U.S. patent application number 11/441853 was filed with the patent office on 2007-11-29 for method and apparatus for manufacturing a muffler for automotive exhaust systems.
This patent application is currently assigned to EAGLE PRECISION TECHNOLOGIES. Invention is credited to Douglas DeVouge, John Esposito, Stanislaw John Pasek, Andrew Karl Tsekrekos.
Application Number | 20070271788 11/441853 |
Document ID | / |
Family ID | 38441725 |
Filed Date | 2007-11-29 |
United States Patent
Application |
20070271788 |
Kind Code |
A1 |
Tsekrekos; Andrew Karl ; et
al. |
November 29, 2007 |
Method and apparatus for manufacturing a muffler for automotive
exhaust systems
Abstract
A method of manufacturing a muffler for an automotive vehicle
includes providing an interior subassembly including spaced apart
end plates and flow tubes extending generally perpendicular to the
end plates. A leading edge of a metal sheet is clamped against the
interior subassembly and the sheet is welded proximal the leading
edge, to the interior subassembly. The interior subassembly is
rotated while maintaining tension on the sheet, thereby causing the
sheet to wrap around the interior subassembly as the interior
subassembly rotates and the sheet is welded at an intermediate
location to the interior subassembly. The rotating of the interior
subassembly is repeated and the sheet is welded proximal a trailing
edge thereof to one of the interior subassembly and an underlayer
of the sheet. The subassembly is then rotated and the sheet is
continuous seem welded to the end plates.
Inventors: |
Tsekrekos; Andrew Karl;
(Hamilton, CA) ; Esposito; John; (Burford, CA)
; Pasek; Stanislaw John; (Brantford, CA) ;
DeVouge; Douglas; (Brantford, CA) |
Correspondence
Address: |
TAROLLI, SUNDHEIM, COVELL & TUMMINO L.L.P.
1300 EAST NINTH STREET, SUITE 1700
CLEVEVLAND
OH
44114
US
|
Assignee: |
EAGLE PRECISION
TECHNOLOGIES
|
Family ID: |
38441725 |
Appl. No.: |
11/441853 |
Filed: |
May 26, 2006 |
Current U.S.
Class: |
29/890.08 |
Current CPC
Class: |
B21C 37/0803 20130101;
F01N 2450/22 20130101; Y10T 29/49398 20150115; F01N 1/084 20130101;
B21C 37/0815 20130101; F01N 13/18 20130101 |
Class at
Publication: |
29/890.08 |
International
Class: |
B21D 51/16 20060101
B21D051/16 |
Claims
1. A method of manufacturing a muffler for an automotive exhaust,
comprising: providing an interior subassembly comprising spaced
apart end plates, and flow tubes extending generally
perpendicularly to the end plates; clamping a leading edge of a
sheet against the interior subassembly; welding said sheet proximal
said leading edge, to said interior subassembly; rotating the
interior subassembly while maintaining tension on the sheet,
thereby causing the sheet to wrap around the interior subassembly
as the interior subassembly rotates; welding the sheet at an
intermediate location to said interior subassembly; repeating said
rotating the interior subassembly; welding said sheet proximal a
trailing edge thereof to an underlayer of said sheet.
2. The method according to claim 1, comprising repeating said
rotating the interior subassembly and welding the sheet at said
intermediate location at least once.
3. The method according to claim 1, wherein clamping said leading
edge comprises pinching a portion of said sheet proximal said
leading edge between a clamp bar and said interior subassembly.
4. The method according to claim 1, comprising forcing a trailing
portion of said sheet against said interior subassembly, prior to
welding said sheet proximal said leading edge.
5. The method according to claim 3, comprising applying said force
against said sheet, on a trailing side of said clamp bar by
pinching a trailing portion of said sheet between a roller clamp
and said interior subassembly, prior to welding said sheet proximal
said leading edge.
6. The method according to claim 5, wherein said welding said sheet
proximal said leading edge comprises laser spot welding said sheet
to said end plates and to baffles located between said end plates,
between said clamp bar and said roller clamp.
7. The method according to claim 1, wherein rotating the interior
subassembly includes laterally translating said interior
subassembly.
