U.S. patent application number 12/215749 was filed with the patent office on 2009-01-15 for exhaust apparatus and method.
Invention is credited to James R. Cannaley.
Application Number | 20090014082 12/215749 |
Document ID | / |
Family ID | 40252120 |
Filed Date | 2009-01-15 |
United States Patent
Application |
20090014082 |
Kind Code |
A1 |
Cannaley; James R. |
January 15, 2009 |
Exhaust apparatus and method
Abstract
A rotary swaging method for the tapering of metal tubes is
disclosed. The method comprises the use of a rotary swaging machine
comprising a die comprising a die taper comprising a length of
greater than about 12 inches, a diameter reduction of greater than
about 30%, and/or a taper angle of less than about 12 degrees.
Inventors: |
Cannaley; James R.;
(Holland, OH) |
Correspondence
Address: |
SHUMAKER LOOP & KENDRICK
101 E. KENNEDY, SUITE 2800
TAMPA
FL
33672-0609
US
|
Family ID: |
40252120 |
Appl. No.: |
12/215749 |
Filed: |
June 30, 2008 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60947116 |
Jun 29, 2007 |
|
|
|
Current U.S.
Class: |
138/177 ;
138/DIG.11; 428/586; 72/352; 72/370.13; 72/370.25 |
Current CPC
Class: |
B21D 41/04 20130101;
B21J 13/02 20130101; Y10T 428/12292 20150115; B21J 7/16
20130101 |
Class at
Publication: |
138/177 ;
72/370.13; 72/370.25; 72/352; 428/586; 138/DIG.011 |
International
Class: |
B21C 37/16 20060101
B21C037/16; B21K 21/08 20060101 B21K021/08; B21D 37/00 20060101
B21D037/00 |
Claims
1) A method for imparting a taper of length greater than 12 inches
to a tubular metal work piece, said method comprising the steps of:
a) providing a tubular metal work piece; b) providing a rotary
swaging machine comprising a die comprising: a die taper of length
greater than 12 inches; a die taper having a reduction in diameter
of greater than about 30%; or a die taper having a taper angle of
greater than about 12 degrees; c) rotary swaging an endlength of
said tubular metal work piece, with said rotary swaging machine,
through said die, thereby imparting a taper to the work piece;
wherein the taper imparted to the work piece in a single pass has a
length bounded by a first diameter and a second diameter; wherein
the second diameter is less than the first diameter; and wherein
the taper is free of flaking and cracks.
2) A method as in claim 1 wherein the die has the following
specifications: a) a first diameter in the range of from about 2.5
to about 6.0 inches; b) a smallest diameter in the range of from
about 0.5 to about 2.5 inches; and c) a taper length of greater
than about 12 inches.
3) A method as in claim 1 wherein the tubular metal work piece
provided in a) has a diameter less than or equal to the first
diameter.
4) A method as in claim 3 wherein upon completion of step c), the
tubular metal work piece has a smallest diameter equal to the
diameter of the narrow bore diameter.
5) A method as in claim 1 wherein the die comprises 2, 3 or 4 die
elements.
6) A method as in claim 1 wherein in step c), the work piece is fed
into the rotary swaging machine at a rate in the range of from
0.062 to 0.500 inches per second.
7) A method as in claim 1 wherein the workpiece rotates at a speed
of 40-60 rpm.
8) A method as in claim 1 wherein the die comprises a die taper of
length greater than 12 inches and a die taper having a reduction in
diameter of greater than about 30%.
9) A method as in claim 1 wherein the die comprises a die taper of
length greater than 12 inches and a die taper having a taper angle
of greater than about 12 degrees.
10) A method as in claim 1 wherein the die comprises a die taper
having a reduction in diameter of greater than about 30% and a die
taper having a taper angle of greater than about 12 degrees.
11) A tubular metal work piece tapered by the method of claim 1,
and additionally comprising a length of constant diameter tubing
extending from the small diameter end.
12) A tubular metal work piece as in claim 11 wherein the taper
profile comprises at least one convex region.
13) A tubular metal work piece as in claim 11 wherein the taper
profile comprises at least one concave region.
14) A die element having the following specifications: a die taper
of length greater than 12 inches; a die taper having a reduction in
diameter of greater than about 30%; or a die taper having a taper
angle of greater than about 12 degrees.
