U.S. patent application number 10/163005 was filed with the patent office on 2002-12-19 for method of producing powder compacts and foil or film-like mold members for use in the method.
This patent application is currently assigned to Intermetallics Co., Ltd.. Invention is credited to Sagawa, Masato, Watanbe, Toshihiro.
Application Number | 20020192102 10/163005 |
Document ID | / |
Family ID | 26616664 |
Filed Date | 2002-12-19 |
United States Patent
Application |
20020192102 |
Kind Code |
A1 |
Sagawa, Masato ; et
al. |
December 19, 2002 |
Method of producing powder compacts and foil or film-like mold
members for use in the method
Abstract
A powder compact is produced by disposing a foil or film-like
mold member packed with a powder in a cavity of a rubber mold which
is loaded in a die. The rubber mold, the foil or film-like type
mold member and the powder packed in the foil or film-like mold
member are compressed by a punch to obtain a powder compact. The
powder compact with the foil or film-like mold member being
attached thereto is removed, by pressure, from the rubber mold.
Since the powder to be compressed into a compact is not packed
directly in the cavity of the rubber mold, but is packed in the
mold member, no part of the rubber mold is caught in the space
formed by the powder that is in contact with the rubber mold.
Accordingly, cracks and chips in the powder compact can be
prevented even when the rubber mold is restored to its initial
shape and many shape and size variations of the powder compact can
be realized.
Inventors: |
Sagawa, Masato;
(Nishikyo-ku, JP) ; Watanbe, Toshihiro;
(Nishikyo-ku, JP) |
Correspondence
Address: |
Barry E. Bretschneider
Morrison & Foerster LLP
Suite 5500
2000 Pennsylvania Avenue, N. W.
Washington
DC
20006-1888
US
|
Assignee: |
Intermetallics Co., Ltd.
Nishikyo-ku
JP
|
Family ID: |
26616664 |
Appl. No.: |
10/163005 |
Filed: |
June 6, 2002 |
Current U.S.
Class: |
419/8 |
Current CPC
Class: |
B30B 11/001 20130101;
B30B 15/024 20130101 |
Class at
Publication: |
419/8 |
International
Class: |
B22F 007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2001 |
JP |
2001-175016 |
May 10, 2002 |
JP |
2002-134830 |
Claims
1. A method of producing a powder compact, comprising: disposing a
foil or film-like mold member packed with a powder in a cavity of a
rubber mold which is loaded in a die; compressing the rubber mold,
the foil or film-like mold member and the powder packed in the foil
or film-like mold member with a punch to obtain a powder compact;
and removing the powder compact with the foil or film-like mold
member from the rubber mold.
2. A method of producing a powder compact, comprising: disposing a
foil or film-like mold member packed with a powder in a cavity of a
rubber mold which is loaded in a die; compressing the rubber mold,
the foil or film-like mold member and the powder packed in the foil
or film-like mold member by a punch to obtain a powder compact;
removing the powder compact with the foil or film-like mold member
from the rubber mold; and removing the foil or film-like mold
member from the powder compact.
3. A method of producing a powder compact, comprising: packing a
foil or film-like mold member with a powder; disposing the foil or
film-like mold member packed with powder in a cavity of a rubber
mold which is loaded in a die; compressing the rubber mold, the
foil or film-like mold member and the powder packed in the foil or
film-like mold member with a punch to obtain a powder compact; and
removing the powder compact with the foil or film-like mold member
from the rubber mold.
4. An apparatus for producing powder compacts, comprising: a foil
or film-like mold member having an inside portion which is packed
with a powder a rubber mold having a cavity, the foil or film-like
mold member being disposed in the cavity; and a die for receiving
the rubber mold, wherein the rubber mold, the foil or film-like
mold member and the powder packed in the foil or film-like mold
member are compressed by a punch to obtain a powder compact, and
the powder compact with the foil or film-like mold member is
removed from the rubber mold.
5. The apparatus of claim 4, wherein the foil or film-like mold
member is removed from the powder compact after the powder compact
is removed from the rubber mold.
6. The method of claim 1, wherein the foil or film-like mold member
is made of a low melting point metal.
7. The method of claim 1, wherein the foil or film-like mold member
is made of a material selected from the group consisting of tin,
aluminum, copper, iron, nickel, stainless steel, paper and
synthetic resin.
