Process: Resistance seam
Type of steel:Cold-rolled
Thicknesses:0,2 mm - 3 mm
Widths: 510 mm - 2000 mm
Applications: Continuous
annealing
Electro-galvanizing
Galvanizing
Preparation
Reconditioning
Coating
Types of steel: Special steels, silicon steels, stainless steels and other varieties
Joint configuration
Advantages of this technique
High reliability in rapid continuous treatment processes on sheet metal up to 3 mm thick
Single-pass (Pres-Lap) and double-pass (Prep-Lap) welding
Double-cut shear cutting
Cycle time:
- One strip 1900 mm wide and 2.1 mm thick:
- 25 seconds (Pres-Lap)
- 38 seconds (Prep Lap)
Very strong weld
Weld reinforcement less than 10% of the thickness of the strip
Possible options: on-line reprofiling and pre-loading system
Pres-Lap / Description:
These seam welding machines, developed from the Narrow-Lap model, are designed for fast steel industry production lines handling thickness ranges of 0.2 mm to 3 mm.
The welded joints can undergo the same treatment as the sheet metal and can be retained during winding. The small reinforcement of the weld does not mark the adjacent turns. The single-pass welding, crushing power and high welding speed give this equipment an exceptionally short cycle time for the thickness range handled. Consequently, the size of the accumulators of the entry section and the number of dancer rolls are reduced, which leads to a considerable reduction in costs and equipment.
The Pres-Lap machine is equipped with a hydraulically actuated double squaring shear. Planishing wheels are mounted directly behind the welding wheels. The welding operation is thus immediately followed by flattening of the weld while it is still hot. The welded joints give the best possible combination of mechanical strength and appearance: the mechanical strength of the joint is greater than the strength of the strips in the annealed state and its reinforcement will be at most 10% of the thickness of the strip (with a minimum of 0.07 mm).
For example, the time required to carry out a complete butt welding cycle is 25 seconds for a strip 1900 mm wide and 2.1 mm thick, excluding clamping.
With the MALEX S.A. pre-loading system, the total line stoppage time will be limited to 34 seconds.
Prep-Lap / Description:
The Prep Lap welding machine is the ancestor of the Pres Lap machine. It has the same equipment as the Pres Lap and presents the particularity of preparing the joint by a first pass with the planishing wheels. The welding wheels and planishing wheels will then carry out the welding and the final planishing to reduce the reinforcement to a minimum. The cycle time is longer than that of the Pres-lap machine because of the two passes. Prep-Lap machines are currently used on the majority of production lines for cold-rolled steels up to thicknesses of 3 mm.
For example, the welding cycle time will be 38 seconds for a width of 1900 mm and a thickness of 2.1 mm.
Our other conventional solutions