U.S. patent application number 12/082425 was filed with the patent office on 2009-10-15 for device and method for pressing a metal powder compact.
Invention is credited to Mark Haiko, Roger Lawcock, Frank Ma.
Application Number | 20090257904 12/082425 |
Document ID | / |
Family ID | 41161486 |
Filed Date | 2009-10-15 |
United States Patent
Application |
20090257904 |
Kind Code |
A1 |
Lawcock; Roger ; et
al. |
October 15, 2009 |
Device and method for pressing a metal powder compact
Abstract
A method of pressing a powder metal compact comprising partially
filling a die cavity with powder metal, engaging a second die with
the first die, extending radially inwardly punches for forming a
transverse feature in the compact, filling the die cavity with
powder metal, compressing the powder metal with a punch, relieving
pressure on the compact, withdrawing the radially inwardly punches
so as to allow axial movement of the compact, withdrawing the
second die, and ejecting the compact from the die while
simultaneously filling the die cavity.
Inventors: |
Lawcock; Roger; (Burlington,
CA) ; Haiko; Mark; (Burlington, CA) ; Ma;
Frank; (Mississauga, CA) |
Correspondence
Address: |
Jeffrey Thurnau;Tomkins plc, IP Law Dept. 10-A3
1551 Wewatta Street
Denver
CO
80202
US
|
Family ID: |
41161486 |
Appl. No.: |
12/082425 |
Filed: |
April 11, 2008 |
Current U.S.
Class: |
419/66 |
Current CPC
Class: |
B22F 3/03 20130101 |
Class at
Publication: |
419/66 |
International
Class: |
B22F 3/02 20060101
B22F003/02 |
Claims
1. A method of pressing a powder metal compact comprising:
partially filling a die cavity with powder metal; engaging a second
die with the first die; extending radially inwardly punches for
forming a transverse feature in the compact; filling the die cavity
with powder metal; compressing the powder metal with a punch;
relieving pressure on the compact; withdrawing the radially
inwardly punches so as to allow axial movement of the compact;
withdrawing the second die; and ejecting the compact from the die
while simultaneously filling the die cavity.
2. The method as in claim 1 further comprising: ejecting the
compact by extending a shoe for filling the die cavity.
3. The method as in claim 1 further comprising: extending a
plurality of punches for forming different surfaces in the
compact.
4. The method as in claim 1 further comprising: trimming a powder
surface by withdrawing a shoe for filling the die cavity.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a device and method for pressing a
powder metal compact having a transverse feature by use of radially
extending punches, which punches are radially removable upon
release of punch compacting pressure.
BACKGROUND OF THE INVENTION
[0002] The prior art shows a device for pressing metal powder
compacts to be sintered which comprises a split die having a
cylindrical cross section, each die cooperatively engaged in a
horizontal plane, the horizontal plane being perpendicular to the
direction of their longitudinal axis. This device further comprises
punches that are movable toward each other in a direction that is
perpendicular to the horizontal plane, each of which is associated
with the split die and is adapted for pressing one of the metal
powder compacts. The axes of movement of the punches is vertical.
The powdered metal material is fed to the upper die when the punch
associated therewith is lifted from the die. Suitable means are
provided for moving the punches one towards and away from the other
in order to compress the powdered material to press the compact and
to eject the compact.
[0003] The device of the kind described does not, however, permit
pressing of compacts with transverse features which otherwise could
not be removed from the compacts from the dies solely by axial
displacement of the punches and the dies. For instance, with a
device of this kind it is not possible to press compacts having a
recessed transverse feature.
[0004] Representative of the art is U.S. Pat. No. 3,752,622 which
discloses a device for moulding compacts with undercut compacts to
be sintered by compaction of powdered material. A two compact die
forms the chamber in which the compact is moulded. A pair of
opposed punches pass through the die to compact the powdered
material. The two compacts of the die are held firmly in contact
with one another during the stroke of the punches by an annular
collar with inclined surface engaging oppositely inclined surfaces
on the die. After the material has been compacted, the two compacts
of the die are separated in such a direction as not to interfere
with the undercut portions of the compacts. After the die has
opened, one of the punches retracts while the other continues its
stroke to move the compact from between the two compacts of the
die.
[0005] What is needed is a device and method for pressing a powder
metal compact having a transverse feature by use of radially
extending punches, which punches are radially removable upon
release of punch compacting pressure. The present invention meets
this need.
SUMMARY OF THE INVENTION
[0006] The primary aspect of the invention is to provide a device
and method for pressing a powder metal compact having a transverse
feature by use of radially extending punches, which punches are
radially removable upon release of punch compacting pressure.
[0007] Other aspects of the invention will be pointed out or made
obvious by the following description of the invention and the
accompanying drawings.
