JPH0534202B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a powder feeder that feeds a fixed amount of powder into a container. <Prior art> Generally, in the manufacturing process of pharmaceuticals, agricultural chemicals, foods, etc., when filling a fixed amount of powder into containers such as dies or vials, or when handling powder with poor fluidity or adhesive properties, it is of course necessary to fill as much powder as possible. It is important to supply the powder while maintaining a good fluidity, and special equipment is required for this purpose. Furthermore, it is necessary that fluctuations in the dynamic pressure applied to the powder at the powder outlet of the powder feeder be as small as possible. FIG. 1 is a sectional view showing an example of a conventional basic powder feeder. This conventional feeding machine uses the hopper 1 as it is as a powder feeding machine, and the hopper 1
Stirring blades 2 and 3 are arranged inside and at the discharge port 1a, and while rotating the stirring blades 2 and 3, the discharge port is opened intermittently to supply the powder into a die hole or a container (not shown) in measured quantities. ing. <Problems to be Solved by the Invention> By the way, according to the conventional powder feeder as described above, the weight of the powder in the hopper 1 is directly applied to the discharge port 1a, so that the rotation of the stirring blade 3 is not enough. The drawback is that it is difficult to impart fluidity to the powder. In order to solve these drawbacks, conventionally, Hopper 1
Measures have also been taken to introduce air into the tank and use so-called ventilation agitation, but this tends to cause bubbling, channeling, and slugging.
This results in the disadvantage of variations in the amount of powder supplied due to local variations in bulk specific gravity. In addition, in the conventional powder feeder described above, the powder flowing into the discharge port 1a is likely to receive repulsion due to the rotation of the stirring blade 3 at the flow inlet 1c, so the amount of powder flowing into the discharge port 1a is likely to fluctuate.
Therefore, there is also the problem that quantitative quality cannot be guaranteed in powder supply from the discharge port 1a. Furthermore, hoppa 1
Since the rotational speed of the stirring blades 3 and the like is not adjusted in response to fluctuations in the amount of powder in the powder, stable supply cannot be achieved. As described above, with conventional powder feeders, it is difficult to always accurately feed powder in a fixed amount. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a powder feeder that can stably feed a fixed amount of powder. <Means for Solving the Problems> In order to achieve the above object, the powder feeder of the present invention fills a die hole with a fixed amount of powder from a supply source, and then discharges and fills the powder into a container. The powder feeder uses a short cylindrical supply drum with a large diameter, the drum is installed so that its side end face is positioned in the vertical direction, and there is a stirring device inside the drum that rotates along the inner circumferential surface of the drum. A machine is provided, a powder discharge hole to the die hole is provided at the lower end of the peripheral wall on the drum side, and a powder receiving port from the supply source is provided near the center of the drum side end surface, and the powder is supplied through the powder receiving port. It is characterized by the provision of a conveyor which feeds powder from a source into said drum at a predetermined feed rate. <Function> Powder from the conveyor is supplied into the drum from the powder receiving port provided near the center of the side end surface of the supply drum, but the agitator in this supply drum is installed along the inner circumferential wall of the drum. Since it is rotating, the powder flows smoothly into the supply drum without being affected by the agitator. As a result, the amount of powder in the supply drum becomes stable, and pressure fluctuations near the powder discharge hole provided at the lower end of the peripheral wall of the drum side are reduced, resulting in deterioration of the fluidity of powder at the powder discharge hole and the accompanying amount of outflow. Fluctuations and local variations in bulk specific gravity are suppressed, and the powder always flows into the die hole with approximately constant fluidity, dynamic pressure, and bulk specific gravity, making it possible to achieve the intended purpose. <Example> FIG. 2 is a cross-sectional view of a main part of an example of the present invention, and FIG. 3 is a cross-sectional view thereof. The device includes a hopper 10 that is a supply source, and a hopper 10 that is a supply source.
A conveyor 20 that conveys powder from the conveyor 20, a supply drum 30 that receives an appropriate amount of powder sent from the conveyor 20, an agitator 40 that stirs the inside of this supply drum 30, and a predetermined amount of powder from the supply drum 30. It consists of a rotating die wheel 50 that receives the die wheel and a control device for these. The supply drum 30 has a large diameter and a short cylindrical shape, that is, the length of the cylinder is short and the diameter of the cylinder is larger than the length of the cylinder, and the side end surface 31 thereof is positioned in the vertical direction. Further, a receiving port 32 is provided near the center of the side end surface 31, and the powder is received from near the center. Further, a powder discharge hole 33 to the rotating die wheel 50 side is provided at the lower end of the side peripheral wall 34 of the supply drum 30. The conveyor 20 is equipped with a helical delivery blade 21, and the rotation of the blade 21 feeds the powder in the hopper 10 into the receiving port 32 of the supply drum 30. The stirrer 40 has stirring blades 4 inside the supply drum 30.
