JP2003103566A - Equipment for removing gas for melt molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide equipment for removing gas for a melt molding machine which can remove excellently a bad gas produced in a cylinder of the melt molding machine, by a simple constitution. SOLUTION: A vacuum pump 17 is connected to the cylinder 4 of the melt molding machine, and on the occasion of molding a resin, a dry gas is introduced intermittently from a purge gas inflow port part 19, while the pressure inside the cylinder 4 is reduced by the vacuum pump 17. Then, in the cylinder 4, the state of the reduced pressure till then is opened by the introduced dry gas, and the resin being melted and the air in the cylinder 4 are agitated thereby forcibly. A passage through which the bad gas produced from the resin stagnating in the cylinder 4 escapes to a feed pipe 11 is formed by the agitation, and thereby the bad gas produced in the whole of the cylinder 4 can be removed excellently by the vacuum pump 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas removing device for a melt molding machine, and more specifically, in a melt molding machine such as an injection molding machine or an extrusion molding machine, water vapor or volatile gas generated from a raw material melted in a cylinder. The present invention relates to a gas removing device of a melt molding machine used for removing such as.

[0002]

2. Description of the Related Art Conventionally, when molding plastic by injection molding or extrusion molding, a resin raw material is fed from a supply hopper into an injection molding machine or an extrusion molding machine, and the fed resin raw material is stored in a cylinder. After melting, in an injection molding machine, the molten resin raw material is injected into a mold, and in an extrusion molding machine, the molten resin raw material is extruded into a prescribed shape from a die. I am trying to do it.

In such a melt molding machine such as an injection molding machine or an extrusion molding machine, when the resin raw material charged from the supply hopper is melted in the cylinder, moisture and other volatile components contained in the resin raw material are removed. , Generated as water vapor or volatile gas, which causes burns in the mold, or defective products (for example, voids) in the obtained molded product.
Is known to occur.

Therefore, for example, a system for removing defective gas such as water vapor and volatile gas generated in a cylinder of an injection molding machine is disclosed in, for example, the 11th Japan Society of Plastic Molding Processing (June 7, 2000). Development of injection molding system for undried resin by vacuum plasticization ”.

According to this report, a vacuum pump is connected to the supply hopper to maintain a vacuum inside the supply hopper and the cylinder, and the supply hopper is equipped with a metering feeder so that the cylinder is filled with the resin raw material. By controlling the supply so that there is no such problem (starvation supply), the escape path for defective gas from the entire inside of the cylinder is formed, and the defective gas generated in the entire cylinder is removed by vacuuming from the supply hopper side. It is suggested to do so.

[0006]

However, in the above method, it is necessary to equip the feeding hopper with a metering feeder, more specifically, a cutting feeder and the like.
A control structure is also required to supply the starvation, which complicates the device structure and inevitably increases costs.

The present invention has been made in view of the above circumstances. An object of the present invention is to melt a defective gas that can be satisfactorily removed with a simple structure in a cylinder of a melt molding machine. It is to provide a gas removing device for a molding machine.

[0008]

In order to achieve the above object, the invention according to claim 1 is to reduce the pressure in a cylinder of a melt molding machine, and to reduce the pressure in the cylinder by the pressure reducing means. It is characterized in that it is provided with a decompression releasing means for intermittently releasing the decompressed state therein.

With such a construction, the inside of the cylinder of the melt molding machine is depressurized by the depressurizing means in the state where the raw material is charged, but the depressurized cylinder is intermittently depressurized by the depressurizing releasing means. It will be released. Then,
In the cylinder, the depressurized state up to that point is released, and the raw material and the air in the cylinder are forcibly stirred, so that the agitation path through which the defective gas generated from the raw material escapes to the depressurizing means is formed by the stirring. Bad gas generated in the entire cylinder is satisfactorily removed by the pressure reducing means. Therefore, for example, even if the starvation supply is not performed by controlling the cylinder so that it is not filled with the raw material, it is possible to satisfactorily remove the defective gas with a simple configuration, and to supply the metering required for the starvation supply. It is possible to achieve good removal of bad gas at low cost without using a machine or the like.

In the invention according to claim 2, the pressure reducing means for reducing the pressure in the cylinder of the melt molding machine, the purge gas supplying means for supplying the purge gas into the cylinder, and the pressure reducing means for reducing the pressure are provided. Introducing control means for intermittently introducing the purge gas supplied from the purge gas supply means is provided in the cylinder.

