Presses – Methods – With winding or folding
Reexamination Certificate
2000-10-06
2003-02-04
Bray, W. Donald (Department: 3725)
Presses
Methods
With winding or folding
C100S041000, C100S168000, C264S118000
Reexamination Certificate
active
06513424
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a powder grain processing technique used for manufacturing medicines, foods, agricultural chemicals, resins, fertilizers, and the like, and particularly to a technique effectively applicable to a dry granulation apparatus in which powder grains are compacted and formed to manufacture a product.
BACKGROUND ART
As methods for granulating powder grains to manufacture medicines and foods, there are a wet granulation method using wet materials such as water, alcohol or the like, and a dry granulation method in which dried powder grains are compacted and formed by a pair of compression rollers. The dry granulation method obtains stable granules without necessitating wet material and have advantages of shortening of processing time and increasing efficiency of production in order to omit an intermediate step used the wet granulation method. In recent years, frequency in use of the dry granulation method is promoted.
In this dry granulation method, both of the compression rollers receive such a force from supplied powder grains that pushes and opens between the rollers, as a reaction to a compressing force generated during compacting and forming. Therefore, in conventional cases, one of the compression rollers is provided with a hydraulic mechanism to press the other compression roller and, thereby, the other roller is prevented escaping from the one. A dry granulation apparatus of this kind is described, for example, in Japanese Patent Application Laid-Open No. 49-125281 and No. 50-56373. FIGS.
14
(
a
) to
14
(
c
) and
15
are explanatory views showing structures thereof.
Firstly, in the dry granulation apparatus shown in FIG.
14
(
a
), a powder grain container hopper
101
is provided at an upside thereof to temporarily store powder grains
109
that are materials and are transported with air. A feeder
102
that have screw wings for transporting the powder grains
109
supplied from the hopper
101
in a lateral direction is installed at a lower portion of the container hopper
101
. Compression rollers
104
for pressing, with a high pressure, the powder grains
109
fed by the feeder
102
to compress them at a high density are provided below the feeder
102
. In this case, a press cylinder
105
is attached to one of the compression rollers
104
. Further, the one roller
104
is pressed against other roller
104
, so that the other roller
104
is prevented escaping from the one roller
104
during the compacting and forming.
A needle-shearing device
106
for shearing a compacted object that is fed from the rollers
104
is provided below the rollers
104
. Provided below the shearing device
106
is a cutter-shearing device
107
for further shearing granulation sheared by the shearing device
106
to obtain granulation of appropriate shape. A grain refiner
108
for refining the sheared granulation is provided further below the device
107
. Note that these devices are always disassembled into component parts for every lot of products or the like at every appropriate period in order to prevent contamination therein. The parts and process rooms are individually cleaned. In this manner, even with respect to medicinal supplies that should avoid mixture of foreign ingredients, an operation of granulation or the like can be achieved while the devices are consistently kept clean.
Meanwhile, even if the one roller
104
are pressed so as to prevent the other roller escaping from the one roller during the compacting, then powder grains for granulation escape from both end surfaces of the rollers
104
. This results in insufficient compression force and causes a drawback that solid tablets having uniform quality cannot be obtained. To prevent this escape of the powder grains, the granulation apparatus shown in FIG.
14
(
a
) is provided with seal plates
111
and
111
as shown in FIG.
14
(
b
), in a positional relationship as shown in FIG.
14
(
c
). In this case, a pressure-resistant device
113
that is operated by oil pressure or the like is provided on a back part of one of the seal plates
111
. Also, by the pressure-resistant device
113
, the seal plates
111
and
111
are pressed so as not to come apart from end surfaces of the rollers
104
. Accordingly, the powder grains supplied between the rollers
104
and
104
are compacted and formed without escaping and flowing from therebetween.
And, the granulation apparatus shown in FIG.
15
(
a
) is also provided with similar seal plates
125
and
125
. In the granulation apparatus shown in FIG.
15
(
a
), powder grains are supplied from a powder grain container hopper
121
through a screw feeder
122
to a pair of compression rollers
123
and
123
. To prevent the supplied powder grains from escaping between the rollers
123
and
123
during the compacting and forming, seal plates
125
are provided on both end surface sides of the rollers. A hydraulic cylinder
124
is also provided at one of the rollers
123
as described above.
Next, with respect to supply of powder grains to the compression rollers, a screw feeder is used to supply powder grains in many cases as described above. A screw feeder is frequently used in apparatuses, which must feed powder grains, such as a powder packaging apparatus, a powder scale apparatus, and the like, including a granulation apparatus. In this case, there are, in particularly, no problems caused by supply efficiency of the screw feeders in powder grains having a small apparent specific volume. However, there is a drawback that the supply efficiency decreases as the apparent specific volume increases. For example, in a process of performing the compacting and forming by means of compression rollers, the compacting and forming is carried out without problems in case of powder grains having a small apparent specific volume (2.5 and less). On the other hand, if the apparent specific volume is slightly larger (4 to 5), the supply efficiency of the screw feeders decreases. This results in making bad a thrust of the powder grains between the compression rollers, decreasing capacity for compacting and forming the powder grains, and reducing production efficiency. Additionally, if the powder grains have a much larger apparent specific volume (5 and more), the thrust of the powder grains is made worse and, thereby, it is no longer possible to compact and form the powder grains.
Therefore, if the powder grains have a large apparent specific volume, then it is necessary to compress the powder grains twice by the rollers or to compress the powder grains after the powder grains are pre-compressed by another compression device and the apparent specific volume thereof is reduced. That is, this processing has some wasteful steps. Although various methods and apparatuses using a tapered screw, a wave-form roll, a large-diameter roller, or the like have been proposed, any of them cannot be a satisfactory solution. On the other hand, tries for reduction of the apparent specific volume of powder grains have been made. For example, in a fine powder granulation apparatus described in Japanese Patent Application Laid-Open No. 64-44300, a structure is proposed in which fine powder containing much air is subjected to degassing during transportation thereof.
In the apparatus according to the Japanese Patent Application Laid-Open No. 64-44300, as shown in
FIG. 16
, a filter cylinder
132
is provided inside a trough
131
, and screw wings
133
are provided in this filter cylinder
132
. In this case, a ring-like chamber
134
is formed between the trough
131
and the filter cylinder
132
. In addition, the ring-like chamber
134
is connected to a vacuum pump not shown through a communication tube
135
. In this apparatus, the fine powder
137
supplied to a hopper
136
is degassed by the vacuum pump while being fed to the compression rollers
138
by the screw wings
133
. Accordingly, the fine powder
137
comes to have the small apparent specific volume and is supplied between the compression rollers
138
.
Meanwhile, various control methods about a po
Isobe Shigemi
Iwasaki Akira
Kashiwagi Shigetoshi
Sasaki Toshinari
Bray W. Donald
Freund Industrial Co. Ltd.
McCormick Paulding & Huber LLP
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