8. The method according to claim 1, comprising continuous seam
welding said sheet to each of said end plates.
9. The method according to claim 1, wherein welding said sheet
proximal a trailing edge thereof comprises continuous seam welding
said sheet proximal said trailing edge.
10. The method according to claim 1, comprising continually
applying a force against a trailing portion of said sheet to pinch
said trailing portion against said interior subassembly during
welding said sheet proximal said leading edge, rotating the
interior subassembly, and welding said sheet at said intermediate
location.
11. An apparatus for manufacturing a muffler for an automotive
exhaust: a housing a turning device coupled to said housing for
holding an interior subassembly of said muffler and for rotating
said interior subassembly; a sheet feeder connected to said housing
for feeding a sheet of metal in alignment with and adjacent said
interior subassembly; a clamping apparatus cooperating with said
sheet feeder for clamping a leading edge of a sheet against the
interior subassembly when said sheet is fed to said subassembly; a
welding apparatus for welding said sheet to said interior
subassembly; and control equipment for controlling rotation of the
interior subassembly while the sheet feeder maintains tension on
the sheet, thereby causing the sheet to wrap around the interior
subassembly as the interior subassembly rotates, and for
controlling welding of the sheet.
12. The apparatus according to claim 11, wherein said clamping
apparatus comprises a clamp bar for clamping said leading edge of
said sheet against said interior subassembly.
13. The apparatus according to claim 11, comprising a second
clamping apparatus for forcing a trailing portion of said sheet
against the interior subassembly.
14. The apparatus according to claim 13, wherein said second
clamping apparatus comprises a roller clamp.
15. The apparatus according to claim 11, wherein said welding
apparatus comprises a laser welding apparatus.
16. The apparatus according to claim 13, wherein said welding
apparatus comprises a laser welding apparatus and said laser
welding apparatus is located for directing a laser weld beam
between said clamping apparatus and said second clamping
apparatus.
17. The apparatus according to claim 11, wherein said rotation
device includes a pair of chucks for clamping said interior
subassembly.
18. The apparatus according to claim 17, wherein said mounting
mechanism includes a lateral translation mechanism for laterally
translating the chucks during rotation thereof, thereby laterally
translating the interior subassembly during rotation.
19. The apparatus according to claim 11, comprising a feeder
mechanism for feeding said interior subassembly into said mounting
mechanism.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the manufacture of muffler
or silencer devices for use in automotive exhaust systems.
BACKGROUND OF THE INVENTION
[0002] Mufflers are employed in automotive exhaust systems for
reducing the sound from an automotive exhaust. These mufflers
commonly include an inner space defined by an outer shell and end
plates. The inner space is divided into chambers by interior
baffles that are generally parallel with the end plates and flow
tubes join the chambers and exhaust the gas. The manufacture of
these mufflers involves a number of steps in a manufacturing line
that requires significant floor space.
[0003] An outer shell is created by wrapping a sheet of metal
around a mandrel to provide the desired size and shape and the ends
of the sheet of metal are locked together in a lock seam by folding
one side over the other and then folding the seam along the surface
of the outer shell. Outer flanges are then formed at either end of
the outer shell by bending the outer edges outwardly.
[0004] The flow tubes are inserted into apertures of the baffles
and the flow tubes and baffles are fixed together such that the
flow tubes run generally perpendicularly to the baffles. The
baffles and flow tubes are inserted into the outer shell such that
the baffles are generally parallel to each other and the outer
shell spot welded to the baffles to fix the interior components in
place. For a muffler with more than two baffles, the first two
baffles and flow tubes are first inserted and the spot welded into
place. Additional baffles are then inserted and spot welded to the
outer shell.
[0005] End plates are then placed at each end of the outer shell
and the edge of each end plate is folded over along the surface of
the outer shell to form a mechanical lock joint. Each end plate
includes an aperture through which respective flow tubes extend
from the interior of the muffler.
[0006] While such manufacturing methods produce a generally
acceptable product, the manufacturing line includes several steps
requiring extensive floor space. Further, each muffler shape and
size requires a different mandrel for forming the shell and
different tooling for each step of the process.
