JP2002347073A - Material resin feeder of injection molding machine by vacuum hopper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the on-off failure of a shutter, seal failure or the like without sharply altering the structure of a hopper itself by the feed of a material due to a blower and the negative pressure eliminating vent valve employed in the pipeline of a vacuum pump for reducing the pressure in a material feed chamber. SOLUTION: The hopper 1 is airtightly demarcated into an upper material suction chamber 4 and a lower material feed chamber 5 by the shutter 3, and the on-off device 18 of the shutter 3 is provided to the hopper 1. A feed pipeline 8 is provided over the material suction chamber 4 and a material tank 7 and the suction blower 10 is connected to the material suction chamber 4. The pressure reducing vacuum pump 13 and a level detector 19 for detecting the level of the material resin 21 in the material feed chamber 5 are provided to the material feed chamber 5. A weighing part 9 for controlling a material feed amount on the basis of an open time is provided to the feed pipeline 8, and the negative pressure eliminating vent valve 15 of the material feed chamber 5 is provided to the pipeline 14 of the vacuum pump 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material resin supply device for an injection molding machine using a vacuum hopper.

In an injection molding machine, a synthetic resin material supplied from a hopper is melt-kneaded by rotating a screw in a heating cylinder of an injection device, and the molten resin is measured into a tip portion of the heating cylinder by retreating the screw. Therefore, a desired synthetic resin product is formed by injection filling in a mold.

[0003] In the process of melting and kneading the material resin, when air flowing from a hopper or a gas generated by heating an additive in the material resin by heating is taken into the molten resin, this is taken into the cavity surface of the mold. As a cause of the gas contamination, the molded product may be burnt, or may have molding defects such as poor gloss, dimensional variations, or the like.

[0004] As means for solving such molding defects, a vacuum hopper capable of sucking air or gas in the material supply section of the injection device and the rear portion of the heating cylinder by a vacuum pump, or a vacuum pump and an inert gas For example, a material supply device including both of the injection devices is employed.

In the conventional vacuum hopper, the inside of the hopper is airtightly divided into an upper hopper by a shutter and a lower hopper connected to a supply port of an injection device, and the lower hopper can be depressurized by a vacuum pump. Air is prevented from flowing into the inside, or gas generated in the heating cylinder is sucked into the lower hopper and exhausted.

[0006] Material is supplied to the injection device by storing material resin in both the upper hopper and the lower hopper, and when the remaining amount of the lower hopper reaches a set amount, the shutter is opened to reduce the pressure in the lower hopper. Then, the material resin of the upper hopper is supplied, and after the supply, the shutter is closed again to feed the material resin to the upper hopper.

In such a vacuum hopper, the air pressure inside the hopper differs between the upper and lower sides of the shutter, and the lower hopper side has a negative pressure. Therefore, the shutter inside the hopper is always pulled toward the lower hopper. In many cases, the lower surface of the shutter is pressed against the seal member on the lower hopper side, and this causes frictional resistance, so that opening and closing cannot be performed smoothly.

Further, depending on the sealing structure, fine resin chips mixed into the upper hopper together with the resin material are sucked into the sliding clearance between the shutter and the sealing member by the negative pressure on the lower hopper side during the blockage, and enter. Alternatively, the powder resin enters the shutter receiving groove due to the closing during the supply of the material to the lower hopper, which causes a problem such that the hermetic seal is damaged or the shutter is opened and closed poorly. In particular, such a phenomenon frequently occurs in a crushed recycled material containing a large amount of powder, and therefore, there is also a problem that a material resin blended with the recycled material is limited in its mixing ratio.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to employ a suction blower for feeding a material to a hopper and a vent valve for eliminating a negative pressure in a pipe of a vacuum pump. To provide a new resin supply device for an injection molding machine using a new vacuum hopper that can solve shutter opening / closing defects and sealing defects without significantly changing the structure of the hopper itself. is there.

[0010]

According to the present invention, the upper part is airtightly partitioned by a shutter into a material suction chamber and the lower part into a material supply chamber, and the lower end opening of the material supply chamber is connected to a supply port for injection. A vacuum hopper having a closed structure erected on the device, a shutter opening / closing device, a feed pipe provided over the material suction chamber and the material tank, and a suction blower connected to the material suction chamber, A vacuum pump for decompression connected to the material supply chamber, and a level detector for the material resin in the material supply chamber, and a metering unit for controlling the amount of material supplied by the open time in the supply line; A ventilation valve for eliminating the negative pressure of the material supply chamber is provided in the pipeline of the vacuum pump, and the amount of material supplied to the material supply chamber is determined by an opening time in the measuring section after the shutter is opened. Yo Control and composed, there is also a thing called.

In the above structure, in the material suction chamber above the hopper, fine resin chips and powdery resin in the material resin sucked and fed from the material tank are suctioned and separated by the suction blower and discharged from the vacuum hopper, Shutter opening / closing and airtightness problems due to those resins are eliminated.

