U.S. patent application number 14/858243 was filed with the patent office on 2016-03-24 for method for the manufacture of an exhaust gas converter, tool for a ring press for the manufacture of an exhaust gas converter, ring press comprising a tool, and exhaust gas converter manufactured with a ring press.
The applicant listed for this patent is Eberspacher Exhaust Technology GmbH & Co. KG. Invention is credited to Daniel MANICKE, Herbert MARTIN, Karsten RUDOLPH.
Application Number | 20160084141 14/858243 |
Document ID | / |
Family ID | 54106209 |
Filed Date | 2016-03-24 |
United States Patent
Application |
20160084141 |
Kind Code |
A1 |
MARTIN; Herbert ; et
al. |
March 24, 2016 |
METHOD FOR THE MANUFACTURE OF AN EXHAUST GAS CONVERTER, TOOL FOR A
RING PRESS FOR THE MANUFACTURE OF AN EXHAUST GAS CONVERTER, RING
PRESS COMPRISING A TOOL, AND EXHAUST GAS CONVERTER MANUFACTURED
WITH A RING PRESS
Abstract
A method for manufacturing an exhaust gas converter and a tool
for the method are provided. The method includes providing a
cylindrical metal pipe and a cylindrical substrate surrounded in a
circumferential direction by a mat mount. The substrate is
deposited with the mat mount surrounding it inside the metal pipe.
A compression force is exerted on the metal pipe, directed in a
radial direction, for reducing the cross-section of the metal pipe
to a desired size. Regions to which a compression force is applied
alternate along the circumferential direction of the metal pipe
with regions to which no compression force is applied. A number of
regions where no compression force is applied to the metal pipe
exceeds the number of tools used for applying the compression
force. The tool (4), for a ring press, includes a tool body
including a mounting section and a work section with recesses
(45).
Inventors: |
MARTIN; Herbert; (Erkner,
DE) ; RUDOLPH; Karsten; (Dresden, DE) ;
MANICKE; Daniel; (Dresden, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eberspacher Exhaust Technology GmbH & Co. KG |
Neunkirchen |
|
DE |
|
|
Family ID: |
54106209 |
Appl. No.: |
14/858243 |
Filed: |
September 18, 2015 |
Current U.S.
Class: |
422/168 ; 29/890;
72/402; 72/469 |
Current CPC
Class: |
B21D 53/88 20130101;
F01N 13/1872 20130101; B21D 17/02 20130101; B21D 39/048 20130101;
F01N 3/2853 20130101; Y02T 10/20 20130101; F01N 2350/04 20130101;
F01N 3/0211 20130101; Y02T 10/12 20130101; F01N 13/18 20130101 |
International
Class: |
F01N 13/18 20060101
F01N013/18; B21D 39/04 20060101 B21D039/04; B21D 17/02 20060101
B21D017/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 19, 2014 |
DE |
10 2014 218 960.8 |
Claims
1. A method for the manufacture of an exhaust gas converter, the
method comprising the steps of: providing a cylindrical metal pipe;
providing a cylindrical substrate surrounded in a substrate
circumferential direction by a mat mount, the cross-section of the
substrate including the mat mount being smaller or equal to a
cross-section of the metal pipe; disposing the substrate with the
mat mount surrounding the substrate inside the metal pipe; and
exerting a compression force on the metal pipe with tools, the
compression force being directed in a radial direction of the metal
pipe for reducing the cross-section of the metal pipe to a desired
size, wherein regions to which a compression force is applied
alternate along a metal pipe circumferential direction with regions
to which no compression force is applied; and wherein a number of
the regions to which no compression force is applied exceeds a
number of the tools used for applying the compression force.
2. A method in accordance with claim 1, further comprising the
steps of heating of the metal pipe to a temperature of between
100.degree. C. and 300.degree. C. prior to exposing the metal pipe
to a compression force.
3. A tool for a ring press, the tool comprising a tool body with an
extension in an axial direction of the ring press, an extension in
a radial direction of the ring press, and an extension in a
circumferential direction of the ring press, the tool body
comprising: a mounting section configured for fixing the tool on
the ring press; and a work section wherein the mounting section and
the work section are formed on two opposite sides, with respect to
a radial direction of the ring press, the work section comprising a
tangential surface having a right cylinder lateral area shape and
being configured for exerting compression on an encasement of an
exhaust gas converter and a plurality of recesses, the recesses
having, along a radial direction, a maximum depth of at least 1/20
mm wherein the recesses are oriented in an axial direction of the
ring press and are spaced apart from one another in a
circumferential direction of the ring press wherein the mounting
section and the work section are formed on two opposite sides, with
respect to a radial direction of the ring press.
4. A tool in accordance with claim 3, wherein the recesses have,
along the radial direction, a maximum depth of not more than 20
mm.
5. A tool in accordance with claim 3, wherein: at least one recess
extends in the axial direction across a whole of the extension of
the work section; or all recesses extend in the axial direction
across the whole of the extension of the work section.
6. A tool in accordance with claim 3, wherein the recesses are
equidistantly spaced in pairs.
7. A tool in accordance with one of claim 3, wherein the recesses
each have an extension in a longitudinal direction and an extension
in a transverse direction, the extension in the longitudinal
direction and the extension in the transverse direction being
orthogonal with respect to each other and orthogonal with respect
to the extension in the radial direction; and the extension in the
longitudinal direction is at least 20 times as long as the
extension in the transverse direction, or the extension in the
longitudinal direction is at least 80 times as long as the
extension in the transverse direction.
