovery pipe 29e. Thus, in the injection molding apparatus S of the present example, the resin material can be easily taken out without taking time after the molding process.

Next, the operation of supplying the resin material by the material supply unit 20 will be described. The following operation is automatically performed by an operation signal from the control means 100.
Before the injection molding is started by the injection molding apparatus S, an unfilled detection signal is sent from the sensor 27a, and the first supply valve 23 and the second supply valve 26 are in an open state. The vacuum tank 92 is evacuated to a vacuum state by a vacuum pump 91, and the electromagnetic valves 28a, 28b, and 19 are closed.
First, the control means 100 sends an open signal to the first supply valve 23 to keep the open state, and sends a close signal to the second supply valve 26 to make it closed.

  In addition, if the 1st supply valve 23 and the 2nd supply valve 26 are the types which are always a closed state by supply of compressed air (normally closed type), it will be in a closed state by canceling | releasing an open signal. In this specification, when a normally closed valve is in an open state, sending a close signal to close the valve means releasing the open signal. In addition, when the normally open valve is in the closed state, sending an open signal to open the valve means releasing the close signal.

  The control means 100 sends an open signal to the electromagnetic valve 28a to make it open, on condition that the first supply valve 23 is open and the second supply valve 26 is closed. As a result, a passage from the external tank 3 to the vacuum tank 92 through the material suction pipe 23c, the material supply tank 25, the pipe 28, and the electromagnetic valve 28a is formed. It is carried into the supply tank 25.

The control means 100 sends a close signal to the first supply valve 23 after the set time has elapsed since the electromagnetic valve 28a is in the open state, and sets the closed state. The set time can be set in advance in the control means 100, and an amount of resin material corresponding to the set time is carried into the material supply tank 25.
In this example, the first supply valve 23 is closed after a set time has elapsed since the solenoid valve 28a was opened. However, the present invention is not limited to this, and the electromagnetic valve 28a is opened after the set time has elapsed after the solenoid valve 28a is opened. The valve 28a may be closed. Thus, the supply amount of the resin material can be controlled by the opening time of the first supply valve 23 or the electromagnetic valve 28a.

  When the first supply valve 23 is closed, the control means 100 sends an open signal to the second supply valve 26 to make it open. Accordingly, the resin material in the material supply tank 25 is dropped downward and stored in the material holding unit 27. When the resin material is stored in the material holding unit 27, the sensor 27a detects filling of the resin material, and sends a detection signal indicating that the resin material is in a predetermined amount to the control means 100.

  At this time, the second supply valve 26 and the electromagnetic valve 28a are in an open state, the first supply valve 23 and the electromagnetic valve 28b are in a closed state, and the material holding unit 27 is exhausted to a predetermined degree of vacuum. Further, by evacuating the material holding unit 27 to a predetermined degree of vacuum, the inside of the cylinder 11 communicating with the material holding unit 27 is also evacuated to a predetermined degree of vacuum.

  In a state where the material holding unit 27 is held at a predetermined degree of vacuum, the resin material is sequentially supplied from the material holding unit 27 into the cylinder 11 heated by the band heater 15, and the resin material is rotated by the rotating screw 12. Is plasticized and kneaded.

  After the resin material is carried into the material supply tank 25, the electromagnetic valve 28a is closed, the electromagnetic valve 28b and the electromagnetic valve 19 are opened, and hot air in the heat cover 16 is supplied into the material supply tank 25. You may make it do. In this way, the resin material in the material supply tank 25 can be dried and heated even when the resin material is initially supplied. Then, after a predetermined time, the solenoid valve 28b and the solenoid valve 19 are closed, the solenoid valve 28a is opened again, the inside of the material supply tank 25 is evacuated, the second supply valve 26 is opened, and the material holding portion 27 is filled with resin. It can be configured to discharge material.

Next, a case where the resin material in the material holding portion 27 is insufficient while resin molding is repeated will be described with reference to FIG. FIG. 6 shows a timing chart.
When the molten resin injection operation is repeated and the resin material accumulated in the material holding unit 27 becomes less than a predetermined amount and the sensor 27a cannot detect the resin material, a detection signal indicating that there is no predetermined amount of resin material is It is sent from the sensor 27a to the control means 100 (a in FIG. 6).

When the control means 100 receives a detection signal indicating that there is no predetermined amount of resin material, the control means 100 sends a close signal to the second supply valve 26 after a predetermined time to make it closed (b in FIG. 6).
When the second supply valve 26 is closed and a predetermined time elapses, the control means 100 sends an open signal to the first supply valve 23 to make it open (c in FIG. 6).

  When the first supply valve 23 is opened, a passage is formed from the external tank 3 to the vacuum tank 92 via the material suction pipe 23c, the material supply tank 25, the pipe 28, and the electromagnetic valve 28a. Thereby, the resin material is sucked out from the external tank 3 and carried into the material supply tank 25. At this time, the internal pressure of the material supply tank 25 approaches the atmospheric pressure from a predetermined vacuum state.