According to this structure, the inside of the cylinder of the melt molding machine is depressurized by the depressurizing means in the state where the raw material is charged, and the inside of the depressurized cylinder is
The purge gas from the purge gas supply means is intermittently supplied by the control of the introduction control means. Then, in the cylinder, the supplied purge gas releases the depressurized state until then, and the raw material and the air in the cylinder are forcibly stirred, so that the defective gas generated from the raw material is discharged to the depressurizing means by the stirring. A loophole is formed,
As a result, the defective gas generated in the entire cylinder is satisfactorily removed by the pressure reducing means while being expelled by the purge gas. Therefore, for example, even if the starvation supply is not performed by controlling the cylinder so that it is not filled with the raw material, it is possible to satisfactorily remove the defective gas with a simple configuration, and to supply the metering required for the starvation supply. It is possible to achieve good removal of bad gas at low cost without using a machine or the like.

The invention described in claim 3 is the same as claim 1
Or in the invention described in 2, a supply part for supplying a raw material to the cylinder, and a joint part for connecting the supply part and the cylinder are provided, and the supply part protrudes toward the cylinder. On the other hand, the joint portion is formed into a tubular shape that covers the outer periphery of the supply tubular mouth portion at a predetermined interval, and the decompression means is connected to the joint portion. It is characterized by being.

According to this structure, the raw material supplied from the supply section is supplied from the supply tube opening projecting into the cylinder, while the defective gas generated in the cylinder is jointed with the supply tube opening. Passing between the department
Removed by decompression means. Therefore, even if the raw material supply passage for supplying the raw material and the defective gas removing passage for removing the defective gas are constituted by the flows in opposite directions in one joint portion, they can be reliably separated from each other. It is possible to reliably remove the defective gas while stably supplying the raw material from the mouth of the supply cylinder.

[0014]

1 is a schematic configuration diagram showing an embodiment of a melt molding machine equipped with a gas removing device for a melt molding machine according to the present invention. 1, in this system (molding apparatus), a melt molding machine 1, a raw material supply unit 2 for supplying a resin as a raw material to the melt molding machine 1, and a gas removal unit equipped in the raw material supply unit 2 And part 3.

The melt molding machine 1 is a molding machine for melting a resin to form a predetermined shape, and is composed of, for example, an injection molding machine or an extrusion molding machine. The melt molding machine 1 includes a cylinder 4, a screw 5 rotatably provided in the cylinder 4, and a motor 6 for driving the screw 5. The cylinder 4 has a cylindrical shape, and a cylindrical receiving port 7 for receiving a resin is formed at one end thereof, and the other end is
A discharge part 8 for extruding the melted resin is provided. Further, a heater (not shown) for melting the resin is provided in the cylinder 4 along the axial direction. The motor 6 is connected to one end of the screw 5 in the axial direction, and by driving the motor 6 to rotate the screw 5 in the cylinder 4, the resin received from the inlet 7 is discharged to the discharge portion 8. A heater (not shown) is used to gradually move it while melting it. It should be noted that the inside of the cylinder 4 is airtightly held in a state where the screw 5 is arranged.

The raw material supply section 2 includes a raw material storage tank 9 for storing resin, a supply hopper 10 as a supply section, a connection pipe 11 as a joint section for connecting the supply hopper 10 and the cylinder 4, and a line filter 12. And a suction blower 13.

The raw material storage tank 9 stores a resin for melt molding in the form of powder or granules such as pellets. The supply hopper 10 is composed of a tubular container having an upper and lower portions formed in a funnel shape, the upper portion of which is connected to the raw material storage tank 9 through the raw material supply line 14, and the lower portion of which is connected to the connecting pipe 11. It is connected to the cylinder 4 via.

More specifically, at the lower end portion of the supply hopper 10, a cylindrical supply cylinder port portion 15 protruding toward the cylinder 4 is formed so as to protrude downward, while the connection pipe 11 is formed.
Has a tubular shape, the lower end of which is closely connected to the inner peripheral surface of the receiving port 7 of the cylinder 4 and the upper end of which is
It is connected to the lower part of the supply hopper 10 in a close contact manner, whereby the connection pipe 11 is provided as a double cylinder structure so as to cover the outer periphery of the supply cylinder mouth portion 15 at a predetermined interval.