8. A tool in accordance with claim 7, wherein the extension of the
recesses in the transverse direction does not exceed 10 mm.
9. A tool in accordance with claim 3, wherein the recesses each
have a cross-section, a form of which corresponds to a segment of a
circle or to a trapezoid.
10. A tool in accordance with claim 3, wherein the work section
comprises, in a circumferential direction of the tool, at least one
first section and one third section having recesses formed therein,
and one second section located between the first and the third
sections having no recesses formed therein; and the first, second,
and third sections each extend across at least 5% and not more than
50% of the work section in the circumferential direction of the
tool.
11. A tool in accordance with claim 3, wherein the recesses occupy
at least 3% of a surface of the work section.
12. A ring press comprising: a plurality of tools, each tool
comprising a tool body with an extension in an axial direction of
the ring press, an extension in a radial direction of the ring
press, and an extension in a circumferential direction of the ring
press, the tool body comprising: a mounting section configured for
fixing the tool on the ring press; and a work section wherein the
mounting section and the work section are formed on two opposite
sides, with respect to a radial direction of the ring press, the
work section comprising a tangential surface having a right
cylinder lateral area shape and being configured for exerting
compression on an encasement of an exhaust gas converter and a
plurality of recesses, the recesses having, along a radial
direction, a maximum depth of at least 1/20 mm wherein the recesses
are oriented in an axial direction of the ring press and are spaced
apart from one another in a circumferential direction of the ring
press wherein the mounting section and the work section are formed
on two opposite sides, with respect to a radial direction of the
ring press, wherein the plurality of tools are fixed in the ring
press by the mounting sections, wherein the ring press is
configured to move each tool of the plurality of tools in either of
two opposite directions of movement, the opposite directions of
movement following straight lines and the directions of movement of
all tools of the plurality of tools intersecting in one point,
whereby the ring press can take part in a method of manufacturing
an exhaust gas converter with a provided cylindrical metal pipe and
cylindrical substrate surrounded in a substrate circumferential
direction by a mat mount, the cross-section of the substrate
including the mat mount being smaller or equal to a cross-section
of the metal pipe with the substrate deposited with the mat mount
surrounding the substrate inside the metal pipe by exerting a
compression force on the metal pipe with tools, the compression
force being directed in a radial direction of the metal pipe for
reducing the cross-section of the metal pipe to a desired size,
wherein regions to which a compression force is applied alternate
along a metal pipe circumferential direction with regions to which
no compression force is applied; and wherein a number of the
regions to which no compression force is applied exceeds a number
of the tools used for applying the compression force.
13. The ring press in accordance with claim 12, wherein the tools
are fixed in the ring press along a circle; and an air gap is
provided between two tools, disposed adjacent thereto, along the
circle.
14. An exhaust gas converter comprising: a cylindrical encasement
made from sheet material; a cylindrical substrate disposed inside
the encasement; and a mat mount located between the substrate and
the encasement, wherein the encasement comprises at least three
protrusions, wherein the protrusions are oriented in an axial
direction of the encasement and are spaced apart from one another
in a circumferential direction of the encasement, and wherein the
protrusions have, in a radial direction of the encasement, a
maximum height of at least 1/20 mm.
15. An exhaust gas converter in accordance with claim 14, wherein
the protrusions in the radial direction of the encasement have a
maximum height of not more than 20 mm.
16. An exhaust gas converter in accordance with claim 14, wherein:
the at least one protrusion extends in the axial direction of the
encasement across the whole of the extension of the encasement; or
all protrusions extend in the axial direction of the encasement
across the whole of the extension of the encasement.
17. An exhaust gas converter in accordance with claim 14, wherein
the protrusions are equidistantly spaced in pairs.
18. An exhaust gas converter in accordance with claim 14, wherein:
the protrusions each have an extension in the longitudinal
direction and an extension in the transverse direction, the
extension in the longitudinal direction and the extension in the
transverse direction of the respective protrusion being orthogonal
with respect to each other and orthogonal with respect to the
extension in the direction of a height of the respective
protrusion; and the extension in the longitudinal direction is at
least 20 times as long as the extension in the transverse
direction.
19. An exhaust gas converter in accordance with claim 18, wherein
the extension of the protrusions in the transverse direction is not
more than 10 mm.
20. An exhaust gas converter in accordance with claim 14, wherein
the protrusions each have a cross-section, the shape of which
corresponds to a segment of a circle, a segment of an arc of a
circle, or a segment of a trapezoid.
21. An exhaust gas converter in accordance with claim 14, wherein
the protrusions occupy at least 5% of the surface of the encasement
and not more than 50% of the surface of the encasement.