1, and is rotated by rotation of a rotary drive shaft 42 located on the center line of the supply drum 30. 43 is axis 4
This is the second rotary drive device. The stirring blade 41 is the rib 4
The distal end portion of 1a is formed wide so that the stirring blade 41 rotates in close proximity to the inner circumferential surface 35 of the supply drum 30. A plurality of die holes 51 are arranged radially in the rotating die wheel 50, and by rotating intermittently, the die holes 5 are sequentially opened from the powder discharge hole 33.
1 is supplied with powder, and the powder is discharged and filled into a container 60. Note that 52 is a drive source for the rotary die wheel 50. To explain the control mechanism, pressure sensor 7
For example, a semiconductor pressure sensor is provided near the powder discharge hole 33 on the inner circumferential surface of the supply drum 30 to detect the dynamic pressure applied to the powder near the inner circumferential surface 35 of the supply drum 30. Further, a torque meter 80 is attached to the rotary drive shaft 42 of the stirrer 40 to detect a substitute value for the powder retention amount in the supply drum 30, and the information is input to the control section 90. The control unit 90 compares the pressure value input from the pressure sensor 70 with a set value, sends a control signal to the stirrer 40 so that a predetermined dynamic pressure is achieved, and adjusts its rotation speed. In addition, the control unit 90 compares the torque value input from the torque meter 80 with a set value, and sends a control signal to the conveyor 20 so that the torque value becomes a predetermined value, thereby reducing the amount of powder retained in the supply drum 30 to a predetermined amount. Adjust. The functions of the supply drum 30 and stirring blade 41 will be further explained. First, the supply drum 30
can be said to be a member specially provided for supplying powder in fixed quantities. In other words, in the conventional system, the hopper that stores a large amount of powder is also used as a fixed-quantity feeder for powder, whereas in the present invention, the hopper 10 only serves as a powder supply source, and the supply drum 30 is used to supply the desired amount of powder. supply. In this way, supply drum 3
By separately providing 0, the state of the powder immediately before supply can be stably maintained in an optimum state for quantitative supply. In other words, it is possible to ensure the fluidity and uniform dispersibility of the powder immediately before supply (no local variations in bulk specific gravity due to agglomeration of powders or uneven distribution of voids, etc.), and the accompanying powder discharge hole 33 It becomes possible to stabilize the dynamic pressure at Of course, these things are accomplished not only by the supply drum 30, but also by the agitator 40, the conveyor 20, and the control equipment 70, 8.
0 and 90 at the same time, but this can only be realized by the presence of the supply drum 30. By providing the supply drum 30 in a short cylindrical shape so that its side end surface 31 is located in the vertical direction, the powder discharge hole 33 can be located at the lower end of the drum side peripheral wall 34 suitable for powder discharge. Sliding contact with the die wheel 50 at the powder discharge hole 33 portion can be easily made. Furthermore, the reduction in internal volume of the supply drum 30 caused by shortening the axial dimension of the supply drum 30 (short cylinder) to facilitate powder supply to the die wheel 50 can be avoided by increasing the diameter of the drum 30. By compensating for this, a certain amount of powder can be maintained with respect to the amount of powder supplied to the die hole 51.
This makes it possible to prevent the influence of changes in the amount of powder within the drum 30. In this embodiment, the drum 30 has an inner diameter of 300 mm and an inner width of 30 mm. In terms of tolerance, it is preferable that the inner diameter is 200 mm or more and the inner width is about 10 to 50 mm. Furthermore, in the present invention, since the powder receiving port 32 from the conveyor 20 is provided near the center of the side end surface 31 of the supply drum 30, which is provided separately from the hopper 10, the influence of repulsion due to the rotation of the stirring blade 41 is also reduced. , the powder can be carried into the drum 30 smoothly. The stirring blades 41 play the role of loosening the powder in the drum 30 to give it fluidity, and applying dynamic pressure to the powder to discharge it from the discharge hole 33 to the die hole 51 . Therefore, the tip of the stirring blade 41 is connected to the drum 3.
The powder is rotated along the inner circumferential surface 35 of the drum 30 to greatly stir the internal space of the drum 30 and apply necessary dynamic pressure to the powder. In the example, the drum 30
A rectangular blade with a side of 20 mm is attached to an internal width of 30 mm. The dynamic pressure applied to the powder is the stirring blade 4.
