The instrument for laser inspection of tubes, bars and small diameter barrels straightness

Device for laser control of straight pipe, rods and the like small diameters

Laser control device is designed to control the pipes with an inner diameter of 7.5 mm.

The device consists of:

• Prisms for securing the measured component;
• Linear motion systems for the stock, on which the aligning device with laser axis generator is mounted;
• Receiving device.

Measuring principle

The measured item is fixed in the prisms. In automatic mode, the stock, mounted on the carriage, moves along the item. A tripod-type centering device, in the centre of which a laser axis generating module is rigidly fixed, is fastened to the end of the stock through the precision propeller shaft. The module with laser from the centering device is mechanically decoupled from the stock and by its position repeats the inner profile of the measured items. 

The laser beam projected onto the receiver at each point in time provides information about the deviation of the axis by internal diameter of the item based on equal length of the centering device (~ 30 mm). A specialized software calculates the straightness of the item: along the entire length, at a certain control area, and generates a graph - the dependence of the deviation from the axis along the length of the item, when scanning the item along the length or along the array of instantaneous measurements.

Laser module with an optical system forms a parallel beam of light, structured for the several circles inscribed in each other. The receiver receives the image of these circles on the CCD matrix and defines the center of the laser line on the set of points. The use of circles, rather than the usual laser line, eliminates a number of uncertainties associated with the possible misalignment of the elements of the measuring system and enables the subpixel image processing with increased accuracy.

Technical and metrological characteristics

• Item length up to 1200 mm.
• Device length – the length of 2 items + 250 mm. 
• Device arrangement - table mounted.
• Accuracy of determining the deviation from the axis +/- 0.01 mm.
• Positional accuracy of OX axis measurements +/- 0.1 mm.
• Measuring time ~ 3 min.
• Minimum diameter of the controlled item - 7.5 mm.