Modeling and Simulation of the Engraving Process in Different Life Stages of Small Caliber Guns

Author(s):  
Mohamed Dhouibi ◽  
Hamza Ousji ◽  
Oussama Atoui ◽  
Rachid Nasri ◽  
Marc Pirlot

Abstract Effects of erosion phenomenon on the performance of a given gun barrel have been analyzed throughout numerical and experimental studies. Mainly, qualitative observations were performed. Theoretical relations between the evolution of the inner barrel profile and the provided interior ballistics are limited. This paper focuses on the development of a numerical model to predict the engraving resistance evolution in terms of the inner barrel profile in the different weapon's life stages. Four test barrels "12.7x99mm NATO" with different chamber volumes were considered. First, a Coordinate Measuring Machine (CMM) with a contact scanning probe was used to measure the inner dimension of the guns. Second, piezoelectric sensors with a special doppler radar were considered to measure the (i) pressure and (ii) the bullet velocity in the test weapons. Finally, based on the obtained experimental results, a Finite Element (FE) analysis using the commercial software LS-DYNA was developed and validated. The obtained numerical results were used as insights to quantify the relationship between the engraving resistance and the chamber volume of small caliber guns.

2018 ◽  
Vol 208 ◽  
pp. 03004
Author(s):  
Bin Wang

The measuring accuracy of CMM (Coordinate Measuring Machine) is influenced by many factors, such as temperature, humidity, measuring force and method of signal acquisition. For thin parts, the influence of measuring force is especially obvious. In this paper, the relationship between measuring force and measurement accuracy is studied for a thin part with a U-shaped cross-section. By analyzing the structure of the probe and establishing the force model, the influencing factors of the accuracy of CMM are obtained, and the influence of the contact deformation and the bending deformation on the measurement accuracy is analyzed from the point of view of material mechanics. At the same time, the measurement accuracy of different measuring cross-sections is analyzed. Through the research of this paper, the relationship between measuring force and CMM is established, and an effective method to improve the accuracy of CMM is also found.


1996 ◽  
Vol 118 (4) ◽  
pp. 595-603 ◽  
Author(s):  
Chenggang Che ◽  
Jun Ni

A new tetrahedron-target-based approach is presented for the extrinsic calibration of a non-contact “light-striping” (structured light) optical coordinate measuring machine (CMM). The procedure makes automated on-line calibration possible. The system modeling is based on a unique skewed frame representation without the use of pin-hole camera model assumption. It is demonstrated that the extrinsic calibration matrix can be decomposed into two classes of transformations, one homogeneous and the other nonhomogeneous. The nonhomogeneous transformation between a Cartesian world frame and the non-Cartesian skewed sensor frame is studied. The sensitivity of the dimensional deformation on the two skew angles is simulated. Experimental studies show that a micron level calibration accuracy can be achieved.


Machines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 33
Author(s):  
Peng-Hao Hu ◽  
Ying-Jun Lei ◽  
Yang-Kai Ou

This paper systematically summarized the technical state of art and research results on the motion error of a linear guideway, corrected some misconceptions, and further clarified the relationship between the straightness error of the guide rail itself and the motion error of the linear stage. Moreover, a new method based on parallel mechanism is provided to study the motion errors of the linear guide pair. The basic idea is to abstract the structural relationship between the stage and the guide rail into a 4-bar parallel mechanism. Thus, the stage can be considered as a moving platform in the parallel mechanism. Its motion error analysis is also transferred to moving platform position analysis in the parallel mechanism. The straightness motion error and angular motion error of the stage can be analyzed simultaneously by using the theory of parallel mechanism. Some experiments were conducted on the linear guideway of a self-developed parallel coordinate measuring machine. The experimental data and analysis verify the feasibility and correctness of this method.


