Note: Descriptions are shown in the official language in which they were submitted.
CA 02421604 2006-08-15
1
POWDER FEEDING APPARATUS WITH A FILLING SHOE AND MASK
Background of the invention
As can be seen from Fig. 5, there are generally known dies 1
comprising a die opening 2, in which at least one punch 3 - 5
is arranged being movable in an upward and a downward
direction. A filling device having the form of a filling shoe
7 and having arranged at least one filling hose 8 for filling
a filling shoe chamber 10 with powder, slides above the die
surface 6. In order to move the filling shoe 7 forward and
backward above the die surface 6 the filling shoe 7 is
coupled to driven guide rods 9. Advantageously, the guide rod
arrangement 9 reaches over bolts 9b, which laterally protrude
out of the filling shoe 7. In order to feed the die opening 2
in an area above lowered punches 3, 4 with powder 11 the
filling shoe 7 is moved over the die opening 2, being the
filling shoe 7 previously already filled with powder.
It is a problem to feed the die opening 2 with different
sorts of powder 11, and 11a, respectively, into different
sections of the die opening. E. g., if the filling shoe 7
away from the die opening 2 is re-fed with powder 11a after
previously being filled another kind of powder 11 in one die
opening section, the result is, that, when following
displacement of the filling shoe 7 over already fed area
occurs, powder particles of powder 11a which is located in
the filling shoe chamber 10 will mingle with superficial
part=icles of the other powder 11 in the die opening 2. In
case that the powder 11a being in the filling shoe chamber 10
has a clearly higher density than the powder 11 being in the
die opening 2, then an even deeper and far-reaching mixing of
powder 11 in the die opening 2 will take place. Especially,
a break-down in the peripheral areas takes place, in the
course of which the heavier powder 11a from the filling shoe
CA 02421604 2006-08-15
2
chamber 10 along the edge of the die opening 2 penetrates
deeply into the die opening 2, while away from it light
powder 11 will be brought upward from the die opening 2 into
the filling shoe chamber 10.
Summary of the invention
The object of the invention is to improve a powder feeding
apparatus, to improve a filling shoe for such an apparatus
and to improve a method for feeding of a die opening with
powder, respectively. Especially, there should be avoided
that different powder materials are mixed together by being
dragged along, and that superficial areas get polluted or
mixed together. Furthermore and advantageously, the effect of
break-down in the marginal areas of the die has to be
avoided.
In one embodiment of a powder feeding apparatus, especially
for metallurgical powders, the powder feeding apparatus
comprises at least one die, comprising a die surface and at
least one die opening within it, one, two or more punches
being shiftable within the die opening in upward and downward
direction, a feeding device, comprising a filling shoe being
moveable above the die surface into at least one position
above the die opening in order to feed it and into at least
one position which is distant of the die opening, and a
powder filling device for filling the powder, at least one
mask comprising at least one mask opening, and at least one
mask guiding device. Said mask guiding device comprises means
to temporarily cover the die opening with the mask in such a
way that the mask opening or the mask openings, respectively,
are arranged above a part of the die opening which has to be
filled with powder, when the filling shoe moves in direction
to and over the die opening and for removing the mask from
the die opening when or after the filling shoe moves away
from the die opening.
CA 02421604 2006-08-15
3
In one embodiment a filling shoe comprises a filling shoe
guiding device and a powder feeding device. A mask guiding
device is configured for putting on a mask above a die
opening having at least one mask opening when the filling
shoe moves in direction to and over the die opening and for
removing the mask from the die opening when the filling shoe
moves away from the die opening.
In one embodiment method for feeding with pulverized or
granulated material a die opening within a powder feeding
apparatus and/or by means of a filling shoe, wherein a mask
will be arranged upon the die opening before it will be fed,
which comprises a die opening in order to feed a pre-
determined space of the die opening in a well-directed way,
at least one filling device will be driven into a feeding
position above the die opening embedded in the die and into a
non-feeding position away from the die opening above the
die's upper side and wherein the pulverized or granulated
material in the feeding position is being filled from the
fil_Ling device into a hollow space, which is being built in
the die opening above of at least one punch which is moveable
in <~n upward and a downward direction within it. The mask
with the mask opening is placed above the die opening before
or during the moving of the filler device above the die
opening.