After a set time elapses after the first supply valve 23 is in the open state, the control means 100 sends a close signal to the electromagnetic valve 28a to set it in the closed state (d in FIG. 6). This set time can be set in the control means 100 in advance. When the electromagnetic valve 28 a is closed, the resin material is not transferred from the external tank 3 to the material supply tank 25. That is, an amount of the resin material corresponding to the opening time of the electromagnetic valve 28 a is conveyed from the external tank 3 to the material supply tank 25.
In this example, the supply amount of the resin material is controlled by the opening time of the electromagnetic valve 28a. However, the present invention is not limited to this, and the electromagnetic valve 28a is kept open and the resin material is closed by closing the first supply valve 23. The supply amount may be controlled. That is, the supply amount of the resin material can be controlled by the opening time of the first supply valve 23.

  After a predetermined time has elapsed since the solenoid valve 28a is closed, the control means 100 sends a close signal to the first supply valve 23 and an open signal to the solenoid valve 28b and the solenoid valve 19 (e in FIG. 6). As a result, the material supply tank 25 is opened to the atmosphere via the electromagnetic valve 28b. Further, by the operation of the fan 17, hot air in the heat cover 16 is supplied into the material supply tank 25 through the pipe 18, and the resin material in the material supply tank 25 is dried and heated. Hot air is discharged to the outside through the pipe 28 and the electromagnetic valve 28b.

  Thus, whenever the resin material is supplied to the material supply tank 25, it is dried and heated with hot air. As a result, the resin material is easily plasticized and kneaded in the cylinder 11, and the plasticized and kneaded molten resin does not contain moisture and can form a high-quality molded product.

  When a predetermined time elapses after the electromagnetic valve 28b and the electromagnetic valve 19 are opened, the control means 100 sends a close signal to the electromagnetic valve 28b and the electromagnetic valve 19 to make the electromagnetic valve 28b and the electromagnetic valve 19 closed (f in FIG. 6). Further, the control means 100 sends an open signal to the electromagnetic valve 28a after the predetermined time has elapsed after the electromagnetic valve 28b and the electromagnetic valve 19 are closed (g in FIG. 6). As a result, the material supply tank 25 is exhausted to a vacuum state by the vacuum tank 92.

  When the control means 100 detects that the material supply tank 25 has been evacuated to a predetermined degree of vacuum based on a detection signal from the vacuum meter 25c, the control means 100 sends an open signal to the second supply valve 26 to bring it into an open state (FIG. 6). H). As a result, the material supply tank 25 and the material holding unit 27 communicate with each other, a predetermined amount of the resin material falls from the material supply tank 25 to the material holding unit 27, and the resin material is stored in the material holding unit 27.

When a predetermined amount of resin material is stored, the sensor 27a detects the resin material and sends a detection signal indicating that the predetermined amount of resin material is filled to the control means 100 (i in FIG. 6).
When the sensor 27a detects that the resin material is insufficient (a in FIG. 6), the resin supply process (b to i in FIG. 6) is repeated.

  Thus, in the injection molding apparatus S of this example, the material holding part 27 is always held in a vacuum state during molding. Thereby, the inside of the cylinder 11 is also maintained in a vacuum state, and the resin material can be melted under vacuum.

  Further, in the injection molding apparatus S of this example, the resin material can be sucked from the external tank 3 by the vacuum evacuation means 90 and conveyed to the material supply tank 25. Therefore, it is necessary to provide a blower for sucking the resin material separately. Therefore, the apparatus can be configured compactly.

Next, based on FIG. 7, operation | movement of the injection molding apparatus S of this example is demonstrated. FIG. 7 shows a timing chart.
Note that the operation of supplying the resin material in the material supply unit 20 is omitted. In the injection molding apparatus S of this example, the operation of injecting molten resin into the cavity 30a and the operation of supplying the resin material to the material holding unit 27 can be performed independently as described below.

  Thereby, even if the shortage of the resin material in the material holding portion 27 occurs at any stage of the molten resin injection operation, it is possible to continuously form a molded product without interrupting the molten resin injection operation. .

The operator sets the injection unit 10 and the mold clamping unit 80 from the operation unit 103 in advance.
The control unit 100 sends an operation signal to the mold clamping unit 80 to clamp the movable mold 32 and the fixed mold 31 with a predetermined mold clamping pressure.

When the mold is clamped, a detection signal is sent from the position detection switch 88 to the control means 100 (A in FIG. 7).
Upon receipt of the detection signal, the control means 100 sends an open signal to the electromagnetic valve 59b after the set time has elapsed (B in FIG. 7). As a result, the mold vacuum valve 40 is opened, and the cavity 30a is evacuated to a predetermined degree of vacuum. The set time is set in the control means 100 in advance.

  When the control means 100 detects from the detection signal from the vacuum meter 59c that the cavity 30a has been evacuated to a predetermined degree of vacuum, the control means 100 sends a close signal to the electromagnetic valve 59b after the set time has elapsed (FIG. 5). 7 C). This set time can be set in the control means 100 to an appropriate length according to the volume of the cavity 30a.

