The straightness of the titanium bar is measured by a two-dimensional laser measurement sensor. The two-dimensional laser measurement sensor is a high-precision sensor that can simultaneously measure dimensions in both directions, and its shape characteristics are shown in figure 1. The sensor emits a linear laser, and when the laser hits an object, the diffuse light returns to the sensor's receiving system. The dimensions of the X and Z axes can be measured by processing the return beam.

The bar under test is naturally placed on a flat surface, and the two-dimensional laser measurement sensor is driven by the servo motor of the linear guide rail slide table to conduct the whole scanning process above the titanium rod for data collection. The collected data include the location of the edge of the titanium rod measured by the sensor after the scanning is completed (run-out in the x direction) and the arc vertex of the titanium rod (run-out in the z direction). At the same time, the two data and the servo motor's moving position are matched one by one and stored in the database as the position data of a section. By connecting the difference of the spatial position of all the collected sections, the bending of the workpiece can be restored and the straightness data of the measured workpiece can be obtained.

The whole system of titanium bar straightness and diameter composite measuring instrument mainly consists of measuring instrument, control cabinet, industrial control computer, display, LED display screen, sound-light alarm and so on.

The measuring instrument is mainly composed of a frame, a marble platform, a beam, a linear guide rail slide platform and a two-dimensional measuring sensor. During the detection, the titanium rod is put into the measurement area of the two-dimensional measurement sensor, and the two-dimensional measurement sensor is driven by the linear guide slide table to scan the titanium rod in the whole process. The scanning results are transmitted to the industrial computer in the control cabinet through the data line for processing and calculation, and the straightness error of each position of the titanium rod can be obtained. The maximum value of the selection error is denoted as the straightness error of the titanium rod. When the straightness error exceeds the set tolerance range, the sound-light alarm will give an automatic sound-light alarm to achieve the purpose of qualification determination.

The titanium bar straightness and diameter composite measuring instrument displays the X-axis position and z-axis size in real time, and displays the maximum straightness error and the set straightness tolerance after scanning.

The titanium bar straightness and diameter composite measuring instrument can also realize high quality online testing of other rods in addition to the titanium rod, effectively reducing the cost of single piece inspection after production, and can effectively save the loss of raw materials and reduce personnel demand. It can be used for on-line detection of high temperature titanium rod and can adapt to various working conditions. It is a very practical measuring system.