CA1243364A - Apparatus for laser beam welding the longitudinal edges of a can shell - Google Patents
Apparatus for laser beam welding the longitudinal edges of a can shellInfo
- Publication number
- CA1243364A CA1243364A CA000489572A CA489572A CA1243364A CA 1243364 A CA1243364 A CA 1243364A CA 000489572 A CA000489572 A CA 000489572A CA 489572 A CA489572 A CA 489572A CA 1243364 A CA1243364 A CA 1243364A
- Authority
- CA
- Canada
- Prior art keywords
- shell
- welding
- laser beam
- welded
- edges
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- Laser Beam Processing (AREA)
Abstract
APPARATUS FOR LASER BEAM WELDING
THE LONGITUDINAL EDGES OF A CAN SHELL
ABSTRACT
The invention involves the use of laser beam welding for the mass production of welded shells for sheet metal cans. The high requirements as to the precision of the welded seam are obtained through a guide system for exactly guiding pieces to the welding machine and consist-ing of an X-rail, a guide bar and the spring loaded jaws of a caterpillar tractor. A smooth welded seam is pro-duced on the inner side of the can shell by having the seam welded from the inside of the can shell as well as from the outside by means of a laser beam.
THE LONGITUDINAL EDGES OF A CAN SHELL
ABSTRACT
The invention involves the use of laser beam welding for the mass production of welded shells for sheet metal cans. The high requirements as to the precision of the welded seam are obtained through a guide system for exactly guiding pieces to the welding machine and consist-ing of an X-rail, a guide bar and the spring loaded jaws of a caterpillar tractor. A smooth welded seam is pro-duced on the inner side of the can shell by having the seam welded from the inside of the can shell as well as from the outside by means of a laser beam.
Description
~3~
The present invention rela-tes to any apparatus for laser beam welding the longitudinal edges of a can shell.
In particular the present invention concerns an apparatus for laser beam welding -the edges of a rectangular sheet metal piece bent in-to a can shell which edges are pushed together into abuting relationship and which sheet metal is made of coated or uncoated steel or aluminum sheet, the apparatus including a sheet bending device, inner and outer precise guides for the bent can shell and for the edges to be welded, a transport means for the can shell and at least one laser beam welding device for welding the edges.
One such device is known from U.S. Patent No.
4,354,090. The welding seams created by this device are however of such poor quality that the cans are practically unusable. The poor quality is due to the fact that the entire energy of the welding beam is not effective in the process of wel~ing together the edges. A portion of the energy is reflected by the bright cut edges and is therefore lost. The reflected portion is subject to large variations because the surfaces of the cut edges due to humidity and temperature or other contaminants take on a thin barely visible oxide layer af-ter the cutting. This oxide layer causes a reflectivity of varying value. A beam adjusted at one time to a good welding effect a short -time later mee-ts with a different oxide layer and no longer produces a good welding effect. Welding faults arising in this manner lead in the inside of the can to a sagging weld seam in the case of too strong a beam and to a nonwelded crevasse in the case of a too weak beam.
A crevase has the disadvantage tha-t upon the application of the protective lacquer the lacquer draws away from the crevasse's sharp edges. The can is therefore insufficien-tly protected against corrosion. Moreover, the , .
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weld seam easily rips open at the crevasse especially if it is flanged in the further working of the shell. A sagging weld seam leads likewise to faults in the lacquer and also represents a strength risk.
The invention has as its object the provision of a laser beam welding method for manufacturing cans by means of which method these disadvantages are avoided and through the use of which the weld seam is uniform throughout the entire thickness and by means of which the advantages of the guide as described in U.S. Patent No. 4,35~,909 for very thin sheet material and for mass production, and for guiding the to-be-welded edges which are pushed into abutting relation-ship are retained.
According to the present invention there is provided an apparatus for laser beam welding the edges of a rectangular cut piece of sheet material made of coated or uncoated steel or aluminum bent into a can shell by means of a bending device with the edges pressed into abutting relation with one another, the apparatus including inner and outer exact guides for the bent can shell and ~or the edges to be welded together, a transport means for the can shells and at least one laser beam welding devi~e for welding the edges, the apparatus being characterized by in addition to a first laser beam welding device for welding the outer side of the can shell a second device for projecting a laser beam onto the inner side of the can shell which beam is created outside of the guides and is directed through the space surrounded by a shell as it is moved by the transport means, and a mirror and a concentrating lens located wlthin the space, the guide below the welding point being provided with an opening and the mirror and the concentrating lens being so arranged that the beam is reflected by the mirror, is concentrated by the lens and passes through the opening to the point to be welded.
