U.S. patent application number 13/638051 was filed with the patent office on 2013-08-08 for method and arrangement for manufacturing a component with hot isostatic pressing, a core, a preform for a cladding, and use of the core.
This patent application is currently assigned to METSO MINERALS, INC.. The applicant listed for this patent is Jussi Hellman, Teuvo Kovaniemi, Jari Liimatainen, Mikko Uusitalo. Invention is credited to Jussi Hellman, Teuvo Kovaniemi, Jari Liimatainen, Mikko Uusitalo.
Application Number | 20130202476 13/638051 |
Document ID | / |
Family ID | 42074441 |
Filed Date | 2013-08-08 |
United States Patent
Application |
20130202476 |
Kind Code |
A1 |
Hellman; Jussi ; et
al. |
August 8, 2013 |
METHOD AND ARRANGEMENT FOR MANUFACTURING A COMPONENT WITH HOT
ISOSTATIC PRESSING, A CORE, A PREFORM FOR A CLADDING, AND USE OF
THE CORE
Abstract
A method and an arrangement for manufacturing a component with
hot isostatic pressing occurring in solid form, the component
comprising a shape opening onto the outer surface. The method
comprises forming a sheet metal capsule for metallic powder, and
manufacturing a core by arranging around a core centre made of a
first material, a form layer made of a second material, the shape
of the outer surface of the form layer corresponding to the shape
of the outer surface of the opening shape of the component. The
core is placed in a spot, where the shape opening onto the outer
surface is to be formed, and metallic powder is arranged in the
sheet metal capsule, which forms the body part of the component to
be manufactured. Cladding material is arranged between the outer
surface of the core and the metallic powder, and hot isostatic
pressing is performed to simultaneously compact the metal powder
and the cladding material.
Inventors: |
Hellman; Jussi; (Helsinki,
FI) ; Kovaniemi; Teuvo; (Tampere, FI) ;
Liimatainen; Jari; (Tampere, FI) ; Uusitalo;
Mikko; (Tampere, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hellman; Jussi
Kovaniemi; Teuvo
Liimatainen; Jari
Uusitalo; Mikko |
Helsinki
Tampere
Tampere
Tampere |
|
FI
FI
FI
FI |
|
|
Assignee: |
METSO MINERALS, INC.
Helsinki
FI
|
Family ID: |
42074441 |
Appl. No.: |
13/638051 |
Filed: |
March 31, 2011 |
PCT Filed: |
March 31, 2011 |
PCT NO: |
PCT/FI11/50275 |
371 Date: |
October 22, 2012 |
Current U.S.
Class: |
419/8 ; 425/78;
524/440 |
Current CPC
Class: |
B22F 7/06 20130101; B22F
3/1291 20130101; B22F 7/08 20130101; B22F 3/15 20130101; C23C
24/082 20130101; B22F 7/02 20130101 |
Class at
Publication: |
419/8 ; 425/78;
524/440 |
International
Class: |
B22F 7/02 20060101
B22F007/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2010 |
FI |
20105340 |
Claims
1. A method for manufacturing a component with hot isostatic
pressing occurring in solid form, the component to be manufactured
including a shape opening onto the outer surface of the component,
which method comprises: forming a sheet metal capsule for metallic
powder; manufacturing a core by arranging around a core centre made
of a first material a form layer made of a second material, the
shape of the outer surface of the form layer corresponding to the
shape of the outer surface of the opening shape of the component;
placing the core in a place, where the shape opening onto the outer
surface is to be formed; arranging metallic powder into the sheet
metal capsule, which metallic powder forms the body part of the
component to be manufactured, characterized in arranging cladding
material between the outer surface of the core and the metallic
powder; and in performing hot isostatic pressing in order to
simultaneously compact the metallic powder and the cladding
material.
2. The method according to claim 1, characterized in placing the
core inside the sheet metal capsule before closing and degassing
the sheet metal capsule.
3. The method according to claim 1, characterized in arranging in
the sheet metal capsule a partition wall separating the cladding
material from the metallic powder, which forms the body part of the
component.
4. The method according to claim 3, characterized in arranging
between the partition wall and the core a powder-like cladding
material or a preform including a cladding material and being in
the form of a polymer-bonded mat or paste.
5. The method according to claim 2, characterized in arranging on
the outer surface of the core a preform including a cladding
material and being in the form of a polymer-bonded mat or paste,
before the core is placed in the sheet metal capsule.
6. The method according to claim 4, characterized in evaporating by
thermal degassing at least most of the bonding polymer included in
the preform including a cladding material, prior to the hot
isostatic pressing.
7. The method according to claim 1, characterized in removing the
core centre after the hot isostatic pressing in one piece; and
arranging a new form layer made of a second material around the
removed core centre in order to manufacture a new core.
8. A core, which is suitable for use in the manufacture of a
component, which comprises a shape opening onto the outer surface
of the component, which core comprises: a core centre manufactured
from a first material; and a form layer comprising a second,
different material arranged around the core centre, characterized
in that the form layer is manufactured from a second material,
which has a thermal expansion coefficient which differs from the
thermal expansion coefficient of the first material of the core
centre by at the most 20%, or the form layer is manufactured from a
second material, the density value of which is smaller than the
density value of the first material of the core centre, whereby the
density value is calculated as a ratio of the actual density and
theoretical density of each material.
9. The core according to claim 8, characterized in that the core
centre is manufactured from a material, the density of which is at
least 95%, preferably at least 98%, of the theoretical density of
said material.
10. The core according to claim 8, characterized in that the core
centre is manufactured from an iron-based material, such as steel,
especially carbon steel, or from cast iron, or the core centre is
manufactured from a Ni-based high temperature material.
11. The core according to claim 8, characterized in that the form
layer is manufactured from a material, the density of which is
60-95%, preferably 70-95%, more preferably 80-95%, of the
theoretical density of said material.
12. The core according to claim 8, characterized in that the form
layer is manufactured from a material, which is inert and thermally
stable in conditions of hot isostatic pressing.
13. The core according to claim 8, characterized in that the form
layer is manufactured from a ceramic material, such as oxide
ceramics, nitride ceramics, carbide ceramics, boride ceramics,
beryllium ceramics, or that the form layer is manufactured from
graphite.
14. The core according to claim 8, characterized in that the
bending strength of the form layer is >75 MPa and/or the
compression strength is >140 MPa.