15) A die element as in claim 14 wherein the die comprises a die
taper of length greater than 12 inches and a die taper having a
reduction in diameter of greater than about 30%.
16) A die element as in claim 14 wherein the die comprises a die
taper of length greater than 12 inches and a die taper having a
taper angle of greater than about 12 degrees.
17) A element die as in claim 14 wherein the die comprises a die
taper having a reduction in diameter of greater than about 30% and
a die taper having a taper angle of greater than about 12
degrees.
18) A die as in claim 14 wherein the taper profile is linear.
19) A die as in claim 14 wherein the taper profile comprises at
least one convex region.
20) A die as in claim 14 wherein the taper profile comprises at
least one concave region.
Description
[0001] This claims priority to U.S. Provisional Application No.
60/947,116, filed on Jun. 29, 2007 and titled "EXHAUST APPARATUS
AND METHOD" and it is herein incorporated by reference.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention pertains to the field of metal working
and the processing of tubular metal work pieces into long tapers.
More specifically, the present disclosure relates to exhaust
systems and methods of manufacturing exhaust systems.
[0004] 2. Background Information
[0005] Tapered tubular metal pieces, and tapered exhausts in
particular, are conventionally made using either a rolling or
forming process. In forming tapered metal tubes by the rolling
process, sections are cut from flat sheet stock. The sections are
then rolled into a desired taper, which is then closed with a seam
weld running parallel to the long axis of the taper. The weld is a
point of weakness in the tapered piece in that its raised surface
makes it susceptible to mechanical damage. Furthermore, the weld is
cosmetically undesirable in that it interrupts the contour of the
tapered piece. Prior to further processing, such as plating or
finishing, the raised portion of the weld must generally be ground
flush with the surface of the piece. However, the reduction of the
weld in order to improve the profile of the piece weakens the weld,
and thus the rolling method is limited by this disadvantage. The
process is illustrated in FIGS. 1 and 2.
[0006] In forming tapered metal tubes by the forming process, a
precut tube is machined by press operations such as drawing or
forging until the tube is tapered to the desired diameter
reduction. Cracking, flaking and structural flaws are experienced
at a high rate with these brute force methods, particularly at
taper angles in excess of about 10 degrees. With regard to the
forming process, profile design variations and taper length are
significantly limited due to inherent stamping process parameters,
as illustrated in FIG. 5.
[0007] Both methods above have additional shortcomings in that they
do not include within their scopes the preparation of modified
tapers, in particular, those having untapered tubular extensions of
either end, and in particular, at the small-diameter end. If such
extensions are desired, it is necessary to follow the rolling and
forming processes described above with the connection of a flange
to the small diameter end of the taper by an orbital weld around
the diameter of a precut piece of tubing. One example of such a
connection is the connection of a motor cycle muffler to other
engine exhaust piping.
[0008] Existing exhausts and methods of manufacturing such exhausts
suffer from a number of drawbacks: In most cases all welds must be
ground flush or otherwise controlled for desired cosmetics prior to
further processing such as chrome plating. This additional weld
preparation prior to chrome plating risks breakage at the weld
site.
[0009] Tapered tubular metal work pieces are difficult to prepare
by rotary swaging because the process gives, in many instances, a
worked product having negative structural and cosmetic
characteristics such as flaking and cracking. Such characteristics
give a product which is unusable. The intended function of the
pieces is to absorb acoustic energy from hot exhaust. The muffler
can be heated to high temperatures before cooling to ambient
temperature when engine operation ceases. Such heating and cooling
cycles tend to exacerbate the negative characteristics imparted to
the piece by present methods of metal tapering. Flaked sections
soon separate from the piece, leaving it vulnerable to longitudinal
cracks and splits parallel to the long axis of the piece.
[0010] Furthermore, present methods of tapering metal work pieces
render the pieces difficult to process further into desirable
usable forms. For instance in making a muffler or an exhaust,
present methods of forming the taper do not permit the formation,
during tapering, of an untapered section at the reduced bore end of
the taper. As such a structure is desirable in order to direct
outgoing exhaust after it has passed through the muffler, methods
in common use require that an untapered piece having the small end
diameter of the taper be welded onto the tapered section in an
end-to-end fashion. The additional weld, as with the seam weld
discussed above, may require further processing in order to meet
cosmetic objectives.