SUMMARY OF THE INVENTION
[0007] According to one aspect of an embodiment, there is provided
a method of manufacturing a muffler for an automotive exhaust,
including providing an interior subassembly including spaced apart
end plates, at least two baffles generally parallel with the end
plates and located therebetween, and flow tubes extending generally
perpendicular to the baffles and end plates. A leading edge of a
metal sheet is clamped against the interior subassembly and the
sheet is welded proximal the leading edge, to the interior
subassembly. The interior subassembly is rotated while maintaining
tension on the sheet, thereby causing the sheet to wrap around the
interior subassembly as the interior subassembly rotates and the
sheet is welded at an intermediate location to the interior
subassembly. The rotating of the interior subassembly is repeated
and the sheet is welded proximal a trailing edge thereof to one of
the interior subassembly and an underlayer of the sheet.
[0008] According to another aspect, there is provided an apparatus
for manufacturing a muffler for an automotive exhaust. The
apparatus includes a housing, a mounting mechanism including a
turning device coupled to the housing for holding an interior
subassembly of the muffler and for rotating the interior
subassembly. A sheet feeder is connected to the housing for feeding
a sheet of metal in alignment with and adjacent the interior
subassembly and a clamping apparatus cooperates with the sheet
feeder for clamping a leading edge of a sheet against the interior
subassembly when the sheet is fed to the subassembly. A welding
apparatus is used for welding the sheet to the interior subassembly
and control equipment controls rotation of the interior subassembly
while the sheet feeder maintains tension on the sheet, thereby
causing the sheet to wrap around the interior subassembly as the
interior subassembly rotates, and for controlling welding of the
sheet.
[0009] Thus, an interior subassembly is first manufactured. The
remaining steps of the process are carried out in the apparatus,
therefore requiring fewer stops along a manufacturing line and less
floor space. Advantageously, the chucks can be interchanged using,
for example, a collet arrangement, to allow for the manufacture of
a different muffler size or shape using the apparatus. Similarly,
the control equipment can be programmed to carry out each step for
different muffler types.
[0010] In one particular embodiment, the apparatus includes a
lateral translation mechanism for laterally translating the chuck
during rotation thereof. Thus, the interior subassembly is moved
laterally during rotation to allow for the manufacture of muffler
shapes that are not round in cross-section. The lateral translation
is controlled to ensure that the laser welder is at the same angle
to the sheet as the sheet is wrapped around the interior
subassembly. In another aspect, the leading edge of the metal sheet
is clamped against the interior subassembly with a clamp bar and a
roller clamp is used to force a trailing portion of the sheet
against the interior subassembly. The sheet is welded proximal the
leading edge, between the clamp bar and the roller clamp, to the
interior subassembly. The interior subassembly is rotated while
maintaining tension on the sheet to cause the sheet to wrap in a
tight fit around the interior subassembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will be better understood with
reference to the drawings and to the following description, in
which:
[0012] FIG. 1A is a perspective view of an apparatus for
manufacturing a muffler for an automotive exhaust system according
to one embodiment of the present invention;
[0013] FIG. 1B is an alternative perspective view of the apparatus
of FIG. 1A;
[0014] FIG. 1C is a perspective view of a feeder mechanism of the
apparatus of FIG. 1A;
[0015] FIGS. 1D and 1E are perspective views of a sheet feeder of
the apparatus of FIG. 1A;
[0016] FIGS. 2 to 16 show the apparatus of FIG. 1A at various
stages in a method of manufacturing a muffler for an automotive
exhaust; FIGS. 2 to 8 being perspective views, FIG. 9 being a side
view; FIG. 10A being a perspective view; FIGS. 10B to 10F being
partial views of FIG. 10A, drawn to a larger scale; FIGS. 11 and 12
being perspective views; FIG. 13 being a partial perspective view,
drawn to a larger scale; FIG. 14 being a perspective view; FIG. 15
being a partial perspective view, drawn to a larger scale and FIG.