The present invention rela-tes to any apparatus for laser beam welding the longitudinal edges of a can shell.
In particular the present invention concerns an apparatus for laser beam welding -the edges of a rectangular sheet metal piece bent in-to a can shell which edges are pushed together into abuting relationship and which sheet metal is made of coated or uncoated steel or aluminum sheet, the apparatus including a sheet bending device, inner and outer precise guides for the bent can shell and for the edges to be welded, a transport means for the can shell and at least one laser beam welding device for welding the edges.
One such device is known from U.S. Patent No.
4,354,090. The welding seams created by this device are however of such poor quality that the cans are practically unusable. The poor quality is due to the fact that the entire energy of the welding beam is not effective in the process of wel~ing together the edges. A portion of the energy is reflected by the bright cut edges and is therefore lost. The reflected portion is subject to large variations because the surfaces of the cut edges due to humidity and temperature or other contaminants take on a thin barely visible oxide layer af-ter the cutting. This oxide layer causes a reflectivity of varying value. A beam adjusted at one time to a good welding effect a short -time later mee-ts with a different oxide layer and no longer produces a good welding effect. Welding faults arising in this manner lead in the inside of the can to a sagging weld seam in the case of too strong a beam and to a nonwelded crevasse in the case of a too weak beam.
A crevase has the disadvantage tha-t upon the application of the protective lacquer the lacquer draws away from the crevasse's sharp edges. The can is therefore insufficien-tly protected against corrosion. Moreover, the , .
., ~;"~`, ~
:~L2~3~
weld seam easily rips open at the crevasse especially if it is flanged in the further working of the shell. A sagging weld seam leads likewise to faults in the lacquer and also represents a strength risk.
The invention has as its object the provision of a laser beam welding method for manufacturing cans by means of which method these disadvantages are avoided and through the use of which the weld seam is uniform throughout the entire thickness and by means of which the advantages of the guide as described in U.S. Patent No. 4,35~,909 for very thin sheet material and for mass production, and for guiding the to-be-welded edges which are pushed into abutting relation-ship are retained.
According to the present invention there is provided an apparatus for laser beam welding the edges of a rectangular cut piece of sheet material made of coated or uncoated steel or aluminum bent into a can shell by means of a bending device with the edges pressed into abutting relation with one another, the apparatus including inner and outer exact guides for the bent can shell and ~or the edges to be welded together, a transport means for the can shells and at least one laser beam welding devi~e for welding the edges, the apparatus being characterized by in addition to a first laser beam welding device for welding the outer side of the can shell a second device for projecting a laser beam onto the inner side of the can shell which beam is created outside of the guides and is directed through the space surrounded by a shell as it is moved by the transport means, and a mirror and a concentrating lens located wlthin the space, the guide below the welding point being provided with an opening and the mirror and the concentrating lens being so arranged that the beam is reflected by the mirror, is concentrated by the lens and passes through the opening to the point to be welded.
2 -336~
Preferably, the speed of advancement by the transport means of can shells to be welded and the energy of the laser beams are so adjusted that on each side of a can shell less than the entire thickness of the sheet material is welded.
Preferably, the laser beams on both sides of a can shell are somewhat displaced from one another in the direction of the welding seam.
The welding from both sides has the advantage that the energy of the laser beam can vary in strength on each side so that it welds between fifty to one hundred percent of the sheet thickness. It is of no disadvantage if the middle zone of the sheet thickness is welded from both sides in an overlapping manner behind one another. The overlap-ping area allows for variations of the beam welding effect due to different edge reflectivities.