[0011] A method is disclosed for the rotary swaging of tapers
having a taper angle of greater than about 10 degrees. Further
disclosed is a method for the machining of such tapers from a
single tubular work piece such that the taper has a length of
constant diameter tubing extending from the small diameter end of
the taper. Further disclosed is a machined taper produced by the
method, having, optionally, a length of constant diameter tubing
extending from the small diameter end of the taper. Further
disclosed is method which can be used to machine, in one pass, a
substantially flake-free and crack-free taper having a taper angle
of greater than about 10 degrees, a diameter reduction of greater
than about 20%, and a length of greater than about 12 inches; and a
taper prepared by the method. Further disclosed is a method which
can be used to machine a tubular work piece, in one pass, from one
length of tubing, into the foregoing taper, and additionally
comprising a length of constant diameter tubing extending from the
small diameter end of the taper.
Rotary Swaging
[0012] Rotary swaging is generally performed with a rotary swaging
apparatus. Such an apparatus generally comprises a circular outer
race, a number of cylindrical rollers in contact with the outer
race, and a number of die elements. The die elements are arranged
about the work piece such that by radially closing and releasing
about the work piece, they shape the work piece by forcibly
deforming it into a tapered tubular section having a profile which
is ideally the profile of the die elements. The preferred method is
known as "infeed swaging," in which the work piece is slowly
advanced into the rhythmically opening and closing die assembly.
The profile of the die is tapered, and thus, as the work piece is
advanced into the die, the diameter of the tubular section at any
point on the work piece which has entered the die is being
continually decreased. In some cases, it is desirable to fabricate
a tapered piece having a section of small diameter tubing extending
from the small diameter end of the taper. This is accomplished by
feeding the work piece into the machine until it exits from the
small diameter end of the tapered die. The extruded section is no
longer in contact with the die, and will undergo no further
reduction in diameter.
[0013] The die elements are constrained in their motion by wedge
pieces which fit between the die elements. The wedge elements
prevent the die elements from moving circumferentially with respect
to each other, but allow the elements to move radially with respect
to each other. The die elements and the wedge elements together
form a generally cylindrical assembly called the die assembly. The
die assembly lies within a circular outer race. Between the inner
surface of the outer race and the outer cylindrical surface of the
die assembly lie evenly spaced cylindrical rollers. The rollers
permit the die assembly to turn inside a stationary outer race, or
the outer race to turn outside a stationary die assembly.
[0014] The radial motion of the die elements is caused by the
rollers, and occurs when the die assembly moves with respect to the
outer race. When the die elements are at their most "open" position
(i.e., they have pulled back from the work piece, and the work
piece can be further advanced into the die assembly, if desired)
the outermost surface of the die element extends above the outer
surface of the die assembly. When the die assembly moves with
respect to the outer race, the rollers regularly contact the die
elements and thrust them radially inward in simultaneous fashion as
they roll between the die assembly and the outer race. With each
inward thrust, the die elements come together around the work
piece, forcing the diameter of the work piece to be reduced along
the area where it is in contact with the die elements. No
"spillage" around the edges of the die elements occurs because the
die assembly is generally rotated with respect to the work
piece.
[0015] In general, the outer race and the die assembly rotate with
respect to each other. However, variations on the basic method
allow for the outer race to be rotated with the die assembly held
static (the work piece is then rotated as well); the die assembly
rotated with the outer race held static; or both allowed to rotate
to some degree.
[0016] It has heretofore been thought that the method of rotary
swaging could not be used for tapering operations involving large
reductions in diameter, steep taper angles, or long tapers. For
example, it is known that present methods of rotary swaging are not
suitable for reductions in diameter of greater than about 30% in a
single pass in that they give products with structural and cosmetic
problems such as a flaking or cracking. Furthermore, present
methods are substantially limited in that the angle of taper
between the large and small diameters should not exceed 10-12
degrees. With current methods, the above problems are exacerbated
if long tapers, such as greater than 12 inches, are desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a side view of a muffler shell manufactured by
rolling and welding three separate components according to the
prior art;
[0018] FIG. 2 is a side view of a muffler shell manufactured by
rolling and welding three separate components according to the
prior art;
[0019] FIG. 3 is a side view of a press formed muffler shell
according to the prior art;
[0020] FIG. 4 is a side view of a swaged muffler shell manufactured
according to one aspect of the present invention; and
[0021] FIG. 5 is a side view of a swaged muffler shell manufactured
according to one aspect of the present invention.
