JP2004351894A - Injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding machine capable of changing over a plasticizer to intermittent operation and continuous operation corresponding to an operation condition, eliminating the wasteful disposal of a resin and capable of molding a molded product under a stable plasticizing condition. <P>SOLUTION: This injection molding machine is equipped with the plasticizer 11 for plasticizing a synthetic resin material, an accumulator device 12 comprising the cylinder 30 communicating with the outflow passage 19 of the plasticizer and the piston 31 provided in the cylinder and temporarily storing the plasticized resin supplied from the plasticizer, an injection device 13 metering and injecting the plasticized resin supplied from the accumulator device, and a changeover switch 75 for changing over the plasticizer to a first operation condition for intermittently operating the plasticizer and a second operation condition for continuously operating the plasticizer in synchronous relation to the injection operation of the injection device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an injection molding device in which a plasticizing device for plasticizing a synthetic resin material via an accumulator device and an injection device are connected.
[0002]
[Prior art]
In an injection molding apparatus for molding a molded product by injecting a molten resin into an injection molding mold, a continuous plasticizing apparatus for plasticizing a synthetic resin material, and measuring and injecting the plasticized resin into the injection molding mold. An accumulator device is provided between the injection device and the accumulator device. The plasticized resin supplied from the continuous plasticizing device is temporarily stored in the accumulator device, and the plasticized resin stored in the cylinder of the accumulator device is synchronized with the injection timing of the injection device. 2. Description of the Related Art A continuous plasticization type injection molding apparatus that supplies a plasticized resin to an injection apparatus by a piston is known.
[0003]
In the continuous plasticizing injection molding device, when the continuous plasticizing device is continuously operated and the plasticized resin is extruded from the continuous plasticizing device to the accumulator device, the piston in the cylinder of the accumulator device is pushed up by the resin discharge pressure. Thereby, it is supplied to the cylinder of the accumulator device from the continuous plasticizing device. When the piston in the cylinder is pushed down by the driving device and the opening / closing valve of the cylinder is opened, the plasticized resin stored in the cylinder is supplied to the injection cylinder of the injection device.
[0004]
When the injection plunger of the injection cylinder retreats and the amount of plasticizing resin necessary for one injection is measured, the opening and closing valve of the cylinder closes, the injection plunger advances, and when the opening and closing valve of the injection cylinder opens, the injection cylinder opens. , The plasticized resin is injected into the injection molding die, and one molding cycle is completed.
[0005]
It is also known to operate a resin discharge valve by a time-over signal issued when a preset molding cycle time is exceeded or a cycle time extension signal by a driver, and to change the operation of a plasticizing apparatus. (For example, see Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent No. 3,281,995
[Problems to be solved by the invention]
By the way, the plasticizing device of the continuous plasticizing type injection molding device described above is a continuous operation, while the injection device is an intermittent operation. Therefore, during the injection operation of the injection device, the plasticized resin is supplied from the plasticizing device to the accumulator device and accumulated. That is, while the piston in the cylinder of the accumulator device is pushed up by the plasticizing resin, the plasticizing resin is supplied from the plasticizing device into the cylinder and accumulated.
[0008]
Since the piston of the accumulator device is inside the cylinder, it is difficult for an operator to visually check the position of the piston from outside, that is, the amount of the plasticized resin in the cylinder.
[0009]
Therefore, there is a possibility that the plasticizing resin in the cylinder is excessively supplied from the plasticizing device to the accumulator device, the plasticizing resin in the cylinder becomes excessive in capacity, and the plasticizer flows back to the plasticizing device.
[0010]
Therefore, in Patent Document 1, in this case, the resin discharge valve is operated by a time-over signal output when a preset molding cycle time is exceeded or a cycle time extension signal by a driver, and plasticization in the accumulator device is performed. Resin is discharged (discarded) to the outside. Therefore, there is a problem that the resin is wasted.