A preferred embodiment will now be described, as example without limitative manner, having reference the attached drawings, wherein:
Figs. 1 and 2 are views showing the device for guiding bent can shells to the welding machine, Fig. 3 is a view showing the edges of the sheet in the area between the sheet bending device to shortly before the welding machine, Fig. 4 is a view showing the clamping and guiding of the sheet during the welding, Fig. 5 is a cross section through the can shell at the inner welding ~ocation, Fig. 6 is a view showing the Eorming station for the can shell.
rrhe cut pieces of tin 23 are introduced sidewise into the forming station 22, as seen in Fig. 6, through a
Preferably, the speed of advancement by the transport means of can shells to be welded and the energy of the laser beams are so adjusted that on each side of a can shell less than the entire thickness of the sheet material is welded.
Preferably, the laser beams on both sides of a can shell are somewhat displaced from one another in the direction of the welding seam.
The welding from both sides has the advantage that the energy of the laser beam can vary in strength on each side so that it welds between fifty to one hundred percent of the sheet thickness. It is of no disadvantage if the middle zone of the sheet thickness is welded from both sides in an overlapping manner behind one another. The overlap-ping area allows for variations of the beam welding effect due to different edge reflectivities.
A preferred embodiment will now be described, as example without limitative manner, having reference the attached drawings, wherein:
Figs. 1 and 2 are views showing the device for guiding bent can shells to the welding machine, Fig. 3 is a view showing the edges of the sheet in the area between the sheet bending device to shortly before the welding machine, Fig. 4 is a view showing the clamping and guiding of the sheet during the welding, Fig. 5 is a cross section through the can shell at the inner welding ~ocation, Fig. 6 is a view showing the Eorming station for the can shell.
rrhe cut pieces of tin 23 are introduced sidewise into the forming station 22, as seen in Fig. 6, through a
- 3 -S ' 33~9L
slot 7 and are bent to a can shell 4 by Lhe cylindrically shaped inner space of the forming sta~ion 22. The forming station 22 has in its middle a free cross section 2 extend-ing through it in the longitudinal direction and through which a laser beam from the laser beam source 27 passes.
The forming station 22 has a lower slot 3. A driving dog 5 of a transport mechanism extends through this slot and drives the can shell ~ in the direction toward the welding station 12.
At a first point along the pa-th from the forming station 22 the can shell 4, as shown in Fig. 3, is outwardly slidably guided between guide pieces 6 while it is moved by the dog 5 in the direction toward the welding sta-tion. The end of this section of the path lies at position 21. From this point on the can shell 4 is slidably guided on its inner surface. The conveyor at this point becomes a specially formed caterpillar tractor 24 with spring loaded jaws 7, see Fig. 2. The caterpillar tractor 2~ consists of chain wheels 8, guiderails 9, chain members 10 and jaws 7.
The cut edges of the can shell 4 are next guided to an X-rail 11 which, as shown in Fig. 1, extends from position 25 to position 26. The X-rail guarantees the exact positioning shortly in advance of the welding station 12 of the edges which are to be welded.
The can shell 4 during the welding slides over the inner guide strip 13 and is tensioned by the laterally arranged jaws 7, which work as a pressure applying apparatus, and by a lower pressure roll 14 so that the cut edges are pressed fully against one another and are moved without any air gap -through the welding sta-tion 12 as shown in Figs. 4 and 5. To prevent displacement of the edges at the welding point the can shell is pressed against the guide bar 13 at the cut edges by means of double rolls 15. The laser beam 16 which is applied to the can shell from the . c ; ~
33~i~
outside passes exactly midway between the double rolls 15.
The laser beam 17 which is applied to -the can shell from the inside is displaced from the outside welding point and passes through a window 18 in the guide bar 13.
The guide bar 13 has a groove 19 extending away from the welding window 18 in the vicinity of the body seam for receiving the increased thickness of the seam.
The guide bar 13 is fastened to the forward portion of the X-rail and the X-rail is in turn fastened to a frame 20. The length of the guide bar 13 extends from position 26 to position 23.
The lower welding beam is produced by a laser source 27, is bent by the mirror 28 and is projected onto the inner surface of the can shell by the concentrati~g lens lS 29.
It is possible to derive both laser beams from only one laser source with such laser source producing one beam which is devided into two; each of which two beams is then directed to one of the welding points.
,',?~ '
slot 7 and are bent to a can shell 4 by Lhe cylindrically shaped inner space of the forming sta~ion 22. The forming station 22 has in its middle a free cross section 2 extend-ing through it in the longitudinal direction and through which a laser beam from the laser beam source 27 passes.