8. The method of claim 7, wherein the foil or film-like mold member
is made of a material selected from the group consisting of tin,
aluminum, copper, iron, nickel and stainless steel and has a
thickness in a range of about 0.01 to 1.50 mm.
9. The method of claim 8, wherein the foil or film-like mold member
has a thickness in a range of about 0.03 mm to 1.00 mm.
10. The method of claim 1, wherein the foil or film-like mold
member is made of paper or synthetic resin and has a thickness in a
range of about 0.05 to 3.0 mm.
11. The method of claim 10, wherein the foil or film-like mold
member has a thickness in a range of about 0.1 to 2.0 mm.
12. The method of claim 1, further comprising applying heat to the
powder compact with the foil or film-like mold member after it is
removed from the rubber mold to melt or remove the foil or
film-like mold member.
13. The method of claim 1, further comprising applying heat to the
powder compact with the foil or film-like mold member after it is
removed from the rubber mold at a temperature below the melting
point of the foil or film-like mold member to produce a presintered
compact.
14. The method of claim 2, wherein the foil or film-like mold
member is made of a low melting point metal.
15. The method of claim 2, wherein the foil or film-like mold
member is made of a material selected from the group consisting of
tin, aluminum, copper, iron, nickel, stainless steel, paper and
synthetic resin.
16. The method of claim 15, wherein the foil or film-like mold
member is made of a material selected from the group consisting of
tin, aluminum, copper, iron, nickel and stainless steel and has a
thickness in a range of about 0.01 to 1.50 mm.
17. The method of claim 16, wherein the foil or film-like mold
member has a thickness in a range of about 0.03 mm to 1.00 mm.
18. The method of claim 2, wherein the foil or film-like mold
member is made of paper or synthetic resin and has a thickness in a
range of about 0.05 to 3.0 mm.
19. The method of claim 18, wherein the foil or film-like mold
member has a thickness in a range of about 0.1 to 2.0 mm.
20. The method of claim 2, further comprising applying heat to the
powder compact after it is removed from the rubber mold at a
temperature to produce a presintered compact.
21. The method of claim 3, wherein the foil or film-like mold
member is made of a low melting point metal.
22. The method of claim 3, wherein the foil or film-like mold
member is made of a material selected from the group consisting of
tin, aluminum, copper, iron, nickel, stainless steel, paper and
synthetic resin.
23. The method of claim 22, wherein the foil or film-like mold
member is made of a material selected from the group consisting of
tin, aluminum, copper, iron, nickel and stainless steel and has a
thickness in a range of about 0.01 to 1.50 mm.
24. The method of claim 23, wherein the foil or film-like mold
member has a thickness in a range of about 0.03 mm to 1.00 mm.
25. The method of claim 3, wherein the foil or film-like mold
member is made of paper or synthetic resin and has a thickness in a
range of about 0.05 to 3.0 mm.
26. The method of claim 25, wherein the foil or film-like mold
member has a thickness in a range of about 0.1 to 2.0 mm.
27. The method of claim 3, further comprising applying heat to the
powder compact with the foil or film-like mold member after it is
removed from the rubber mold to melt or remove the foil or
film-like mold member.
28. The method of claim 3, further comprising applying heat to the
powder compact with the foil or film-like mold member after it is
removed from the rubber mold at a temperature below the melting
point of the foil or film-like mold member to produce a presintered
compact.
29. The apparatus of claim 4, wherein the foil or film-like mold
member is made of a low melting point metal.
30. The apparatus of claim 4, wherein the foil or film-like mold
member is made of a material selected from the group consisting of
tin, aluminum, copper, iron, nickel, stainless steel, paper and
synthetic resin.
31. The apparatus of claim 30, wherein the foil or film-like mold
member is made of a material selected from the group consisting of
tin, aluminum, copper, iron, nickel and stainless steel and has a
thickness in a range of about 0.01 to 1.50 mm.
32. The apparatus of claim 31, wherein the foil or film-like mold
member has a thickness in a range of about 0.03 mm to 1.00 mm.
33. The apparatus of claim 4, wherein the foil or film-like mold
member is made of paper or synthetic resin and has a thickness in a
range of about 0.05 to 3.0 mm.
34. The apparatus of claim 33, wherein the foil or film-like mold
member has a thickness in a range of about 0.1 to 2.0 mm.