[0008] The invention comprises a method of pressing a powder metal
compact comprising partially filling a die cavity with powder
metal, engaging a second die with the first die, extending radially
inwardly punches for forming a transverse feature in the compact,
filling the die cavity with powder metal, compressing the powder
metal with a punch, relieving pressure on the compact, withdrawing
the radially inwardly punches so as to allow axial movement of the
compact, withdrawing the second die, and ejecting the compact from
the die while simultaneously filling the die cavity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The accompanying drawings, which are incorporated in and
form a compact of the specification, illustrate preferred
embodiments of the present invention, and together with a
description, serve to explain the principles of the invention.
[0010] FIG. 1 is a perspective cross-sectional view of the
compacting apparatus.
[0011] FIG. 2 is a perspective cross-sectional view of the
compacting apparatus.
[0012] FIG. 3 is a perspective cross-sectional view of the
compacting apparatus.
[0013] FIG. 4 is a perspective cross-sectional view of the
compacting apparatus.
[0014] FIG. 5 is a perspective cross-sectional view of the
compacting apparatus.
[0015] FIG. 6 is a perspective cross-sectional view of the
compacting apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] FIG. 1 is a perspective cross-sectional view of the
compacting apparatus. The apparatus generally comprises a lower die
10 and punches 11, 12, 13, 14 which are axially moveable within die
10. Powdered metal material is filled into the die cavity 16 by a
moveable feeder shoe 15. When not in use, feeder shoe 15 is
withdrawn and rests adjacent to the die 10, for example, upon a
staging surface 17. Feeder shoe 15 is moveable between the position
shown in FIG. 1 and the staging surface 17. Feeder shoe is
connected to a powder material hopper known in the art (not shown)
or other suitable means of conveying the metal powder material to
the die.
[0017] FIG. 2 is a perspective cross-sectional view of the
compacting apparatus. Cavity 16 is first filled with powder. Upper
die 20 is then moved into position over die 10. Upper die 20 can be
moved vertically into position by use of either hydraulic or
mechanical means.
[0018] Upper die 20 comprises radially moveable punches 21.
"Radial" is determined with respect to the direction of movement of
punches 11-14. Punches 11, 12, 13, 14 may each be moved vertically
to compress the powder to form a compact. Punches 12, 13 and 14
each provide the means by which various elevation surfaces are
formed into the compressed "green" compact.
[0019] Radially moveable punches 21 are then moved radially inward
until they contact the outer surface of punch 12. Punches 21 may be
moved by a variety of means, but the preferred method is
hydraulically. The remainder of the cavity is then filled with
powder to a level substantially equal with the top surface 19 of
die 20. Feeder shoe 15 is then withdrawn, and in doing so the upper
surface of the powder material is trimmed of excess powder. This
results in the proper amount of powder in the die cavity, ready for
compaction.
[0020] FIG. 3 is a perspective cross-sectional view of the
compacting apparatus. Punch 22 and punch 23 compress the powder in
cavity 16 by moving axially toward die 10, punches 21, and punches
11, 12, 13, 14. Compression of punch 22 toward punches 11, 12, 13,
14, 21 fully compacts the compact. Punch 23 cooperates with punch
14 to fully form a bore through compact 100.
[0021] During final compaction punch 11 moves vertically toward
punches 22 and 21. This is to avoid damaging portions 21 by
imposing an otherwise unsupported bending moment. Hence, punch 11
compresses one end of the compact in part against portions 21, and
punch 22 compacts the opposite end of the compact in part against
punch 21.
[0022] Feeder shoe 15 is shown withdrawn to surface 17.
[0023] FIG. 4 is a perspective cross-sectional view of the
compacting apparatus. Once compaction is completed, punch 22 and 23
and die 20 are vertically withdrawn, thereby relieving pressure on
radial punches 21. Punches 21 are withdrawn radially. Vertical
movement between punch 11 and die 10 assists in removing compact
100 from die cavity 16 and thereby moving the "green" compact above
the upper surface of die 10. This results in fully undercut
portions or transverse features in the compact which extend
completely through the compact 100. In the preferred embodiment the
apparatus comprises a plurality of extending radially punches 21.
However, the method may use a single punch 21 for forming a desired
single undercut or transverse feature with equal success.
[0024] FIG. 5 is a perspective cross-sectional view of the
compacting apparatus. Die 20 and punches 22, 23 are shown
withdrawn, thereby freeing compact 100 from die 10. At this stage
compact 100 is borne upon punch 11.
[0025] Punches 21 are moveably connected to upper die 20. Punch 22
holds compact 100 stationary while punches 21 are withdrawn.
[0026] FIG. 6 is a perspective cross-sectional view of the
compacting apparatus. The cycle is then repeated when the feeder
shoe 15 is moved across die 10, thereby ejecting compact 100
laterally from die 10 and the apparatus. Feeder shoe 15 then pours
powder material into cavity 16 and the described sequence is
repeated.
[0027] The "green" compressed compact is then processed using known
sintering methods which are not described herein but are well known
in the art.
[0028] Although a form of the invention has been described herein,
it will be obvious to those skilled in the art that variations may
be made in the sequence, construction and relation of parts without
departing from the spirit and scope of the invention described
herein.
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