The forming station 22 has a lower slot 3. A driving dog 5 of a transport mechanism extends through this slot and drives the can shell ~ in the direction toward the welding station 12.
At a first point along the pa-th from the forming station 22 the can shell 4, as shown in Fig. 3, is outwardly slidably guided between guide pieces 6 while it is moved by the dog 5 in the direction toward the welding sta-tion. The end of this section of the path lies at position 21. From this point on the can shell 4 is slidably guided on its inner surface. The conveyor at this point becomes a specially formed caterpillar tractor 24 with spring loaded jaws 7, see Fig. 2. The caterpillar tractor 2~ consists of chain wheels 8, guiderails 9, chain members 10 and jaws 7.
The cut edges of the can shell 4 are next guided to an X-rail 11 which, as shown in Fig. 1, extends from position 25 to position 26. The X-rail guarantees the exact positioning shortly in advance of the welding station 12 of the edges which are to be welded.
The can shell 4 during the welding slides over the inner guide strip 13 and is tensioned by the laterally arranged jaws 7, which work as a pressure applying apparatus, and by a lower pressure roll 14 so that the cut edges are pressed fully against one another and are moved without any air gap -through the welding sta-tion 12 as shown in Figs. 4 and 5. To prevent displacement of the edges at the welding point the can shell is pressed against the guide bar 13 at the cut edges by means of double rolls 15. The laser beam 16 which is applied to the can shell from the . c ; ~
33~i~
outside passes exactly midway between the double rolls 15.
The laser beam 17 which is applied to -the can shell from the inside is displaced from the outside welding point and passes through a window 18 in the guide bar 13.
The guide bar 13 has a groove 19 extending away from the welding window 18 in the vicinity of the body seam for receiving the increased thickness of the seam.
The guide bar 13 is fastened to the forward portion of the X-rail and the X-rail is in turn fastened to a frame 20. The length of the guide bar 13 extends from position 26 to position 23.
The lower welding beam is produced by a laser source 27, is bent by the mirror 28 and is projected onto the inner surface of the can shell by the concentrati~g lens lS 29.
It is possible to derive both laser beams from only one laser source with such laser source producing one beam which is devided into two; each of which two beams is then directed to one of the welding points.
,',?~ '
Claims (3)
1. An apparatus for laser beam welding the edges of a rectangular cut piece of sheet material made of coated or uncoated steel or aluminum bent into a can shell by means of a bending device with the edges pressed into abutting relation with one another, said apparatus including inner and outer exact guides for the bent can shell and for the edges to be welded together, a transport means for the can shells and at least one laser beam welding device for welding the edges, said apparatus being characterized by in addition to a first laser beam welding device for welding the outer side of the can shell a second device for projecting a laser beam onto the inner side of the can shell which beam is created outside of the guides and is directed through the space surrounded by a shell as it is moved by said transport means, and a mirror and a concentrating lens located within said space, said guide below the welding point being provided with an opening and said mirror and said concentrating lens being so arranged that said beam is reflected by said mirror, is concentrated by said lens and passes through said opening to the point to be welded.
2. An apparatus according to claim 1, further characterized in that the speed of advancement by said transport means of can shells to be welded and the energy of the laser beams are so adjusted that on each side of a can shell less than the entire thickness of the sheet material is welded.
3. An apparatus according to claim 1 or 2, further characterized in that the laser beams on both sides of a can shell. are somewhat displaced from one another in the direction of the welding seam.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000489572A CA1243364A (en) | 1985-08-28 | 1985-08-28 | Apparatus for laser beam welding the longitudinal edges of a can shell |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000489572A CA1243364A (en) | 1985-08-28 | 1985-08-28 | Apparatus for laser beam welding the longitudinal edges of a can shell |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1243364A true CA1243364A (en) | 1988-10-18 |
Family
ID=4131263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000489572A Expired CA1243364A (en) | 1985-08-28 | 1985-08-28 | Apparatus for laser beam welding the longitudinal edges of a can shell |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1243364A (en) |
-
1985
- 1985-08-28 CA CA000489572A patent/CA1243364A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |