719 Development of gear measuring machine which has coordinate measuring system and three dimensional analysis on gear flank surface

This article proposes a modified sequential multilateration method for measuring three-dimensional coordinates. The measuring system consists of a single laser tracker and four relay targets whose relative positions have been pre-calibrated by the multilateration method. The laser tracker is fixed on three prescribed positions successively, and these positions can be calibrated by using the distances between the laser tracker and the four relay targets based on the multilateration principle. Subsequently, the three-dimensional coordinates of each under-test point can be determined by the three laser trackers’ positions based on the trilateration principle. This method is more flexible than previous multilateration methods for three-dimensional coordinate collection, especially if the measurement space is partially covered by other objects. The mathematical model of this method is established. Based on the Monte Carlo method, a series of computer simulations are performed to optimize the system arrangement by investigating the performances of the measuring system with different system arrangement, and an optimal system arrangement is finally obtained. Practical measurement is also conducted to demonstrate the validity of the proposed method by comparing with a reference coordinate measuring machine.

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Control Point Position Calibration for Light Pen Coordinate Measuring System

E3S Web of Conferences ◽

10.1051/e3sconf/202020603026 ◽

2020 ◽

Vol 206 ◽

pp. 03026

Author(s):

Sen Wang ◽

Shugui Liu ◽

Qing Mao

Keyword(s):

Control Point ◽

Three Dimensional ◽

Coordinate Measuring Machine ◽

Measuring System ◽

Point Problem ◽

Control Points ◽

Calibration Methods ◽

Measuring Machine ◽

Position Calibration ◽

Light Pen

Light pen coordinate measuring system is a kind of vision-based portable coordinate measuring technique. It implements coordinate measuring by analyzing the image of light pen, which has several control points. With the relative positons of the control points determined and the pixel coordinates of their image points acquired by image processing, the posture of light pen can be obtained by solving perspective- n-point problem. Therefore, the control point positons serve as the measuring basis of the whole system. However, the accuracy of existing calibration methods is not satisfactory. In this paper, a new method of control point positon calibration, which utilizes traditional coordinate measuring machine, is proposed. The light pen is fasten to the measuring arm of a coordinate measuring machine and moves along a three dimensional grid route driven by the machine. A stationary camera is located in front of the machine to capture the image of light pen at each node of the route. For each control point, an individual coordinate system is established. Then the relative positions of control points can be transformed into the differences of a series of translation vectors. Experiments show that, with the proposed method, the accuracy of light pen coordinate measuring system can reach 30m within 10 meters.

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In situ investigation of the primary recrystallization of alpha titanium in HVEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100110313 ◽

1978 ◽

Vol 36 (1) ◽

pp. 634-635

Author(s):

S. Naka ◽

R. Penelle ◽

R. Valle

Keyword(s):

Dimensional Analysis ◽

Texture Evolution ◽

Cold Work ◽

Three Dimensional ◽

Primary Recrystallization ◽

Thin Foils ◽

In Situ Investigation ◽

Grain Growth Model ◽

Alpha Titanium

The in situ experimentation technique in HVEM seems to be particularly suitable to clarify the processes involved in recrystallization. The material under investigation was unidirectionally cold-rolled titanium of commercial purity. The problem was approached in two different ways. The three-dimensional analysis of textures was used to describe the texture evolution during the primary recrystallization. Observations of bulk-annealed specimens or thin foils annealed in the microscope were also made in order to provide information concerning the mechanisms involved in the formation of new grains. In contrast to the already published work on titanium, this investigation takes into consideration different values of the cold-work ratio, the temperature and the annealing time.Two different models are commonly used to explain the recrystallization textures i.e. the selective grain growth model (Beck) or the oriented nucleation model (Burgers). The three-dimensional analysis of both the rolling and recrystallization textures was performed to identify the mechanismsl involved in the recrystallization of titanium.

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