A developed algorithm for simulation of blades to reduce the measurement points and time on coordinate measuring machine (CMM)

Advances in Mechanical Engineering

Zhou

et al. 2018

Parts must be measured to evaluate the manufacturing accuracy in order to check whether their dimension is in expected tolerance. In engineering, parts with free-form surfaces are generally measured by high-precision coordinatemeasuring machines. The measurement accuracy is usually improved by increasing the density of measurement points, which is time-consuming and costly. In this article, a novel sampling method of measurement points for free-form surface inspection is proposed. First, surface inspection is simplified into the inspection of a number of section curves of the surface. Second, B-spline curves constructed with an iterative method are employed to approximate these section curves. Subsequently, data points necessary to construct the B-spline curves are taken as the measurement points. Finally, the proposed method is compared with other two sampling methods. The results indicate that the proposed method greatly reduced the number of measurement points without decreasing the precision of surface modeling.

Section: Introductionmentioning

confidence: 99%

Measurement point sampling method for inspection of parts with free-form surfaces

Zhao

Advances in Mechanical Engineering

Zhou

et al. 2018

“…Common contact probes are inductive displacement transducers [5], coordinate measuring machines, etc. Contact probes are accurate, being able to achieve the repeatability at 1 μm, but time consuming [6]. As the confused structure of coaxial hole parts, the contact probes cannot get all coordinates of measured points in some deep holes.…”

Section: Introductionmentioning

confidence: 99%

A Fast Measuring Method for the Inner Diameter of Coaxial Holes

Yang

et al. 2017

Sensors

A new method for fast diameter measurement of coaxial holes is studied. The paper describes a multi-layer measuring rod that installs a single laser displacement sensor (LDS) on each layer. This method is easy to implement by rotating the measuring rod, and immune from detecting the measuring rod’s rotation angles, so all diameters of coaxial holes can be calculated by sensors’ values. While revolving, the changing angles of each sensor’s laser beams are approximately equal in the rod’s radial direction so that the over-determined nonlinear equations of multi-layer holes for fitting circles can be established. The mathematical model of the measuring rod is established, all parameters that affect the accuracy of measurement are analyzed and simulated. In the experiment, the validity of the method is verified, the inner diameter measuring precision of 28 μm is achieved by 20 μm linearity LDS. The measuring rod has advantages of convenient operation and easy manufacture, according to the actual diameters of coaxial holes, and also the varying number of holes, LDS’s mounting location can be adjusted for different parts. It is convenient for rapid diameter measurement in industrial use.

“…CMM has the advantage of its precision and flexibility with respect to various measured objects. However, CMM requires significant resources in operating time, environment and skillful operators, which leads researches into other directions [3,4]. Pneumatic micrometer is another alternative for assessment of machined holes on the shop floor [5].…”

Section: Introductionmentioning

confidence: 99%

A Laser-Based Measuring System for Online Quality Control of Car Engine Block

2016

Sensors

For online quality control of car engine production, pneumatic measurement instrument plays an unshakeable role in measuring diameters inside engine block because of its portability and high-accuracy. To the limitation of its measuring principle, however, the working space between the pneumatic device and measured surface is too small to require manual operation. This lowers the measuring efficiency and becomes an obstacle to perform automatic measurement. In this article, a high-speed, automatic measuring system is proposed to take the place of pneumatic devices by using a laser-based measuring unit. The measuring unit is considered as a set of several measuring modules, where each of them acts like a single bore gauge and is made of four laser triangulation sensors (LTSs), which are installed on different positions and in opposite directions. The spatial relationship among these LTSs was calibrated before measurements. Sampling points from measured shaft holes can be collected by the measuring unit. A unified mathematical model was established for both calibration and measurement. Based on the established model, the relative pose between the measuring unit and measured workpiece does not impact the measuring accuracy. This frees the measuring unit from accurate positioning or adjustment, and makes it possible to realize fast and automatic measurement. The proposed system and method were finally validated by experiments.