16 being a perspective view.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] Reference is first made to FIGS. 1A to 1E which show an
apparatus for manufacturing a muffler for an automotive exhaust,
according to one embodiment of the present invention. The apparatus
is indicated generally by the numeral 20 and includes a housing 22
and a mounting mechanism 24 including a turning device 50 coupled
to the housing 22 for holding an interior subassembly of the
muffler and for rotating the interior subassembly. A sheet feeder
28 is connected to the housing 22 for feeding a sheet of metal in
alignment with and adjacent the interior subassembly and a clamping
apparatus 30 cooperates with the sheet feeder 28 for clamping a
leading edge of a sheet against the interior subassembly when the
sheet is fed to the subassembly. A welding apparatus 32 is used for
welding the sheet to the interior subassembly and control equipment
34 controls rotation of the interior subassembly while the sheet
feeder 28 maintains tension on the sheet, thereby causing the sheet
to wrap around the interior subassembly as the interior subassembly
rotates, and for controlling welding of the sheet.
[0018] Continued reference is made to FIGS. 1A to 1E to describe in
more detail, an apparatus for manufacturing an automotive exhaust
according to an embodiment of the present invention. As indicated,
the apparatus includes the housing 20. The housing 22 includes a
support frame structure 36 for attachment of each of the components
of the apparatus 20 and for fixing the components to a floor. In
the present embodiment, the housing also includes an upper platform
38 accessible by a set of stairs to one side of the frame structure
36. The use of the upper platform 38 will be further described
below.
[0019] A feeder mechanism 40 is fixed to the frame structure 36 for
feeding an interior subassembly into the mounting mechanism 24. The
feeder mechanism includes a feeder nest 42 for receiving the
interior subassembly and for loading the interior subassembly into
the mounting mechanism 24. The feeder nest 42 includes a carriage
44 with a clamp bar 46 on an upper portion thereof. The carriage 44
is driven vertically between machine loading, chuck loading and
bottom clamping positions, and supported by bearings. The clamp bar
46 provides support to an undersurface of the interior subassembly
when the carriage 44 is in the bottom clamping position during
manufacturing.
[0020] The feeder nest 42 includes two brackets 47 for receiving
opposing tooling plates 48, each with a cutout profiled to snuggly
fit the bottom portion of each end plate of the interior
subassembly. Each tooling plate 48 includes a lip interior to the
subassembly at the face of the respective end plate that faces the
baffles, for supporting the respective end plate when the interior
subassembly is loaded onto the tooling chucks 26, 27. The brackets
48 are connected together by a lead screw 45 that is connected to a
motor for adjusting the pitch between the tooling plates 48 such
that the lip on each tooling plate closely contacts the interior
side of each end plate of the interior subassembly during feeding.
The brackets 48 are also fixed to a horizontal drive 49 for pulling
the interior subassembly onto the fixed-side tooling chuck 26.
Adjustment and operation of the feeder mechanism 40 is controlled
by the control equipment 34.
[0021] The mounting mechanism 24 is fixed within the frame
structure 36 and cooperates with the feeder mechanism 40 for
receiving the interior subassembly of the muffler. The mounting
mechanism 24 includes a turning device 50 for rotation of the
interior subassembly when loaded into the mounting mechanism 24.
The turning device 50 includes a pair of rotatable chucks 26, 27,
both powered by respective motors connected to the control
equipment 34 to control rotation of the chucks 26, 27 and to
thereby control the rotation of the interior subassembly when
loaded into the mounting mechanism 24. Rotation of the rotatable
chucks 26, 27 is synchronized by the control equipment 34. The
rotatable chucks 26, 27 include one fixed-side tooling chuck 26 and
a moving-side tooling chuck 27. The fixed-side tooling chuck 26 is
fixed with respect to movement along the axis of rotation of the
tooling chucks 26, 27 while the moving-side tooling chuck 27 is
movable longitudinally along the axis of rotation of the tooling
chucks 26, 27. A rack and pinion driven by a motor, are responsible
for longitudinal movement and positioning of the moving-side
tooling chuck. Movement along the axis of rotation of the tooling
chucks 26, 27 permits advancement of the moving-side tooling chuck
27 toward the fixed-side tooling chuck 26 when the interior
subassembly is loaded into place, in order to clamp the interior
subassembly in the tooling chucks 26, 27. The tooling chucks 26, 27
include a collet arrangement for replacement of the tooling chucks
26, 27 within the turning device 50. Thus, alternative tooling
chucks 26, 27 can be used for alternative muffler shapes and
sizes.