The fundamental thought concerning such a powder feeding
apparatus, the filling shoe being brought into action within
it and the method for filling in a die opening with a
pulverized or granulated material consists in covering with a
mask the die opening already partially filled with powder in
especially the fed areas, whereby the mask comprises one or
more mask openings in these areas, where the die opening is
to be fed with pulverized or granulated material in a further
working process.
CA 02421604 2006-08-15
4
Advantageously, according to a powder feeding apparatus and
with a die, with automatic control mechanism, at least a
punch within a die opening and a feeding device, especially
with a filling shoe, a mask is provided, having at least one
mask opening, whereby for moving and/or transferring of the
mask in addition a mask guiding device has to be provided.
The mask guiding device facilitates a temporary covering of
the die opening with the mask in such a way that the mask
opening and the mask openings, respectively, is/are arranged
above a part of the die opening which subsequently has to be
filled with powder. Furthermore, the mask guiding device
facilitates the temporary removing of the mask from the die
opening and from the area which surrounds the die opening.
Advantageously, the mask guiding device as such can be
provided by a plurality of designs. On the one hand mask
guiding devices can be designed which are part of the real
feeding apparatus, e. g. drives, which can lift up and
displace a mask or which can swivel a mask around a joint
tied to the place and turn down the mask over the desired die
opening. Further exemplary drives facilitate moving or
swivelling of the mask, while the same slides over the die
sur:Eace during the process, so that the filling shoe
advantageously always can lie on the mask. The mask e. g. in
form of a thin sheet can, advantageously, also be bended
upward by means of a mask guiding device with in particular
turning rolls in the front field of the filling shoe. By
moving the filling shoe in direction of the die opening
advantageously the mask will be bended downward by the
filling shoe and will be put on the die opening and its
surrounding area in the end. When the filling shoe moves
backward the mask again will be bended or pulled upward
through the mask guiding device, particularly carried out by
elastic spring mechanisms or by the influence of weights,
which can exercise a corresponding tensile force upon one end
of the mask via turning rolls. Besides bending the mask by
CA 02421604 2006-08-15
means of a guiding device a mask moving can therefore
generally also occur via other forces F acting on the mask.
Advantageously, on the other hand mask guiding devices can be
5 provided, which already are part of the filling shoe. E. g.
there can be arranged a turning device on the upper side of
the filling shoe, which, driven by means of a spring or a
weight and particularly using a turning roll, pulls the front
end of the mask upward particularly upward in a sloped
direction above the filling shoe. According to a particularly
simple embodiment, however, there can also be designed a mask
leader which is arranged on the front side of the filling
shoe in form of turning rails and which turns the mask coming
out from the front side out of the filling shoe when being
moved backward into an upper direction, particularly turns it
in direction of the backward movement in upward direction
over the filling shoe. When the filling shoe moves in
direction of the opening of the die the mask via forward-
movement of the filling shoe automatically again will be
pulled in front of the filling shoe and under it. In order to
make possible this automation the end of the mask which lies
on the opposite side of the movable end of the mask
purposefully will be fixed on a rigid piece relatively
situated to the die.
Advantageously there can also be used mufti-material filler
and mufti-material filling shoes, respectively, which in a
first working step get inserted the powder via a first powder
hose into their powder chamber in order to get filled in a
further working step via a second filler hose another powder
into their powder chamber. The filling shoe after the feeding
of the filling shoe chamber then will be moved over the die
opening in order to unload the contents of the filling shoe
chamber into the die opening.
Of course it is also possible to insert the powder just in
that very appropriate position in which the filling shoe is
CA 02421604 2006-08-15
6
already situated right above the die opening. Also in this
case it can be advantageous to cover the opening of the die
with a mask leaving an area free which really has to be fed.
Very advantageous is also a sucking or wiping device in order
to clean the mask when being removed from the die opening
from powder residues which stick on the mask. This prevents
contamination at a later working step, at which such powder
residues sticking on the mask could come into the die opening
or into the filling shoe chamber.
