JPS5832144B2 - Fun matsukiyoukiyuusouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powder feeding device that can easily reduce and deaerate powder having a high apparent specific volume (apparently the reciprocal of specific gravity) to supply the powder.

For example, a powder feeding device with a feeding screw for feeding powder, which is used in powder bagging equipment, powder weighing equipment, powder roller compaction equipment, etc., has no problem with powder having a small apparent specific volume. However, as the apparent specific volume increases, the powder feeding ability decreases.

For example, in powder roller compaction equipment that has been commonly used, the apparent small volume is less than 2.5.
Compression molding can be performed without problems with powders having a
When the amount increases, the supply capacity of the powder supply device decreases, and the powder is not easily bitten between the compression rollers, which usually reduces the compression molding ability and hinders production.

Furthermore, when the powder has an apparently large specific volume (5 or more), compression molding is no longer possible with conventional powder roller compaction equipment because the powder is poorly engulfed.

Therefore, if the powder has a large apparent specific volume, it must be compressed twice using rollers, or it must be pre-compressed using another compression device to reduce the apparent specific volume and then compressed using rollers. The current situation is that the process is extremely wasteful and wasteful.

For this reason, various methods and devices have been proposed, such as using a tapered feed screw, increasing the roller diameter, or using a corrugated feed screw, but none of them has been a sufficient solution. .

The inventors of the present invention have conducted various studies to solve these problems, and have found that, unexpectedly, providing a deaeration surface on the hopper wall close to the feed screw biting part can reduce the relative appearance. The present invention was completed based on the knowledge that it is possible to easily reduce the volume, deaerate and efficiently supply powders exhibiting .

That is, the present invention provides a powder feeding device that is provided with a powder feeding hopper and a feeding screw for sending out the powder, in which the taper angles of the upper and lower parts are respectively 55° to 85°, and the taper angle of the upper part is 55° to 85°. A two-stage tapered powder supply hopper with a smaller taper angle than the lower taper angle and a degassing surface are provided at the upper hopper wall of the hopper and close to the feeding screw biting part, and the outer diameter and the root diameter are The ratio between the difference and the valley diameter is 0.
．． 8 or less, the supply screw is characterized by having a ratio of the difference between the outer diameter and the root diameter of the supply screw and the pitch of 0.5 or less, and the high appearance makes it possible to easily reduce the powder that shows the specific volume. This is a powder supply device that can be supplied by deaerating the powder.

The present invention will be explained as follows based on the drawings.

Fig. 1 shows a schematic diagram of the entire roller compaction device equipped with the powder supply device of the present invention, and Fig. 2 is a cross-sectional view of the chip side obtained by vertically dividing the hopper into thirds on the roller compaction surface (the supply screw is a side view). ), Figure 3 is an enlarged view of the degassing surface (the part marked A in Figure 2), and Figure 4 is a longitudinal cross-sectional view of the roller compression surface of a powder feeder equipped with multiple supply screws. In the figure, 1 is a fixed roller, 2 is a movable roller, 3 is a powder supply device, 4 and 4' are screws, 5 is powder, 6 is a motor, 7 is a compression surface, 8 is a degassing surface, and 9 is a blower. -room,
10 is a hopper wall, 11 is a deaeration hole, 12 is a finished cloth, 13 is gold bronze, and 14 is a blower chamber wall.

θ1. θ2 indicates the taper angle of the hopper wall.

Conventional supply screw systems for roller compression do not have the degassing mechanism shown in 8.9, and when feeding powder with a high apparent specific volume to the roller compression section, the air contained in the powder layer is removed from the powder. Because the powder is fed in with the body, the air that is being fed is compressed and trapped, and as a result, the increased air pressure causes it to try to escape to the top, resulting in weaker powder feeding as a whole or no powder feeding at all. It seems that it may not be possible.

In the present invention, a degassing mechanism shown in 8.9 is provided to prevent such a phenomenon.

Moreover, it has been found that it is most effective to attach this degassing surface to the upper part of the supply screw for degassing the air.