Further, the suction type blower 13 is provided in the feeding hopper 1.
Is connected to the upper part of 0 through the exhaust line 16,
The line filter 12 is provided in the middle of the exhaust line 16.

Further, the gas removing section 3 is provided with a vacuum pump 17 as a pressure reducing means, a line filter 18 and a purge gas inflow portion 19 as a purge gas supplying means constituting a pressure reducing releasing means. The vacuum pump 17 is connected to the connecting pipe 11 via a vacuum line 20 that connects the vacuum pump 17 and the connecting pipe 11. The vacuum line 20 is connected to the connection pipe 11 at a position facing the upper portion of the connection pipe 11 closer to the supply hopper 10 than the tip of the supply cylinder port portion 15 of the connection pipe 11. Also, this vacuum line 20
A line filter 18 is provided in the middle of the line.

The purge gas inlet port 19 has one end connected to the purge gas line 21 between the connecting pipe 11 and the line filter 18 in the vacuum line 20.
Is connected to the other end of the vacuum line 20 via the purge gas line 21. From the purge gas inlet port 19, a dry gas such as dry air or dry nitrogen is supplied as a purge gas.

Further, the connecting pipe 11 in the vacuum line 20.
And the purge gas line 21, and between the supply hopper 10 and the line filter 12 in the exhaust line 16,
A branch vacuum line 22 that branches from the vacuum line 20 is connected.

Also, in this system, a slide gate 23 is provided between the raw material storage tank 9 and the supply hopper 10 in the raw material supply line 14. A first opening / closing valve 24 is provided between the line filter 12 and the connecting portion of the branch vacuum line 22 in the exhaust line 16. A second opening / closing valve 25 is provided between the branch vacuum line 22 and the connecting pipe 11 in the vacuum line 20. Further, a third opening / closing valve 26 is provided between the purge gas inlet portion 19 of the purge gas line 21 and the connection portion of the vacuum line 20. In addition, the vacuum line 20 in the branch vacuum line 22
A fourth opening / closing valve 27 is provided between the connection portion with and the connection portion with the exhaust line 16.

Further, these slide gate 23, first opening / closing valve 24, second opening / closing valve 25, third opening / closing valve 2
The opening and closing operations of the sixth and fourth open / close valves 27, and the operation of the suction blower 13 and the vacuum pump 17 are performed by the CPU 2 of the control unit 28 that controls this system.
Controlled by 9. Further, the control unit 28 is provided with a RAM 30 for temporarily storing numerical values and a ROM 31 for storing various control programs, and an introduction control program as an introduction control means constituting a decompression releasing means described later is the ROM 31. It is stored in.

More specifically, the slide gate 23, the first opening / closing valve 24, and the third opening / closing valve 26 are
Although it is opened and closed by compressed air, its specific configuration is omitted in FIG.

To pneumatically transport the resin from the raw material storage tank 9 to the supply hopper 10, for example, first, the slide gate 23 and the first opening / closing valve 24 are opened and the suction blower 13 is operated. Then, the suction blower 13 sucks the inside of the raw material storage tank 9 through the exhaust line 16, the supply hopper 10, and the raw material supply line 14, so that the resin stored in the raw material storage tank 9 becomes
It is pneumatically transported to the supply hopper 10 via the raw material supply line 14. The air after the pneumatic transportation is sent to the suction blower 13 from the exhaust line 16 after dust and the like are removed by the line filter 12, and is exhausted from the suction blower 13 to the atmosphere.

Then, the supply hopper 10 is supplied by pneumatic transportation.
The resin temporarily stored in the melt molding machine 1 is supplied from the supply cylinder port portion 15 formed in the lower portion of the supply hopper 10 to the cylinder 4 of the melt molding machine 1 due to its own weight.
It is thrown in in sequence.

When the pneumatic transportation is completed, the slide gate 23 and the first opening / closing valve 24 are closed.

In this system, the resin is continuously supplied from the supply hopper 10 into the cylinder 4, and the pneumatic transport of the resin from the raw material storage tank 9 is carried out by the level sensor (not shown) inside the supply hopper 10. Is carried out each time it is detected that the amount of the resin is less than the predetermined amount. Alternatively, a slide gate may be separately provided below the supply hopper 10 to batch-feed the resin into the cylinder 4.