22. An exhaust gas converter in accordance with claim 14, formed
with a ring press comprising: a plurality of tools, each tool
comprising a tool body with an extension in an axial direction of
the ring press, an extension in a radial direction of the ring
press, and an extension in a circumferential direction of the ring
press, the tool body comprising: a mounting section configured for
fixing the tool on the ring press; and a work section wherein the
mounting section and the work section are formed on two opposite
sides, with respect to a radial direction of the ring press, the
work section comprising a tangential surface having a right
cylinder lateral area shape and being configured for exerting
compression on an encasement of an exhaust gas converter and a
plurality of recesses, the recesses having, along a radial
direction, a maximum depth of at least 1/20 mm wherein the recesses
are oriented in an axial direction of the ring press and are spaced
apart from one another in a circumferential direction of the ring
press wherein the mounting section and the work section are formed
on two opposite sides, with respect to a radial direction of the
ring press, wherein the plurality of tools are fixed in the ring
press by the mounting sections, wherein the ring press is
configured to move each tool of the plurality of tools in either of
two opposite directions of movement, the opposite directions of
movement following straight lines and the directions of movement of
all tools of the plurality of tools intersecting in one point,
whereby the ring press manufactures the exhaust gas converter with
a provided cylindrical metal pipe and cylindrical substrate
surrounded in a substrate circumferential direction by a mat mount,
the cross-section of the substrate including the mat mount being
smaller or equal to a cross-section of the metal pipe with the
substrate deposited with the mat mount surrounding the substrate
inside the metal pipe by exerting a compression force on the metal
pipe with tools, the compression force being directed in a radial
direction of the metal pipe for reducing the cross-section of the
metal pipe to a desired size, wherein regions to which a
compression force is applied alternate along a metal pipe
circumferential direction with regions to which no compression
force is applied; and wherein a number of the regions to which no
compression force is applied exceeds a number of the tools used for
applying the compression force.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority under 35
U.S.C. .sctn.119 of German Patent Application 10 2014 218 960.8
filed Sep. 19, 2014, the entire contents of which are incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for the
manufacture of an exhaust gas converter and to an exhaust gas
converter that can be manufactured using a ring press. The present
invention further relates to a ring press and a special tool for
said ring press.
BACKGROUND OF THE INVENTION
[0003] A manufacture of exhaust gas converters often requires
disposing a substrate inside a metal jacket. The substrate may be,
for example, a metal support or a ceramic support. The substrate
may be a monolithic substrate, for example. Between the substrate
and the metal jacket a mat mount is often provided. The process of
disposing the substrate inside the metal jacket is also referred to
as "canning" The objective of canning is to safely dispose the
substrate inside the metal jacket, whereby any damage to the
substrate is to be avoided. Respective exhaust gas converters also
include catalytic converters.
[0004] Different canning procedures are known for this purpose:
[0005] In the push canning procedure, the substrate is pushed into
a metal pipe together with the mat mount surrounding the substrate.
A connection geometry is then fitted to both ends of the metal
pipe, which prevents the substrate and the mat mount from slipping
out of the metal pipe. A detriment of the procedure is the
comparatively large clearance required between an inner wall of the
metal pipe and an outer side of the mat mount surrounding the
substrate to allow the substrate to be placed inside the metal pipe
without damaging the mat mount. There is also a risk that the
clearance increases in response to the mat mount being compacted on
a later stage during operation.
[0006] In the wrap canning procedure, the substrate with the mat
mount surrounding the substrate is wrapped with a sheet metal
strip. The sheet metal strip's circumferential lines are joined
together in an airtight manner. A detriment of this procedure is
that it makes manufacture complex. Further, long seams remain whose
leak tightness has to be ensured.
[0007] In the shrink canning procedure, the substrate with the mat
mount surrounding the substrate is pushed into a pipe section with
the pipe section being gauged from outside afterwards. Thereafter,
a connection geometry is fitted to both ends of the metal pipe,
which prevents the substrate and the mat mount from slipping out of
the metal pipe again. A ring press configured for being used for a
manufacture of exhaust gas converters according to the shrink
canning procedure is known from WO 2011/011893 A1. As an
alternative to usage of a ring press it is known from U.S. Pat. No.
7,316,142 B2 to use a spin forming method and apparatus to form
different diameters and shapes on a workpiece such as a metal tube.
In a spin forming apparatus and method, various spin forming
rollers are actuated to extend and retract radially relative to a
workpiece therein. The workpiece is rotated around its axis while
the spin forming rollers apply pressurize the workpiece in radial
direction. The spin forming rollers may be shifted in axial
direction of the workpiece during pressurizing the workpiece. It is
typical for the spin-forming method and apparatus that the spin
forming rollers perform a rolling movement along the
circumferential surface of the workpiece.
[0008] In the half-shell canning procedure, the substrate with the
mat mount surrounding the substrate is placed between half-shells
made from metal sheet. The half-shells are then sealed in a press.
A detriment are the resulting relatively long seams whose leak
tightness has to be ensured.
[0009] The canning procedures described above are disadvantageous
in that they are either complex, are problematic with respect to
their reliability because of their long seams, or have too much
clearance between the metal jacket and the substrate surrounded by
the mat mount.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to provide a method
for the manufacture of an exhaust gas converter, a ring press
configured for carrying out the method, an appropriate tool for the
ring press, and an exhaust gas converter manufactured using the
ring press, the ring press enabling a manufacturing of the exhaust
gas converter at low cost. The clearance between the metal jacket
and the substrate of a thus manufactured exhaust gas converter
should further be small and by avoiding long seams a reliable
converter should be achieved.
[0011] Embodiments of a method for a manufacture of an exhaust gas
converter comprise the steps of providing a cylindrical metal pipe,
providing a cylindrical substrate surrounded in a circumferential
direction by a mat mount, with the cross-section of the substrate
including the mat mount being less or equal than the cross-section
of the metal pipe, of disposing the substrate with the mat mount
surrounding the substrate inside the metal pipe, and of applying a
compression force to the metal pipe, the compression force being
directed in a radial direction of the metal pipe for reducing the
cross-section of the metal pipe to a given size. In the step of
applying a compression force to the metal pipe, regions having the
compression force applied thereon alternate with regions having no
compression force applied thereon in at least one of the
circumferential direction and the axial direction. The number of
regions where no compression force is applied to the metal pipe
further exceeds the number of tools used for applying the
compression.