[0022] FIG. 6 is the schematic for a die capable of machining a
taper having a length greater than 20 inches.
[0023] FIG. 7 is the schematic for a die capable of machining a
taper having both convex and concave sections
[0024] FIG. 8 is the schematic for a die capable of machining a
short taper having a taper angle of greater than 12 degrees.
DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERRED
EMBODIMENTS
[0025] In general, the tubular metal work piece can be of a wide
variety of dimensions and comprised of a wide variety of materials.
With respect to materials which can be used, carbon steel tubing,
stainless steel tubing and aluminum tubing can be used, as well as
other materials having appropriate malleability and ductility
characteristics. The gauge of the tubing is preferably in the range
of from about 20 gauge (035) to 11 gauge (125).
[0026] While medium diameter tubing may be machined according to
the method more easily than tubing having very large or very small
diameters, in general, the method can be used to machine tubular
work pieces of any diameter, but preferably having a diameter of
about 6 inches or less, and in preferred embodiments, a diameter in
the range of from about 6 inches to about 0.5 inches. Most
preferred are embodiments in which the diameter is in the range of
from about 6 inches to about 2 inches.
[0027] The die can be made of a wide variety of materials, subject
to wear considerations. Generally, D2 High strength steel is
preferred, but other materials having suitable wearing parameters
can be used as well. For example, shock steel, such as 50 to 100,
can be used. Other materials having appropriate hardness and wear
characteristics include other types of steel such as carbon
steel.
[0028] The "taper angle" is the angle between the largest diameter
and the smallest diameter of the taper. Thus, looking at a die or a
tapered work piece in profile, the taper angle is the acute angle
between the taper profile line and the axis of the work piece.
Because the swaging die essentially imparts its own angle to the
tubular work piece, in order to swage a taper having given
characteristics such as taper angle, diameter reduction, and taper
length, it is necessary to use a die having the properties. As
described above, and known in the art, the taper dies, when closed
together about a work piece, define a tapered tube. Thus, when
referring to a tube having a given taper, the die by which it was
formed must possess the same taper profile. As the work piece is
advanced into the die, the diameter profile of the tube is reduced
to conform to the diameter profile of the die. Once the work piece
has been advanced to such a degree that the end inserted initially
reaches the small diameter end of the die, its diameter no longer
changes upon further insertion of the work piece, and a length of
tubing having the smaller diameter is formed at the small diameter
end of the taper. The length of the small diameter tubing increases
as the work piece is fed into the die assembly. It should be noted
that as the piece of tubing is processed by the die, it is
generally lengthened, and as the diameter of a given section is
reduced, the section generally undergoes an increase in wall
thickness. Thus, the method of the present invention is
characterized by the use of a die having a die taper angle of
greater than about 10 degrees, and in additional embodiments,
greater than about 12, 14, 15, 16, 17 and 18 degrees. In general,
the method can be used to achieve a taper having a taper angle of
greater than about 10 degrees, and in additional embodiments,
greater than about 12, 14, 15, 16, 17 and 18 degrees. The method of
the present invention also can be used to form extremely long
tapers in one pass, for example, up to, including, and longer than
about 24 inches. In such cases, the taper angle may be even less
than about 10 degrees. Current methods require multiple passes
through successively stretched tapers in order to form such long
tapers.
[0029] The maximum taper length is dependent upon the length of the
die taper. In general, a die taper of a given length can be used to
form tapers of that length and shorter, with the shorter tapers
formed by processing a work piece only partially. Fully processing
a work piece (i.e., such that the inserted end reaches the small
diameter end of the die taper) results in a taper having the length
of the die taper. Further insertion of the work piece gives a
length of tubing attached to the small diameter end of the taper,
with the taper having the same length as the die taper.
[0030] While the method of the present invention can be useful in
the preparation of tapers of a wide variety of dimensions,
preferably the taper has a length in the range of from about 10 to
about 22 inches, more preferably in the range of from about 12 to
about 20 inches, even more preferably in the range of from about 15
to about 20 inches. Furthermore, the method of the present
invention can be used to form a taper having extensions of tubing
from its small diameter end. Such lengths of tubing can be as long
as desired.