[0011]
The present invention has been made in view of the above circumstances, and an object thereof is to switch a plasticizing apparatus between an intermittent operation and a continuous operation in accordance with the operation conditions of the apparatus, thereby reducing wasteful waste of resin. An object of the present invention is to provide an injection molding apparatus which can eliminate a molded article under stable plasticizing conditions.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a plasticizing device for plasticizing a synthetic resin material, a cylinder communicating with an outflow passage of the plasticizing device, and a piston provided in the cylinder. An accumulator device for temporarily storing the plasticized resin supplied from the plasticizing device, an injection device for measuring and injecting the plasticized resin supplied from the accumulator device, and the plasticizing device, An injection molding apparatus, comprising: switching means for switching between a first operating condition for intermittent operation in synchronization with an injection operation of the injection device and a second operating condition for continuous operation.
[0013]
A second aspect of the present invention is characterized in that the switching means of the first aspect is a changeover switch.
[0014]
According to a third aspect of the present invention, there is provided an informing means for informing when the first operating condition for intermittently operating the plasticizing device according to the first or second aspect is provided.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 shows a first embodiment, and is a schematic configuration diagram of a continuous plasticizing type injection molding apparatus. First, a schematic configuration will be described. An injection molding device is provided with a plasticizing device 11 for plasticizing a synthetic resin material and provided in communication with the plasticizing device 11 to temporarily store the supplied plasticized resin. The control unit 14 includes an accumulator device 12 for performing measurement, an injection device 13 for measuring and injecting the plasticized resin supplied from the accumulator device 12, and a control panel 14a.
[0017]
Next, the plasticizing device 11 will be described. A parallel biaxial plasticizing screw 16 is provided inside a horizontal plasticizing cylinder 15. A supply port 18 having a hopper 17 is provided at an upper portion on the base end side of the plasticizing cylinder 15. An outflow passage 19 is provided on the tip side of the plasticizing cylinder 15. Further, a heater 15a is wound around the plasticizing cylinder 15, so that the synthetic resin material inside the plasticizing cylinder 15 is heated and melted.
[0018]
Further above the hopper 17, a feeder 20 for supplying a synthetic resin material is provided. The feeder 20 includes a feeder cylinder 21 and a screw 22, and the screw 22 is rotated by a servomotor 23. A material supply hopper 24 for supplying a powdery synthetic resin material is provided at an upper portion on the base end side of the feeder cylinder 21, and a material discharge port 25 is provided at a lower portion on the tip side. The rotation of the screw 22 allows the synthetic resin material to be supplied from the material discharge port 25 to the hopper 17 of the plasticizing cylinder 15.
[0019]
Rotational force is transmitted from the rotating shaft 27 of the inverter motor 26 via the gear box 28 to the plasticizing screw 16 having two parallel axes so that the plasticizing screw 16 rotates in the same direction at the same speed. The plasticized screw 16 is divided into screw elements having different screw shapes so as to function as, for example, a feed section, a kneading section, and a compression section from the base end side in the axial direction to the tip end side. In addition, the plasticizing screw 16 having two parallel axes is continuously rotated in the same direction while contacting inside the plasticizing cylinder 15, and the synthetic resin material is kneaded while being heated by the heater 15a.
[0020]
Therefore, the plasticizing device 11 can knead and plasticize the supplied synthetic resin material while heating it even if it is a powder or a pulverized material. The conventional general plasticizing device has a low kneading capacity because it is a single-shaft plasticizing screw. For this reason, the synthetic resin material in powder form is heated and kneaded to granulate into pellets, and the synthetic resin in pellet form is supplied to the plasticizing apparatus. Since the synthetic resin material can be plasticized, the granulation step can be omitted, and labor and energy can be saved.
[0021]
Next, the accumulator device 11 will be described. A vertical cylinder 30 is provided, and a piston 31 is provided in an accumulator chamber 29 inside the cylinder 30 so as to be vertically movable. A heater 30a is wound around the cylinder 30 to heat the plasticized resin inside to keep the plasticized state.