15. The core according to claim 8, characterized in that between
the core centre and the form layer is arranged an anti-adhesion
layer, the properties of which differ from the core centre and the
form layer, and which preferably comprises aluminium oxide or boron
nitride.
16. The core according to claim 8, characterized in that an
anti-adhesion cladding is arranged on the form layer on the outer
surface of the core.
17. The core according to claim 8, characterized in that an open
channel is arranged through the core centre, which channel extends
from the first end of the core centre to its second end, in order
to even out the pressure during the hot isostatic pressing.
18. A preform for a cladding, which comprises: particles of
metallic powder of the cladding material, the particles having a
size of 0.5-1000 .mu.m; and a bonding polymer, the amount of which
in the preform is 1-50 weight-% of the weight of the metallic
powder particles.
19. The preform for a cladding according to claim 18, characterized
in that the bonding polymer is selected from a group consisting of
polyethylene; polyacrylates; polyisobutylenes; cellulose derivates;
polyvinylbutyral; polyfluoroethylene; polyester; polyolefin;
polyamide or polyimide comprising a low or high molecular weight
component; or phenolic resin, such as epoxy resin, alkyd resin or
silicone.
20. The preform for a cladding according to claim 18, characterized
in that the metallic powder particles are of a metallic powder,
which is mainly for example of a nickel-, cobalt- and
titanium-based alloy, stainless steel or a hard metal, for example
nickel-chromium alloy Inconel.RTM. 625 or nickel-copper alloy
Monel.RTM..
21. An arrangement for manufacturing a component with hot isostatic
pressing occurring in solid form, the component comprising a shape
opening onto the outer surface of the component, which arrangement
comprises: a sheet metal capsule for metallic powder; a core, which
can be arranged in connection with the sheet metal capsule
characterized in that the core is a core according to claim 8.
22. The arrangement according to claim 21, characterized in that it
comprises a partition wall, which is arranged at a distance from
the wall of the sheet metal capsule, and which partition wall is
arranged to define the space meant for the metallic powder between
the partition wall and the sheet metal capsule.
23. A use of a core according to claim 8 for manufacturing valves,
pump casings or ductwork components by hot isostatic pressing.
Description
[0001] The invention relates to a method and arrangement for
manufacturing a component with hot isostatic pressing, which
component comprises a shape opening onto the outer surface of the
component, according to the preamble of the independent claims
presented below. The invention also relates to a core and a preform
for a cladding to be used in the method, and the use of the
core.
FIELD OF THE INVENTION
[0002] Capsules manufactured from sheet metal are often used for
manufacturing powder metallurgic products with hot isostatic
pressing. Metallic powder, which is used as raw material for the
products is filled into the sheet metal capsule, which is closed in
a gas-tight manner and degassed, and after this hot isostatic
pressing is performed for compacting the powder and obtaining the
final shape of the component. There is empty space in the sheet
metal capsule after the filling of powder, in the case of a
gas-atomised round-particle powder typically about 30-40 volume-%,
whereby the shrinkage of the component is of the same magnitude
when the powder is compacted in the hot isostatic pressing. It is
preferred that this dimensional change occurring during the hot
isostatic pressing can be predicted and controlled as precisely as
possible. If the control of the dimensional change is not precise
enough, the dimensions of the component do not fulfil the given
requirements, or alternatively large working allowances should be
used. As the size of the component to be manufactured increases,
the probability for dimensional deviations increases.
[0003] By using metallic or non-metallic cores it is possible to
control the shapes of a component as the powder in the sheet metal
capsule is compacted. The control of the inner shapes of the
component to be manufactured can be especially governed by using
cores, since they may, in a way, be used to force the shape of the
component to be manufactured closer to the desired dimension,
provided the core is not damaged during the hot isostatic pressing
and its deformation/shrinkage is small and predictable.
[0004] The use of a core for the control of the inner shape of a
component in hot isostatic pressing generally increases costs,
especially if the core is expensive to manufacture and/or if the
core cannot be used repeatedly. For example boron nitride has been
used as a non-metallic core material in applications demanding high
precision, but the use has been restricted by the high cost of the
material. On the other hand, the use of some other non-metallic
core materials is restricted by their fragility and tendency to
fracture during the heating and the compaction of the component to
be manufactured. This is a problem especially when manufacturing
large components and when using large cores. Cores have been
manufactured also from metal, such as steel. One problem has then
been that despite a possible surface treatment, the metallic core
has a tendency to stick to the sheet metal capsule or component to
be manufactured during the hot isostatic pressing, whereby the
removal of the core is possible only by machining or etching. The
costs of both removal methods are high, especially when using
large-size cores. In that case the core is also for single-use.
[0005] It is often preferred to manufacture components, which have
cavities or shapes opening onto the outer surface of the component,
which are clad with another material, which differs from the
material of the body part itself. Such components are for example
valve components in the oil and gas industry, where it is preferred
to clad only the flanges and inner parts of the valves with an
expensive, corrosion-resistant material, instead of manufacturing
the entire valve component from the expensive, corrosion resistant
material. Nowadays the cladding of such components is typically
performed as a welding cladding. However, a problem with welding
cladding is that the materials of the cladding and the body part to
be clad are mixed at the interface, which weakens the corrosion
resistance of the cladding. Welding cladding normally requires
several cladding layers, which naturally increases the time needed
for the cladding and the consumption of the cladding material.
Simultaneously also the control of the thickness of the cladding is
decreased: the thickness of the cladding layer is preferably
constant, and during manufacturing, the cladding is made with
exactly the right thickness. In practice the cladding layer must be
manufactured too thick and machined afterwards to the right
thickness. Welding cladding also causes deformations in the
component, which further increases the necessary working
allowances. For all these reasons, the manufacture of clad
components is technically demanding and expensive.
OBJECT AND SHORT DESCRIPTION OF THE INVENTION
[0006] An object of this invention is to reduce or even completely
eliminate disadvantages and problems in the prior art.
[0007] One object of the invention is to provide a method and an
arrangement, which enables the manufacture of components comprising
clad cavities or opening shapes in a cost-effective and reliable
manner.
[0008] Another object of the invention is to provide a method and
an arrangement, which makes the manufacture of components
comprising clad cavities or opening shapes faster and simpler.
[0009] A further object of the invention is to provide a core,
which is at least partly reusable.