Brief description of the drawings
An embodiment with different designs is described below in
more detail with reference to the drawings. There is shown
in:
Fig. 1 sequence of 7 cut representations shown in parts
1A - 1G through a die and a die opening, a feeding procedure
for a die opening in several working steps;
Fig. 2 three different mask guiding devices;
Fig. 3 three diagrams illustrating operation of a multi-
material filling device with at the same time displacement of
the mask between the single feeding steps;
Fig. 4 a powder feeding apparatus with a plurality of
feeding stations in two designs and
Fig. 5 a cut through a powder feeding apparatus during the
over-sliding of a filling shoe over an already partly with
powder fed die opening according to the prior art.
Detailed description of certain inventive embodiments
CA 02421604 2006-08-15
7
As can be seen from Fig. 1 with sub-Fig. 1A-1G a die 1
comprises a die opening 2, in which is arranged at least one
punch being movable in upward and downward direction
preferably, however, a plurality of such punches 3 - 5. By
moving downward of the individual punches above these punches
there is created a space in the die opening 2 able to be fed
with powder.
A filling shoe which preferably can be driven into two basic
positions serves for feeding the die opening 2 with powder
11. The filling shoe 7 is coupled to a powder feeding
apparatus 8 particularly coupled to one or more powder hoses
8, through which powder can be filled into an interior
filling shoe chamber 10.
In a preferred construction the filling of powder 11a into
the filling shoe chamber 10 takes place in a basic position,
in which the filling shoe 7 is arranged on the die surface 6
away from the die opening 2. For transferring the filling
shoe 7 over the upper side of the die 1, i. e. over the plate
of the die respectively the die surface 6 there serves a
filling shoe driver preferably having a guide rod arrangement
9 which is coupled to the filling shoe 7. In a very preferred
design, part of inversely U-shaped guide rods 9 reach over
bolts 9b which laterally protrude from the filling shoe 7 and
the filling device 7, respectively.
As can be seen from Fig. 1A, the filling shoe 7 when being in
an advanced stage of the process is situated already above
the die opening 2, whereby powder 11 falls into the die
opening above the down-sunk punches 3 and 4 from the filling
shoe chamber 10. Usually the filling shoe 7 with already
powder-filled filling shoe chamber 10 and with not yet down-
lowered punches 3 - 5 will be driven above the die opening 2.
Only if the filling shoe 7 with its filling shoe chamber 10
is situated above the punches 3, 4 to be lowered, then the
punches 3 and 4 will be lowered whereby the powder falls out
CA 02421604 2006-08-15
8
of the filling shoe chamber 10 into the space or cavity,
respectively, which now is created above the down-lowered
punches 3 and 4 in the die opening 2. As a result of creating
lower pressure above the punches 3 and 4 by down-lowering
them, this method is also called suction-filling.
After the die opening 2 has been fed with powder 11, the
filling shoe 7 again is moved back into the other basic
position as it can be seen from Fig. 1B. In that other basic
position the filling shoe chamber 10 of the filling shoe 7
then again will be fed with powder 11a, being the powder 11a
introduced via a filling hose 8 out of a hopper, as it also
can be seen from Fig. 1C. The powder 11a mostly is another
powder 11a than powder 11, which has been filled into the die
opening 2 in the preceding cycle of the process.
As can be seen from Fig. 1D, the filling shoe 7 is again
moved above the die opening 2 in the following step of the
procedure. Together when or before moving the filling shoe 7
above the die opening 2, however, a mask , particularly a
stencil or a sheet, will be put over the die surface 6 and
the die opening 2. The mask 12, particularly a flexible
sheet, comprises at least one mask opening 13, which comes to
lie above an area of the die opening 2, whereby in the
following into this area the powder 11a should be fed from
the filling shoe chamber 10. The mask opening 13 is adapted
to the die opening 2 especially in view of the form of the
section which has to be fed, it can, however, also be adapted
to certain demands in a finely-structured manner, e. g. in
order to produce an electrically finely structured conductive
circuit on a normally rigid compact.