35. The apparatus of claim 4, further comprising a heater for
applying heat to the powder compact with the foil or film-like mold
member after it is removed from the rubber mold to melt or remove
the foil or film-like mold member.
36. The apparatus of claim 4, further comprising a heater for
applying heat to the powder compact with the foil or film-like mold
member after it is removed from the rubber mold at a temperature
below the melting point of the foil or film-like mold member to
produce a presintered compact.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method of producing
powder compacts in which a powder packed in an intended space is
compressed into a powder compact, and a foil or film-like mold
member for use in the method. The resultant powder compact may be
used as it is or as a sintered compact after sintering.
[0003] 2. Description of Related Art
[0004] A conventional method of producing powder compacts is now
described referring to FIG. 4.
[0005] A cylindrical die is denoted by the numeral 1. A lower punch
2 is provided at its upper end portion with an annular recess into
which a ring-shaped backup ring 2a, made of a hard synthetic resin
or the like, is fitted and is inserted into the die 1. An
internally extending edge part 1a, formed at the lower end portion
of the die 1, is engaged with a tiered part between the upper
larger diameter portion 2b and a lower smaller diameter portion 2c
of the lower punch 2 to prevent the die 1 from moving upward with
respect to the lower punch 2. A support table on which the lower
punch 2 is mounted is denoted by numeral 3. An appropriate number
of disc springs 4 is provided at the smaller diameter portion 2c of
the lower punch 2 between the bottom face of the die 1 and the
upper surface of the support table 3. An upper punch 5 is provided
such that the bottom face 5a thereof is placed on the upper surface
1b of the die 1. A backup ring 5c made of hard synthetic resin is
fitted into an annular groove 5b formed in the bottom face 5a of
the upper punch 5. The backup ring 5c is arranged so that it covers
the boundary area between the die 1 and a rubber cover m1 for
covering a rubber mold M described later. Rubber mold M can be
loaded into a space formed by the die 1 and the lower punch 2
inserted therein. For example, the rubber mold M has an elongated
cylindrical cavity m2 to accommodate a powder P to be packed
therein to produce an elongated bar-like powder compact.
[0006] In the process of producing powder compacts, the powder P is
packed into the cavity m2 of the rubber mold M. The rubber cover m1
is then attached. The upper punch 5 is lowered and placed on the
upper surface 1b of the die 1. The upper punch 5 is then further
lowered so that the die 1 descends together with the upper punch 5,
resisting the disc springs 4 provided between the die 1 and the
support table 3. While the upper punch 5 and the die 1 descend as
discussed above, the lower punch 2, being held by the support table
3, does not move. Accordingly, the space 6 formed by the die 1 and
the lower punch 2 is reduced in depth so that the powder particles
P packed in the cavity m3 of the rubber mold M are compressed in a
pseudo-isostatic manner through the rubber mold M, thereby forming
an elongated cylindrical powder compact. Subsequently, the upper
punch 5 is lifted and the cover m1 is detached. The resultant
powder compact is then taken out of the rubber mold M. Meanwhile,
the compact shaped in the above manner can be sintered in an
appropriate manner to obtain a sintered compact.
[0007] In the above-described conventional method of producing
powder compacts, as FIG. 5(a) illustrates for example, the rubber
mold M has not yet been caught in the spaces s formed between the
powder particles P, which are in contact with the rubber mold M
before the pressing process is carried out by the upper punch 5 and
the lower punch 2. However, as FIG. 5(b) illustrates for example,
in the final pressing step by the upper punch 5 and lower punch 2,
the rubber mold M is caught in the spaces s formed between the
powder particles P that is in contact with the rubber mold M. In
this condition, when the upper punch 5 is lifted and the pressure
on the rubber mold M is released, the rubber mold M moves in the
direction away from the powder compact which has been compressed
while contained in the cavity m2 of the rubber mold M. Since stress
is generated when the rubber mold M, which has been caught in the
spaces s formed between the powder particles P in contact with the
rubber mold M, is separated from the powder compact, the powder
compact is cracked or chipped.
[0008] In the process of compressing the powder into a powder
compact mentioned above, the rubber mold M enters and leaves the
spaces s formed by the powder particles P in contact with the
rubber mold M. When the rubber mold M repeatedly enters and leaves
the space s, the areas of the rubber mold M which are in contact
with the powder particles P are damaged. This shortens the life of
the rubber mold M.