[0010] In addition, a further object of the invention is to provide
a precursor for a cladding, by means of which the manufacture of
clad components and the manufacture of cladding with a uniform
thickness is easier.
[0011] The present invention is characterised in what is defined in
the characterising parts of the independent claims presented
further below.
[0012] Some preferred embodiments according to the invention are
disclosed in the dependent claims presented further below.
[0013] A typical method according to the invention for
manufacturing a component with hot isostatic pressing occurring in
solid form, the component to be manufactured comprising a shape
opening onto the outer surface of the component, comprises [0014]
forming a sheet metal capsule for metallic powder, [0015]
manufacturing a core by arranging around a core centre made of a
first material a form layer made of a second material, the shape of
the outer surface of the form layer corresponding to the shape of
the outer surface of the opening shape of the component, [0016]
placing the core in a place, where the shape opening onto the outer
surface is to be formed, [0017] arranging metallic powder into the
sheet metal capsule, which metallic powder forms the body part of
the component to be manufactured, [0018] arranging cladding
material between the outer surface of the core and the metallic
powder, and [0019] performing hot isostatic pressing in order to
simultaneously compact the metallic powder and the cladding
material.
[0020] A typical core according to the invention, which is suitable
for use in the manufacture of a component, which comprises a shape
opening onto the outer surface of the component, comprises [0021] a
core centre manufactured from a first material, and [0022] a form
layer comprising a second, different material, arranged around the
core centre, whereby [0023] the form layer is manufactured from a
second material, which has a thermal expansion coefficient which
differs from the thermal expansion coefficient of the first
material of the core centre by at the most 20%, or [0024] the form
layer is manufactured from a second material, the density value of
which is smaller than the density value of the first material of
the core centre, whereby the density value is calculated as a ratio
of the actual density and theoretical density of each material.
[0025] A typical preform for a cladding according to the invention
comprises [0026] particles of metallic powder of the cladding
material, the particles having a size of 0.5-1000 .mu.m, and [0027]
a bonding polymer, the amount of which in the preform is 1-50
weight-% of the weight of the metallic powder particles.
[0028] A typical arrangement according to the invention for
manufacturing a component with hot isostatic pressing occurring in
solid form, the component comprising a shape opening onto the outer
surface of the component, comprises [0029] a sheet metal capsule
for metallic powder, [0030] a core, which can be arranged in
connection with the sheet metal capsule, which is the core
according to the invention.
[0031] The core according to the invention is typically used for
manufacturing valves, pump casings or ductwork components by hot
isostatic pressing.
DETAILED DESCRIPTION OF THE INVENTION
[0032] Now it has surprisingly been found that by arranging
cladding material between the outer surface of the core and the
metallic powder forming the body part of the component, and by
simultaneously compacting both the metallic powder and the cladding
material in one work stage with hot isostatic pressing, components
comprising clad shapes opening onto the outer surface can be
manufactured substantially easier and more cost-effectively than
earlier. By means of the invention, the number of time-consuming
and complicated work stages, such as welding cladding, can be
decreased. Simultaneously it may be striven towards even more
precise cladding thicknesses, which decreases the amount of
cladding material used and generates savings in material costs. By
means of the invention the control of the shape of the component
during the compressing is also improved, since the cladding and
body material are compressed in a hot isostatic pressing process by
using a core as aid. This increases the reliability of the process
and decreases the number of invalid components formed during the
manufacturing.
[0033] In one embodiment of the invention the core is placed inside
the sheet metal capsule before the sheet metal capsule is closed
and degassed. This promotes that the cladding material is compacted
evenly around the core during the hot isostatic pressing, and the
form of the shape or the cavity, which opens onto the outer surface
of the component to be manufactured, precisely conforms to the form
of the outer surface of the core. In this embodiment the
manufacture of a complicated two-walled sheet metal capsule is also
avoided. In certain embodiments of the invention the core may be
placed outside the sheet metal capsule.
[0034] According to a preferred embodiment of the invention the
metal powder particles of the cladding material preform are
metallic powder, which mainly is for example a nickel-, cobalt- and
titanium-based alloy, stainless steel or a hardmetal. One example
of a metallic powder material suitable for the cladding material is
a nickel-chromium alloy, which comprises at least 58 weight-%
nickel and 20-23 weight-% chromium and which is generally known by
the name Inconel.RTM. 625. Another example of a metallic powder
materials suitable for the cladding material are nickel-copper
alloys, which are generally known by the name Monel.RTM.. Metallic
powders may be manufactured for example by gas atomisation, water
atomisation, spray drying, by grinding to a suitable particle size,
and by different chemical and electrolytic methods. These methods
are as such known by a person skilled in the art, and they are not
described here further. Gas atomisation is preferably used for the
manufacture of metallic powder, whereby metal particles are
obtained, which have a spherical shape and a low oxygen content.
The particle size of the metallic powder used as cladding material
is typically 0.5-1000 .mu.m, preferably 1-500 .mu.m, more
preferably 1-200 .mu.m, very preferably 5-100 .mu.m or even more
preferably 10-50 .mu.m.
[0035] According to another embodiment of the invention the
powder-like cladding material comprises a mixture of metallic and
ceramic material, i.e. cermet, or only ceramic material. In cermet
the metal, such as for example cobalt, nickel, titanium, iron,
molybdenum or one of their alloys, functions as a binder, the
concentration of which in the cermet is typically 0.5-80 volume-%.
In cermet the ceramic material is generally a carbide material,
such as tungsten carbide (WC), titanium carbide (TiC), vanadium
carbide (VC), chromium carbide (CrC) or a mixture of several of
said carbides. The ceramic material functioning as a powder-like
cladding material may be an oxide material, for example aluminium
oxide, or a nitride material, for example titanium nitride, or
another corresponding ceramic material. The particle size of the
cermet or ceramic material used as cladding material corresponds to
the particle size of the metallic powder used as cladding material.
The powder-like cladding material comprises mainly particles of
cladding material.
[0036] In one embodiment of the invention a powder material is used
as the cladding material, which powder material is a metal matrix
composite, i.e. a mixture of metallic powder and ceramic powder, or
a mixture of metallic powder, metallic binder and ceramic
powder.
[0037] Metallic powder used as the cladding material and metallic
powder used for the body part of the component to be formed are
different, i.e. they differ from each other in respect to their
chemical composition and/or their physical properties. Metallic
powder used for the body part of the component is typically
ferritic steel, austenitic-ferritic steel or duplex steel or
stainless steel.
