Electric heating – Metal heating – By arc
Reexamination Certificate
1999-11-10
2001-12-25
Elve, M. Alexandra (Department: 1725)
Electric heating
Metal heating
By arc
C219S121640, C219S121670, C219S121720, C219S121760
Reexamination Certificate
active
06333482
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to method for producing can bodies made of sheet metal for the manufacture of cans by bringing together and placing one on top of the other of two sheet metal strips which have been rolled to a finished thickness and the width of which is a multiple of half of the circumference of a can body, joining of the sheet metal strips, which are placed one on top of the other, by means of several joint welds which extend continuously in the longitudinal direction of the strip, the mutual spacing of which welds in the transverse direction of the strip corresponds to half of the body circumference, by continuous moving of the sheet metal strips, which are placed one on top of the other, past a laser welding device which has several laser heads arranged at corresponding mutual spacings, longitudinal cutting of the sheet metal strips, which are welded together, by laser cutting along each weld joint in order to produce several adjacent flat tubes, possibly rolling up of the flat tubes for interim storage and/or transportation, unrolling of the possibly rolled-up flat tubes, cutting of the flat tubes into flat tube sections, the length of which corresponds roughly to the height of the can, and spreading of the individual flat tube sections into one, especially cylindrical, can body respectively.
BACKGROUND OF THE INVENTION
A method of this type is known from DE 197 02 265 Al. In the case of this known method, the mutual welding of the sheet metal strips and the longitudinal cutting of the sheet metal strips, which are welded together, is effected in two successive operational steps. At each welding station, the two sheet metal strips are first of all welded together by means of several laser heads which are arranged next to one another so that said metal strips firstly form flat tubes, which are connected to one another, along the joint welds. At a cutting station assigned to the welding station at a spacing, the sheet metal strips are then separated from one another by means of cutting lasers along the centre of each joint weld. Several flat tubes, which are arranged adjacently and separated from one another by cuts, are thus produced and wound up into cylinders. The cylinders are then delivered to a filling machine where they are cut into lengths by relatively simple machines and spread into can bodies. The technical costs for carrying out this known method are relatively high because separate laser heads are required for welding and for cutting respectively. By adjusting the mutual spacing of the laser heads in the direction of the strip, the width of the flat tubes to be produced can be altered to the respectively desired diameter of the can bodies to be manufactured later therefrom. Provision must be made thereby that the mutual spacing of the welding lasers corresponds absolutely precisely to the mutual spacing of the cutting lasers. In addition, the cutting lasers must be in exact alignment with the welding lasers in the longitudinal direction of the strip since otherwise the cutting lasers do not cut apart the previously produced joint welds exactly in the centre.
SUMMARY OF THE INVENTION
The object underlying the invention is thus to improve the method mentioned initially for producing can bodies made of sheet metal for the manufacture of cans such that the method can be carried out with lower technical expenditure and also with greater operational reliability and manufacturing precision.
This is achieved according to the invention in that the welding and the longitudinal cutting are effected simultaneously with one and the same laser head respectively, the laser beam of which has an inner beam path of high energy density for the longitudinal cutting and a beam path of lower energy density for welding the regions of the sheet metal strips which are placed one on top of the other and situated on both sides of the cut.
The invention starts thus from the idea of carrying out the mutual welding of the two sheet metal strips and the longitudinal cutting respectively at the same time and in the same place by means of one single laser head, the laser beam of which has a corresponding energy density distribution. As a result, the device for carrying out the method is substantially simpler because a second laser head, which in the case of the method used to date was only provided for the longitudinal cutting is dispensed with. In addition, there are no problems with the new method with respect to the exact adjustment of the cutting laser relative to the assigned welding laser because the welding and the cutting are performed by one and the same laser beam. As a result, adjustment operations are simplified, the operational reliability of the method is improved and the operational precision is also increased.
REFERENCES:
patent: 4315132 (1982-02-01), Saurin et al.
patent: 5430270 (1995-07-01), Findlan et al.
patent: 5653899 (1997-08-01), Odake et al.
patent: 5658473 (1997-08-01), Ziemek
patent: 5731566 (1998-03-01), Steinhart
patent: 5997232 (1999-12-01), Sauer
patent: 6034347 (2000-03-01), Alber et al.
patent: 19702265 (1998-07-01), None
patent: 197 02 265 (1998-07-01), None
Kern Karl-Heinz
Sauer Reiner
Elve M. Alexandra
Flynn ,Thiel, Boutell & Tanis, P.C.
Rasselstein Hoesch GmbH
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