[0012] Since the cross-section of the metal pipe prior to
application of compression is bigger than the substrate including
the mat mount, the substrate with the mat mount surrounding the
substrate may easily be disposed inside the metal pipe. Due to the
reduced cross-section of the metal pipe after application of the
compression, the mat mount surrounding the substrate safely mounts
the substrate inside the metal pipe of the exhaust gas converter.
Also a compacting of the mat mount at a later time due to
temperature action may hereby be taken into account. The metal pipe
thus provides an enclosure wall (a metal jacket) of the exhaust gas
converter and protects the substrate from mechanical and chemical
impacts from outside. The application of compression enables a true
to dimension sizing of the metal pipe's cross-section. Since the
number of regions where no compression is applied to the metal
jacket exceeds the number of tools used for applying the
compression, at least one of the tools used for applying
compression has more than one region, where the tool abuts against
the metal pipe to be compressed. This results in a reduction of the
friction between the metal pipe and the tool, thus enabling a
sliding of the metal pipe relative to the tool during application
of compression resulting in a better distribution of the material
of the metal pipe displaced due of the compression.
[0013] According to an embodiment, the cylindrical metal pipe is
stationary when the tool abuts against the pipe to be compressed.
Thus, the cylindrical metal pipe is not rotated when being
pressurized. According to an embodiment, even the tool does not
rotate about the cylindrical metal pipe when applying pressure on
the cylindrical metal pipe.
[0014] According to an embodiment, the cylindrical metal pipe has a
circular cross-section. According to an alternative embodiment, the
cylindrical metal pipe has an oval cross-section.
[0015] The metal pipe may for instance be made of stainless steel.
The diameter of the metal pipe may for instance be from within 200
mm to 400 mm and the length of the metal pipe may be up to 400 mm.
The wall thickness of the metal pipe may for instance be from 0.3
mm to below 1 mm and/or within 1 mm to 3 mm. According to an
embodiment, the wall thickness of the metal pipe is constant along
the whole of the metal pipe's circumference and length.
[0016] The mat mount may for instance be a high-temperature
insulation wool (e.g. alkaline earth wool, aluminium silicate wool,
or polycrystalline wool comprising Al.sub.2O.sub.3 in a content of
more than 70% by weight), and provides a thermal insulation between
the substrate and the metal pipe. The mat mount may further provide
a certain damping effect and thus prevent damage to the regularly
brittle substrate caused by mechanical impacts.
[0017] The substrate may for instance be a metal support or a
ceramic support having a catalyst applied thereon and providing
fine channels for the exhaust gas to be purified.
[0018] According to an embodiment, the application of compression
reduces the cross-section of the metal pipe by at least 3% or at
least 5%, or at least 10% with regard to the diameter of the metal
pipe prior to applying compression.
[0019] According to an embodiment, the cross-section of the metal
pipe after application of compression is smaller than the
cross-section of the substrate including the mat mount prior to
application of compression. Hence, the mat mount is slightly
compressed by the metal pipe after application of compression to
the metal pipe.
[0020] According to an embodiment, the method comprises a capping
of the metal pipe's axial ends with funnels, the funnels being
welded, soldered or flanged to the metal pipe. Applying compression
allows the cross-section of the metal pipe to be formed into a
desired shape, enabling low tolerances for fitting the funnels to
the metal pipe. Low tolerances of less than 0.8 mm allow placing
steady welding seams between the metal pipe and the funnels.
[0021] According to an embodiment, the method further comprises a
heating of the metal pipe to a temperature of between 100.degree.
C. and 600.degree. C. prior to exposing the metal pipe to a
compression force. At this temperature, the metal pipe can be
formed very easily while having sufficient stability.
Alternatively, an application of compression force may also be
performed within a temperature range from 20.degree. C. to
100.degree. C.
[0022] Embodiments of a tool for a ring press comprise a tool body.
The tool body may be made from metal and in particular from
hardened tool steel. The tool body may be solid. The tool body
extends in an axial direction of the ring press, extends in a
radial direction of the ring press, and extends in a
circumferential direction of the ring press. The tool body
comprises a mounting section and a work section, the mounting
section and the work section being provided on two, with respect to
a radial direction of the ring press, opposite sides of the tool
body. The mounting section is configured for mounting the tool at
the ring press. The mounting section may hereto be provided with
appropriate protrusions, grooves or threads configured to engage in
grooves, protrusions or threads of the ring press. The work section
comprises a tangential surface resembling a lateral area of a right
cylinder. In other words, the work section is shaped like a gutter.
The curvature of the gutter, in a direction transverse to a
longitudinal extension of the gutter, may hereby be constant or
variable. The work section is configured to exert pressure onto a
jacket of the exhaust gas converter. The working section further
comprises a plurality of recesses, the maximum depth of the
recesses in radial direction being at least 1/20 mm or at least
1/10 mm or at least 1/5 mm. The recesses are ignored by the
tangential surface. Resulting from this, the tool comprises more
than one region where the tool's work section abuts against the
jacket of the exhaust gas converter.
[0023] In order to match the inner diameter of the tubular metal
jacket of an exhaust gas converter to the outer diameter of a
substrate received in the metal jacket, the metal jacket with the
substrate disposed inside the metal jacket and the mat mount
positioned between the substrate and the metal jacket is put in a
ring press that applies a radial pressure to it. Ring presses are
also referred to as radial presses or (when the material to be
processed is heated-up beforehand) as radial forging machines. For
this purpose, the ring press comprises several tools that can be
moved in a radial direction and allowing to exert pressure onto the
work piece (the jacket of the exhaust gas converter in this case).
Respective tools are also referred to as "shrinker jaws". Allowing
a radial movement of the tools requires provision of a gap between
each of the tools disposed adjacently in a circumferential
direction of the ring press. Due to the gap present between the
tools, exerting a compression pressure to the work piece may result
in material advancing between the tools. In the worst case this may
result in the work piece being ruptured and becoming unusable.
[0024] By providing, according to the invention, recesses in the
work section of the tool, the area abutting the jacket of an
exhaust gas converter to which compression is to be applied is
reduced. This results in a reduction of friction caused by adhesion
between the tool and the jacket of the exhaust gas converter. The
recesses ventilate the jacket of the exhaust gas converter. The
jacket may thus perform a sliding movement relative to the tool in
the circumferential direction of the jacket. This enables a
two-dimensional distribution of the pressurized material of the
exhaust gas converter's jacket as far as possible. A creasing of
the jacket concentrating on the circumferential line of the tool's
work section may thus be prevented. The recesses also provide
additional space for the material to be displaced in a controlled
manner.
[0025] According to an embodiment the whole area of each work
section of the tools is in contact with an outer surface of the
metal jacket when pressurizing the metal jacket; however, the
recesses of the tools are not in contact with an outer surface of
the metal jacket when pressurizing the metal jacket. According to
an embodiment the tools are not suitable to perform a rolling
movement along an outer surface of the metal jacket when
pressurizing the metal jacket.
[0026] According to an embodiment the term "a plurality of
recesses" includes the case in which one single recess or more than
one recess is provided in the working section of each tool.
According to an alternative embodiment the term "a plurality of
recesses" includes the case in which at least two recesses are
provided in the working section of each tool.
[0027] According to an embodiment, the shape of the work section
corresponds to a desired final form of the exhaust gas converter's
jacket. According to an embodiment, the curvature of the tangential
surface of the work section corresponds to the desired curvature of
the jacket of the exhaust gas converter.
[0028] According to an embodiment, the maximum depth of the
recesses in a radial direction is not more than 20 mm or not more
than 10 mm or not more than 5 mm or not more than 2 mm or not more
than 0.5 mm. More shallow depths of the recess guarantee that the
jacket of the pressurized exhaust gas converter nevertheless abuts
the working section of the tool two-dimensionally.
[0029] According to an embodiment, at least one recess extends
along the whole extension of the work section in an axial direction
or circumferential direction. In other words, the recess runs
through the entire extension of the work section.
[0030] According to an embodiment, all recesses extend in the axial
direction or in the circumferential direction across the whole
length of the work section.
[0031] According to an embodiment, the recesses do not
intersect.
[0032] According to an embodiment, the recesses are equally spaced
in pairs. Hence, the recesses are arranged regularly at least in
sections of the tool's work section.
[0033] According to an embodiment, the angular distance between
adjacent recesses is of from between 1.degree. and 5.degree., and
in particular 2.degree. relative to the center of the tangential
area of the work section forming the lateral side of the
corresponding cylinder.
[0034] According to an embodiment, the distance between adjacent
recesses is from between 10 mm and 2 mm or from between 6 mm and 4
mm.
[0035] According to an embodiment, each of the recesses extends
into the longitudinal direction and into the transverse direction,
with the extension in the longitudinal direction and the extension
in the transverse direction being orthogonal with respect to each
other and orthogonal with respect to the extension in the radial
direction, and with the extension in the longitudinal direction
being at least 20 times as long as the extension in the transverse
direction, or the extension in the longitudinal direction being at
least 80 times as long as the extension in the transverse
direction. Hence, the recesses have an elongated shape. According
to an embodiment, the extension of the recess in the longitudinal
direction defines the orientation of each recess.
[0036] According to an embodiment, an extension of the recesses in
the transverse direction does not exceed 10 mm, or does not exceed
5 mm, or does not exceed 3 mm. According to an embodiment, an
extension of the recesses in the transverse direction is at most 5
times or 3 times or 1 time the wall thickness of the jacket of the
exhaust gas converter to be pressurized. Hence, the recesses are
comparatively narrow.
[0037] According to an embodiment, each of the recesses has a
cross-section in the shape of a segment of a circle or in the shape
of a trapezoid.
[0038] According to an embodiment, the work section of the tool is
polished at least in those regions where no recesses are present.
Hence, the work section has a smooth surface.
[0039] According to an embodiment, the work section of the tool is
chamfered at its transitions to the recesses and/or its
circumferential line. Hence, the work section has no sharp
edges.
[0040] According to an embodiment, the work section of the tool
comprises in the circumferential direction at least one first and
one third section having the recesses provided therein, and a
second section located between the first and third sections having
no recesses provided therein. Each of the first, second and third
sections extend in the circumferential direction of the tool across
at least 5% and at most 50% of the work section. According to an
embodiment, the first and third sections are located adjacent to an
outer boundary of the tools's work section.
[0041] According to an embodiment, the recesses occupy at least 3%
or at least 30% of the work section's surface.
[0042] Embodiments of a ring press configured for implementing the
above method comprise a plurality of tools as described above. The
ring press hereby retains the plurality of tools at their
respective mounting sections. The ring press is further configured
to move each tool of the plurality of tools in either of two
opposite directions of movement, the opposite directions of
movement running along straight lines, and the directions of
movement of all tools of the plurality of tools intersect in one
point. Respective ring presses are also referred to as radial
presses, since the compressive force exerted on the body to be
pressurized along a circular strip is applied in radial
direction.
[0043] According to an embodiment, the tools are mounted in the
ring press in a circular arrangement, and an air gap is provided
between each two tools disposed adjacently along the circular
arrangement.
[0044] According to an embodiment, the tools are mounted in the
ring press in an oval arrangement, and an air gap is provided
between each two tools disposed adjacently along the oval
arrangement.
[0045] According to an embodiment the ring press is adapted to
prevent rotation of the pressurized body (such as the metal jacket)
during pressurizing the body.
[0046] Embodiments of an exhaust gas converter that may for
instance be obtained by the above method using, for example the
above ring press, comprise a cylindrical encasement made from sheet
material, a cylindrical substrate disposed inside the encasement,
and a mat mount located between the substrate and the encasement.
The encasement thereby corresponds to the metal pipe described
above. The encasement comprises a plurality of at least three
protrusions. In a radial direction of the encasement, the
protrusions have a maximum height of at least 1/20 mm or a maximum
height of at least 1/10 mm or a maximum height of at least 1/5
mm.
[0047] The protrusions receive a part of the material of the
originally smooth encasement of the exhaust gas converter, and thus
make sure that the diameter of the encasement is reduced with
respect to its original diameter. The protrusions also increase the
stability of the encasement and result in a self-centering of the
encasement, for instance upon connecting funnels to the end section
of the encasement.
[0048] According to an embodiment, the cylindrical encasement has a
circular cross-section. According to an alternative embodiment, the
cylindrical encasement has an oval cross-section.
[0049] According to an embodiment, the protrusions have, in a
radial direction of the encasement, a maximum height of not more
than 20 mm, or a maximum height of not more than 5 mm, or a maximum
height of not more than 2 mm, or a maximum height of not more than
0.5 mm. The residual height different can be spanned well by
welding seams, when the maximum height of the protrusions is less
than 0.8 mm.
[0050] According to an embodiment, the at least one protrusion
extends across the whole extent of the encasement in an axial
direction or in a circumferential direction of the encasement.
According to an embodiment, all protrusions extend across the whole
extent of the encasement in an axial direction or a circumferential
direction.
[0051] According to an embodiment, the protrusions are
equidistantly spaced in pairs.
[0052] According to an embodiment, the protrusions extend in the
longitudinal direction and in the transverse direction, the
extension in the longitudinal direction and the extension in the
transverse direction being for each protrusion orthogonal with
respect to each other and orthogonal with respect to the extension
in the direction of the height of each protrusion. The extension in
the longitudinal direction is also either at least 20 times as long
as the extension in the transverse direction, or the extension in
the longitudinal direction is at least 80 times as long as the
extension in the transverse direction.
[0053] According to an embodiment, the extension of the protrusions
in the transverse direction does not exceed 10 mm, or does not
exceed 5 mm, or does not exceed 3 mm.
[0054] According to an embodiment, the cross-section of each
protrusion has a shape like a segment of a circle, an arc of a
circle, or a trapezoid.
[0055] According to an embodiment, the encasement of the exhaust
gas converter comprises in the circumferential direction at least
one first and one third section having the protrusions formed
therein, and the encasement of the exhaust gas converter comprises
in the circumferential direction further a second section located
between the first and third sections and having no protrusions
formed therein. Along the circumferential direction of the
encasement, the first, second, and third sections thereby extend
across at least 5% and at most 50% of the encasement.
[0056] According to an embodiment, the protrusions occupy at least
3% or at least 30% of the encasement's surface.
[0057] Further features of the invention will be apparent from the
following description of exemplary embodiments together with the
claims and the Figures. In the Figures, like or similar elements
are indicated by like or similar reference signs. It is noted that
the invention is not limited to the embodiments of the exemplary
embodiments described, but is defined by the scope of the attached
claims. In particular, embodiments according to the invention may
implement individual features in a different number and combination
than the examples provided below. In the following explanation of
exemplary embodiments of the invention, reference is made to the
enclosed Figures. The various features of novelty which
characterize the invention are pointed out with particularity in
the claims annexed to and forming a part of this disclosure. For a
better understanding of the invention, its operating advantages and
specific objects attained by its uses, reference is made to the
accompanying drawings and descriptive matter in which preferred
embodiments of the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0058] In the drawings:
[0059] FIG. 1 is a schematic cross-sectional view through a ring
press according to an embodiment of the invention;
[0060] FIG. 2A is a schematic cross-sectional view through an
embodiment of a tool configured for being used in the ring press
from FIG. 1, with one edge of the tool shown in an enlarged
representation;
[0061] FIG. 2B is a top view of part of a work section of the tool
from FIG. 2A;
[0062] FIG. 3 is a flow diagram according to an embodiment of a
method for a manufacture of an exhaust gas converter;
[0063] FIG. 4A is a schematic cross-sectional view through an
embodiment of an exhaust gas converter; and
[0064] FIG. 4B is a top view of an encasement of the exhaust gas
converter from FIG. 4A.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0065] Referring to the drawings, FIG. 1 shows a schematic
cross-sectional view through a ring press 1 according to an
embodiment of the invention.
[0066] The ring press 1 comprises a machine body 2 made from cast
iron and supporting a plurality of hydraulic cylinders 3. The
hydraulic cylinders 3 respectively allow a shifting of tools 4
supported by the hydraulic cylinders 3 between two extreme
positions in a linear translation. The double arrows in FIG. 1
illustrate this. In the embodiment shown, eight hydraulic cylinders
3 are arranged along a ring such that the tools 4 supported by the
hydraulic cylinders 3 may be moved towards a common point or may be
moved away from this common point. Taking the arrangement of the
hydraulic cylinders 3 along the ring into account, each of the
tools moves along a radial direction of the ring press 1.
