Electric heating – Metal heating – For bonding with pressure
Reexamination Certificate
2000-08-29
2002-09-17
Elve, M. Alexandra (Department: 1725)
Electric heating
Metal heating
For bonding with pressure
C219S064000, C219S081000
Reexamination Certificate
active
06452128
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of feeding a welding machine for lap seam welding in which the welding stock is fed into a guide rail on the welding roller side and welding is effected thereafter in a direction opposite to the direction of feeding. The invention further relates to a rolled seam welding machine, having a guide rail for the edges of the welding stock to be welded with an overlap and two welding rollers, the first welding roller of which can be moved towards the second welding roller disposed in front of the inlet region of the guide rail in order to apply welding force. The invention also relates to an automatic feeding device for the welding machine and to an arrangement of two rolled seam welding machines.
Hand-fed welding machines (semi-automatic machines) are known for the rolled seam welding of the overlap of welding stock which is formed from a curved sheet metal section, e.g. sheet metal tubes with a “butterfly overlap” or container bodies. The actual welding electrode can be formed by a wire electrode which is continuously renewed and which travels on the electrode rollers. In these machines, feeding is effected from the welding roller side, which is adjoined in the direction of feeding by a guide rail which is termed a Z rail and into which the edges of the material which are to be welded have to be introduced. For this purpose, the operator opens the rolled welding stock and guides it past the welding rollers into the Z rail. Thereafter, clamping jaws are brought into engagement with the welding stock in the known manner, at the end of the welding stock which is remote from the welding rollers. Said clamping jaws are disposed on a carriage, and the welding stock is conveyed through the welding rollers, with its edges brought into overlap by the Z rail, in a direction opposite to the direction of feeding, wherein at the start of welding the upper welding roller is lowered from its inoperative position into the welding position. At the start of welding, the operator holds the welding stock firmly so that it is pressed into the channels of the Z rail. The seam is welded between the roller electrodes or wire electrodes and the welded material is received by the operator on the feeding side, after which renewed feeding with fresh welding stock is effected. The upper welding roller is spring-mounted in the known manner in order to apply the welding force (e.g. about 80 kg), and is thus able to sink slightly into the welding stock, which is squeezed during welding. Moreover, the upper welding roller can be folded away upwards from the fixed lower welding roller in order to maintain the machine and so as to be able to thread in the welding wire and to release any wire loops which are formed in operation by pulling on the wire.
One example of a known machine of this form of construction is tile semi-automatic ZSHa or CSTW rolled seam welding machine manufactured by SMAG Schweissmaschinen AG, Bergdietikon, Switzerland. Manual feeding is particularly suitable for piece parts or very small production runs. There is also a desire, however, for machines such as these to be fed automatically for larger numbers of pieces,
For this reason, automatic feeding devices have been created which roll the welding stock laterally into the existing Z rail, so that feeding is effected behind the welding rollers. If the metal sheet which is rolled into the Z rail in this manner is grasped by the rear clamping jaws and is pushed towards the welding rollers, this results in an edge position in the Z rail which is not defined sufficiently accurately at the welding rollers, which is why these known automatic feeding devices comprise sizing tools, e.g. a roller collar or diabolo rollers, in the region of the welding rollers, in order to ensure satisfactory seam quality. Sizing tools such as these are expensive to manufacture and to adjust. Moreover, since a relative movement occurs therein between the welding stock and the tool, they give rise to problems with very sensitive welding stock, e.g. stainless steel drum bodies, since imprints of the tool can be formed on the welding stock.
The underlying object of the present invention is therefore generally to improve the feeding of a rolled seam welding machine of the type cited at the outset, and in particular is to facilitate simplified, inexpensive, automatic feeding which also makes it possible to weld sensitive welding stock.
SUMMARY OF THE INVENTION
The object of the invention is achieved for the method cited at the outset by means of moving the welding roller situated in front of the inlet of the guide rail for feeding so that the inlet can be fed directly from the front. The welding roller is moved back after feeding into its inoperative position situated in front of the guide rail. For the welding machine cited at the outset, this object is achieved by providing the machine with a second welding roller that can be moved so that the first welding roller exposes the inlet region in order to feed the welding stock into the guide rail.
Because the fixed lower welding roller according to the prior art is disposed so that it can be moved away from the inlet region of the guide machine, feeding can be effected in a much simpler manner from the front, and can be effected in particular without opening the rolled welding stock to a particularly wide extent and with linear introduction of the edges into the channels of the rail, which makes manual feeding, and particularly automatic feeding, considerably easier, because the latter can now also be effected from the front. After feeding, said welding roller is moved back into its normal position, and welding is performed in a conventional manner by moving the other welding roller into its welding position and moving the welding stock through the rollers. It is preferable if the automatic feeding device holds the welding stock until shortly before the start of the welding operation, so that the edge position of the welding stock is defined in the guide rail or Z rail. This enables the aforementioned tools to be dispensed with in a simple manner. As soon as the welding procedure has ensured defined conditions at the start of the weld seam or at the start of the overlapping edge, any further holding can be dispensed with, or it is sufficient to employ the holding technique which is already known, namely holding the material at its rear end by the known clamping jaws.
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Elpatronic AG
Elve M. Alexandra
McCormick Paulding & Huber LLP
Stoner Kiley
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