JP2004255284A - Degassing method and apparatus for powder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for intensely degassing and tightening a bulky and fluffy powder containing air. <P>SOLUTION: The degassing apparatus (10) is provided with at least three hopper units (12, 14, 16) connected to one another up and down and each hopper unit comprises damper mechanisms (30, 56, 58) opening and closing a discharge port of the hopper and degassing chambers (32, 80, 90). The degassing chambers (32, 80) in the units (12, 14) in the first and second steps are vacuum evacuated by a vacuum source (66) and the damper (56) of the unit (14) in the second step is opened to drop the powder in the dispersed state in the vacuum to degas the powder. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and apparatus for degassing and tightening fluffy, bulky powders containing air (herein powders also include short fibers).
[0002]
[Prior art]
Certain powders having a small interparticle force (Van der Waals force), such as amorphous silica powder added as a reinforcing filler to plastic injection molding materials and alumina fine powder, are used in the production stage and pneumatic transportation. When it is subjected to aeration at a stage or handling stage, it becomes a fluffy state containing air.
[0003]
[Problems to be solved by the invention]
If the powder is airy and bulky as described above, the filling efficiency is deteriorated when bagging or packing into a container, and a large bag or container is required, so that the distribution cost is increased.
In addition, when cutting out the reinforcing silica powder or the like from the hopper to the extruder in order to add the reinforcing filler to the main material of the injection molding, if the powder is airy and fluffy, the powder easily forms a bridge in the hopper.
Conversely, in some cases, the powder containing air may exhibit fluidity like water (flushing phenomenon), which also makes it difficult to handle the powder.
[0004]
Therefore, the present inventor has previously carried out pneumatic transport of the powder to a destination container using a vacuum conveyor, and then fully closed the entrance of the vacuum conveyor and then vacuum-sucked the destination container to obtain the destination. It has been proposed to forcibly deaerate the powder in the container (JP-A-2001-287701).
[0005]
An object of the present invention is to improve the above-mentioned method and to provide a method and an apparatus for degassing powder which are more excellent in degassing effect.
[0006]
[Means for Solving the Problems]
The present invention is characterized in that the powder is degassed by dropping the powder in a parallel and vacuum (negative pressure) atmosphere while dispersing the powder.
As described above, if the powder is degassed while being dropped in a vacuum in a state where the powder is dispersed, the air between the particles is easily taken, so that the powder is quickly degassed and tightened.
According to the present invention, compared to the case of deaeration in a stationary state, the deaeration was able to be performed in a shorter time and at a volume shrinkage rate of 20 to 30%.
[0007]
In another aspect, the present invention provides a powder degassing device for carrying out the above degassing method, comprising: at least three modular hopper units connected one above the other in a gas-tight manner. A hopper having a powder discharge port, a damper mechanism for opening and closing the powder discharge port of the hopper, and a deaeration chamber below the hopper in cooperation with a hopper of a lower hopper unit. At least the uppermost and middle hopper units are provided with means for applying a negative pressure to the deaeration chamber at a predetermined time.
This device opens the damper of the top hopper unit, loads the powder into the hopper of the middle hopper unit, closes the damper of the top hopper unit, and loads the powder into the deaeration chambers of the top and middle hopper units. After applying pressure, by opening the damper of the middle hopper unit, the powder is dispersed and dropped to the hopper of the lowest hopper unit across the deaeration chamber under negative pressure of the middle hopper unit. It is characterized by degassing the powder.
[0008]
In a preferred embodiment, the apparatus further applies a negative pressure to a fourth hopper unit connected below the third hopper unit and a deaeration chamber of the third hopper unit at a predetermined time. Means for performing further degassing by dropping the powder in a dispersed state across the degassing chamber under negative pressure of the third-stage hopper unit to the hopper of the fourth hopper unit. I have.
[0009]
The above-described features and effects of the present invention, as well as other features and effects, will be further clarified as described in the following examples.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the degassing method and apparatus of the present invention will be described with reference to the accompanying drawings showing non-limiting embodiments. FIG. 1 shows a first embodiment of the present invention.
Referring to FIG. 1, the deaerator 10 includes three hopper units 12, 14, and 16 connected vertically. These hopper units 12, 14, 16 can be configured in the form of a common compatible module in order to reduce the cost by sharing the components. These hopper units 12, 14, 16 are connected in a gas-tight and separable manner by a plurality of buckle devices 18 and other connecting means via appropriate packings (not shown).