On the other hand, the inside of the cylinder 4 of the melt molding machine 1 is controlled by the introduction control program during molding.
The second opening / closing valve 25 and / or the fourth opening / closing valve 27 are always open and the vacuum pump 17 is operating. The inside of the cylinder 4 is constantly depressurized by the vacuum pump 17, and in the depressurized state, The resin supplied from the supply hopper 10 is supplied from the supply cylinder port portion 15 protruding toward the inside of the cylinder 4, and is filled in the cylinder 4. Either one or both of the second opening / closing valve 25 and the fourth opening / closing valve 27 are appropriately opened depending on the capacity of the supply hopper 10, the required dryness of the resin, the molding conditions, and the like. For example, usually
When the second opening / closing valve 25 is in the open state and the resin temporarily stored in the supply hopper 10 needs to be dried, the fourth opening / closing valve 27 is also used. Also, during molding,
The third opening / closing valve 26 is normally closed.

Then, the injected resin is gradually melted in the cylinder 4 by the screw 5, and the discharging portion 8
The third opening / closing valve 26 is temporarily opened / closed by the control of the introduction control program while moving toward.

Then, the dry gas is supplied from the purge gas inlet port 19, and the dry gas flows from the connecting pipe 11 into the cylinder 4 through the vacuum line 20 when the second opening / closing valve 25 is in the open state. If it is introduced and the fourth opening / closing valve 27 is open, the vacuum line 20
And is introduced into the supply hopper 10 via the branch vacuum line 22 and further introduced into the cylinder 4 from the supply hopper 10 via the supply cylinder port 15.

In the cylinder 4, the decompressed state up to that point is released by the introduced dry gas, and the resin to be melted and the air in the cylinder 4 are forcibly agitated. Bad gas generated from the resin staying in the resin 4 (that is, water vapor and organic components generated by volatilization of water and volatile components contained in the resin until being melted by heating in the cylinder 4). (A volatile gas of an inorganic component) is formed in the supply pipe 11 so that a defective gas generated in the entire cylinder 4 is expelled by the dry gas (that is, replaced by the dry gas). When the second opening / closing valve 25 is in the open state, the second opening / closing valve 25 passes between the connection pipe 11 and the supply cylinder port portion 15, and the vacuum line 2 By a vacuum pump 17 via,
Further, when the fourth opening / closing valve 27 is in the open state, the fourth opening / closing valve 27 passes through the supply tube port 15 and the supply hopper 10 and is favorably removed by the vacuum pump 17 via the branch vacuum line 22 and the vacuum line 20. .

Therefore, for example, in order to prevent the cylinder 4 from being filled with the raw material, the third opening / closing operation is performed without controlling the starvation supply such that the supply hopper 10 is provided with a cutting feeder or the like to quantitatively supply the resin. With a simple configuration that only controls the opening and closing of the valve 26, the defective gas can be satisfactorily removed. As a result, it is possible to achieve good removal of bad gas at low cost without the need for a feeding feeder or the like required for starvation supply. Can be removed.

The control by the introduction control program is as follows.
Although it is appropriately determined depending on molding conditions and the like, for example, the inside of the cylinder 4 is normally depressurized by opening the second opening / closing valve 25 and / or the fourth opening / closing valve 27 before starting the injection of the resin into the cylinder 4. It should be noted that, after the resin is put into the cylinder 4, it is appropriately determined at any time after the resin starts to melt (the type of resin, the capacity of the cylinder, the heating temperature of the heater of the cylinder, etc. In terms of control, the third open / close valve 26 is opened for several seconds to several tens of seconds.

More specifically, when the melt molding machine 1 is an extrusion molding machine, the resin is continuously charged and molded. Therefore, at the time of molding, the second opening / closing valve 25 and / or the fourth opening / closing valve 25 is used. The opening / closing valve 27 is normally opened, and the third opening / closing valve 26 is intermittently opened / closed at an arbitrary interval. The interval for opening / closing operation is appropriately determined according to molding conditions.

Further, when the melt molding machine 1 is an injection molding machine, the resin is injected and molded for each shot, so that at the time of molding, the second opening / closing valve 25 and / or
Alternatively, the fourth opening / closing valve 27 is normally opened and the third opening / closing valve 26 is opened / closed at least once per shot. The third opening / closing valve 26
The number of times of the opening and closing operation is appropriately determined by molding conditions such as the cycle time of one shot, but it is preferable that the number of times of opening and closing is large as long as the moldability is not impaired.