[0038] In one embodiment of the invention a partition wall is
arranged in the sheet metal capsule, the partition wall separating
the cladding material from the metallic powder, which will form the
body part of the component. Powder-like cladding material is thus
arranged between the partition wall and the core. The partition
wall is manufactured from a material, which fulfils the
requirements and/or restrictions set by the use of the product to
be manufactured. The partition wall may typically be manufactured
for example from a low carbon constructional steel, where the
amount of carbon is <0.3 weight-%, or from stainless steel,
where the chromium content is typically >12 weight-%. The
partition wall is arranged at a distance from the wall of the sheet
metal capsule and it is thus arranged to define the space intended
for the metallic powder between the partition wall and the sheet
metal capsule. The partition wall may for example be welded to the
capsule at a suitable distance from the wall of the sheet metal
capsule. The partition wall may be arranged at a suitable position
also with spacer elements, which may be arranged between the
partition wall and the core, or between the partition wall and the
wall of the sheet metal capsule, which is toward the core. Such
spacer elements may be manufactured for example from the cladding
material, which is being used, whereby they become part of the
cladding layer during the hot isostatic pressing. The location of
the partition wall in the sheet metal capsule is determined such
that after the shrinkage caused by the hot isostatic pressing, the
thickness of the finished cladding layer corresponds to the desired
thickness of the cladding layer, added with working allowances. A
typical distance existing between the partition wall and the core
is 5-25 mm, more typically 10-15 mm.
[0039] According to one embodiment of the invention the thickness
of the manufactured cladding is typically 1-30 mm, more typically
2-10 mm, preferably 3-6 mm.
[0040] In an embodiment of the invention a powder-like cladding
material or a preform including a cladding material, which is in
the form of a polymer-bonded mat or paste, is arranged between the
partition wall and the core. The preform for the cladding material
thus comprises a bonding polymer and cladding powder, and depending
on the amount of binder and cladding powder, the preform may be
either in the form of a polymer-bonded mat or a polymer-bonded
paste. Now it has surprisingly been found that the preform for the
cladding significantly facilitates the arranging of the cladding
material into the sheet metal capsule. When the cladding is in the
form of a cladding powder, its packing evenly into the sheet metal
capsule is difficult, especially if the component to be
manufactured with hot isostatic pressing has a complicated shape,
and comprises for example small corners or grooves. When using a
preform for a cladding, it may either be glued to the surface of
the sheet metal capsule, in case the preform is mat-like, or a
paste-like preform may be spread onto the surface of the sheet
metal capsule with a suitable spreading tool, for example a
spatula. Correspondingly in another embodiment of the invention a
preform containing a cladding material may be arranged onto the
outer surface of a core, which preform is in the form of a
polymer-bonded mat, paste or suspension, before the core is placed
in the sheet metal capsule.
[0041] The cladding powder for the preform for the cladding may be
either a metallic powder or a powder-like cermet, as has been
described earlier in this application in connection with the
powder-like cladding material. A typical preform for a cladding
comprises 45-99 weight-%, more typically 90-99 weight-% metallic
powder and 1-45 weight-%, more typically 1-10 weight-% bonding
polymer. The preform also comprises air and other possible
substances, such as solvents. The cladding preform may comprise one
or more metallic powders, which are the same that are used also as
the powder-like cladding material, and which have been described
earlier in this application.
[0042] The particle size of the cladding powder to be used in the
cladding preform corresponds to the particle size of the metallic
powders described earlier in this application, however so that a
cladding powder particle size of 5-100 .mu.m is especially
preferable. If the preform comprises several metal or cermet
powders, the different powders are usually mixed together
uniformly, and do not form separate layers or areas for example in
the height direction of the mat. The cladding preform, which is a
polymer-bonded mat, is thus to its properties uniform and even, and
no layers are formed therein.
[0043] In one embodiment of the invention two or more differing
layers have been arranged in the mat-like cladding preform. The
layers may differ from each other either with regards to their
bonding polymer or cladding powder or both their bonding polymer
and their cladding powder. A cladding preform comprising layers may
be used for example to control the mixing of substances and to
decrease it.
[0044] The bonding polymer of the cladding preform may be selected
for example from the group consisting of polyethylene,
polyacrylates, polyisobutylenes and cellulose derivates. The
bonding polymer may also be polyvinylbutyral; polyfluoroethylene;
polyester; polyolefin; polyamide or polyimide comprising a low or
high molecular weight component; or a phenolic resin, such as epoxy
resin, alkyd resin or silicone. The cladding preform may in
addition to a bonding polymer also comprise various organic
solvents or other additives, such as for example one or more
plasticizers. Examples of solvents are aliphatic hydrocarbons,
glycols, glycol ethers and alcohols. One example of a plasticizer
is phthalate plasticizers. The solvents and plasticizers included
in the preform are well-known by those skilled in the art.
[0045] When using a cladding preform in a mat-like form it is
possible to control the thickness of the cladding material layer to
be formed more precisely than before, because the mat-like preform
is in practice uniform in thickness, whereby also the thickness of
the formed cladding is very uniform. The thickness of the mat-like
preform is typically 0.5-10 mm, more typically 1-4 mm. In case it
is desired to manufacture thick cladding layers, several preform
layers may be arranged on top of each other.
[0046] Powder-like cladding material or cladding preform may be
arranged between the partition wall and the core. If a powder-like
cladding material is used, a powder filling connection is arranged
in the sheet metal capsule, which connection leads into the space
between the partition wall and the core, and through which the
powder-like cladding material may be lead into the space defined by
the partition wall and the outer surface of the core. A mat-like
cladding preform may be arranged on the side of the partition wall,
which is towards the core, for example by gluing it to the
partition wall. A cladding preform in paste-form may, for its part,
be arranged on the side of the partition wall, which is toward the
core, for example by spraying, spreading or forming a layer on the
partition wall. After this the core is placed in the sheet metal
capsule, and the polymer-bonded mat or paste forming the cladding
layer exists between the outer surface of the core and the
partition wall delimiting the body material.