In order to increase the powder storage capacity of the upper hopper unit 12, it is preferable to connect the silo 20 on the first unit 12.
[0011]
Since the three hopper units 12, 14, 16 can be configured identically, only the upper hopper unit 12 will be described.
Referring to FIG. 2, in the illustrated embodiment, the hopper unit 12 includes a flanged cylindrical body 22 formed of stainless steel or the like, a flanged hopper 24 formed of stainless steel or the like, and a hopper 24. A damper mechanism 30 having a flap valve 28 for opening and closing the powder discharge port 26 is provided.
Below the hopper 24, inside the main body 22, a sealable deaeration chamber 32 is defined in cooperation with the hopper of the lower hopper unit 14.
On the side wall of the main body 22, a pressure introducing pipe 34 opened to the deaeration chamber 32 to apply a negative pressure to the deaeration chamber 32 is attached.
[0012]
2 and 3, in the illustrated non-limiting embodiment, the damper mechanism 30 includes a flap valve 28, a swing arm 38 with rollers 36 for swinging the flap valve 28 upward, For example, a 90-degree swing vane-type pneumatic actuator 40 for swinging the swing arm 38 is provided.
[0013]
The flap valve 28 is attached to, for example, a pair of left and right swing arms 42, and ends of the swing arms 42 are pivotally attached to a mounting bracket 44 fixed to the hopper 24 by welding or the like via a pivot 46. Can be.
2, the lower edge of the hopper 24 is provided with an elastomeric lip-shaped seal ring 48 for sealing between the lower edge of the hopper 24 and the flap valve 28. In order to ensure the sealing even if the seal ring 48 is severed or worn, the pivot 46 of the swing arm is provided with an elongated hole (not shown) in the mounting bracket so that the pivot 46 can slightly move up and down. It is installed.
The swing arm 38 with the roller 36 can be pivotally attached to the mounting bracket 44 via the output shaft 50 of the actuator 40.
[0014]
Referring to FIG. 1, the pneumatic actuator 40 of the damper mechanism 30 of the hopper unit 12 can be controlled by a controller 54 via an air signal line 52.
Similarly, the pneumatic actuators of the damper mechanisms 56, 58 of the middle and lower hopper units 14, 16 are controlled by the controller 54 via air signal lines 60, 62, respectively.
[0015]
With further reference to FIG. 1, the pressure inlet tube 34 of the hopper unit 12 can be connected by a conduit 64 to a vacuum source 66. As the vacuum source 66, a blower such as a turbo blower, a roots blower, a multi-stage ring blower, an ejector type vacuum pump, or any other type of vacuum pump can be used.
The conduit 64 is provided with an air-operated shut-off valve 68 controlled by the control device 54 via, for example, an air signal line 70. When the shut-off valve 68 is opened, the vacuum or negative pressure of the vacuum source 66 is reduced. Is applied to the deaeration chamber 32.
Similarly, the pressure inlet tube 72 of the middle hopper unit 14 can be connected to a vacuum source 66 by a conduit 74. The pneumatic shut-off valve 76 provided in the conduit 74 is controlled by the controller 54 via an air signal line 78. When the shut-off valve 76 is opened, a negative pressure is applied to the deaeration chamber 80 of the hopper unit 14.
[0016]
Preferably, the pressure introduction pipe 82 of the lower hopper unit 16 and the pressure introduction pipe 72 of the middle hopper unit 14 are provided with an air-operated shut-off valve 84 controlled by the controller 54 via an air signal line 88. Connected by bypass conduit 86. In this case, the shut-off valve 84 is opened, and the atmospheric pressure in the lower chamber 90 of the lower hopper unit 16 is introduced into the deaeration chamber 80 of the middle hopper unit 14, whereby the damper mechanism of the lower hopper unit 16 is released. The pressure before and after the flap valve 58 is equalized, and this flap valve can be quickly opened.
[0017]
Next, an operation mode of the deaerator 10 and an embodiment of the deaeration method of the present invention will be described with reference to the schematic diagram of FIG.
The deaerator 10 can be installed, for example, at a deaeration station provided at a later stage of the powder production line, and can perform a deaeration process continuously with the powder production process. Alternatively, it can be provided at the end of the air transport line.