[0067] It is noted that the present invention is not limited to a
machine body made from cast iron or to cylinders activated
hydraulically. The cylinders may, for example, alternatively be
moved pneumatically or using a screw mechanism. Also the number
and/or arrangement of cylinders may vary.
[0068] Having hydraulic cylinders 3 support the tools 4 allows the
ring press 1 to apply a force to a work piece (the encasement of an
exhaust gas converter 6) located in the center of the ring press 1.
The hydraulic cylinders 3 are thereby coupled electrically or
mechanically such that either all tools 4 move towards the work
piece or all tools 4 move away from the work piece, and each of the
hydraulic cylinders 3 exerts the same force on the work piece. To
prevent the tools 4 moved by the hydraulic cylinders 3 from
blocking each other, an air gap 5 of sufficient size is provided
between tools 4 disposed adjacently in the circumferential
direction of the ring press 1. The air gap 5 is sized to be
substantially closed for the tools having reached their radial
inboard target position. In the target position of the tools 4, for
example, the distance between two tools 4 and thus the air gap 5
may in the circumferential direction of the radial press 1 be
smaller than 1 mm.
[0069] Referencing FIGS. 2A and 2B, the tools 4 mounted on the
hydraulic cylinders 3 of ring press 1 are explained in more detail
below. FIG. 2A thereby shows a schematic cross-sectional view and
FIG. 2B a schematic top view of a section of a tool 4 of the
plurality of tools 4.
[0070] Tool 4 comprises a solid tool body 41 made from hardened
tool steel. On one side, the tool body 41 has a work section 42 and
on an opposite side a mounting section 43. As shown in the enlarged
view of the edge surrounding the work section 42, this edge of the
tool has a radius R1. Along the longitudinal sides of the tool, the
radius R1 (shown on the right side of FIG. 2A in an enlarged view)
is less than 0.5 mm (in the embodiment of FIG. 2A, the radius along
the longitudinal sides is 0.3 mm), and along the transverse sides
(i.e. orthogonally to the edge shown in an enlarged view in FIG.
2A; on of theses edges is shown on the top of FIG. 2B) between 1 mm
and 3 mm (In the embodiment of FIG. 3A, the radius along the
broadsides is 2 mm). The longitudinal sides of tools disposed
adjacently in the ring press 1 are positioned in parallel and
adjacently in pairs.
[0071] On the mounting section 43, an elongate mount 43a made from
unhardened tool steel and having a trapezoidal cross-section is
fixed, configured for being inserted into a correspondingly shaped
recess on a hydraulic cylinder 3 of the ring press 1 so that the
tool 4 is fixed to the corresponding hydraulic cylinder 3 of the
ring press 1 in a torque-proof manner.
[0072] The complete work section 42 of the tool body 41 is curved
with its form generally resembling a shallow gutter. In the
following, the tangential surface 44 corresponding to the work
section 42 matches a section of a right cylinder's lateral area.
For a better overall view, the tangential surface 44 is delineated
from the work section 42 in FIG. 2A by a small distance. In fact,
the tangential surface 44 clings to the work section 42 with the
distance between the tangential surface 44 and the work section 42
being zero.
[0073] As can well be seen from an overall view of both FIGS. 2A
and 2B, parallel recesses 45 are introduced along a longitudinal
extension of the work section 42 each having a width B of 3 mm and
a depth of 0.5 mm. The angular distance between adjacent recesses
45 in the embodiment shown is, with respect to the center of the
cylinder defined by the tangential surface 44 2.degree.. The
absolute distance between respective adjacent recesses 45 is 3
mm.
[0074] Although FIG. 2B does not show the tool body 41 of tool 4 in
its entire longitudinal extension, some of the recesses 45 extend
in the longitudinal direction of the work section 42 and thus, in
the axial direction of the ring press, along the entire length of
the tool body 41. Other recesses 45 do not extend along the entire
length of work section 42, the recesses 45 thus having different
lengths. Alternatively, all recesses may have the same lengths. The
recesses may, for example, extend up to the beginning of radius R1
formed at an edge of work section 42.
[0075] As can be seen from FIG. 2B, the recesses 45 are not
distributed evenly over work section 42 of tool body 41 of tool 4.
In the embodiment shown instead, two regions S1, S3 having recesses
are provided at each of work section's 42 end sections defining the
extension of work section 42 in the circumferential direction of
ring press 1, when the tool 4 is inserted in the ring press 1, and
between the two regions a region S2 having no recesses is provided.
In the embodiment shown, the regions S1 and S3 each extend across
25% of the work section's 42 surface, and region S2 across 50% of
the work section's 42 surface. In the embodiment shown, the
recesses 45 occupy in total about 25% of the work section's 42
area.
[0076] As can be seen from FIG. 2A, recesses 45 each have a
cross-section corresponding to a segment of a circle. The
transitions from the recesses 45 to the work section are thereby
chamfered.
[0077] By providing recesses 45, the work section 42 of tool 4 has
more than one location where the work section 42 abuts the work
piece to be pressurized. This results in a reduction of the
friction between the work piece and the tool 4, allowing the work
piece to slide relative to tool 4 upon compression and thus a
better distribution of the work piece's material displaced due to
the compression. According to this it is possible to prevent an
undesired piling up of material inside the air gap 5 between two
tools 4 disposed adjacently along the circumferential direction of
ring press 1 that would damage the work piece processed.