[0022]
An opening is provided in the side wall of the cylinder 30, and the opening communicates with the outflow passage 19 of the plasticizing cylinder 15. Further, a resin outflow passage 32 is provided at a lower end portion of the cylinder 30, and a first opening / closing valve 33 formed of a rotary valve is provided in the resin outflow passage 32.
[0023]
The main body 34 of the piston 31 is formed to have an outer diameter that is in close contact with the inner peripheral surface of the cylinder 30, and the lower end of the main body 34 is formed with an inclined surface 34a so that the outflow path 19 side is high and the opposite side is low. ing. Further, a protruding small-diameter portion 35 protruding below the inclined surface 34a and having a diameter smaller than the inner diameter of the cylinder 30 is provided. Therefore, when the piston 31 is at the lower limit position, the highest position of the inclined surface 34 a is located above the outflow passage 19, and an annular flow passage 36 is formed between the small projecting portion 35 and the inner peripheral surface of the cylinder 30. It has become so.
[0024]
The piston rod 31a of the piston 31 projects upward through a through hole 30b provided at the upper end of the cylinder 30, and the piston rod 31a is connected to a plunger 37 of a hydraulic cylinder 38 as a driving device. The upper chamber 38a of the hydraulic cylinder 38 is connected to a tank 41 via a first relief valve 39 and a first switching valve 40. When the pressure in the upper chamber 38a exceeds the set pressure P1 of the first relief valve 39, the pressure oil in the upper chamber 38a is released to the tank 41, and the first switching valve 40 is switched, so that the first switching valve 40 is switched. Pressure oil controlled to a predetermined pressure and flow rate is supplied from a hydraulic pressure source 42 via a first switching valve 40 and a check valve 43. The lower chamber 38 b of the hydraulic cylinder 38 is connected to the first switching valve 40.
[0025]
The piston rod 31a is provided with, for example, a linear scale 45 as measuring means for measuring the amount of plasticized resin in the cylinder 30. The linear scale 45 is attached to the cylinder 30. The linear scale 45 includes an indicator needle 46 that moves up and down integrally with the piston rod 31a, and measures the position of the indicator needle 46 to measure the position of the piston 31, such as an optical scale, a magnetic scale, and a potentiometer. It is configured. The linear scale 45 outputs the measured value as an electric signal so that the height position of the piston 31 in the cylinder 30 can be measured. The electric signal of the linear scale 45 is digitally displayed on the operation panel 14a or the like of the control unit 14, and the operator can monitor the position of the piston 31 while operating the operation panel 14a or the like.
[0026]
Next, the injection device 13 will be described. An injection plunger 55 is provided inside a horizontal injection cylinder 54 so as to advance and retreat. Around the injection cylinder 54, a heater 53 that heats the internal plasticized resin to maintain a molten state is wound. Further, a measuring chamber 56 is formed in a bore on the distal end side of the injection cylinder 54, and the measuring chamber 56 communicates with the resin outflow passage 32 provided in the cylinder 30 of the accumulator device 11. The measuring chamber 56 is connected to the injection nozzle 58 via a second opening / closing valve 57 composed of a rotary valve.
[0027]
A through hole 59 is provided at the rear end of the injection cylinder 54, and the plunger rod 60 of the injection plunger 55 is connected to the plunger 62 of the hydraulic cylinder 61 as an injection drive unit through the through hole 59.
[0028]
The rear chamber 61a of the hydraulic cylinder 61 is connected to a tank 65 via a second relief valve 63 and a second switching valve 64. When the pressure in the rear chamber 61a exceeds the set pressure P2 of the second relief valve 63, the pressure oil in the rear chamber 61a is released to the tank 65, and the second switching valve 64 is switched, so that the second switching valve 64 is switched. Pressure oil controlled to a predetermined pressure and flow rate is supplied from a hydraulic source 66 via a second switching valve 64 and a check valve 67. The front chamber 61 b of the hydraulic cylinder 61 is connected to a first switching valve 64.