In addition, the communication between the vacuum pump and the atmosphere by the opening operation of the ventilation valve can eliminate the negative pressure in the material supply chamber without stopping the vacuum pump. Can be opened, so that the problem of the shutter opening operation due to the negative pressure can be solved.

Further, the measurement of the material resin into the vacuum hopper is performed irrespective of the shutter opening time as in the past.
Since the shutter can be operated only for maintaining the airtightness of the material supply chamber because the measurement can be performed during the opening time of the measuring section of the feed line, there is no difference in the measurement due to the opening and closing timing of the shirt, so that the measuring accuracy is also improved. .

The material tank or the like in the present invention means a material bag, a material container, a drier device or the like which can be used as a material resin tank in a commonly used material bag.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes an injection device having a screw inside, and 2 denotes a vacuum hopper having a closed structure, a large-diameter upper portion having a lower peripheral wall formed in a funnel shape, and a lower portion connected to the lower peripheral wall. The upper part of the tubular lower part is horizontally and airtightly partitioned by a shirt 3, and the upper part is constituted by a material suction chamber 4 and the lower part is constituted by a material supply chamber 5. The lower end opening 5 is connected to the supply port 6 and is erected on the injection device 1.

At the upper part of the material suction chamber 4, a transparent feed pipe 8 extending to the material tank 7 is mounted. In the middle of the feed pipe 8, the opening and closing of the pipe and the material suction chamber are provided. A metering unit 9 is also provided which also controls the supply amount of the material resin to 4. A suction pipe 11 of a suction blower 10 is attached to a ceiling plate of the material suction chamber 4, and a filter 12 made of a mesh plate or a perforated plate is stretched inside the ceiling plate to provide a granular or flake-like shape. The resin 21 is prevented from being sucked and discharged, and only fine resin dust and powdery resin can be separated and discharged by suction of the blower 10.

The measuring section 9 includes a cylindrical valve case 9.
1 and a rotary valve having a rotatable valve body 92 provided therein with through holes 93 and 94 having the same diameter as the pipe inner diameter.
8b is provided in the feed line 8 by being attached to the connection portion. In such a measuring section 9, the feed pipe 8 can be opened and closed by rotating the valve body 92 by 90 ° by a driving device 95 such as an air or electric motor, and the length of the opening time can be set arbitrarily. Thereby, the material resin fed to the vacuum hopper 2 can be accurately measured.

A pipe line 14 of a vacuum pump 13 for reducing the pressure of the material supply chamber 5 to a set pressure when the shutter 3 blocks the material suction chamber 4 is connected to a lower portion of the material supply chamber 5. An electromagnetically operated ventilation valve 15 for connecting and disconnecting the pipeline from the atmosphere is attached to the pipeline 14, and the vacuum pump 1 is opened by opening the ventilation valve 15.
Even when 3 is operating, the negative pressure due to the reduced pressure in the material supply chamber 5 is eliminated so that the shutter can be opened smoothly.

The shutter 3 is slidably fitted from the side into a receiving groove 16 provided horizontally around the upper part of the tube of the material supply chamber 5 and is embedded in the lower receiving surface of the receiving groove 16. The lower surface of the material suction chamber 4 and the material supply chamber 5 are hermetically partitioned by contacting the lower surface of the seal member 16a. The outer end of the shutter 3 is connected to a piston rod 18a of an air cylinder 18 horizontally mounted on the hopper side via a flat box-shaped guide member 17, and the shutter 3 is moved by the air cylinder 17. The material supply chamber 5 can be opened and closed by sliding back and forth.

Reference numeral 19 denotes a level detector of the material resin 21 in the material supply chamber such as a photoelectric tube, which is attached to the tube side of the material supply chamber 5 and connected to the controller 20. The controller 20 includes a driving device 95 for the measuring section 9 and a blower 10 and a vacuum pump 1 (not shown).
3 is connected to the excitation unit of the ventilation valve 15, the drive source of the air cylinder 17, and the like.
Are sequentially started by an electric signal from

FIG. 2 shows another embodiment of the measuring section 9 in which the front and rear pipes 8a and 8b of the feed pipe 8 are vertically connected via a chamber 96, and a material tank is provided in the chamber. A plate 97 for opening and closing the opening of the front conduit 8a on the side is provided by being attached to a piston rod 99 of an air cylinder 98 outside the chamber.
The opening and closing of the feed pipe 8 and the measurement of the material resin 21 to the vacuum hopper 2 based on the opening time can be performed in the same manner as the measuring section 9 shown in FIG.

Next, a series of supply operations of the material resin according to the embodiment shown in FIG. 1 will be described in order with reference to FIGS. FIG. 3 shows a state in which the molding machine is operating, the granular material resin 21 in the material supply chamber 5 has been consumed, and the remaining level of the material resin 21 has fallen below the set level.
The feed line 8 is closed with the drive device 95 of the FF and the measuring unit 9 also turned off, and the supply of the material resin from the material tank 7 is stopped. Further, the shutter 3 is in the forward position, airtightly shuts off the material suction chamber 4 and the material supply chamber 5, the vacuum pump 13 is on, the ventilation valve 15 is off, and the pressure in the material supply chamber is reduced.