As can be seen from embodiment shown in Fig. 1D the mask 12
is provided in the form of a sheet which is rolled off over
the die surface 6 by a rolling movement in a similar way like
a carpet is unrolled. There, the placement of the mask 12 on
the die surface 6 and on the die opening 2 can be carried out
CA 02421604 2006-08-15
9
synchronously to the movement of the filling shoe but it also
can be done independently of the movement of the filling
shoe.
In particular, it is possible to put on the sheet from
another side than the side of the position the filling shoe
being filled. Particularly preferred, however, are designs,
where the filling shoe is permanently arranged on the mask
being therefore not necessary to move the filling shoe over
an edge of the mask.
As can be seen from 1E, in a following moment the filling
shoe 7 with a heavy powder 11a, for example, is located above
the die opening 13 in the mask 12. When being moved into this
position there does not occur contamination of the powder
which already has been filled into the die opening 2, because
the mask 12 is placed between. In a further step the
appropriate punch 5 below the opening of the die 13 will be
lowered, as a result of which the powder 11a is being sucked
or falls from the filling shoe chamber 10 into the area which
is created above punch 5.
Then the filling shoe 7 again will be moved into the other
basic position i. e. into the position where the filling shoe
is fed, as can be seen from Fig. 1G. On that occasion,
automatically or apart from it, the mask 12 can be removed
from the die opening 2 again.
As can be seen from Fig. 2A - 2C, there are a plurality of
different designs for mask guiding devices. Besides stencils
and rigid masks flexible masks 12 e.g. sheets are
particularly preferred. The thinner the mask the less powder
possibly will stand over the basic height of the plate of the
die or the die surface 6 after removal of the mask.
As can be seen from Fig. 2A, a particularly simple mask
guiding device consists of a guide mechanism, a guiding rail
CA 02421604 2006-08-15
for example. A simple guide mechanism can exist in the form
of a mask guide 20 which is spaced at the front side of the
filling shoe 7. The mask guide reaches down with its lower
end until the die plate 6 (see Fig. 1F) being preferably bent
5 in a slightly arched way to the front, then to the upper side
and lastly sloped back in direction of above the filling shoe
7. As a result of this the mask 12 is bent from the die
surface 6 in an upward direction and lastly in a backwardly
direction tilted above the filling shoe 7. The mask guide 20
10 preferably is fixed on the front side of the housing of the
filling shoe 7 with the appropriate fixing and spacing
elements 21.
When the filling shoe 7 moves in forward direction, it
presses the mask 12 in downward direction by the edge of its
front and lower edge and, correspondingly, causes the mask 12
to be retracted when moving in forward direction. When the
filling shoe 7 is moved in backward direction away from the
die opening 2 into the resting position of the filling shoe
and into the position where the filling shoe has to be fed,
respectively, the mask 12, however, in the front side slides
into the mask guide 20 and through the mask guide 20 into an
upper direction, tilted above the filling shoe 7,
respectively, being lastly as a result of it lifted off of
the die surface 6.
In a particularly preferred design a sucking device 31 can be
provided, which on one side or on both sides sucks the
remaining powder from the off-lifted mask 12. On the lower
side of the mask 12 powder can remain stuck from the opening
of the die 2, on the upper side of the mask 12 remaining
powder from the filling shoe chamber 10 also can remain
stuck. Particularly powder containing carbon would remain
stuck on the mask 12 in a stronger way than simple metallic
powder.
CA 02421604 2006-08-15
11
The mask 12 can be produced out of different sorts of
materials to provide flexibility demanded pursuant to the
designs of Fig. 2A-2C. Preferably, the mask 12 can be made
out of a thin stable synthetic sheet or a thin metal sheet
with sufficient flexibility.
As can be seen from Fig. 2B, the mask 12 also can be pulled
in an upwardly inclined direction from the front side of the
filling shoe 7 by means of a frame which is arranged on the
upper side of the filling shoe 7. The device shown consists
of a linkage 23 which protrudes from the upper side of the
filling shoe in the upward direction, on the upper side of
which a roll 24, for example, as a turning device is
mounted. From the end of the mask 12 preferably a tensile
rope 25 leads over the roll 24 to a spring 26, which is
mounted on the upper side of the filling shoe 7 with its
other end. Therefore, the spring 26 always pulls the front
end of the mask 12 in an upward direction. The mask 12 is,
consequently, pulled in an upward direction in an area in
front of the filling shoe 7. The longer the distance through
which the filling shoe 7 has to be moved in a forwardly or
backwardly direction, the higher the linkage 23 which,
accordingly, has to be used.