[0029]
The set pressures P1 and P2 of the first and second relief valves 39 and 63 are suitable for plasticizing the pressure of the plasticized resin extruded from the outlet 19 of the plasticizing device 11, that is, the back pressure of the plasticizing device 11. The piston 31 and the injection plunger 55 are respectively retracted according to the flow of the plasticized resin into the accumulator chamber 29 and the metering chamber 56 of the accumulator device 12 while maintaining the back pressure at a desired value. It has become so.
[0030]
The servo motor 23 of the feeder 20, the inverter motor 26 of the plasticizing device 11, the first opening / closing valve 33, and the second opening / closing valve 57 are controlled by the control unit 14.
[0031]
The injection nozzle 58 of the injection cylinder 54 is joined to the nozzle touch surface 71 of the injection mold 70 at the time of injection. The injection molding die 70 is provided with a cavity 73 communicating with the nozzle touch surface 71 via the resin passage 72. Further, a cooling water passage 74 for circulating cooling water to cool the plasticized resin filled in the cavity 73 is provided around the cavity 73.
[0032]
The control panel 14a of the control unit 14 is provided with a changeover switch 75 as a changeover means. The changeover switch 75 can switch the plasticizing device 11 between a first operating condition of intermittent operation (discontinuous operation) and a second operating condition of continuous operation in synchronization with the injection operation of the injection device 13, When switching to the first operating condition for (discontinuous operation), an operator or the like can be notified by a lamp 76 or a buzzer as a notification means, a screen display, or the like.
[0033]
When the plasticizing device 11 is set to the first operating condition of intermittent operation (discontinuous operation) in synchronization with the injection operation of the injection device 13, the plasticizing device 11 may be used under irregular operation conditions such as setting of molding conditions. It is mainly when the plasticization state is unstable, and can be notified to an operator or the like by a lamp, a buzzer, a screen display or the like. Further, when the plasticizing device 11 is set to the second operating condition for continuous operation, the setting of conditions for forming conditions and the like is completed, and stable continuous forming can be expected.
[0034]
Next, the operation of the injection molding apparatus configured as described above will be described.
[0035]
First, when the plasticizing device 11 is switched to the first operating condition in which the plasticizing device 11 is intermittently operated in synchronization with the injection operation of the injection device 13 by the changeover switch 75, the operator or the like is notified by a lamp 76 or a buzzer as a notification means, a screen display, or the like. Be informed.
[0036]
The material supply hopper 24 and the feeder cylinder 21 of the feeder 20 contain a synthetic resin material, for example, a material in which powder such as polypropylene and a reinforcing material such as mica or a filling material is mixed. When the servomotor 23 is driven and the screw 22 rotates, the synthetic resin material in the feeder cylinder 21 falls from the discharge path 25 to the hopper 17 of the plasticizing device 11 and is supplied to the plasticizing cylinder 15 through the supply port 18. You. The powder such as polypropylene and the reinforcing material such as mica or the filling material may be supplied by separate feeders.
[0037]
When the inverter motor 26 of the plasticizing device 11 is driven, the rotation of the rotating shaft 27 of the inverter motor 26 is transmitted to the biaxial plasticizing screw 16 via the gear box 28. The plasticizing screw 16 has a screw functioning as a feed portion, a kneading portion, and a compressing portion in the axial direction, continuously rotates in the same direction while contacting inside the plasticizing cylinder 15, and is heated by the heater 15a. The powdery synthetic resin material is uniformly heated, melted and kneaded to become a plasticized resin.
[0038]
The plasticized resin passes through the cylinder 30 of the accumulator device 12 from the outflow passage 19, flows into the measuring chamber 56 of the injection cylinder 54 through the first opening / closing valve 33 of the outflow passage 32, and retreats the injection plunger 55. .
[0039]
When a predetermined amount of the plasticized resin necessary for one injection is measured in this way, the inverter motor 26 of the plasticizing device 11 stops, and the rotation of the plasticizing screw 16 stops. Extrusion stops.
