Classifying – separating – and assorting solids – Sifting – Plane sifters
Reexamination Certificate
2000-10-03
2002-08-13
Walsh, Donald P. (Department: 3653)
Classifying, separating, and assorting solids
Sifting
Plane sifters
C209S002000, C209S404000, C414S392000
Reexamination Certificate
active
06431367
ABSTRACT:
RELATED APPLICATIONS
This application relates to and claims priority to corresponding Japanese Patent Application No. 288705/1999 filed Oct. 8,1999 and which is incorporated by reference herein.
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a sifter in which a plurality of sifter frames provided with sifting nets which are stacked one on top of the other within one and the same machine frame in the sequence of sizes of meshes, the machine frame being rotatingly oscillated with respect to the horizontal plane by a vertical rotary oscillating axis thereby sifting powdery particles on the basis of particle diameters, and more particularly to an apparatus for exchanging sifter frames in which, during the maintenance (exchange of the sifter frames) of the sifter, the sifter frames can be easily taken out of the machine frame.
(2) Description of the Related Art
A prior art sifter as shown in
FIG. 1
is known, in which a plurality of sifter frames provided with sifting nets are stacked one on top of the other within one and the same machine frame in the sequence of sizes of meshes, the machine frame being rotatingly oscillated with respect to the horizontal plane by a vertical rotary oscillating shaft thereby sifting powdery particles on the basis of article diameters.
FIG. 1
shows an outside appearance of the prior art sifter in which a plurality of sifter frames
101
are stacked on a sifting machine frame
102
, and are fixed unitarily to the sifting machine frame
102
by bolts
103
and nuts
104
. The sifting nets of the sifter frames
101
are stacked one on top of the other in such a way that lower the nets are positioned the meshes of the nets gradually become finer, and that material particle objects are introduced from the topmost sifting net and finer particles can be taken out from lower sifting nets. The sifting machine frame
102
has at its central portion a vertical rotary shaft
105
for effecting rotary oscillation and, with the rotation of the rotary shaft
105
, the sifting machine frame
102
is caused to oscillate in a horizontal direction. When the sifting machine frame is oscillated, the sifter frames
101
in the machine frame are also oscillated. The particle objects introduced from the inlet
106
onto the uppermost sifter frame are sifted due to the rotary oscillation of the sifting nets and different meshes of the sifting nets, and the sifted particles are discharged from the outlet
107
below. The sifter frames are supported at their four corners by glass fiber rods
108
so as to allow the oscillation of the sifter frames.
The conventional sifter is configured as above so that, for exchanging the sifter frames
101
, first the bolts
103
and the nuts
104
of the sifter frames
101
which are unitarily stacked on the sifting machine frame
102
are loosened, and the sifter frames, one at a time, are taken out from the sifting machine frame
102
. Thereafter, the inspection is made for any holes in the nets, the tense conditions of the nets, any leakage of particle objects, etc. and, if any problems are found, the sifter frames
101
are replaced by new ones. When exchanging for the new sifter frames
101
, the reverse work is performed, that is, the sifter frames
101
are stacked in the sifting machine frame
102
one by one and, on reaching a predetermined number, they are unitarily fastened by the bolts
103
and nuts
104
.
The exchanging operation as above involves heavier work as the number of the sifter frames increases. For example, in the case where there are six sifting chambers and, in each chamber, there are 20 to 30 stages of the stacks of the sifter frames
101
, the time required for exchanging the sifter frames is about 80 minutes for each chamber, which means that the total time of eight hours is required for six sifting chambers and shows that such a great time is necessitated in the conventional exchanging operation.
Further, the sifter frames stacked in 20 to 30 stages reach the height of two to three meters from the ground which required working on a stepladder in a precarious condition, and there was a risk of collapsing of the stacked sifter frames. Also, the total weight of the sifter frames stacked in 20 to 30 stages amounted to 200 Kg so that the exchanging work itself involved risk.
SUMMARY OF THE INVENTION
In view of the above problems, an object of the present invention is to provide means for exchanging sifter frames which enables the reduction in the hard work involved in exchanging the sifter frames and in the exposure of the workers to the risk and which enables easy exchange of the sifter frames.
In order to solve the problem, according to one aspect of the invention, there is provided a method for exchanging sifter frames of a plan sifter, in which a plurality of sifter frames having nets of different meshes are stacked one on top of the other, the stacked sifter frames are accommodated and fixed in a sifting chamber provided within a machine frame, and the machine frame is suspended from above and caused to be oscillated for sifting powdery particles, the method comprising the steps of:
stacking the plurality of sifter frames in advance outside the machine frame and holding the sifter frames in a unitary form;
placing the unitary formed sifter frames in the sifting chamber when accommodating the sifter frames in the sifting chamber;
fixing the unitary formed sifter frames accommodated in the sifting chamber; releasing the fixing of the sifter frames when drawing out the sifter frames from the sifting chamber; and
drawing out the sifter frames to outside the machine frame in the state in which the sifter frames are stacked in the unitary form.
With the above configuration, when the sifter frames are taken out from a plurality of sifting chambers provided within the machine frame, it is not necessary to take out the sifter frames one at a time from each sifting chamber to inspect the existence of any holes in the nets, any problem in the tense condition of the nets, any leakage of particle objects, etc. and then to exchange the sifter frames and, when the sifter frames are accommodated into each of the sifting chambers, the sifter frames are stacked in advance outside the machine frame and the unitary formed sifter frames are accommodated in each sifting chamber so that, even when the number of the sifter frames is large, the exchanging operation can be easily carried out. Also, the number of the stacked sifter frames can, in that state, be taken out of the machine frame. Then, the accommodated unitary formed sifter frames are fixed in each sifting chamber for sifting operation and, when the sifter frames are taken out from each sifting chamber, the fixed state of the sifter frames is released and the stacked unitary formed sifter frames are taken out of the machine frame. For example, in the case of the plan sifter where there are 20 to 30 stages of the sifter frames in each sifting chamber and there are 6 sifting chambers, the time conventionally required for exchanging operation was about 80 minutes for each chamber but this has been reduced to about 40 minutes, half the time, and in the case of the plan sifter having 6 chambers, only about 4 hours are required, half the time which was conventionally required.
According to another aspect of the invention, there is also provided an apparatus for exchanging sifter frames of a plan sifter in which a plurality of sifter frames having nets of different meshes are stacked one on top of the other, the stacked sifter frames are accommodated and fixed in a sifting chamber provided in a machine frame, and the machine frame being suspended from above and caused to be oscillated or shaken for sifting powdery particles, the apparatus comprising:
means to stack the plurality of sifter frames and hold the unitary formed sifter frames;
means to transport the unitary formed sifter frames to the sifting chamber for accommodating the sifter frames in the sifting chamber, and from the sifting chamber for drawing out the sifter frames; and
Orihashi Akira
Sakaki Hideki
Satake Satoru
Beauchaine Mark J
Satake Corporation
Walsh Donald P.
Wells St. John Roberts Gregory & Matkin
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