In the state shown in FIG. 3, when the level detector 19 detects that the material has been reduced, a detection signal is input to the controller 20, and the signal from the controller 20 causes the detection signal shown in FIG.
As shown in (1), first, the ventilation valve 15 is turned on to open, and then the air cylinder 18 of the shutter 3 is moved backward to open the shutter 3.

When the vent valve 15 is opened, the pipe line 1 is opened.
4 communicates with the atmosphere. As a result, the atmosphere is
As a result, the pressure in the material supply chamber 5 is not reduced, and the pressure in the material supply chamber 5 rises, thereby eliminating the negative pressure. Further, since the pressure contact of the shutter 3 to the seal member 16a due to the negative pressure is also eliminated, the frictional resistance upon opening is small, and the shutter 3 smoothly retreats to open the material supply chamber 5 to the material suction chamber 4. I do.

Following the opening operation of the shutter 3,
The metering section 9 and the blower 10 are turned on by a signal from the controller 20, and as shown in FIG.
The feed line 8 is opened by rotating by 0 °. At the same time, the suction operation of the blower 10 is performed. As a result, the granular material resin 21 in the material tank 7 is sucked and transferred to the material suction chamber 4 through the feed pipe 8. The opening time of the valve body 92 is set in the controller 20 in advance, and the material resin 21 is measured using the opening time as the measuring time. The opening time is limited to a range in which the amount of the granular material resin 21 passing through does not exceed the shutter position, thereby preventing malfunction of the material resin when the shutter is closed.

In the material suction chamber 4, the granular material resin 2
The fine resin dust and powdery resin mixed in 1 pass through the filter 12 and are sucked into the conduit 11 and are discharged and removed outside the hopper. Further, the granular material resin 21 falls into the material supply chamber 5 by its own weight and accumulates. When the weighing time ends, the weighing unit 9 is closed by a signal from the controller 20, and the valve body 92 rotates 90 °. As a result, as shown in FIG. 6, the feed line 8 is closed by the measuring unit 9, and subsequently, the blower 10 is turned off to stop the material suction, and the material supply from the material tank 7 is stopped.

Next, the controller 20 controls the air cylinder 18
Is switched to forward operation, and the ventilation valve 15 is closed to open the OF valve.
F. The shutter 3 is moved forward in the receiving groove 16 by the piston rod 18a of the air cylinder 18, and again shuts off the material suction chamber 4 and the material supply chamber 5 in an airtight manner. Further, the pipe 14 is isolated from the atmosphere by the closing operation of the ventilation valve 15,
The pressure of the material supply chamber 5 is reduced again by the vacuum pump 13.

Therefore, every time the material resin is consumed,
Intermittent material measurement and supply are performed by repeating the above series of operations. Except during material supply, moisture and gas, etc., generated from the molten resin in the heating cylinder are exhausted to the outside under reduced pressure, and defects in the molded product are detected. To prevent occurrence of molding and molding defects.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of one embodiment of a material supply device of an injection device using a vacuum hopper according to the present invention.

FIG. 2 is an explanatory diagram of a weighing unit according to another embodiment of the present invention.

FIG. 3 is an explanatory diagram of a state before material supply.

FIG. 4 is an explanatory diagram showing an opening operation state of a ventilation valve and a shutter before material supply.

FIG. 5 is an explanatory diagram showing a material supply state.

FIG. 6 is an explanatory diagram showing a state after material supply.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection apparatus 2 Vacuum hopper 3 Shutter 4 Material suction chamber 5 Material supply chamber 6 Supply port 7 Material tank 8 Feeding line 9 Measuring unit 10 Suction prower 12 Filter 13 Vacuum pump 14 Pipeline 15 Vent valve 16 Shutter reception Groove 18 Shutter air cylinder 19 Level detector 20 Controller 21 Material resin

Claims (2)

[Claims] A vacuum hopper having a closed structure in which an upper portion is air-tightly partitioned by a shutter into a material suction chamber and a lower portion into a material supply chamber, and a lower end opening of the material supply chamber is connected to a supply port and erected in an injection device. An opening and closing device for the shutter, a feed line provided over the material suction chamber and the material tank, and the like,
A suction blower connected to the material suction chamber, a vacuum pump connected to the material supply chamber for reducing pressure, and a material resin level detector in the material supply chamber. Material supply of an injection molding machine by a vacuum hopper, characterized in that a metering section for controlling the feed rate by an open time is provided, and a ventilation valve for eliminating a negative pressure in a material supply chamber is provided in a line of the vacuum pump. apparatus. 2. A material for an injection molding machine using a vacuum hopper according to claim 1, wherein the amount of material supplied to said material supply chamber is controlled by an opening time in said measuring section after said shutter is opened. Resin supply device.