[0040]
Next, the first opening / closing valve 33 is closed, the second opening / closing valve 57 is opened, and the second switching valve 64 is moved from the illustrated position to the left to switch to the right switching position. Pressure oil is supplied from the second hydraulic pressure source 66 to the rear chamber 61a of the hydraulic cylinder 61 via the check valve 67, the injection plunger 55 is advanced, and the plasticized resin in the measuring chamber 56 is injected from the injection nozzle 58 for injection molding. The molding is performed by injecting into the cavity 73 of the mold 70.
[0041]
After the pressure-holding operation is completed, the injection plunger 55 is retracted and the metering operation is started. Then, the inverter motor 26 of the plasticizing device 11 is restarted, and the plasticizing screw 16 is rotated and kneaded, and the accumulator is discharged from the outlet passage 19. The plasticized resin is extruded into the cylinder 30 of the device 12. Then, it again flows into the measuring chamber 56 through the outflow passage 32 of the cylinder 30. As described above, the accumulator device 12 does not operate only when the plasticized resin passes when the plasticizing device 11 is operating, and the plasticizing device 11 intermittently synchronizes with the injection operation of the injection device 13. When the plasticizer is operated and a predetermined amount of the plasticized resin required for one injection is measured, the plasticizing device 11 is stopped.
[0042]
Next, a case in which the changeover switch 75 is switched to the second operating condition for continuously operating the plasticizing device 11 will be described.
[0043]
When the plasticized resin is extruded from the outflow passage 19 of the plasticizing cylinder 15 of the plasticizing device 11 that is continuously operated and extruded into the cylinder 30 of the accumulator device 12, the plasticized resin pushes up the piston 31.
[0044]
At this time, the rise of the piston 31 enlarges the accumulator chamber 29 while being controlled by the set pressure of the first relief valve 39, and the plasticized resin is accumulated therein.
[0045]
During this time, the injection plunger 55 of the injection device 13 performs the injection and pressure-holding process one cycle before. When the pressure holding step is completed, the second opening / closing valve 57 is closed, the second switching valve 64 is returned to the neutral position in the drawing, and the first opening / closing valve 33 is opened.
[0046]
Next, the first switching valve 40 is moved leftward from the illustrated position to switch to the right switching position, and a predetermined pressure and a predetermined flow rate of hydraulic oil from the first hydraulic pressure source 42 are passed through the check valve 43. The oil is supplied to the upper chamber 38a of the hydraulic cylinder 38. Thereby, the piston 31 descends at a predetermined speed. At this time, the rear chamber 61a of the hydraulic cylinder 61 is connected to the tank 65 via the second relief valve 63 and the second switching valve 64. As described above, the set pressure P2 of the second relief valve 63 is set so as to maintain the back pressure of the outflow passage 19 at a predetermined value, similarly to the first relief valve 39. Therefore, the plasticized resin in the accumulator chamber 29 flows into the metering chamber 56 from the lower outlet passage 32 through the first opening / closing valve 33 without interrupting the supply of the plasticized resin from the outlet passage 19, and is injected. The plunger 55 is retracted.
[0047]
The piston 31 of the accumulator device 12 is lowered to the illustrated extrusion limit position and is held at this position. At this time, the amount of the plasticized resin that joins from the accumulator chamber 29 and the plasticizing device 11 and is sent to the measuring chamber 56 of the injection cylinder 54 is determined to be equal to or less than the amount required for one injection. .
[0048]
When the piston 31 is located at the extrusion limit position, since the annular flow path 36 is formed in the accumulator chamber 29, the plasticized resin continuously extruded from the outflow path 19 is supplied to the measuring chamber 56 via the annular flow path 36. Sent without stagnation.
[0049]
When a predetermined amount of the plasticized resin necessary for one injection is measured in this way, the first opening / closing valve 33 is closed, the second opening / closing valve 57 is opened, and the second switching valve 64 is illustrated. From the position to the left to switch to the right switching position. Then, pressure oil is supplied from the second hydraulic pressure source 66 to the rear chamber 61 a of the hydraulic cylinder 61 via the check valve 67, the injection plunger 55 is advanced, and the plasticized resin in the measuring chamber 56 is injected from the injection nozzle 58. The molding is performed by injecting into the cavity 73 of the molding die 70.