That is, if there is a degassing surface at the top of the supply screw, the powder layer shown in 5 can be degassed in advance, and the wall resistance increases at the top wall surface 8 of the supply screw, so that the pushing of the powder by the supply screw is effective. This is thought to be due to the fact that it is carried out on a regular basis.

For such a powder feeding device, the taper angle of the hopper wall should be 55° to 85°, the ratio of the difference between the outer diameter and the root diameter of the feed screw to the root diameter should be 0.8 or less, and the outer diameter of the feed screw and the root diameter should be 0.8 or less. It has been found that when the ratio of the difference in diameter to the pitch is 0.5 or less, it becomes possible to more effectively supply powder exhibiting a higher apparent specific volume.

In conventional powder feeding devices, the shape of the feeding screw and the taper angle of the hopper have only been designed based on the calculation of the volumetric feed rate of the feeding screw, the calculation of the cross-sectional area ratio of the feeding screw, etc. There were no cases where the feed amount became small.

The taper angle of the hopper wall is 55 to 85 degrees, preferably 60 to 80 degrees, and the ratio of the difference between the outer diameter of the supply screw and the root diameter to the root diameter is 0.8 or less, preferably 0.2 to The ratio of the pitch to the difference between the outer diameter and the root diameter of the supply screw is preferably 0.5 or less, preferably 0.2 to 0.4.

The difference between the outer diameter and the root diameter of the feed screw is 20 mm when feeding to a powder compactor with a roller diameter of 500 mm or less.
It is preferable to set it to about 60 mm.

Further, by providing two or more supply screws together as shown in FIG. 4, powder can be uniformly supplied to a wider range than the diameter of the supply screws.

Further, the deaeration surface of the hopper wall may be of any type as long as it does not allow the powder to pass through but allows the gas supplied to the powder to pass therethrough.

The blower does not need to be very powerful, usually 20
It may be about 0 to 1 ooo H20.

Next, experimental results will be shown in which the apparatus of the present invention was used in a powder compressor with a roller diameter of 400 mm.

The control is a commercially available product.

A button, a degassing surface, and a punching with a diameter of 8 mm were installed on the hopper wall, and about 750 d of cloth (cotton material) was placed on the hopper.
Inhaled at rLH20.

A sample of lactose + white carbon, which has an apparently large specific volume, contains a lot of air in the powder, but even with such a powder, the taper angle of the hopper wall can be adjusted to 60 degrees by using the device of the present invention.
00, by making the lower part 800 double-tapered and installing a deaeration device on the upper hopper wall, a large amount of air can be removed from the upper stage with a gentle angle, and the powder from which air has been removed from the upper stage can no longer be used. Since it is not necessary to make the angle gentle, the amount of powder to be compressed can be increased by making the angle steep.

On the other hand, in the case of the conventional machine, the taper angle of the hopper wall is the same as the device of the present invention, and the taper angle of the hopper wall is two steps, but since there is no deaerator, the powder feeding ability is not sufficient.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram of the entire roller compaction device equipped with the powder supply device of the present invention, and Fig. 2 is a sectional view of the chip side in which the hopper is vertically divided into thirds by the roller compaction surface. , Figure 3 shows the degassing surface (
FIG. 4 shows a longitudinal cross-sectional view of a powder supply device equipped with a plurality of screws on the roller compression surface (the screws are a side view).

Claims (1)

[Claims] 1. In a powder feeding device equipped with a powder feeding hopper and a feeding screw for sending out powder, the taper angle of the upper and lower parts is 55° to 85°, respectively, and the taper angle of the upper part is smaller than the taper angle of the lower part. A degassing surface is provided in the step-tapered powder supply hopper and the upper hopper wall of the hopper at a location close to the biting part of the supply screw, and the difference between the outer diameter and the root diameter and the ratio of the root diameter are set to 0. 8 or less, characterized by the provision of a supply screw with a ratio of the difference between the outer diameter and the root diameter of the supply screw to the pitch of 0.5 or less, and whose high appearance makes it easy to produce powders with a specific volume. A powder feeding device that can reduce the volume and degas it.