[0022] The mounting mechanism 24 also includes a lateral
translation mechanism 54 for lateral translation of the turning
device 50, perpendicular to the axis of rotation of the turning
device 50 during manufacturing of the muffler. The turning
mechanism 50 is fixed to the lateral translation mechanism 54,
which in turn is fixed to the support frame structure 36. The
lateral translation mechanism 54 includes a servomotor coupled to a
ball screw assembly at each side (fixed side and moving side) of
the turning device 50 while linear bearings guide the lateral
translation. The control equipment 34 is responsible for
synchronizing the servomotors at each side of the turning device
50. Lateral translation provides for the manufacture of muffler
devices that are not round in cross-section as the lateral
translation is controlled to ensure that the beam from the laser
welding apparatus 32 is at a consistent angle with respect to the
interior subassembly during certain manufacturing steps of the
muffler.
[0023] Referring still to FIGS. 1A to 1E and, in particular, FIGS.
1D and 1E, which show the Sheet Feeder 28 in an opened, non-working
position and in a closed, working position, the sheet feeder 28 is
connected to the support frame structure 36 and aligned with the
mounting mechanism 24 for feeding a sheet of metal for welding to
the interior subassembly to form the exterior shell of the muffler
during manufacturing. The sheet feeder 28 includes a row of
free-turning rollers 56 for supporting the sheet and the roller 58
closest to the tooling chucks 26, 27 is belt-driven by a reversible
motor to control the sheet feeding. A pulley that is coupled to the
roller shaft of the belt-driven roller includes a clutch mechanism
to limit the tension applied to the sheet. In the present
embodiment, the belt-driven roller 58 is coated with a pliable
material such as urethane for enhanced grip and to inhibit marking
of the sheet of metal. Pressure rollers 60 are coated with a
similar pliable material and are located to pinch the sheet of
metal against the belt-driven roller 58 from above, for maintaining
tension in the sheet of metal. Small drives are connected to the
pressure rollers 60 to retract the pressure rollers 60 when a new
sheet of metal is loaded into the sheet feeder 28. The sheet feeder
28 also includes a row of passive, free-turning side rollers 62 for
guiding each edge of the sheet of metal. The row of side rollers 62
closest to the fixed tooling chuck 26 is fixed in position to
maintain alignment of the sheet of metal with the fixed tooling
chuck 26. A motor connected to the control equipment 34 drives a
lead screw for adjusting the position of the side rollers 62 at the
opposite edge of the sheet during set-up for a new muffler
geometry. Incoming sheets of metal are directed into the sheet
feeder by rows of passive rollers 63 above the free-turning rollers
56 that support the sheet.
[0024] A clamping apparatus 30 is fixed to the support frame
structure 36 and cooperates with the sheet feeder 28 for clamping
the sheet of metal against the interior subassembly during
manufacturing of the muffler. The clamping apparatus 30 includes a
vertical drive controlled by the control equipment 34 for advancing
a clamp bar 64 to clamp a leading edge of the sheet of metal
against the interior subassembly when the leading edge is fed to
the interior subassembly by the sheet feeder 28.
[0025] A second clamping apparatus 68 is also fixed to the support
frame structure 36 for clamping the sheet of metal against the
interior subassembly during manufacture. The second clamping
apparatus 68 also includes a vertical drive controlled by the
control equipment 34 for advancing a roller 72 to clamp a trailing
portion of the sheet metal against the interior subassembly. The
roller 72 contacts the sheet of metal on the trailing side of the
clamp bar 64, between the sheet feeder 28 and the clamp bar 64. The
vertical drive of the second clamping apparatus 68 is separately
operable from the vertical drive of clamping apparatus 30. Thus,
the roller 72 is separately engageable with the sheet of metal
during manufacture. The roller 72 and clamp bar 64 are spaced apart
to permit welding of the sheet to the interior subassembly at
points located between the roller 72 and the clamp bar 64.