[0050]
Next, at the same time as closing the first opening / closing valve 33 again, the first switching valve 40 is switched to the neutral position shown in the figure, and the plasticized resin continuously sent out from the outflow passage 19 is again accumulated in the accumulator chamber 29.
[0051]
As described above, while the plasticizing device 11 operates continuously, the injection device 13 operates intermittently to inject the plasticized resin into the injection mold 70 to perform molding. The plasticized resin continuously fed from the storage device is temporarily stored in the accumulator device 12, and the plasticized resin can flow into the measuring chamber 56 from the accumulator device 12 in accordance with the injection timing of the injection device 13.
[0052]
When the plasticized resin is supplied to the accumulator device 12, the piston 31 in the cylinder 30 is pushed up by the plasticized resin and rises. Therefore, the linear scale 45 measures the position of the piston 31, and the electric signal of the controller 14 Digital display on operation panel etc. Therefore, the operator can grasp the height position of the piston 31 displayed on the operation panel or the like, that is, the amount of the plasticized resin accumulated in the accumulator chamber 29.
[0053]
In the above embodiment, the hydraulic cylinders 38 and 61 are used for the accumulator device 12 and the injection device 13 and are driven by hydraulic pressure. However, as the drive device, the rotational motion is converted into linear motion by a servomotor and a ball screw / nut. It may be driven in such a manner.
[0054]
In the above-described embodiment, the inclined surface 34 a is provided on the main body 34 of the piston 31 in the accumulator device 12, and the protruding small-diameter portion 35 that protrudes below the inclined surface 34 a and has a diameter smaller than the inner diameter of the cylinder 30 is provided. Therefore, when the piston 31 is at the lower limit position, the highest position of the inclined surface 34 a is located above the outflow passage 19, and an annular flow passage 36 is formed between the small projecting portion 35 and the inner peripheral surface of the cylinder 30. It has become so. However, the shape of the piston 31 is not limited to the above embodiment. If the cylinder 30 is provided so that the resin outflow path 32 of the cylinder 30 is higher than the outflow path 19 of the plasticizing device 11, the piston 31 Even when the shape is in close contact with the inner peripheral surface of the cylinder 30, the outflow path 19 and the resin outflow path 32 can be communicated when the piston 31 is at the lower limit position.
[0055]
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements in an implementation stage without departing from the scope of the invention. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiment. Further, components of different embodiments may be appropriately combined.
[0056]
【The invention's effect】
As described above, according to the present invention, the switching means for switching the plasticizing device between the first operating condition for intermittent operation and the second operating condition for continuous operation in synchronization with the injection operation of the injection device is provided. Thereby, the plasticizing device can be switched between the intermittent operation and the continuous operation according to the operating conditions of the device, and there is an effect that wasteful disposal of the resin is eliminated and a molded article can be molded under stable plasticizing conditions.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an injection molding apparatus showing a first embodiment of the present invention.
[Explanation of symbols]
11 plasticizing device, 12 accumulator device, 13 injection device, 14 control unit, 16 plasticizing screw, 29 accumulator chamber, 30 cylinder, 31 piston, 75 switch

Claims (3)

A plasticizer for plasticizing the synthetic resin material,
An accumulator device comprising a cylinder communicating with an outflow passage of the plasticizing device and a piston provided in the cylinder, and temporarily storing the plasticized resin supplied from the plasticizing device;
An injection device for measuring and injecting the plasticized resin supplied from the accumulator device,
Switching means for switching the plasticizing device to a first operating condition for intermittent operation and a second operating condition for continuous operation in synchronization with the injection operation of the injection device;
An injection molding apparatus comprising: 2. The injection molding apparatus according to claim 1, wherein the switching unit is a switch. The injection molding apparatus according to claim 1, further comprising a notification unit configured to provide notification when the first operation condition for intermittently operating the plasticizing apparatus is provided.

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