SUMMARY OF THE INVENTION
[0009] The primary, but not sole, object of the present invention
is to solve the problems mentioned above which the conventional
method of producing powder compacts has suffered.
[0010] In order to achieve the above stated object, the present
invention provides a method of producing powder compacts comprising
disposing a foil or film-like-like mold member packed with a powder
in a cavity of a rubber mold which is loaded in a die; compressing
the rubber mold, the foil or film-like type mold member and the
powder packed in the foil or film-like mold member with a punch to
obtain a powder compact; and subsequently using pressure to remove
the powder compact with the foil or film-like mold member still
being attached thereto from the rubber mold.
[0011] The present invention also provides a method of producing
powder compacts comprising disposing a foil or film-like mold
member packed with a powder in a cavity of a rubber mold which is
loaded in a die; compressing the rubber mold, the foil or film-like
type mold member and the powder packed in the foil or film-like
mold member with a punch to obtain a powder compact; subsequently
removing the powder compact with the foil or film-like mold member
being attached thereto by pressure from the rubber mold; and
thereafter removing the foil or film-like mold member that is
attached to the powder compact.
[0012] The invention further provides a foil or film-like mold
member for use in the aforementioned method of producing powder
compacts, the foil or film-like mold member being provided inside a
space portion into which powder can be packed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIGS. 1(a) and 1(b) are a perspective views of an example
mold member used in the method of producing powder compacts
according to the invention.
[0014] FIG. 2 shows an elevational cross section of an apparatus
for producing powder compacts for use in the method of producing
powder compacts according to this invention.
[0015] FIG. 3 shows an elevational cross section of the apparatus
shown in FIG. 2.
[0016] FIG. 4 shows an elevational cross section of an apparatus
used in a conventional method of producing powder compacts.
[0017] FIGS. 5(a) and 5(b) illustrate contact states between the
rubber mold and powder in the conventional apparatus for producing
powder compacts shown in FIG. 4.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Preferred embodiments of this invention are hereinafter
described. However, this invention is not limited to these specific
embodiments but may be modified in other ways without departing
from the scope of the invention. In the drawings, like components
are denoted by like numerals throughout and will not be further
explained.
[0019] An example of a produced elongated columnar powder compact
which is difficult to produce by the above-mentioned conventional
powder compacting method is explained below.
[0020] In FIGS. 1(a) and (b), foil or film-like mold members T1 and
T2 are shown.
[0021] These mold members are made of a soft, low melting point
metal and are capable of holding a packed powder. These mold
members are configured to be inserted into the cavity m2 of the
rubber mold M. Specifically, FIG. 1(a) shows a foil or film-like
mold member T1 made of a soft, low melting point metal and formed
integrally with a bottom. FIG. 1(b) shows a foil or film-like mold
member T2 having an integrally formed, jointless pipe t1 made of a
soft, low melting point metal, and a bottom plug t2, which is made
of a material such as rubber or synthetic resin or the like, is
fitted into the lower opening of the bottomless pipe t1.
[0022] The foil or film-like mold member T1 or T2 (hereinafter
simply referred to as T) is inserted into the cavity m2 of the
rubber mold M in the manner shown in FIG. 2 either before or after
the mold member T is filled with powder P. In the case of the foil
or film-like mold member T not being filled with powder P before
being inserted into the cavity m2 of the rubber mold M, the mold
member T is packed with the powder P after being inserted into the
cavity m2 of the rubber mold M. Then, the rubber cover m1 is
mounted on the rubber mold M.
[0023] Subsequently, in the same manner as described above, the
upper punch 5 is lowered so as to pseudo-isostatically compress the
foil or film-like mold member T which has been packed with the
powder P and inserted into the cavity m2 formed within the rubber
mold M, thereby forming the powder P packed in the foil or
film-like mold member T into a powder compact. The upper punch 5 is
then lifted and the cover m1 is detached. The powder compact having
the foil or film-like mold member T attached by pressure is taken
out of the cavity m2 of the rubber mold M.
[0024] The powder compact obtained through the above-mentioned
process and contained in the foil or film-like mold member T may be
used as it is. Otherwise, the powder compact contained in the foil
or film-like mold member T may be heated at an appropriate
temperature above the melting point of the foil or film-like mold
member T to melt and remove the foil or film-like mold member T.
