JP3783205B2 - Material resin supply device for injection molding machine by vacuum hopper - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a material resin supply apparatus for an injection molding machine using a vacuum hopper.
[0002]
In the injection molding machine, the synthetic resin material supplied from the hopper is melted and kneaded by rotating the screw in the heating cylinder of the injection device, and the molten resin is measured into the tip of the heating cylinder by retreating the screw. The mold is injection-filled to form a desired synthetic resin product.
[0003]
In the process of melting and kneading the material resin, if the air that flows in from the hopper or the gas that is generated by evaporation of the additive in the material resin is taken into the molten resin, this causes gas contamination on the cavity surface of the mold. As a result, the molded product may be burned, or molding defects such as poor gloss and dimensional variations may occur.
[0004]
As a means for solving such molding defects, a vacuum hopper capable of sucking air or gas in the material supply part of the injection device and the rear part of the heating cylinder with a vacuum pump, or a vacuum pump and an inert gas injection device. A material supply device equipped with both is employed.
[0005]
The conventional vacuum hopper is hermetically partitioned into an upper hopper by a shutter and a lower hopper connected to the supply port of the injection device, and the lower hopper can be depressurized by a vacuum pump so that the inside of the hopper The inflow of air is prevented or the gas generated in the heating cylinder is sucked into the lower hopper and exhausted.
[0006]
In addition, the material supply to the injection device is made by storing the material resin in both the upper hopper and the lower hopper, and when the remaining amount of the lower hopper reaches the set amount, the shutter is opened and the lower hopper is constantly depressurized. The material resin of the hopper is supplied, and after the supply, the shutter is closed again and the material resin is fed to the upper hopper.
[0007]
In such a vacuum hopper, the air pressure in the hopper is different up and down from the shutter, and the lower hopper side is negative pressure, so the shutter in the hopper is always pulled to the lower hopper side, The lower surface is pressed against a seal member on the lower hopper side, and this often becomes a frictional resistance and cannot be opened and closed smoothly.
[0008]
Depending on the seal structure, fine resin scraps mixed with the material resin into the upper hopper may be sucked into the sliding clearance between the shutter and the seal member due to the negative pressure on the lower hopper side during closing, or enter the lower hopper. Due to the closing during the material supply to the resin, the powdered resin enters the shutter receiving groove, which causes problems such as damage to the hermetic seal and poor opening / closing of the shutter. In particular, such a phenomenon is likely to occur frequently in a pulverized recycled material containing a large amount of powder. For this reason, a material resin blended with the recycled material has a problem that the mixing ratio is limited.
[0009]
The present invention has been conceived from the above circumstances, and its purpose is to employ a suction blower for feeding material to the hopper and a vent valve for eliminating negative pressure in the pipe line of the vacuum pump. Accordingly, it is an object of the present invention to provide a material resin supply device for an injection molding machine using a new vacuum hopper, which can solve a shutter opening / closing failure and a sealing failure without significantly changing the structure of the hopper itself.
[0010]
[Means for Solving the Problems]
According to the above-mentioned object, the invention has a hermetically sealed vacuum in which the upper part is hermetically partitioned by the shutter and the lower part is hermetically divided into the material supply chamber, and the lower end opening of the material supply chamber is connected to the supply port to stand upright in the injection device A hopper, a shutter opening and closing device, a feed pipe provided between the material suction chamber and the material tank, a blower of a suction pipe connected to the material suction chamber, and a pressure reducing pressure connected to the material supply chamber A vacuum pump and a level detector for the material resin in the material supply chamber, and in the feed line, the shutter is opened after the shutter is opened, and the blower is suctioned simultaneously. Is provided in a range that does not exceed the shutter position according to the opening time, and the vacuum pump pipe is opened before the shutter is opened after the material loss is detected. Formed by providing a vent valve to eliminate the pressure, is that.
[0011]
In the above configuration, in the material suction chamber at the top of the hopper, fine resin waste and powdery resin in the material resin sucked and fed from the material tank is sucked and separated by the suction blower and discharged from the vacuum hopper, and the resin The problems of shutter opening and closing and airtightness due to the above will be solved.
[0012]
In addition, the negative pressure in the material supply chamber can be eliminated without stopping the vacuum pump by communicating the vacuum pump with the atmosphere by opening the vent valve, which eliminates the negative pressure on the material supply chamber side and opens the shutter. Since it can be performed, the malfunction of the shutter opening operation due to the negative pressure is solved.