Also, one can imagine any other design, for example using a
weight instead of a spring 26. Instead of the roll 24 there
also can be used a roller like turning device via which not
only a tensile rope but also the mask 12 itself can get
turned in its course. Also, e. g. the spring can be arranged
directly acting on the front side of the mask 12 from the
upper end of the linkage.
As can be seen from design shown in Fig. 2C the mask 12 is
not pulled into the upward direction by means of a mask
guiding device which is arranged on the filling shoe 7
itself, but via a mechanical frame device 28, which has been
mounted rigidly relative to the die 1. The illustrated
CA 02421604 2006-08-15
12
mechanical device 28 again shows rolls 27 which change the
course of a tensile rope, which is tensioned between the mask
12 and a weight 29.
Alternative mask guiding devices also can be constructed as
rolls or drums in order to roll up the mask, being it
therefore possible to roll out and to roll up the mask 12
like a carpet.
While according to the three embodiments shown in the figure
with the aid of the filling shoe 7 the mask 12 is pressed
against the die surface 6 or above the die opening 2,
respectively, when being moved into the position above the
die opening 2. However, the putting of the mask 12 onto the
die surface 6 or above the die opening 2, respectively, and
the moving or transferring of the filling shoe 7 also can be
carried out independently of each other. In particularly
preferred designs, however, the single moving steps are
coupled synchronously one to each other.
An exemplary design for the movement of the mask 12 and the
movement of the filling shoe 7 the one moving independently
from the other is outlined by the sequences shown in Fig. 3A-
3C.
As can be seen from Fig. 3A in plan view a die 1 again
comprises a die surface 6 with a die opening 2 embedded
therein. Above the die surface 6 a filling shoe 7 moves
forwardly and backwardly. The movement in forward and
backward directions of the filling shoe 7 again is done via
guide rods 9, which again preferably reaches over bolts 9b
which laterally protrude out of the filling shoe 7. According
to a particularly preferred design of the mufti-material
filler it is possible to move the filling shoe 7 not only in
forwardly and backwardly directions but also crosswise to
said moving direction above the die surface 6. Instead of
separate movements in forwardly and backwardly directions and
CA 02421604 2006-08-15
13
to the left or to the right, respectively, there is also
possible a swivelling movement overlying these movements or
independent of them around a swivelling axis 9c, which is
situated in the guide rods 9 or in the area of the drive of
the guide rods 9, such as is generally known.
The filling shoe 7 which is shown is designed as a multi-
material filler and preferably comprises two or more filling
hoses 8a, 8b in order to feed the filling shoe chamber 10.
Instead of feeding only one filling shoe chamber 10 also more
filling shoe chambers can be designed in the filling shoe 7.
According to the procedural step shown in Fig. 3A the die
opening 2 is already partly fed with powder. Before moving
the filling shoe 7 over the opening of the die in a further
step the mask 12 will be laid over the die opening 2. The
mask 12 shown comprises a mask opening 13 in the form of a
cylindrical hoop. Such a mask opening 13 can be formed by
leaving a filled circle with smaller diameter within a
tubular opening in the mask 12. For fixing the inner circle
there can be left thin rods, which do not cause problematic
interference when the die opening 2 below is being fed
evenly.
After moving the filling shoe 7 in a forward direction over
the mask opening 13 and the below-lying die opening 2 and
after the act of feeding by means of the powder being carried
with the filling shoe 7 will again be drawn back to the
starting point for being fed. When the filling shoe is at the
starting point or during the act of drawing back the mask 12,
the mask 12 will be pulled laterally in relation to the
movement in the forwardly and backwardly directions of the
filling shoe 7 using a mask transferring drive 30. The
mask transferring drive 30 is situated on the die 1 or on a
frame device as can be seen from Fig. 3B. Effectively, the
transfer of the mask happens only when it has been removed
from the die opening 2, in order to prevent dragging of
CA 02421604 2006-08-15
14
powder 11 and 11a situated in the die opening 2,
respectively, over the die surface 6.