[0047] In another embodiment of the invention cladding preform is
arranged on the outer surface of the core as a mat or paste, before
the core is placed in the sheet metal capsule. A flexible mat-like
preform may be arranged on the outer surface of the core, i.e. on
the outer surface of the form layer of the core, by cutting the mat
first into pieces of a suitable size, which are then placed and
glued to the outer surface of the core. A polymer material may be
used as the glue, which polymer material is the same or a similar
polymer material as the bonding polymer of the cladding preform. A
paste-like cladding material may be arranged on the outer surface
of the core by spreading or coating. It is one advantage of this
embodiment that attaching the cladding material to the outer
surface of the core is relatively easy. The core may also be dipped
in a paste-like preform, whereby the preform forms a layer on its
surface, or a layer of the paste-like preform may be formed around
the core. The suitable way to arrange cladding material between the
partition wall and the core depends on the properties of the
cladding material, for example the viscosity of the preform, and
the geometry of the core and the partition wall in the sheet metal
capsule.
[0048] It is also possible that preform for cladding material is
arranged in connection with the outer surface of the core, for
example by gluing or spreading, whereby it is not necessary to
arrange a separate partition wall in the sheet metal capsule to
separate the cladding preform and the material of the body part of
the component to be manufactured. In this case the cladding preform
is thus arranged on the outer surface of the core, the core is
arranged in the sheet metal capsule without a partition wall, and
the metallic powder forming the body part of the component is
arranged between the cladding preform layer on the surface of the
core and the outer wall of the sheet metal capsule.
[0049] According to one embodiment of the invention at least most
of the bonding polymer included in the preform including cladding
material is evaporated from it by thermal degassing before the hot
isostatic pressing. The thermal degassing of the filled capsule may
be performed in a evaporation temperature characteristic for the
bonding polymer, which may be for example in the range
400-600.degree. C., before the conventional hot isostatic pressing,
where the temperature is raised for example to the range
1000-1200.degree. C. By first evaporating most of the bonding
polymer, it is possible to ensure that the gas formation caused by
the cladding material during the hot isostatic pressing may be
minimised.
[0050] The present invention may also be used to improve the
dimensional precision of the clad cavity or shape opening onto the
outer surface to be manufactured, which has previously been a
significant problem. A two-part core is preferably placed inside
the sheet metal capsule, which core comprises a core centre and a
form layer, whereby the clad form of the shape opening onto the
outer surface of the component to be manufactured is determined by
the outer surface of the core, i.e. the outer surface of the form
layer. It has now surprisingly been found that when the materials
of the core centre and the form layer are selected so that their
thermal expansion coefficients are the same or almost the same, the
dimensional precision of the shape opening onto the outer surface
of the component to be manufactured may be controlled even more
precisely.
[0051] It is also an advantage of the two-part core according to
the present invention that it can be used to easily and simply
manufacture components, which have opening shapes with a negative
clearance. Traditionally negative clearance can be manufactured
only in components, where the core is not reusable, i.e. the core
must be broken in order to remove it from the opening shape of the
manufactured component, which has a negative clearance. In one
embodiment of the invention a core centre having a positive
clearance, may be manufactured, and on top of it a form layer
having a negative clearance. Thus the core centre is reusable and
only the form layer used for manufacturing the negative clearance
is disposable and must be broken in order to remove the core from
the manufactured component.
[0052] In some embodiments the two-part core may be placed also
outside the sheet metal capsule. In that case the sheet metal
capsule comprises a first outer wall and a second inner wall,
between which the metallic powder to be compacted is arranged. The
shape of the inner wall determines the opening shape of the
component to be manufactured. The core is arranged in the space
defined by the inner wall of the sheet metal capsule, whereby it is
in contact with the inner wall and supports the inner wall and its
shape during the hot isostatic pressing. The sheet metal capsule
may also in this case have two or more parts, whereby it comprises
separate parts for the body material and the cladding material. In
that case separate powder filling connections for each part of the
sheet metal capsule are naturally arranged in the sheet metal
capsule, for filling metallic powders and for degassing the parts
of the capsule.
[0053] In one embodiment of the invention the core centre is
removed in one piece after the hot isostatic pressing, and a new
form layer made of a second material is arranged around the removed
core centre in order to manufacture a new core. After the hot
isostatic pressing the sheet metal capsule is thus opened and the
core centre is removed from the capsule. In the core centre may be
arranged a pulling member, such as a loop or hook, by means of
which the removal of the core centre from the sheet metal capsule
is made easier. The pulling member is thus arranged in the core
centre surface remaining visible, when the core is arranged in the
sheet metal capsule. Manufacture of the core so that it comprises a
core centre and a form layer speeds up the removal of the core from
the sheet metal capsule, makes possible its partial reuse and
increases its durability. All these advantages are important
factors, which affect manufacturing costs.
[0054] According to one embodiment of the invention the core centre
is manufactured from a material, the density of which is at least
95%, preferably at least 98%, of the theoretical density of said
material. This means that the core centre is manufactured from a
dense, non-porous material, which in practice is non-compactable
during the hot isostatic pressing. Non-compactable in this context
means that the change in the volume of the core centre during the
hot isostatic pressing it at the most 5%, preferably less than
5%.
[0055] According to one embodiment of the invention the core centre
is manufactured from an iron-based material, such as steel,
especially carbon steel, or from cast iron, or the core centre is
manufactured from a Ni-based high temperature material having a Ni
content, which is typically over 50 weight-%. The used carbon steel
typically comprises <0.2 weight-% carbon and <2 weight-%
other alloy components. According to one embodiment of the
invention the core centre may be manufactured also from a ceramic
material, such as an oxide material, for example aluminium oxide,
or a nitride material, for example titanium nitride or some other
corresponding ceramic material. The core centre and the form layer
may be of the same material with regards to their chemical
composition, however so that the mechanical or physical properties
of the core centre and form layer differ from each other. The core
centre and form layer may typically for example have different
densities. Mostly the core centre and the form layer differ from
each other also with regards to their chemical composition.
[0056] In one embodiment an anti-adhesion layer may be arranged on
the outer surface of the core centre, between the core centre and
the form layer, the properties of which anti-adhesion layer differ
from the core centre and form layer. The anti-adhesion layer makes
the separating of the core centre from the form layer easier after
the hot isostatic pressing. A layer comprising aluminium oxide or
boron nitride may for example advantageously function as the
anti-adhesion layer. The thickness of the anti-adhesion layer is
essentially smaller than the thickness of the form layer, for
example its thickness may be <1 mm.