[0026] The welding apparatus 32 is located on the upper platform 38
of the housing 22 for accessibility from the upper platform 38, and
is controlled by the control equipment 34. As will be understood by
those skilled in the art, the welding apparatus 32 is a remote
laser welder including a laser resonator 76 and a scanner 78 for
directing a laser welding beam (non-visible, far infrared) to
desired locations along the sheet of metal on the interior
subassembly. It will be appreciated that the laser resonator 76
produces the laser beam while the scanner 78, which includes lens
and mirror actuators, focuses and directs the beam to the desired
location. Simple trigonometric relationships control the lens and
mirror actuators according to the effective radius of the muffler
at the point of weld, and the location of the weld along the
longitudinal axis of the muffler.
[0027] The control equipment 34 is connected to each of the feeder
mechanism 40, the mounting mechanism 24, the sheet feeder 28, the
two clamping apparatus 30, 68, and the welding apparatus 32 for
control and timing of operation of each. In the present embodiment,
the control equipment 34 includes programmable devices, the coding
of software for which is well within the scope of a person of
ordinary skill in the art.
[0028] In use, an interior subassembly for a muffler is loaded into
the feeder mechanism 40 by loading into the feeder nest 42 from
preassembly, as shown in FIG. 2. An exemplary interior subassembly
is also shown in FIG. 2. The exemplary interior subassembly 100
includes preassembled baffles 102, end plates 104 and flow tubes
106. As shown, the end plates 104 are spaced apart and are
generally parallel. In the present example, three baffles 102 that
are generally parallel with the end plates 104 are located at
spaced positions therebetween. The flow tubes 106 extend through
apertures in the baffles 102 and the end plates 104 and are fixed
thereto such that the flow tubes 106 are generally perpendicular to
the end plates 104 and the baffles 102. The feeder nest 42 is then
raised to the loading position to thereby lift the interior
assembly 100 into position adjacent the fixed-side tooling chuck
26, as shown in FIG. 3.
[0029] Referring now to FIG. 4, the tooling chucks 26, 27 are then
rotated into loading position and translated by the lateral
translation mechanism 54 to align with the position of the end
plates 104 of the interior subassembly 100 and the interior
subassembly 100 is fed onto the fixed-side tooling chuck 26.
[0030] Next, the moving-side tooling chuck 27 is moved toward the
fixed-side tooling chuck 26, to clamp the interior subassembly 100
between the tooling chucks 26, 27, as shown in FIG. 5. The feeder
nest 42 is then lowered as shown in FIG. 6. Thus, the interior
subassembly 100 is loaded into the mounting mechanism 24.
[0031] After loading the interior subassembly 100, the tooling
chucks 26, 27 are rotated and translated to thereby rotate and
translate the interior subassembly 100 into a first welding
position.
[0032] Next, a metal sheet 110 that is precut to a specified size
and length to form an exterior shell of the muffler is fed by the
sheet feeder 28 to a start position as shown in FIG. 7. As best
shown in FIG. 10B, the side edge of the metal sheet 110 fits
against the face of the fixed-side tooling chuck 26.
[0033] Referring to FIG. 8, the feeder nest 42 is raised such that
the clamp bar 46 of the feeder nest 42 contacts the underside of
the interior subassembly 100 to provide support thereto. The clamp
bar 64 is lowered by the vertical drive to clamp the leading edge
of the metal sheet 110 against the interior subassembly 100 by
pinching the metal sheet proximal the leading edge between the
clamp bar 64 and the interior subassembly 100. After the clamp bar
64 is lowered to a clamping position, the sheet feeder 28 reverses
in an attempt to retract the metal sheet 110. Because the metal
sheet 110 is still clamped by the clamp bar 64, the sheet feeder
applies tension to the metal sheet 110. As indicated above, a
clutch mechanism in the sheet feeder 28 is used to limit the
applied tension.
[0034] The roller 72 is then advanced by the vertical drive to
pinch a trailing portion of the metal sheet 110 between the roller
and the interior subassembly 100, as shown in FIG. 9.
[0035] Referring now to FIGS. 10A to 10F the welding apparatus 32
laser spot welds the metal sheet 110, near a leading edge of the
metal sheet 110, to the interior subassembly 100 by directing the
laser beam successively to points on the metal sheet 110, to
thereby spot weld at one end plate 104, each successive baffle 102,
and then the final end plate 104. FIGS. 10B to 10F show partial
perspective views of the apparatus 20 in greater detail during spot
welding. FIG. 10B shows spot welding at the first end plate 104,
FIGS. 10C, 10D and 10E show spot welding at each successive baffle
102, and FIG. 10F shows spot welding at the final end plate 104.