The powder can be continuously or intermittently supplied to the upper hopper unit 12 of the deaerator 10 from a production line or a pneumatic transportation line.
[0018]
At the start of the deaeration cycle, the shut-off valves 68 and 76 of the upper and middle hopper units 12 and 14 are closed, respectively, but the shut-off valve 84 of the lower hopper unit 16 is opened and the middle hopper unit 14 Atmospheric pressure is introduced into the air chamber 80 (FIG. 4A).
All the flap valves are closed, the powder is supplied to the hopper 24 of the upper hopper unit 12, and the hopper of the lower hopper unit 16 contains the powder degassed in the previous cycle. .
[0019]
When the damper mechanism 30 of the upper hopper unit 12 is operated to open the flap valve 28 and the damper mechanism 58 of the lower hopper unit 16 is operated to open the flap valve 92, the powder in the upper hopper 24 is opened. Is charged into the hopper 96 of the middle hopper unit 14, and the powder in the lower hopper unit 16 which has been degassed in the previous cycle is discharged downward (FIG. 4 (2)).
Since the pressure before and after the flap valve 92 is equalized by opening the shut-off valve 84 in advance, the flap valve 92 is easily opened.
[0020]
Next, after closing the flap valves 28 and 92 and the shut-off valve 84 and opening the shut-off valves 68 and 76, the negative pressure from the vacuum source 66 is applied to the deaeration chamber 32 of the upper hopper unit 12 and the middle hopper unit 14. (FIG. 4 (3)).
[0021]
After the degassing chambers 32 and 80 before and after the flap valve 94 of the middle hopper unit 14 are set to a vacuum or a negative pressure atmosphere, the damper mechanism 56 of the middle hopper unit 14 is operated to open the flap valve 94. The powder in the hopper 96 of the middle hopper unit 14 is allowed to fall by gravity to the lower hopper unit 16 and accumulates in the lower hopper 98 (FIG. 4 (4)).
In the process of gravity drop from the middle hopper unit 14 to the lower hopper unit 16, the powder falls in a vacuum in a state of being dispersed separately, so that the air between the particles is easily taken away and the powder has a strength. Degassed and tightened.
[0022]
When the degassing is completed, the flap valve 94 and the shutoff valves 68 and 76 are closed, and the shutoff valve 84 is opened to introduce the atmospheric pressure into the degassing chamber 80 (FIG. 4A). By repeating the above steps, charging, degassing, and discharging of the powder are performed in a batch system.
[0023]
FIG. 5 shows a second embodiment of the degassing method and apparatus of the present invention. This embodiment is characterized in that the degassing device has four hopper units, and the powder undergoes degassing twice during one cycle.
In FIG. 5, components that are the same as or equivalent to the components of the first embodiment described above are denoted by the same reference numerals, and redundant description will be omitted.
[0024]
Only the differences from the first embodiment will be described. In this embodiment, a fourth hopper unit 100 similar to the first to third units 12, 14, 16 is connected below the third hopper unit 16. The fourth unit 100 has a flap valve 102 and a lower chamber 104.
In this embodiment with four hopper units, the lower chamber 90 of the third unit 16 acts as a deaeration chamber. For this purpose, the pressure introduction pipe 82 of the third unit 16 is connected to the vacuum source 66 via a conduit 108 having a shut-off valve 106.
The pressure introduction pipe 110 of the fourth unit 100 can be connected to the deaeration chamber 90 of the third unit 16 by a bypass conduit 86.
[0025]
To explain the operation of the second embodiment, the shut-off valve 76 can be kept open at all times, and a negative pressure can always be applied to the deaeration chamber 80 of the second hopper unit 14.
Initially, all the flap valves 28, 92, 94, 102 are closed, and by opening the shutoff valves 76, 106, a negative pressure is applied to the deaeration chambers 80, 90 of the second and third hopper units 14, 16. (FIG. 5A).
The powder is put into the hopper 24 of the first hopper unit 12, and the powder degassed in the previous cycle is put into the hopper of the third hopper unit 16.
[0026]
First, when the flap valve 28 of the first hopper unit 12 is opened and the flap valve 92 of the third hopper unit 16 is opened, the powder in the hopper 24 of the first hopper unit 12 is transferred to the hopper 96 of the second hopper unit 14. While being charged, the powder in the third hopper unit 16 that has been degassed in the previous cycle is allowed to fall into the fourth hopper unit 100, and accumulates in the lowermost hopper (FIG. 5 (2) )).
