When strict consideration of quality is required, calibration and compensation directly affect cycle time. A machine tool that operates at high speed within the specified accuracy range can maintain machining precision. Calibration allows for in-process workpiece inspection, saving time by eliminating the need for workpieces to be shuttled back and forth between the machine tool and coordinate measuring machines. Additionally, regular calibration can be used to predict whether the machine tool is likely to deviate from the accuracy specifications.
When using an online inspection bending machine, a suitable probe is used instead of a cutting tool to measure the dimensions of the workpiece. The spatial positioning errors can be listed in an error table or compensation table to allow the software to correct the measured probe position. By employing spatial error correction, the geometric and positioning errors of the machine tool itself can be eliminated, providing accurate dimensional measurements. Therefore, with the accuracy requirement of a 4:1 gage, a CNC machine tool with spatial error compensation can achieve the same high precision functionality as a coordinate measuring machine.
The trajectory of the moving target is not a straight line and involves significant lateral movement. Traditional interferometers cannot perform these measurements because they do not allow for such large lateral displacements. However, single-aperture laser interferometers such as Laser Doppler Displacement Meters are not affected by large lateral movements. Using a flat mirror as the target, the parallel movement to the mirror does not shift the laser beam or change the distance from the light source.
After refining the above repeatable basic steps, acceptable performance and precision levels can be determined. Additionally, it is necessary to measure and establish the baseline of the machine tool. The measurement of the machine tool is systematic and conducted at specified intervals. Through analysis, maintenance and repair forecasts can be integrated with production scheduling.
With technological advancements, the cost of laser calibration equipment has significantly decreased, and there is no longer a need for specialized metrology personnel or external services, leading to reduced machine tool downtime. A mechanic trained in laser calibration for a day can complete spatial measurements for a 1 cubic meter machine tool within half a day. The software can automatically generate compensation tables and upload them to the controller of the machine tool.
Previously, operating laser calibration instruments required specialized metrology personnel. Opening the machine tool enclosure was necessary to adjust optical components on the worktable, spindle, and independent tripod. The process of spatial calibration took several days, depending on the size of the machine tool. Therefore, when workpieces are measured within tolerance range by coordinate measuring machines, spatial calibration becomes less necessary.
Using a bending machine with spatial detection capability to inspect workpieces during the machining process can significantly reduce cycle time and improve machining precision. In the aerospace industry, online inspection has not been widely adopted because it would introduce the same positioning errors as the machining on the same machine tool.