The clamp bar 64 is not shown in these figures for the purpose of
illustration of the directed laser weld beam. It will be understood
that the laser weld beam is shown for the purpose of illustration
only and that the laser weld beam is not, in fact, visible as it
falls outside the visible light spectrum.
[0036] Referring now to FIG. 11, the clamp bar 64 is retracted by
the vertical drive, thereby unclamping the leading edge of the
metal sheet 110. At the same time, the feeder nest 42 is lowered
out of contact with the underside of the interior subassembly
100.
[0037] The interior subassembly 100 is rotated by the turning
device 50 to a next weld position, as depicted in FIG. 12. The
roller 72 of the second clamping apparatus maintains clamping
pressure on the metal sheet 110, against the interior subassembly
100 during rotation by rolling as the metal sheet 110 is fed to the
interior subassembly 100. Also, the sheet feeder 28 feeds the metal
sheet 110 to the interior subassembly 100 while maintaining tension
in the metal sheet 110. It will be appreciated that as the interior
subassembly 100 is rotated by the turning device 50, the metal
sheet 110 wraps around the interior subassembly 100. After rotation
to a desired location, the welding apparatus 32 again laser spot
welds the metal sheet 110 to the end plate 104, each successive
baffle 102, and the final end plate 104, thereby welding the metal
sheet 110 at an intermediate portion, to the interior subassembly
100 (FIG. 13). This step of rotating and welding is repeated to
weld the metal sheet 110 at more than one position between the
leading and trailing edges, to the interior subassembly 100. In the
present embodiment, the step of rotating and welding is carried out
at least three times.
[0038] After spot welding at the intermediate positions, the metal
sheet 110, which is now wrapped around the interior subassembly
100, is continuous-seam welded to the recessed portions of each of
the end plates 104, as depicted in FIG. 14. This is carried out by
continuously welding the metal sheet 110 to one end plate while the
turning device 50 rotates and the lateral translation mechanism 54
moves laterally. It will be appreciated that in the present
embodiment, the muffler shape does not have a circular cross
section and thus, the lateral translation mechanism 54 moves the
interior subassembly 100 (by moving the entire turning device 50)
to maintain a consistent angle between the weld beam and the
surface of the metal sheet 110 when welding the metal sheet 110 to
the end plate 104. After completing the continuous seam weld at the
first end plate 104, the process is repeated for the final end
plate 104.
[0039] Next, the trailing edge of the metal sheet 110 is continuous
seam welded to an underlayer of the same metal sheet 110, as shown
in FIG. 15, thereby sealing the exterior shell of the muffler.
[0040] After welding of the trailing edge of the metal sheet 110,
the roller 72 is removed from contact with the muffler and the
muffler is rotated and translated to an unload position (FIG. 16).
An unloading apparatus such as a robotic arm (not shown), enters
the machine and holds the muffler. The moving-side tooling chuck 27
is then moved away from the end plate 104 of the muffler,
permitting removal of the muffler from the mounting mechanism 24 by
the unloading apparatus.
[0041] While the embodiment described herein is directed to a
particular implementation of the method and apparatus for
manufacturing a muffler for an automotive exhaust, it will be
understood that modifications and variations to this embodiment are
within the sphere and scope of the present application. For
example, rather than continuous seam welding the trailing edge to
an underlayer of the metal sheet as described above, the metal
sheet can be wrapped around the interior subassembly more than one
time and the trailing edge of the metal sheet can be laser spot
welded to the underlayer of the metal sheet. Thus, rather than a
continuous weld seal, a labyrinth seal is formed by wrapping the
interior subassembly with the metal sheet more than one time. Also,
the size and shape of many of the features can vary. Further, many
of the features can be replaced by other features for carrying out
similar functions.
[0042] Many other modifications and variations may occur to those
skilled in the art. All such modifications and variations are
believed to be within the sphere and scope of the present
application.
* * * * *