[0031] The method of the present invention can be used to prepare
tapers having a diameter reduction (between starting diameter and
smallest finishing diameter) of greater than 30%. Preferably, the
diameter reduction is greater than 10%, and more preferably it is
greater than 20%.
[0032] The method of the present invention includes the use of a
die with the above angles, and it should be noted that in general,
with an angle given above, the length of the die can vary greatly
without departing from the scope of the present invention. Commonly
desired taper lengths, such as those lengths which are useful in
the motorcycle muffler industry, for example, in the range of from
about 12 to about 24 inches, as well as lengths outside this range
are within the scope of the present invention. It should be noted
that not all combinations of starting diameter, taper length and
taper angle are geometrically possible, however, the method of the
present invention enfolds the production of tapers having the above
parameters, to the extent that they are geometrically sensible.
[0033] The present invention encompasses tapers which are not
linear in profile, i.e., tapers having convex profiles, concave
profiles, or regions of both. Note the die given in example 7. The
die taper profile begins with a convex section followed by a short
concave section (note that the initial concavity is for the purpose
of aiding the entrance of the work piece into the die assembly). In
such cases the taper angle is calculated as with straight tapers
above using the initial and smallest diameters.
[0034] While the inventive process disclosed herein relies on the
use of a specially dimensioned die, many of the details of the
rotary swaging process are standard. The work piece can be fed into
the rotary swaging machine at wide variety of rates. Typical feed
rates are in the range of from about 0.062 to 0.500 inches per
second. The velocity of the work piece is in the range of from
about 40 to 60 rpm, with the outer race velocity generally faster.
The holding clamp pressure on the work piece is in the range of
from about 20# to about 60#. Note that the clamp releases the work
piece at intervals when the die pressure on the work piece is at a
minimum, and the work piece is rotated slightly, generally by the
die assembly. In general, the die assembly rotates at a higher rate
relative to the work piece. The work piece is fed into the die
assembly at a hydraulic pressure in the range of from about 800 to
1500#. The number of die elements ("pieces") is preferably 2, 3 or
4.
[0035] The invention is described with reference to the drawings in
which like elements are referred to by like numerals. The
relationship and functioning of the various elements of this
invention are better understood by the following detailed
description. However, the embodiments of this invention as
described below are by way of example only, and the invention is
not limited to the embodiments illustrated in the drawings. It
should also be understood that the drawings are not to scale and in
certain instances details have been omitted, which are not
necessary for an understanding of the present invention.
[0036] FIGS. 4 and 5 illustrate a swaged muffler shell according to
one aspect of the present invention. To manufacture a swaged
muffler, precut tube pieces are rotary swaged to desired taper or
profile. This method is more flexible in that the degree of taper
and taper length is significantly more variable due to more
flexible process parameters associated with rotary swaging.
[0037] This method also allows rotary swaging of the taper or
profile and the connecting flange in one piece. This eliminates the
need for secondary welding operations and cosmetic grinding removal
of weld prior to chrome plating. This method is significantly less
costly and more cosmetically desirable. No welding required.
[0038] It is therefore intended that the foregoing detailed
description be regarded as illustrative rather than limiting, and
that it be understood that it is the following claims, including
all equivalents, that are intended to define the spirit and scope
of this invention.
EXAMPLES
[0039] The rotary swaging method of the present invention was used
to create, in one pass, a taper having a taper angle which exceeded
12 degrees. The taper had a starting diameter of 4.500 inches, a
small diameter of 2.008 inches, and a taper length 2.768 inches.
The small diameter end of the taper had a length of straight tubing
extending from it. The tube has a starting gauge of 14 gauge.
[0040] The swaging method of the present invention was used to
create, in one pass, a taper having a 30% reduction in diameter.
The taper had a starting diameter of 4.500 inches, a small diameter
of 2.184 inches, and a taper length 5.504 inches. The reduction in
diameter was 51.5%. The small diameter end of the taper had a
length of straight tubing extending from it. The tube has a
starting gauge of 14 gauge.
[0041] The swaging method of the present invention was used to
create, in one pass, a taper having a taper angle which exceeded 12
degrees. The taper had a starting diameter of 2.500 inches, a small
diameter of 1.610 inches, and a taper length 26.910 inches. The
tube has a starting gauge of 16 gauge.
* * * * *