Author(s):  
Mert Safak Tunalioglu ◽  
Turgut Torun

Gears are commonly used in every field of industry as power and motion transmission elements. According to the usage areas, they are manufactured from materials such as steel, aluminium, plastics, cast and bronze. There are different manufacturing methods according to material type. Plastic gears are preferred in textile, automotive and aviation industries where the supported load is low, and corrosion and lightness are considerably important. They work more quietly than metal gears. Plastic gears are manufactured by an injection moulding or hobbing method. The disadvantages of the plastic injection method are high cost of the injection moulds and strength losses in the moulded parts due to the internal clearance faults, whereas the disadvantage of the hobbing method is defects in tooth profiles due to operational faults. In this study, wear strengths of plastic spur gears manufactured via a three-dimensional printer with the fused deposition modelling technique as an alternative manufacturing method were experimentally examined. In the experimental studies, polylactic acid pinion gear manufactured with the three-dimensional printer was subjected to wear tests with St37-2 gear. Wear strengths of plastic spur gears were compared in wear tests performed with Forschungsstelle für Zahnrader und Getriebebau equipment under various loads and rotational speeds. Wear depths that occurred in plastic gears were examined via coordinate measuring machine equipment. As a result of the experimental studies, it is found that wear is increased with the increase of load affecting the gear, and wear is decreased with the increase of rotational speed. As a result of this study, it was shown that plastic spur gears manufactured with three-dimensional printers can be used in areas where lightness and corrosion resistance is important under low loads.


Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Guanbin Gao ◽  
Hongwei Zhang ◽  
Hongjun San ◽  
Xing Wu ◽  
Wen Wang

Articulated arm coordinate measuring machine (AACMM) is a specific robotic structural instrument, which uses D-H method for the purpose of kinematic modeling and error compensation. However, it is difficult for the existing error compensation models to describe various factors, which affects the accuracy of AACMM. In this paper, a modeling and error compensation method for AACMM is proposed based on BP Neural Networks. According to the available measurements, the poses of the AACMM are used as the input, and the coordinates of the probe are used as the output of neural network. To avoid tedious training and improve the training efficiency and prediction accuracy, a data acquisition strategy is developed according to the actual measurement behavior in the joint space. A neural network model is proposed and analyzed by using the data generated via Monte-Carlo method in simulations. The structure and parameter settings of neural network are optimized to improve the prediction accuracy and training speed. Experimental studies have been conducted to verify the proposed algorithm with neural network compensation, which shows that 97% error of the AACMM can be eliminated after compensation. These experimental results have revealed the effectiveness of the proposed modeling and compensation method for AACMM.


2021 ◽  
Author(s):  
Shixiang Wang ◽  
Chi Fai Cheung ◽  
Lingbao Kong

Abstract In this paper, a fiducial-aided reconfigurable artefact is presented for estimating volumetric errors of a multi-axis machine tools. The artefact makes use of an adjustable number of standard balls as fiducials to build a 3D artefact which has been calibrated on a coordinate measuring machine (CMM). This 3D artefact shows its reconfigurability in its number of fiducials and their locations according to the characteristics of workpieces and machine tools. The developed kinematics of the machine tool was employed to identify the volumetric errors in the working space by comparing the information acquired by the on-machine metrology with that by the CMM. Experimental studies are conducted on a five-axis ultra-precision machine tools mounted with the 3D artefact composed of five standard spheres. Factors including the gravity effect and measurement repeatability are examined for the optimization of the geometry of the artefact. The results show that the developed 3D artefact is able to provide information of the volume occupied by the workpiece.


1994 ◽  
Vol 116 (4) ◽  
pp. 482-490 ◽  
Author(s):  
K. B. Smith ◽  
Y. F. Zheng

This paper presents a new technique for digitizing an unknown sculptured surface using a new multi-Laser Displacement Sensor (LDS) and an articulated Coordinate Measuring Machine (CMM). The new multi-LDS measures the tangents, curvatures, and displacement of the surface. This local information is utilized in the technique to extrapolate the surface position and normal vector at the next location to be digitized. In addition, this paper derives the relationship between the digitizing error parameters and the ratio of sampling arc length to the radius of maximum curvature. This technique is illustrated experimentally using a six degree-of-freedom PUMA robot and a Keyence LDS.


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