[0013]
Furthermore, since the measurement of the material resin to the vacuum hopper can be performed with the opening time of the metering section of the feed line, regardless of the shutter opening time as before, the shutter functions only to maintain the airtightness of the material supply chamber. What is necessary is that there is no difference in measurement depending on the opening / closing timing of the shirter, which also improves the measurement accuracy.
[0014]
In addition, the material tank etc. in this invention means what can be used as a tank of material resin in the normally used material bag, material container, and also a dryer apparatus.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, 1 is a screw-injection injection device, 2 is a vacuum hopper with a closed structure, and has a large-diameter upper part having a lower peripheral wall formed in a funnel shape, and a tubular structure connected to the lower peripheral wall and continuously extending downward. The upper portion of the tubular lower portion is horizontally and airtightly partitioned by the shirter 3, the upper portion is configured as the material suction chamber 4, and the lower portion is defined as the material supply chamber 5, and the lower end opening of the material supply chamber 5 is the supply port 6 and connected to the injection device 1.
[0016]
A transparent feed line 8 extending to the material tank 7 is attached to the upper part of the material suction chamber 4. The pipe is opened and closed and connected to the material suction chamber 4 in the middle of the feed line 8. A metering unit 9 is provided which also serves to control the supply amount of the material resin.
In addition, a suction pipe 11 of a suction blower 10 is attached to the ceiling plate of the material suction chamber 4, and a filter 12 made of a mesh plate or a porous plate is stretched inside the ceiling plate to form particles or flakes. The material resin 21 is prevented from being sucked and discharged, and only fine resin waste and powdered resin can be separated and discharged by suction of the blower 10.
[0017]
The measuring section 9 is composed of a rotary valve in which a cylindrical valve case 91 and a valve body 92 rotatably provided therein are provided with through holes 93 and 94 having the same diameter as the pipe inner diameter. A valve case 9a is attached to the connecting portion of the front and rear pipelines 8a and 8b and is provided in the feed pipeline 8.
In such a metering section 9, the feed pipe 8 can be opened and closed by rotating the valve body 92 by 90 ° by a drive device 95 such as air or an electric motor, and the length of the opening time can be arbitrarily set. Therefore, the material resin fed to the vacuum hopper 2 can be accurately measured.
[0018]
Connected to the lower portion of the material supply chamber 5 is a pipe line 14 of a vacuum pump 13 for reducing the material supply chamber 5 to a set atmospheric pressure in a state where the material suction chamber 4 is shut off by the shutter 3. Further, an electromagnetically operated ventilation valve 15 that connects and disconnects the pipe line and the atmosphere is attached to the pipe line 14. Even if the vacuum pump 13 is operated by opening the vent valve 15, the material supply chamber 5 The negative pressure due to decompression is eliminated and the shutter can be opened smoothly.
[0019]
The shutter 3 is fitted into a receiving groove 16 horizontally provided around the upper portion of the tube body of the material supply chamber 5 so as to be slidable from the side, and a seal member 16a embedded in a lower receiving surface of the receiving groove 16. The material suction chamber 4 and the material supply chamber 5 are airtightly partitioned by contacting the lower surface thereof. The outer end of the shutter 3 is connected to a piston rod 18a of an air cylinder 18 mounted horizontally on the side of the hopper via a flat box-shaped guide member 17, and the shutter 3 The material supply chamber 5 can be opened and closed by sliding back and forth.
[0020]
Reference numeral 19 denotes a level detector for the material resin 21 in the material supply chamber such as a photoelectric tube, which is attached to the side of the tube body of the material supply chamber 5 and connected to the controller 20. The controller 20 includes a driving device 95 for the metering unit 9 and a driving device for the blower 10 and the vacuum pump 13, an excitation operating unit for the ventilation valve 15, and a driving source for the air cylinder 17, which are omitted in the drawing. A series of material supply operations are sequentially started by the controller 20 in response to an electric signal from the level detector 19.
[0021]
FIG. 2 shows another embodiment of the metering unit 9, in which the front and rear pipes 8a and 8b of the feed pipe 8 are connected vertically through a chamber 96, and the front of the material tank side is placed in the chamber. A plate 97 for opening and closing the opening of the pipe line 8a is provided by being attached to the piston rod 99 of the air cylinder 98 outside the chamber, and the opening and closing movement of the opening and closing plate 97 by the air cylinder 98 causes the same as the measuring unit 9 shown in FIG. The material resin 21 can be weighed into the vacuum hopper 2 according to the opening and closing time of the feed line 8 and the opening time.