The powder compact may be sintered to be used as a sintered
compact. It is possible to heat the powder compact contained in the
foil or film-like mold member T at a temperature below the melting
point of the foil or film-like mold member T to obtain a
presintered compact with the foil or film-like mold member T
tightly attached thereto. Then, the foil or film-like mold member T
can be mechanically removed from the presintered compact so that
the presintered compact is fully sintered thereafter and used as a
sintered compact formed in a desired shape.
[0025] According to this embodiment, the powder P to be compressed
into a compact is not packed directly in the cavity m2 of the
rubber mold M. Rather, the powder P is packed in the foil or
film-like mold member T. Accordingly, the problem where a part of
the rubber mold M is caught in the space s formed by the powder P
that is in contact with the rubber mold M does not arise during the
compression by the upper punch 5. It is therefore possible to
prevent the powder compact from cracking or chipping even when the
rubber mold M is restored to its initial shape when the pressure is
released by lifting the upper punch 5.
[0026] In addition, unlike the conventional case, since the powder
P is not directly in contact with the rubber mold M, damage to the
rubber mold M due to contact with the powder P does not occur. The
life of the rubber mold M is therefore extended.
[0027] The shape of the foil or film-like mold member T is designed
such that a compact with a desired shape can be obtained after
compaction. A wide variety of materials may be employed for the
foil or film-like mold member T including metals such as tin,
aluminum, copper, iron, nickel and stainless steel, paper and
synthetic resin. The most appropriate material will be determined
according to the properties, treatment temperature, or proposed use
of the desired compact. The thickness of the foil or film-like mold
member T, when it is metal, is in the range of about 0.01 to 1.50
mm, and preferably, it is about 0.03 mm to 1.00 mm. The thickness
of the foil or film-like mold member T, when it is paper or
synthetic resin, is in the range of about 0.05 to 3.0 mm, and
preferably it is about 0.1 to 2.0 mm.
[0028] To make the foil or film-like mold member T most easily, a
flat foil or film is wound around a master mold with the desired
shape and bonded at the ends. To fabricate a metal foil mold member
T, any kind of plastic working process may be employed such as
pressing, forging, drawing, and extrusion. The most appropriate
process is determined according to the shape and material of the
metal foil mold member T. When it is made of synthetic resin,
injection molding or casting may be used. The foil or film-like
mold member T is formed so as to closely fit into the cavity m2 of
the rubber mold M, and may or may not have a bottom.
[0029] The above-described embodiment is arranged such that the
upper punch 5 is lowered to be mounted on the upper surface of the
die 1, and further lowered so as to compress the rubber mold M,
foil or film-like mold member T and powder P packed in the foil or
film-like mold member T. However, the arrangement may be such that
with the upper punch 5 being fixed, the support table 3 provided
with the lower punch 2 and die 1 is moved up and down, thereby
compressing the powder into a powder compact.
[0030] The example above shows an apparatus for compacting powder,
which comprises the die 1, the lower punch 2 inserted into the die
1, the upper punch 5 to be mounted on the upper surface of the die
1, and the disc springs 4 provided at the smaller diameter portion
2c of the lower punch 2 between the bottom face of the die 1 and
the upper surface of the support table 3. However, it is also
possible to employ an apparatus for compacting powder which
comprises a die having an opening in its upper part and a bottom,
and an upper punch to be inserted into the die, in which the lower
punch 2 and disc springs 4 in the above apparatus are omitted.
[0031] Being structured as described above, the present invention
provides the following effects.
[0032] Since the powder to be compressed into a compact is not
packed directly in the cavity of the rubber mold, but is packed in
the mold member, the problem where a part of the rubber mold is
caught in the space formed by the powder that is in contact with
the rubber mold will not arise. Accordingly, cracking or shipping
of the powder compact can be prevented even when the rubber mold is
restored to its initial shape. Thus, the ranges of shape and size
variations possible for the powder compact can be largely expanded.
In addition, since this invention allows coarse powders with large
grain sizes to be compressed into various powder compacts, product
cost can be reduced and the variety of products can be
increased.
[0033] Unlike the conventional method, the powder does not directly
come into contact with the rubber mold in this invention.
Therefore, damage to the rubber mold due to the direct contact with
the powder P does not occur, thereby extending the life of the
rubber mold.
[0034] In addition, since the powder compact is protected by the
mold member, it does not suffer damage when it is ejected from the
rubber mold or loaded into a sintering furnace. Handling the powder
compact is therefore made easier.
* * * * *