Once the shape and dimensions of stirring blade 1 are determined, they are determined by the rotation speed, so by adjusting the rotation speed of stirring blade 41, the dynamic pressure measured by pressure sensor 70 can be maintained at a desired dynamic pressure. Furthermore, since the amount of powder discharged from the powder discharge hole 33 is approximately determined by the dynamic pressure near this discharge hole 33 and the amount of powder inside the supply drum 30, in addition to adjusting the pressure using the pressure sensor 70, etc. By detecting a substitute value for the powder amount and keeping the powder retention amount constant, it is also possible to more stably supply the powder in fixed amounts. The amount of powder retained in the drum 30 is preferably about 30% of the volume. FIG. 4 is a partial sectional view showing another example of the stirring blade. In this example, the stirring blade 41 is constituted by a plurality of elongated divided blades 41b such that slits are formed between them. When such a blade 41 is used, even powders with poor fluidity or powders that tend to coagulate can be sufficiently loosened and their fluidity improved compared to those shown in FIGS. 2 and 3. Can be given as a powder. Table 1 shows the comparison results of powder feeding experiments between the conventional powder feeding machine shown in FIG. 1 and the powder feeding machine according to the present invention. The diameter of the powder discharge hole to the rotating die wheel side is 12 mm. The powder used in the experiment was
A powder having an average diameter of about 5 μm was obtained by pulverizing with a jet mill. Then, the amount of powder discharged in 0.5 seconds was determined for both the conventional machine and the powder feeder according to the present invention.
Measurement was performed 100 times, and the average value and standard deviation were determined.

[Table] As is clear from the above results, the present invention can supply a larger amount without variation within the same time compared to the conventional machine. This means that when supplying the same amount, it can be supplied faster and more accurately. <Effects of the Invention> As explained above, according to the present invention, a short cylindrical supply drum with a large diameter is used, the supply drum is provided so that its side end surface is located in the vertical direction, and there is a A stirrer that rotates along the inner peripheral surface of the drum is provided, a powder discharge hole to the die hole is provided at the lower end of the drum side peripheral wall, and a powder receiving port from the supply source is provided near the center of the drum side end surface, Since we have provided a conveyor that feeds the powder from the supply source into the supply drum at a predetermined supply speed through this powder receiving port, the powder can be stored inside the supply drum without being repulsed by the rotation of the internal agitator. The powder flows smoothly from the supply source, and fluctuations in the amount of powder inside are reduced, reducing the deterioration of powder fluidity due to pressure fluctuations near the powder supply port to the die hole (powder discharge hole of the supply drum). , there was no fluctuation in the amount of powder flowing out from this discharge hole, and furthermore, there was no local variation in the bulk specific gravity of the powder, and the powder always had almost constant fluidity, dynamic pressure, and bulk specific gravity. In addition, the powder is efficiently guided to the die by the stirring air that rotates along the inner peripheral surface of the supply drum, which is compared to conventional feeders of this type. do,
It has become possible to supply powder more rapidly and stably in fixed quantities. According to the experiment, as shown in Table 1,
The supply speed has improved by about 30%, and the standard deviation of supply amount has improved by about 40%. Furthermore, it has been confirmed that the present invention has the advantage that, due to its structure, the filling amount can be increased or decreased even when using the same die hole by changing settings such as the rotation speed of the stirrer.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional powder feeder, Figure 2
The figure is a cross-sectional view of main parts showing the configuration of the embodiment of the present invention.
The figure is a sectional view thereof, and FIG. 4 is a partial sectional view showing an example of a stirring blade according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 10... hopper, 20... conveyance machine, 30... supply drum, 31... side end surface of supply drum, 32...
...Powder receiving port, 33...Powder discharge hole, 34
... Side peripheral wall of the supply drum, 35 ... Inner peripheral surface of the supply drum, 40 ... Stirrer, 41 ... Stirring blade,
50... Rotating die wheel, 51... Die hole,
60... Container, 70... Pressure sensor, 80... Torque meter, 90... Control unit.

Claims (1)

[Scope of Claims] 1. A powder feeder that once fills a fixed amount of powder from a supply source into a die hole and then discharges and fills the powder into a container, using a large-diameter, short cylindrical feed drum. , the drum is provided so that its side end surface is located in the vertical direction, a stirrer that rotates along the inner circumferential surface of the drum is provided in the drum, and a powder discharge hole to the die hole is provided at the lower end of the drum side circumferential wall. a conveying machine that is provided with a powder receiving port from the supply source near the center of the drum side end face, and supplies the powder from the supply source into the drum at a predetermined supply speed through the powder receiving port; A powder feeding machine characterized by being provided with. 2. The powder feeder according to claim 1, wherein the agitator has a variable rotation speed. 3. A pressure sensor is provided near the powder discharge hole on the inner peripheral surface of the supply drum, and a control means is provided for controlling the rotation speed of the stirrer according to the result of the dynamic pressure detection of the powder by the pressure sensor. A powder feeder according to claim 2. 4. Claims 1 and 2 are characterized in that the conveying machine has a variable powder supply speed.
3. Powder feeding machine according to item 3 or 3. 5. A torque detector for detecting the stirring torque of the stirrer is provided, and a control means is provided for controlling the amount of powder supplied to the supply drum by the conveyor based on the output of the torque detector. A powder feeder according to claim 4.