[0022]
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 material is in operation, the granular material resin 21 in the material supply chamber 5 is consumed, and the remaining amount level of the material resin 21 is equal to or lower than the set level. The driving device 95 of the measuring unit 9 is also turned off, the feed pipe 8 is closed, and the feeding of the material resin from the material tank 7 is in a stopped state. The shutter 3 is in the forward position, and the material suction chamber 4 and the material supply chamber 5 are hermetically shut off, the vacuum pump 13 is ON, the vent valve 15 is OFF, and the material supply chamber is in a decompressed state.
[0023]
In the state of FIG. 3, when the level detector 19 detects material loss, a detection signal is input to the controller 20, and the vent valve 15 is first turned ON by the signal from the controller 20 as shown in FIG. Then, the air cylinder 18 of the shutter 3 is moved backward, and the shutter 3 is opened.
[0024]
By opening the vent valve 15, the pipe line 14 communicates with the atmosphere. As a result, the air flows into the pipe line 14 by suction by the vacuum pump 13, so that the material supply chamber 5 is not depressurized, the atmospheric pressure in the material supply chamber 5 rises, and the negative pressure is eliminated. Further, since the pressure contact of the shutter 3 to the seal member 16a due to the negative pressure is eliminated, the frictional resistance at the time of opening is small, and the shutter 3 moves backward smoothly to open the material supply chamber 5 to the material suction chamber 4. To do.
[0025]
Subsequent to the opening operation of the shutter 3, the measuring unit 9 and the blower 10 are turned on by a signal from the controller 20, and as shown in FIG. 5, the valve body 92 is rotated 90 ° to open the feeding line 8. To do. At the same time, the blower 10 is suctioned.
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 conduit 8. The opening time of the valve body 92 is preset in the controller 20, and the material resin 21 is measured using the opening time as the measuring time. This opening time is limited to a range in which the passage amount of the granular material resin 21 does not exceed the shutter position, thereby preventing malfunctions due to biting of the material resin when the shutter is closed.
[0026]
In the material suction chamber 4, fine resin waste and powdered resin mixed in the granular material resin 21 pass through the filter 12 and are sucked into the pipe line 11 and discharged out of the hopper. Further, the granular material resin 21 falls into the material supply chamber 5 due to its own weight and accumulates.
When the metering time ends, the metering 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 feeding pipe line 8 is closed by the measuring unit 9, the blower 10 is subsequently turned OFF, the material suction is stopped, and the material supply from the material tank 7 is stopped.
[0027]
Next, the controller 20 switches the air cylinder 18 to the forward operation, and closes the ventilation valve 15 to turn it OFF. The shutter 3 moves forward in the receiving groove 16 by the piston rod 18a of the air cylinder 18, and shuts off the material suction chamber 4 and the material supply chamber 5 in an airtight manner again. Further, the conduit 14 is shut off from the atmosphere by closing the ventilation valve 15, and the material supply chamber 5 is decompressed again by the vacuum pump 13.
[0028]
Therefore, every time the material resin is consumed, intermittent material measurement and supply are performed by repeating the above series of operations, and moisture, gas, etc. generated from the molten resin in the heating cylinder except during material supply Is exhausted to the outside by decompression to prevent generation of wrinkles and molding defects in the molded product.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of an embodiment of a material supply device of an injection device by 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 view showing an open operation state of a ventilation valve and a shutter before material supply.
FIG. 5 is an explanatory view showing a material supply state.
FIG. 6 is an explanatory view showing a state after material supply.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Injection device 2 Vacuum hopper 3 Shutter 4 Material suction chamber 5 Material supply chamber 6 Supply port 7 Material tank 8 Feeding line 9 Weighing part 10 Suction prower 12 Filter 13 Vacuum pump 14 Pipe 15 Ventilation valve 16 Shutter receiving Groove 18 Shutter air cylinder 19 Level detector 20 Controller 21 Material resin

Claims (1)

A vacuum hopper with a sealed structure in which the upper part is hermetically partitioned into a material suction chamber by a shutter and the lower part is airtightly divided into a material supply chamber, and the lower end opening of the material supply chamber is connected to the supply port, and the shutter is opened and closed. An apparatus, a feed line provided between the material suction chamber and the material tank, a blower of a suction pipe connected to the material suction chamber, a vacuum pump for decompression connected to the material supply chamber, and the material supply It consists of a level detector for the resin material in the room,
The feeding line is provided with a measuring unit that opens simultaneously with the suction operation of the blower following the opening operation of the shutter, and controls the material feeding amount within a range not exceeding the shutter position by the opening time, Injection molding with a vacuum hopper, characterized in that a vacuum valve is provided in the vacuum pump line before the opening of the shutter after the material loss is detected to release the negative pressure in the material supply chamber. Machine resin supply device.

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