Continuous resistance welding apparatus and method

A welding system comprising:

• a resistance station including welding means positioned at a welding point for continuously welding along predetermined straight and curved aligned marginal portions of superimposed and aligned workpiece sections and means for conveying the superimposed workpiece sections past said point, said superimposed workpiece sections to be welded having aligned opposite straight parallel marginal portions, at least one aligned pair of which are to be welded and a straight marginal portion extending transversely between said opposite straight parallel portions, said curved marginal portions interconnecting the ends of said transversely extending straight marginal portion with said opposite straight parallel marginal portions of said superimposed workpiece sections;
• guide apparatus and workpiece-rotating apparatus for respectively guiding the straight and curved aligned marginal portions of said workpiece sections along predetermined paths of travel including a linear path for welding said superimposed straight marginal portions and a non-linear path for welding said superimposed curved marginal portions of the superimposed workpiece sections, said paths passing through said weld position point of said welding means, said guide apparatus including first and second side guide means positioned respectively to engage said opposite straight parallel marginal portions of the superimposed workpiece sections, to hold said workpiece sections in superimposed contact with each other during welding of the straight marginal portions, said second side guide means being v-shaped to apply a clamping together force on the outer opposite straight parallel marginal portions of the superimposed workpiece sections as the innermost ends of same are being moved past said welding point and to push the latter marginal portions against said first side guide means to guide the workpiece sections slidably engaging the same, said second guide means adapted to be moved into and out of engagement with the adjacent straight marginal portions of the superimposed workpiece sections as required to allow said portions thereof to be welded to travel said predetermined path, and said workpiece rotating apparatus being adapted to rotate said superimposed workpiece sections so that the curved marginal portions thereof are moved past said weld position point;
• sensing means for sensing the passage of the leading edges of superimposed workpiece sections approaching said welding means for moving said second side guide means against the outer straight marginal portions thereof to push the same against said first guide means to stabilize the position of the workpiece sections fed by said welding means, and, upon termination of the welding of straight marginal portions of said workpiece sections, for moving said second side guide means away therefrom to permit rotation of said workpiece sections.

A welding system comprising:

• a welding station including welding means positioned at a weld position point for continuously welding along superimposed and aligned predetermined marginal portions of superimposed workpiece sections and means for conveying the superimposed workpiece sections past said point;
• guide apparatus and workpiece-rotating apparatus respectively including guide wall means for guiding the portion of said superimposed workpiece sections to be welded along a predetermined linear path through the weld position point of said welding means and a workpiece-rotating tracking system for guiding said superimposed workpiece sections to be welded along a non-linear path of travel through said weld position point;
• sensing means for sensing the operating parameters of said system including the presence or absence of said superimposed workpiece sections as they move in said linear path and for producing suitable signals indicative of said parameters, and said sends means including first, second and third sensor means adapted to signal the presence and/or absence of said superimposed workpiece sections at various locations as they move along said path into and through said welding means, said first sensor means being located to detect the presence or absence of a pair of superimposed workpieces in points where a movable guide means can be moved thereagainst to stabilize the lateral position thereof and points where said movable guide means can be moved away from the superimposed workpieces to release the same therefrom so that said tracking system can move the superimposed workpieces in a non-linear path;
• said second sensor means being located to detect the position of said workpieces at a point where welding is to begin, and said third sensor means being located to detect the position of said superimposed workpiece section at a point where said tracking system is to be operative to move said superimposed pieces in a non-linear path;
• and
• a controller means interactively connected with said welding means, a tracking system and said sensing means to control the operations of said welding means and tracking system to move said workpiece at a rate of speed along said path into and through said welding means to complete a continuous weld.

A method of automatically welding a plurality of pairs of superimposed aligned workpiece sections each having a center of percussion and aligned longitudinal edges terminating at one end in one or more aligned, partially circular corners or margins, said workpiece sections to be welded at least along one of the aligned longitudinal edges thereof and the aligned partially curved corner or margin at the end of said aligned longitudinal edges, said method comprising the steps of:

• conveying the aligned longitudinal edges to be welded of each pair of superimposed workpiece sections through welding means at a welding station;
• arranging said pairs of superimposed workpieces fed to said station so that, upon termination of the welding of said sections along aligned longitudinal edges of a pair of superimposed workpiece sections, the superimposed workpiece sections are arranged to be pivotally mounted next to said welding means at said one end about an axis at the center of the partially circular corner or margins to be welded;
• and
• exerting a force against one of the aligned longitudinal edges of the pair of workpiece sections involved at a point where the center of percussion arc intersects the same such that the forces are, in effect, exerted at or near the center of percussion of the superimposed workpiece sections being welded, so that the workpiece sections are pivoted with minimum vibration about said axis to move the aligned partially circular corners or margins being welded through said welding means.

A method of continuously welding aligned, superimposed workpiece sections, said workpiece sections having initially aligned pairs of longitudinally and transversely extending linear marginal edge portions and non-linear marginal bridging edge portions interconnecting the adjacent ends of said linear marginal edge portions, said method comprising the steps of:

• assembling in superimposed relation a plurality of workpiece sections with said pairs of marginal edge portions thereof to be welded together in alignment and lying in contact with each other;
• positioning said superimposed assembled workpiece section on a conveying means with a first pair of initially aligned longitudinally extending marginal edge portions of said superimposed workpiece sections abutted against a first longitudinally extending guide wall means and a second opposite longitudinal marginal edge portion thereof slidably received in a second longitudinally extending guide wall means;
• guiding said pairs of workpiece sections in a longitudinal linear path between said first and second guide means into the nip of a pair of rotating weld rollers, drawing the workpiece sections by means of said pair of rotating weld rollers through welding points along the length of one of the first initially aligned longitudinal marginal edge portion of the superimposed workpiece sections;
• removing said second guide wall means from contact with and location near said workpiece sections, and moving said superimposed workpiece sections in a non-linear path by exerting a lateral force against said aligned first pair of longitudinal marginal edge portions of said workpiece section at or near the point of intersection thereof of the center of percussion arc.