[0057] According to one embodiment of the invention the form layer
is manufactured from another material having a thermal expansion
coefficient which preferably differs from the thermal expansion
coefficient of the first material of the core centre by at the most
15%, even more preferably at the most 10%, typically at the most
5%. According to one embodiment the form layer is manufactured from
another material having a thermal expansion coefficient which is
the same or almost the same as the thermal expansion coefficient of
the first material of the core centre.
[0058] According to another embodiment of the invention the thermal
expansion coefficient of the core centre may be at least about 15%,
preferably 20%, even more preferably 30% higher than the thermal
expansion coefficient of the body material of the component to be
manufactured and/or of the form layer of the core. Thus the core
centre shrinks during the cooling down and can easily be detached
after the hot isostatic pressing process.
[0059] According to one embodiment of the invention the form layer
is manufactured from a material, the density of which is 60-95%,
preferably 70-95%, more preferably 80-95%, of the theoretical
density of said material. The compressibility i.e. shrinkage of the
form layer is preferably 5-15% in the hot isostatic pressing. The
form layer is preferably manufactured from a material, which is
inert and thermally stable in hot isostatic pressing conditions,
where the temperature is typically at the most about 1200.degree.
C. and the pressure at the most about 100 MPa. Inert and thermally
stable in this context mean that the material does not form
compounds with the surroundings or the used metallic powders, and
no phase transitions occur in the material as the temperature
changes. When components are manufactured in hot isostatic pressing
process with the aid of a two-part core, the components comprising
opening shapes, which have corners, turns or bends, the bending
strength of the form layer is typically >75 MPa and/or the
compression strength is typically >140 MPa. When, on the other
hand, components are manufactured in a hot isostatic pressing
process with the aid of a two-part core, which components comprise
opening shapes, which are straight or almost straight, the form
layer may preferably be manufactured from a ceramic material, which
remains un-sintered during the hot isostatic pressing. Thus the
ceramic material forming the form layer is not compacted, and does
not form a solid piece in the hot isostatic pressing process,
whereby the removal of the form layer of the core from the opening
shape of the finished component is very easy. In such a case the
bending strength of the form layer is in practice about 0 MPa.
[0060] According to one embodiment of the invention the form layer
is manufactured from a ceramic material, such as oxide ceramics,
nitride ceramics, carbide ceramics, boride ceramics, beryllium
ceramics, or the form layer is manufactured from graphite. Examples
of suitable oxide ceramics are for example Al.sub.2O.sub.3,
SiO.sub.2, ZrO.sub.2 and CaO. The form layer may also be
manufactured from a mixture of two or more oxide ceramics. Examples
of suitable nitride ceramics are for example BN, AlN and
Si.sub.3N.sub.4, and hexagonal boron nitride (BN) can especially be
mentioned. The core centre is preferably manufactured from metal
and the form layer from ceramic.
[0061] A ceramic form layer may be manufactured by casting, whereby
the core centre is arranged in the cast mould and the form layer is
cast around it, however so that at least a part of the core centre
remains visible on some surface of the core. The form layer may be
arranged around the core centre also by coating, dipping or
pressing. The form layer of the core may be manufactured also by
using a finished component, which is meant to be manufactured, as a
cast mould.
[0062] In one embodiment an anti-adhesion cladding may be arranged
on the outer surface of the core, on top of the form layer. The
anti-adhesion cladding prevents or decreases the sticking of the
form layer to the surface of the component to be manufactured and
makes the detaching of the form layer easier after the hot
isostatic pressing. If the form layer can be detached from the
manufactured component in one piece, the core centre does not
necessarily need to be detached separately, but the two-part core
can be removed from the sheet metal capsule in one piece and
reused. It is especially preferable to arrange an anti-adhesion
cladding on the outer surface of the form layer if the form layer
is manufactured from graphite, whereby the anti-adhesion cladding
decreases or in practice prevents the diffusion of carbon from the
form layer to the cladding layer of the component to be
manufactured.
[0063] In one embodiment an open channel may be arranged through
the core centre, which channel, preferably in the direction of the
symmetry axis of the centre, extends from the first end of the core
centre to its second end in order to even out the pressure during
the hot isostatic pressing. Through the open channel the pressure
may enter also inside the core during the hot isostatic pressing,
whereby the channel does not change its shape during the hot
isostatic pressing. With the aid of the channel a lighter core may
be manufactured, and simultaneously achieve savings in the material
costs of the core.
[0064] After the removal of the core centre the main part of the
form layer may be crushed and removed as crushed aggregate from the
cavity or opening shape of the manufactured component. The form
layer may have been manufactured from a water-soluble material,
whereby it may be removed by dissolving, or it may have been
manufactured from a material, which is soluble in some other
solvent, such as alcohol, whereby it may be removed by dissolving
in the solvent in question. The separate removal of the core centre
and the destroying of the form layer for example by crushing or
dissolving is preferable especially in cases, where the shape
opening onto the outer surface of the component does not allow for
the core to be removed in one piece. Also in such cases, the core
centre may be utilised and reused with the aid of the invention,
which decreases the overall costs of the process.
[0065] In one embodiment the form layer may be manufactured from a
ceramic material, which shrinks during the hot isostatic pressing.
The form layer may be manufactured from a ceramic material, which
typically has a density of 65-95 volume-%, possibly 65-70 volume-%
or it may be manufactured from a partly porous material, which has
a density of 70-95%, possibly 80-95 volume-%. When the used ceramic
material and the particle size of the used ceramic powder is known,
the shrinkage of the ceramic form layer is also known. This known
shrinkage may be utilised for the control of the dimensions of the
opening shape of the component to be manufactured. The form layer
is preferably manufactured from an un-sintered ceramic material,
which has not been sintered before the hot isostatic pressing and
which is also not sintered during the hot isostatic pressing. Thus
the deformation of the form layer is a small as possible and the
control of the dimensional precision is good. A form layer
manufactured from an un-sintered ceramic material also promotes the
detaching of the ceramic from the finished component. According to
one embodiment of the invention the thickness of the form layer is
0.2-30 mm, typically 3-15 mm.
[0066] According to one embodiment the form layer of the core is
manufactured from a non-shrinking ready-sintered ceramic material,
whereby the deformation of the form layer is also as small as
possible.