At that time, in the process of falling from the third hopper unit 16 to the fourth hopper unit 100, the powder that has already been subjected to the first degassing action in the previous cycle is further subjected to the second degassing action, and Tighten.
[0027]
Next, by closing all the flap valves 28, 92, 94 and 102 and opening the shutoff valve 68, a negative pressure from the vacuum source 66 is applied to the deaeration chamber 32 of the first hopper unit 12 (FIG. 3)). Further, in preparation for opening of the flap valve 102, the shutoff valve 84 is opened to introduce the atmospheric pressure into the degassing chamber 90.
[0028]
Next, when the flap valve 94 of the second hopper unit 14 is opened and the flap valve 102 of the fourth hopper unit 100 is opened, the powder falls in the process of falling from the first hopper unit 12 to the second hopper unit 14. The powder in the fourth hopper unit 100 is discharged downward while being subjected to the second degassing operation (FIG. 5D).
When the first degassing is completed, all the flap valves 28, 92, 94, and 102 are closed, the shut-off valve 84 for introducing the atmospheric pressure is closed, and the shut-off valve 106 for applying the negative pressure is opened. A negative pressure is applied to the deaeration chamber 90 (FIG. 5A). By repeating the above steps, charging, degassing, and discharging of the powder are performed in a batch system.
[0029]
Although a specific embodiment of the present invention has been described above, the present invention is not limited to this, and various changes and modifications can be made. For example, silo 20 is not essential. As the damper mechanism, a type in which the flap valve is directly opened and closed by an actuator can be used.
[0030]
【The invention's effect】
According to the present invention, since the powder is strongly degassed and tightened, it is possible to improve the filling efficiency of bagging and the like and reduce the distribution cost. The present invention also contributes to preventing bridging and flushing during cutting and handling of the powder.
According to the present invention, compared with the case of deaeration in a stationary state, the deaeration was able to be performed in a shorter time and at a volume shrinkage of 20 to 30% more strongly.
If the deaeration is performed in two stages as in the second embodiment, the deaeration effect can be further enhanced.
[Brief description of the drawings]
FIG. 1 is a partially cutaway side view of a first embodiment of a deaerator according to the present invention.
FIG. 2 is a partially cutaway side view of a hopper unit of the deaerator shown in FIG.
FIG. 3 is a perspective view of a damper mechanism of the hopper unit shown in FIG. 2 as viewed obliquely from below.
FIG. 4 is a schematic view showing the operation of the first embodiment of the deaerator shown in FIG.
FIG. 5 is a schematic diagram showing the operation of a second embodiment of the deaerator according to the present invention.
[Explanation of symbols]
10: Deaerator 12, 14, 16, 100: Hopper unit 22: Main body 24: Hopper 30, 56, 58: Damper mechanism 32, 80, 90: Deaeration chamber 34/64/68; 72/74/76; 82/106/108: negative pressure applying means

Claims (3)

A method of degassing a powder by dropping the powder in a vacuum atmosphere while dispersing the powder. A powder degassing device for performing the degassing method according to claim 1, wherein:
Comprising at least three hopper units that are connected to each other in a gastight manner,
Each hopper unit defines a deaeration chamber in cooperation with a hopper having a powder discharge port, a damper mechanism for opening and closing the powder discharge port of the hopper, and a hopper of a lower hopper unit below the hopper. And a cylindrical main body that
At least the uppermost and middle hopper units include means for applying a negative pressure to the deaeration chamber at a predetermined time,
Opening the damper of the top hopper unit, loading the powder into the hopper of the middle hopper unit, closing the damper of the top hopper unit, and applying a negative pressure to the deaeration chambers of the top and middle hopper units After that, by opening the damper of the middle hopper unit, the powder is dispersed by dropping the powder in a dispersed state across the deaeration chamber under negative pressure of the middle hopper unit to the hopper of the lowest hopper unit. A powder degassing device characterized by the fact that A fourth hopper unit connected below the lowermost hopper unit; and means for applying a negative pressure to a degassing chamber of the lowermost hopper unit at a predetermined time, further comprising: a lowermost hopper unit. The powder is further degassed by dropping the powder in a dispersed state across the degassing chamber under negative pressure to the hopper of the fourth hopper unit. Qi device.

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