[0078] A method for the manufacture of an exhaust gas converter
using the ring press 1 shown in FIG. 1 with tools 4 from FIGS. 2A
and 2B is explained below referencing FIG. 3.
[0079] First, a cylindrical metal pipe and a cylindrical substrate
surrounded by a mat mount are provided in steps S1 and S2. The
substrate surrounded by the mat mount thereby has a smaller
cross-section than the inside cross-section of the cylindrical
metal pipe. The shape of the cross-section of the substrate
surrounded by the mat mount corresponds to the inside cross-section
of the metal pipe.
[0080] Next, the substrate with the mat mount surrounding it is
placed inside the metal pipe in step S3. This is achieved by
pushing the substrate with the mat mount into the metal pipe.
[0081] Then, the metal pipe is heated in step S4 to a temperature
of between 100.degree. C. and 300.degree. C., prior to applying
compression force on the metal pipe in step S5. The latter is
achieved by moving the tools 4 radially towards the metal pipe 1
disposed in the interior of ring press 1, using the hydraulic
cylinders 3 of ring press 1.
[0082] Afterwards, the hydraulic cylinders 3 are retracted into
their starting position, and the metal pipe with the substrate and
the mat mount placed therein is removed before the axial ends of
the metal pipe are capped with funnels in final step S6. This may
for instance be accomplished by putting on the funnels and welding
the remaining seam.
[0083] An exhaust gas converter which may be obtained using the
ring press shown in FIG. 1 and the method illustrated in FIG. 3
will be described below referencing FIGS. 4A and 4B.
[0084] The exhaust gas converter 6 comprises an encasement 61,
having the form of a right cylinder and being made from sheet
material, in the present case from stainless steel having a wall
thickness of 1.5 mm. The diameter of the encasement is 300 mm, the
length 400 mm. A cylindrical ceramic substrate 63 having a diameter
of 290 mm and a length of 380 mm is located inside the encasement
61. A mat mount 62 made from aluminum silicate is placed between
the substrate 63 and the encasement 61. The encasement 61 thereby
slightly pressurizes the mat mount with regard to the substrate
63.
[0085] In the embodiment shown, the encasement 61 has at its outer
face twelve protrusions 64 being 0.5 mm in height. The low number
of protrusions 64 shown in FIGS. 3A and 3B has been chosen for a
clear presentation only. Since each of the tools 4 inserted into
the ring press 1 from FIG. 1 has, according to FIGS. 2A and 2B,
eight recesses, and since eight tools 4 are inserted into the ring
press 1, the actual number of protrusions would be at least 64. To
this further 8 protrusions may be added that are located in the
regions of the ring gaps 5 between tools 4 disposed adjacently
along the circumferential direction of the ring press 1.
[0086] As can be seen well from the top view in FIG. 3B, the
protrusions 64 extend along a straight line with adjacent
protrusions being spaced equidistantly. Some protrusions 64 extend
across the entire longitudinal extension of the encasement 61,
other protrusions 64 do not extend across the entire longitudinal
extension of the encasement 61, resulting in the protrusions 64
having different lengths. Alternatively, it is, however, also
possible to have all protrusions 64 have the same length.
[0087] Corresponding to the shapes of recesses 45 in the work
section 42 of tools 4, each of the protrusions 64 has a
cross-section corresponding to a segment of a circle.
[0088] Using ring press 1 shown in FIG. 1 together with the tools
shown in FIGS. 2A and 2B, the protrusions would occupy 25% of the
surface of the encasement 61 of the exhaust gas converter 6. This
is not shown in FIGS. 3A and 3B.
[0089] The protrusions 64 facilitate a centering when connecting a
(not shown) metal funnel to the axial ends of encasement 61. Due to
the small height of protrusions 64, a remaining gap may easily be
welded and closed. Furthermore, material displaced upon compression
of encasement 61 can be received in the protrusions 64.
[0090] Also on the surface of the encasement 61 of the exhaust gas
converter 6 regions A1, A3 having protrusions 64 formed therein
alternate in the circumferential direction of encasement 61 with
regions A2 having not protrusions formed therein.
[0091] Although in the above embodiments, the recesses in the work
section of the tool are oriented parallel to an axial direction of
the tool inserted into the ring press, the present invention is not
limited thereto. The recesses may rather also be oriented at an
angle to the axial direction, and even be orthogonal to the axial
direction.
[0092] Although in the above embodiments, the protrusions on the
encasement of the exhaust gas converter are oriented parallel to an
axial direction of the encasement, the present invention is not
limited thereto. The protrusions may also be oriented at an angle
to the axial direction, and even be orthogonal to the axial
direction.
[0093] Although in the above embodiments, the recesses in the work
section of the tool and the corresponding protrusions on the
encasement of the exhaust gas converter extend rectilinear, the
present invention is not limited thereto. The recesses and
protrusions may instead also be curvilinear. Further, there is no
need for the recesses and protrusions to run across the entire
extension of the work section of the tool and the encasement,
respectively. There is even no need to have the recesses and
protrusions formed elongate. The recesses and protrusions may
alternatively be circular when shown in a top view.
[0094] Although the above embodiments of the present invention have
been explained by way of example only, those skilled in the art
will recognize that numerous modifications, additions, and
replacements may be made without departing from the scope and
spirit of the invention disclosed in the claims below. While
specific embodiments of the invention have been shown and described
in detail to illustrate the application of the principles of the
invention, it will be understood that the invention may be embodied
otherwise without departing from such principles.
* * * * *