[0067] The method according to the invention may generally be used
for manufacturing composite-structured components, for example for
manufacturing components, where corrosion and wear resistant
material should preferably be used on the surfaces of the cavities
or opening shapes of the components. The method according to the
invention is especially suitable for manufacturing valves, pump
casings or ductwork components for offshore applications by hot
isostatic pressing. The method is especially suitable for
manufacturing valves, pump casings or ductwork components for the
oil and gas industry.
DESCRIPTION OF THE DRAWINGS
[0068] In the following, the invention is described in more detail
with reference to the enclosed schematic drawings:
[0069] FIG. 1 shows an arrangement according to an embodiment of
the invention,
[0070] FIG. 2 shows an arrangement according to an embodiment of
the invention,
[0071] FIG. 3 shows an arrangement according to an embodiment of
the invention,
[0072] FIG. 4 shows an arrangement according to an embodiment of
the invention,
[0073] FIG. 5 shows an arrangement according to an embodiment of
the invention,
[0074] FIG. 6 shows an arrangement according to an embodiment of
the invention,
[0075] FIG. 7 shows an arrangement according to an embodiment of
the invention,
[0076] FIG. 8 shows an arrangement according to an embodiment of
the invention,
[0077] FIG. 9 shows an arrangement according to an embodiment of
the invention, and
[0078] FIG. 10 shows an arrangement according to an embodiment of
the invention.
[0079] FIG. 1 shows an arrangement according to one embodiment of
the invention for manufacturing a clad component with hot isostatic
pressing. FIG. 1 shows a sheet metal capsule 1, which is divided
with a partition wall 2 into a first powder space 3 and a second
powder space 3', which is also delimited by a second partition wall
2'. A first powder material, which will form the body part of the
component to be manufactured, is arranged into the first powder
space 3 through a first powder filling connection 4. A second
powder material, which will form a cladding layer on the surface of
the shape opening onto the outer surface of the component to be
manufactured is arranged into the second powder space 3' through a
second powder filling connection 4'. A core 20 is arranged inside
the sheet metal capsule 1, lid 10 of the sheet metal capsule 1 is
closed and the powder spaces 3, 3' are degassed using the powder
filling connections 4, 4'. After this hot isostatic pressing is
performed to compact the first and second powder material into its
final shape.
[0080] It is clear that it is not necessary to place a second
partition wall between the core and the cladding material, but the
cladding material may also be in direct contact with the form layer
of the core, i.e. the outer surface of the core.
[0081] In FIG. 1 the core 20 comprises a core centre 5 made of
metal, for example steel, and a non-metallic form layer 6 made for
example from aluminium oxide. It is possible to use the core centre
5 several times, whereas the form layer 6 may be broken in order to
remove it from the opening shape of the manufactured component.
With the aid of the form layer 6, the shape opening onto the outer
surface of the component to be manufactured is controlled. The core
20 placed inside the sheet metal capsule 1 supports the shape of
the component to be manufactured during the hot isostatic
pressing.
[0082] FIG. 2 shows an arrangement according to a second embodiment
of the invention for manufacturing a clad component with hot
isostatic pressing. FIG. 2 shows a sheet metal capsule 1, inside
which is arranged a core 20, which comprises a core centre 5 made
of metal, for example steel, and a non-metallic form layer 6 made
for example from aluminium oxide. Before the core 20 is placed
inside the sheet metal capsule 1, a layer 7 formed from a mat-like
cladding preform is glued onto its surface. This preform layer 7
will form a cladding layer on the surface of the shape opening onto
the outer surface of the component to be manufactured. The sheet
metal capsule has a powder space 3, into which is arranged a first
powder material through a first powder filling connection 4, which
powder material will form the body part of the component to be
manufactured. The first powder material is thus arranged between
the first wall 1' of the sheet metal capsule 1 and the mat-like
preform layer 7.
[0083] Before the hot isostatic pressing the lid 10 of the sheet
metal capsule 1 is closed and the powder space 3 is degassed using
the powder filling connection 4. At least most of the polymer
functioning as binder is evaporated from the mat-like cladding
preform 7 by using thermal degassing, after which hot isostatic
pressing is performed in order to compact the first powder material
and the cladding material layer into its final shape.
[0084] FIG. 3 shows an arrangement according to a third embodiment
of the invention for manufacturing a clad component with hot
isostatic pressing. FIG. 3 shows a sheet metal capsule 1, inside
which is arranged a core 20, which comprises a core centre 5 made
of metal, for example steel, and a non-metallic form layer 6 made
for example from aluminium oxide. The sheet metal capsule has a
powder space 3, into which is arranged a first powder material
through a first powder filling connection 4, which powder material
will form the body part of the component to be manufactured. Inside
the sheet metal capsule is also arranged a solid binder-free
cladding material layer 8, which is typically a nickel- or
cobalt-based material, for example a material having the nickel
content >50 weight-% or having the cobalt content >50
weight-%. The solid binder-free cladding material layer may be
manufactured for example from a plate-like metallic material by
bending and welding. The solid binder-free cladding material layer
8 comes into contact with the outer surface of the form layer 6 of
the core 20 and the first powder material is arranged between the
first wall 1' of the sheet metal capsule 1 and the solid
binder-free cladding material layer 8. The lid 10 of the sheet
metal capsule 1 is closed, the powder space 3 is degassed using the
powder filling connection 4, and hot isostatic pressing is
performed in order to compact the first powder material and the
solid binder-free cladding material layer into its final shape.
[0085] FIG. 4 shows an arrangement according to one embodiment for
manufacturing a component with hot isostatic pressing. FIG. 4 shows
a sheet metal capsule 1, which comprises a first wall 1' and a
second wall 1'', and a core 20, which comprises a core centre 5
made of metal, for example steel, and a non-metallic form layer 6
made for example from aluminium oxide. The core centre 5 is
intended to be used several times, and the form layer 6 is used to
control the inner shape of the component to be manufactured. The
core 20 is placed outside the sheet metal capsule 1, in a space
defined by the second wall 1'' of the sheet metal capsule 1. After
this the powder space 3 of the sheet metal capsule 1 is filled with
a first powder material through the powder filling connection 4,
the sheet metal capsule is closed and degassed, and hot isostatic
pressing is performed in order to compact the powder forming the
body part of the component to be manufactured into its final shape.
