Welded Pipe Manufacturer uses Laser Scanners

Filed under: 2D Profile Scanner

A global manufacturer of steel pipes, tubes and rods maintains plants around the world that use the latest in factory automation technology.  Engineers from a plant in Brazil wish to improve the fabrication processes of welded steel pipe that is used in the oil and gas indstry.  Their product is formed in a multi-step bending process to steel sheet stock.

In the first step of the pipe fabrication process, a large, 12-m long carbon steel sheet is fed into a press which bends both edges with a slight radius of curvature.  Precision molds sandwich the material at high pressure to introduce the appropriate bend.  The system bends 3-m sections of steel at a time and a conveyor advances the material through the process until the full length of sheet has been bent.  The edge bend introduces a curve approximately 40 mm from the edge, leaving a straight tail at the very edge.

In subsequent steps, the steel sheet is further formed into a tube by using other presses.  Only at the end, the round structure is completed by welding the original edges.  The initial edge bend is critical to final gap alignment for successful welding and proper pipe dimensions and straightness.

The prior method for measuring / verifying the dimensions of the steel sheet edge was manual in nature.  Line workers would use a combination of templates, “feeler gages” and a ruler to verify the radius of the bend in the metal as well as the length of the straight tail between the end of the bend and the edge of the sheet.  Certainly, this method was operator dependent and subject to great variability and innaccuracy.  Over time, the template becomes deformed and worn and defeats the purpose for its initial use.

Replacing the manual verification methods was the implementation of non-contact scanning technology.  A 2D profile-scanning laser is installed aboave the edge and projects a wide laser line across the steel surface.  As the material passes beneath the scanner, it’s dimensional shape profile is captured by the sensor’s CMOS detector array.  This X Z position information is transmitted via Ehternet interface to a PC computer that hosts measurement algorithms (software) which automatically analyzes the high-speed data and calculates the radius of curvature and the length of the straigh tail of steel sheet edge.  At full speed, the laser scanner captures up to 250 profiles per second.

Integrators will install pairs of laser scanners along each edge to measure the desired dimensional information and to track the edge positions to ensure that the sheet is centered along the fabrication process.  Because the scanner captures both depth position and field of view, the representation of the profile is not susceptible to slight material vibrations as it is conveyed through the process by the roller bed.  The video below illustrates the entire process and the implementation of the AccuProfile Scanners in this application.  Contact Acuity with questions.

          

Steel Tank’s End-cap Dimensions

Filed under: Long-distance rangefinders

A manufacturer in Brazil designs and builds tanks and vessels for use in various chemical and petrochemical industries.  The tanks built from carbon or stainless steels, are fabricated in sections and welded together in a final assembly.  They are required to maintain strict dimensional tolerances for the pre and final assemblies.  The company approached Acuity to assist in improving their dimensional measurement practices.

Manufacturers must control the dimensions of the fabricated

Current quality control tool - a wooden template the same shape as the endcap

The manufacturer currently verifies the shape and dimensions using manual methods.  Operators use a tape measure to determine the diameter of the hemisphereical endcap.  The resolution of this measurement technique is 1mm and the accuracy varies on the operator technique.  They have no method for measuring the interior profile dimensions of the tank’s endcap.  For quality verification, operators insert a large, wooden template into each vessel and attempt to assess its fit.  They will look for gaps between the edge of the template and the surface of the vessel.  The plywood template is subject to thermal and moisture-induced expansion and contraction.  The templates require two operators.

The solution to the measurement challenge was to use a non-contact laser distance sensor to measure the interior surface of the end-cap from a central measurement axis.  The rangefinder would be rotated 180°, measuring the distance from one edge, through the base and to the other edge.  This would allow not only the diameter, but also the entire profile of the shape.  This information could be transmitted to a computer for display and archiving.

The AR1000 laser distance sensor has a measurement resolution of 1mm and was successful in measuring all expected surfaces, including bright-ground steel, light oxidation, paint, oiled surfaces, black paint, gray paint, etc.  The planned orientation of the sensor guaranteed a strong laser reflection off shiny surfaces.

          

Brake Line Tip Inspection

Filed under: Confocal Displacement Sensor

Engineers use a precision scanning confocal displacement sensor to inspect the surface of a steel brake line tip for scratches and defects.  They use a new white-light distance sensor from Acuity.  The measurement pen aims down to the sample that is moved on a linear XY stage.  The scanning station includes a turret of several confocal measurement pens, but users can order single-channel systems.