Method and apparatus for manufacturing a muffler for automotive exhaust systems

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood with reference to the drawings and to the following description, in which:

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;

FIG. 1B is an alternative perspective view of the apparatus of FIG. 1A;

FIG. 1C is a perspective view of a feeder mechanism of the apparatus of FIG. 1A;

FIGS. 1D and 1E are perspective views of a sheet feeder of the apparatus of FIG. 1A;

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 housinga 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; andcontrol 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.

Method and apparatus for manufacturing a muffler for automotive exhaust systems

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Description

Claims