In the above description, when the third opening / closing valve 26 is opened, for example, the vacuum pump 1
7 may be stopped.

Further, in the supply hopper 10, the connecting pipe 1
1 is formed as a double cylinder structure so as to cover the outer periphery of the supply cylinder port portion 15 at a predetermined interval, so that one supply pipe 11 is provided when the second opening / closing valve 25 is in the open state.
In the above, the raw material supply passage to which the resin is supplied, that is, the supply cylinder opening portion 15, and the defective gas removal passage from which the defective gas is removed, that is, the connection pipe 11 and the supply cylinder opening portion 15,
Even if they are constituted by the flows in the opposite directions, they are reliably separated, and while the resin is stably supplied from the supply cylinder opening portion 15, the defective gas is connected to the connection pipe 11 and the supply cylinder opening portion 1.
It can be reliably removed from between 5 and 5.

Further, the vacuum line 20 is provided with the supply cylinder port 1
Since it is connected to the supply pipe 11 facing the upper part on the supply hopper 10 side with respect to the tip of the supply pipe 5, the resin injected from the supply tube mouth part 15 closes the connection part of the supply pipe 11 with the vacuum line 20. Is reliably prevented, and a reliable decompression of the vacuum pump 17 is ensured.

In the above description, the dry control gas is intermittently introduced into the cylinder 4 from the purge gas inlet 19 as the purge gas by the intermittent opening / closing operation of the third open / close valve 26 by the introduction control program. However, depending on the type of resin and the gas component to be removed, for example, the purge gas inflow port 19 is formed as an atmosphere opening port so that normal air (outside air) is intermittently introduced into the cylinder 4 as the purge gas. You may That is,
In this case, the depressurized state in the cylinder 4 depressurized by the vacuum pump 17 is only intermittently released to the atmosphere by the intermittent opening / closing operation of the third opening / closing valve 26 by the introduction control program. In the inside of 4, the decompressed state until then is released and the resin to be melted and the air in the cylinder 4 are forcibly stirred, so that the defective gas generated from the resin due to the stirring is generated by the vacuum pump 17
An escape passage is formed through which the cylinder 4
The defective gas generated in the entire inside can be satisfactorily removed by the vacuum pump 17. Therefore, the defective gas can be satisfactorily removed with a simple structure by intermittently opening the atmosphere.

[0042]

As described above, according to the invention described in claim 1, it is possible to satisfactorily remove bad gas by intermittently opening to the atmosphere with a simple structure, and to supply starvation. It is possible to achieve good removal of defective gas at low cost by eliminating the need for a metering and feeding device and the like.

According to the second aspect of the present invention, with a simple structure, the purge gas can be intermittently introduced to satisfactorily remove the bad gas, and the metering feeder required for starvation supply, etc. Therefore, it is possible to achieve good removal of bad gas at low cost.

According to the third aspect of the present invention, in one joint, the raw material supply passage for supplying the raw material and the defective gas removing passage for removing the defective gas are provided by the flow in opposite directions. Even with the configuration, it is possible to reliably separate them, and to reliably remove the bad gas while stably supplying the raw material from the supply cylinder port.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a melt molding machine equipped with a gas removing device for a melt molding machine according to the present invention.

[Explanation of symbols] 1 Melt molding machine 4 cylinders 10 Supply hopper 11 Connection pipe 15 Supply tube mouth 17 Vacuum pump 19 Purge gas inlet 28 Controller unit

Claims (3)

[Claims] 1. A depressurizing unit for depressurizing the inside of a cylinder of a melt molding machine, and a depressurizing releasing unit for intermittently releasing a depressurized state in the cylinder depressurized by the depressurizing unit. A gas removal device, characterized by: 2. A depressurizing unit for depressurizing the inside of a cylinder of a melt molding machine, a purge gas supplying unit for supplying a purge gas into the cylinder, and a purge gas supplying unit for depressurizing the cylinder by the depressurizing unit. And a purge control means for intermittently introducing the purge gas supplied from the means. 3. A supply part for supplying a raw material to the cylinder, and a joint part for connecting the supply part and the cylinder, wherein the supply part has a cylindrical shape protruding toward the cylinder. On the other hand, the joint portion is formed in a tubular shape that covers the outer periphery of the supply tubular mouth portion at a predetermined interval, and the decompression means is connected to the joint portion. The gas removing device of the melt molding machine according to claim 1 or 2, which is characterized.