After lateral transfer of the mask 12 it again will be put
over the opening of the die 2, while, now, other additional
mask openings 13a lie above the die opening 2. As can be seen
from the aforementioned, also these further mask openings 13a
for the appropriate purpose lie above areas of the die
opening 2, below which appropriately moulded punches will be
lowered after the filling shoe 7 has been moved over the die
opening 2 or the mask openings 13a, respectively, in order to
fill powder from the filling shoe 7 into the appropriate
areas of the die opening 2.
As can be seen from Fig. 3A - 3C, the mask openings 13a can
have certain desired circumferential shapes. This is
important in the production of pressed bodies, which, for
example, have lower layers consisting of a solid bearer
material and upper or intermediate layers containing
materials which are electrically conducting or electrically
isolating.
As can be seen from Fig. 4A, a complex powder feeding
apparatus 40 can comprise a plurality of filling stations 43,
which are used for feeding a single die having a die opening
2. According to the design demonstrated the die is situated
in a die slide 41, and can be moved crosswise to the single
filling stations 43. After the die opening 2 has been fed
completely, the die slide 41 advantageously and in a direct
way can move the guided die out of the side of the filling
apparatus into a press 44, in which the powder will be
pressed into a solid compact, as it is known generally. The
feeding of the die opening 2 of course also can be carried
out in a direct way within such a powder press by using the
mask technology being generally described.
CA 02421604 2006-08-15
In the filling apparatus 40 shown, with the first filling
shoe 7 in a position on the left, a first filling shoe 7
carrying a first powder is moved over the die opening 2, in
order to put powder, which is contained in the filling shoe
5 chamber of the filling shoe 7, into the die opening 2. After
the filling shoe 7 has been moved back into the basic
position the die slide 41 is moved into the appropriate
position in front of one of the other filling stations 43. In
this position an appropriate filling shoe 7 will be moved
10 from the other filling station 43 above the die opening 2, in
order to release powder being in the filling shoe 7 into the
opening of the die. In an advantageous way at least one
powder hopper with the appropriate different powder will be
assigned to each of the filling shoes 7 making it possible to
15 fill the filling shoe for each filling station 43 powder of a
different nature and to then fill the die opening 2 with a
desired layer structure of powder. When producing a compact
with a plurality of layers it is also possible to move the
die slide 41 more than one time to a certain filling station
43, if an appropriate powder layer structures is desired.
As can be seen, when using loose filling shoes 7 with coupled
filling hose 8, at the most there can be used a unique
filling shoe drive for the purpose, the frame 9 of which
arranged on the side of the filling shoe can be coupled to
the appropriate filling shoe 7 which is to be moved. Together
with the transfer of the die slide 41 accordingly the guide
rod arrangement 9 for guiding the single filling shoes 7,
will be transferred to another of the filling shoes 7 in
lateral or parallel direction onto the slide guide 42.
As can be seen from Fig. 4B there also can be constructed any
other forms of filling apparatus. Advantageously, there can
also be a central die comprising a die opening 2, around
which there, in a circular arrangement, there are several
filling stations 43 each of which has one filling shoe.
CA 02421604 2006-08-15
16
Particularly, such an arrangement can be part of the powder
press 44.
While the aforementioned description follows the example of
metal powder presses, the basic principle can be taken for
any constructions where a pulverized or granulated material
is to be filled into a receiving space. Also, in the
following there need not be carried out a pressing of the
powder in a powder press as an absolute requirement.
As a pulverized or granulated material there can be used the
most different sort of material, i. e. besides metal powders
also ceramic powders or carbon powders can be used. The
aforementioned described procedure particularly also makes
possible the production of mixed alloys or complex compacts,
where less solid layers are put onto solid layers. It is also
possible to produce compacts, for example, comprising a solid
material on the outer side and a softer material which also
can have greasy attitudes around a central through opening on
the inner side in order to receive a rotating shaft. Further
application areas are for example the production of fuel
cells, i. e. the production of compacts, where very different
materials have to be arranged above each other and/or beside
each other in the compact which is to be produced while
satisfying the requirement for extreme cleanliness of the
single areas.