The core centre 5 is removed for example by pulling, after which it
is ready to be reused. After this the form layer 6 is removed. The
undamaged form layer can be reused, when necessary.
[0086] FIG. 5 shows an arrangement according to a second embodiment
for manufacturing a clad component with hot isostatic pressing.
FIG. 5 shows a sheet metal capsule 1, which comprises a first wall
1' and a second wall 1'', and a core 20, which comprises a core
centre 5 made of metal, for example steel, and a non-metallic form
layer 6 made for example from aluminium oxide. A solid binder-free
cladding material layer 8 is arranged inside the sheet metal
capsule 1, in connection with its second wall 1'', i.e. the solid
cladding material layer is arranged on the wall of the sheet metal
capsule 1, which comes into contact with the outer surface of the
core 20. The solid binder-free cladding material layer may
naturally also be formed on the wall 1'' of the sheet metal capsule
1. The solid binder-free cladding material layer to be arranged
inside the sheet metal capsule may typically be a nickel- or
cobalt-based material, for example a material, having the nickel
content >50 weight-% or having the cobalt content >50
weight-%. The core 20 is placed outside the sheet metal capsule 1,
in a space defined by the second wall 1'' of the sheet metal
capsule 1. After this the powder space 3 of the sheet metal capsule
1 is filled with a powder material through the filling connection
4, the sheet metal capsule 1 is closed and degassed, and hot
isostatic pressing is performed in order to compact the powder
forming the body part of the component to be manufactured into its
final shape.
[0087] FIG. 6 shows an arrangement according to a third embodiment
for manufacturing a clad component with hot isostatic pressing.
FIG. 6 shows a two-part sheet metal capsule 1, which comprises a
first wall 1', a second wall 1'', and between them a third wall 11,
which separates the first powder space 3 and the second powder
space 3' from each other. Both powder spaces 3, 3' are provided
with their own powder filling connection 4, 4'. The core 20, which
comprises a core centre 5 made of metal, for example steel, and a
non-metallic form layer 6 made for example from aluminium oxide, is
placed outside the sheet metal capsule 1, in a space defined by the
second wall 1'' of the sheet metal capsule. Two different metal
powder materials are thus arranged inside the sheet metal capsule
1, each on their own powder space 3, 3'. The first powder material
forms the body part of the component to be manufactured, and it may
preferably be a steel-based metal powder. The second powder
material forms the cladding on the surface of the opening shape of
the component to be manufactured. The sheet metal capsule is filled
with the first and second powder material through the powder
filling connections 4, 4', the sheet metal capsule 1 is closed and
degassed, and hot isostatic pressing is performed to compact the
powder materials into their final shape.
[0088] FIG. 7 shows an arrangement according to one embodiment for
manufacturing a clad component with hot isostatic pressing. FIG. 7
shows a sheet metal capsule 1, which comprises a first wall 1' and
a second wall 1''. A mat-like cladding preform layer 7 is arranged
inside the sheet metal capsule 1, in connection with its second
wall 1''. The arrangement also comprises a core 20, which comprises
a core centre 5 made of metal, for example steel, and a
non-metallic form layer 6 made for example from aluminium oxide.
The core 20 is placed outside the sheet metal capsule 1, in a space
defined by the second wall 1'' of the sheet metal capsule 1. The
mat-like polymer-bonded preform layer 7 is thus arranged on the
wall of the sheet metal capsule 1, which comes into contact with
the outer surface of the form layer 6 of the core 20. After this
the powder space 3 of the sheet metal capsule 1 is filled with a
first powder material through the powder filling connection 4,
closed and thermally degassed, and hot isostatic pressing is
performed in order to compact the first powder material forming the
body part of the component to be manufactured into its final
shape.
[0089] FIG. 8 shows an arrangement according to one embodiment for
manufacturing a clad component with hot isostatic pressing. The
embodiment of FIG. 8 otherwise corresponds to the embodiment shown
in FIG. 7, except that the core 20 differs from the one shown in
FIG. 7. The core 20 comprises a core centre 5 and a form layer 6,
which is arranged asymmetrically around the core centre 5. The
thickness of the form layer 6 around the core centre 5 is thus not
constant, but it may vary according to need. By varying the
thickness of the form layer asymmetric shapes may for example be
made in the component to be manufactured when needed, or the
shrinkage of the component to be manufactured may be controlled
during the hot isostatic pressing. Thus components with different
shapes may also be manufactured using the same core centre, by
using form layers with different shapes.
[0090] FIG. 9 shows an arrangement according to one embodiment for
manufacturing a clad component with hot isostatic pressing. FIG. 9
shows a sheet metal capsule 1, which comprises a first wall 1' and
a second wall 1''. A mat-like preform layer 7 is arranged inside
the sheet metal capsule 1, in connection with its second wall 1''.
The arrangement also comprises a core 20, which is manufactured
from one material, i.e. it is one-piece. The core 20 is placed
outside the sheet metal capsule 1, in a space defined by the second
wall 1'' of the sheet metal capsule 1. The mat-like polymer-bonded
preform layer 7 is thus arranged on the wall of the sheet metal
capsule 1, which comes into contact with the outer surface of the
core 20. After this the powder space 3 of the sheet metal capsule 1
is filled with a first powder material through the powder filling
connection 4, the sheet metal capsule 1 is closed and degassed, and
hot isostatic pressing is performed in order to compact the first
powder material forming the body part of the component to be
manufactured and the cladding preform layer 7 into its final
shape.
[0091] FIG. 10 shows an arrangement according to one embodiment for
manufacturing a clad component with hot isostatic pressing. FIG. 10
shows a sheet metal capsule 1, which comprises a first wall 1' and
a second wall 1''. A mat-like cladding preform layer 7 is arranged
inside the sheet metal capsule 1, in connection with its second
wall 1''. The mat-like polymer-bonded preform layer 7 is thus
arranged on the wall of the sheet metal capsule 1, which forms the
outer surface of the opening shape of the manufactured component.
The body part 30 of the component is formed from a solid cast
material. The sheet metal capsule 1 is closed and thermally
degassed in order to remove the bonding polymers through the
degassing connection 4, after which hot isostatic pressing is
performed to compact the preform layer 7 of the component to be
manufactured into its final shape.
[0092] The invention is not intended to be limited to the
above-presented exemplary embodiments, but the intention is to
apply the invention widely within the inventive idea defined by the
claims defined below.
* * * * *