An operation signal is sent from the control means 100 to the drive unit 14, and the screw 12 is rotated. By this rotation, the resin material supplied from the material supply unit 20 into the cylinder 11 is sent to the front of the cylinder 11, and the molten resin is supplied. Accumulated in front of the cylinder 11.
Since the resin material is plasticized and kneaded under vacuum as described above, gas and moisture generated by melting the resin material are removed.

  In this state, the control means 100 sends an operation signal to the drive unit 14 of the injection means 10, moves the screw 12 forward, and injects a predetermined amount of molten resin from the nozzle 13 into the cavity 30a (FIG. 7). D).

After injection of the molten resin, after a predetermined cooling time has elapsed, the control means 100 sends an operation signal to the injection means 10, and the injection means 10 moves the screw 12 backward (E in FIG. 7).
When screwed back, the control means 100 sends an operation signal to the mold clamping means 80 to retract the movable side mold 32 and open the mold (F in FIG. 7). At this time, a detection signal indicating that the mold has been opened is sent from the position detection switch 88 to the control means 100.
Then, the ejector pin 36A is operated to take out the molded product from the mold (G in FIG. 7).

The injection molding apparatus S repeats the processes such as the mold clamping process, the evacuation process, the injection process, the cooling process, the mold opening process, and the like to continuously form molded products.
In addition, when the cylinder 11 is shifted in the front-rear direction every time the molding is performed and the nozzle 30 is touched by the nozzle, the cylinder 11 is touched after the mold is clamped to exhaust the cavity 30a and screw back. Can be made to retreat.

It is explanatory drawing of the injection molding apparatus which concerns on one Embodiment of this invention. It is explanatory drawing of the metal mold | die which concerns on one Embodiment of this invention. It is explanatory drawing of the control means which concerns on one Embodiment of this invention. It is explanatory drawing of the material supply part which concerns on one Embodiment of this invention. It is explanatory drawing of the vent hole cover of the material supply part which concerns on one Embodiment of this invention. It is a timing chart of the material supply part which concerns on one Embodiment of this invention. It is a timing chart of the metal mold | die vacuum valve which concerns on one Embodiment of this invention.

Explanation of symbols

3 External tank 10 Injection means 11 Cylinder 15 Band heater 16 Heat cover 17 Fan 19 Electromagnetic valve 20 Material supply part 23 First supply valve 23c Material intake pipe 25 Material supply tank 26 Second supply valve 27 Material holding part 27a Sensor 28a Electromagnetic valve (Open / close valve)
28b Electromagnetic valve 30 Mold 31 Fixed side mold 32 Movable side mold 40 Mold vacuum valve 59b Electromagnetic valve 60 Sliding seal 80 Mold clamping means 90 Vacuum exhaust means 91 Vacuum pump 92 Vacuum tank 100 Control means S Injection molding device

Claims (4)

An injection molding apparatus for melting a resin material supplied from a material supply unit at an injection unit, and injecting molten resin into a mold by the injection unit to mold a resin molded product,
The material supply unit
A material suction pipe communicating with an external tank for storing the resin material;
A material supply tank to which a resin material is supplied from an external tank via the material suction pipe;
A material holding unit that communicates with the material supply tank at the upper end side and communicates with the lower end side into the injection unit and supplies a resin material to the injection unit;
A first supply valve for partitioning the material suction pipe and the material supply tank so as to be openable and closable;
A second supply valve for partitioning the material supply tank and the material holding portion so as to be openable and closable,
The material supply tank is connected to a vacuum exhaust means capable of exhausting the material supply tank;
The vacuum evacuation means is capable of sucking and drawing a resin material from an external tank into the material supply tank through the material suction pipe when the first supply valve is open. apparatus. An open / close valve is disposed between the vacuum exhaust means and the material supply tank,
The injection molding apparatus according to claim 1, wherein the amount of the resin material drawn into the material supply tank is controlled by an opening time of the on-off valve or an opening time of the first supply valve.   The injection molding apparatus according to claim 1, wherein the vacuum evacuation unit is further used to evacuate a cavity of the mold. A method of supplying a resin material from an external tank for storing a resin material to an injection unit via a material supply unit of an injection molding device,
The material supply unit includes a material suction pipe that communicates with an external tank that stores the resin material, a material supply tank that is supplied with the resin material from the external tank via the material suction pipe, and an upper end side of the material supply tank. A material holding portion that communicates with a lower end side in the injection portion and supplies a resin material to the injection portion; a first supply valve that partitions the material suction pipe and the material supply tank so as to be openable and closable; and the material A second supply valve that opens and closes between the supply tank and the material holding portion,
The material holding unit is evacuated to a predetermined vacuum state and the second supply valve is closed, and the first supply valve is opened, and the material supply tank is evacuated by vacuum evacuation means capable of evacuating the external tank. A step of sucking and drawing the resin material into the material supply tank from the material suction pipe,
Evacuating the material supply tank to a predetermined vacuum state by the evacuation means after closing the first supply valve;
And opening the second supply valve to discharge the resin material drawn into the resin supply tank to the material holding portion and supplying the resin material into the injection portion. Material supply method.

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