Applied Mechanics and Materials Vols. 599-601

Abstract: For the problems about design and manufacture of the variable pitch tapered end mills, this study proposes a three-dimensional parametric design method of variable pitch mill. Firstly the equation of calculating the optimal angle between the pitch was presented .Considering existing different patches between two cutting edges, helix edge curve and cross-section groove model of tapered end mill were established .Secondly, mathematical expression of ball end teeth for tapered mill was derived, and all points data of tapered mill surface can be determined by established model. Through the graphical representation, the points set are translated into a solid model.

Abstract: According to the conventional fracturing could easily lead to the local stress concentration of coal, the effect of pressure relief and permeability improvement is not ideal. The mechanism of directional hydraulic fracturing is analyzed and the parameters such as the layout of directional hole, the fracturing hole sealing, the minimum cracking pressure are discussed, then the field application tests are carried out. The results show that the directional hydraulic fracturing effect is better than that of ordinary fracturing hole and the maximum concentration and the average drainage scalar is respectively 3.75 times and 4 times of the ordinary hole pumping gas fracturing effects. The effect of permeability improvement is remarkable.

Abstract: For higher geometrical accuracy requirement of optical lens, much research has been conducted either by changing the injection process parameters or changing the material of the mold or the mold manufacturing process. Although some degree of improvements was achieved, those were occasional but not-repeatable. One conventional procedure has been: the injection mold core must be polished several times to obtain qualified lens product in preproduction trial, very uneconomical and inefficient. In this paper, modern engineering tools were applied to simplify the correction process in optical lens fabrication. Combining virtual manufacturing with reverse engineering technology, the method was demonstrated very powerful. For the optical lens of 70x29.1mm in this research, the maximum deviation from the flatness after regular plastic injection molding was 0.208mm. While with combined technology of VM and RE the error was reduced to 0.008mm only by once iteration with an improvement of 96.15%. Not only the technology could be extended to larger or more challenging lens fabrication, it could also be applied to curved surfaces. This is really great tool to achieve higher quality optical lens production with much lower expending in labor and funding.

Abstract: This paper presents the research work involved in the development of knowledge based system (KBS) for blanking die. Automotive covering parts stamping production as one of the important chain of automobile manufacturing, especially the design of blanking die played a vital role. And the success of blanking die design often rely on the experience and knowledge of experts. And because of the knowledge of "privacy", new mold production designer is difficult to be familiar with the design processes and structure parameters in a short period. Such a phenomenon extended the production cycle, and increased manufacturing costs. This topic from the perspective based on knowledge, by means of integration, in view of the blanking die design of similar offers ways and means to solve the problem.

Abstract: Singularity problem in attitude estimation of small tail-sitter aircraft with traditional algorithm is researched. According to the flight characteristics of small tail-sitter aircraft, a new algorithm is proposed. Vertical Euler angles whose singularity points are away from standard Euler angles are introduced. Only one set of angles are used in horizontal or near-vertical state to avoid singularity. Simulation results show that attitude angles can vary continuously and have high accuracy under the condition of a large tilting angle.

Abstract: This paper establishes a system that can automatically generate CNC code based on readable image formats such as *. jpg, *. gif, *. bmp, *. pcd, *. tif, and make use of machine tool for CNC machining. This system first vectorizes an image by using preprocessing such as smooth processing, edge detection, and contour tracking, and converts it into CNC code, then generates a program that can be identified by PMAC, and drives machine tool to process CNC machining. At last, an example proves the validity of this method.

Abstract: Simulation model of landing gear hydraulic system is built based on AMESim, several key influence factors of performance degradation of landing gear hydraulic system are analyzed, such as changes of restrictor orifice diameter, initial pressure of accumulator, viscosity and gas percentage of oil , etc. The simulation results bring valuable reference to aircraft maintenance.

Abstract: For the purpose of the fabrication of the sheet-metal parts with non-horizontal end face using the sheet metal CNC incremental forming technology, two kinds of path generating methods, namely the level path perpendicular to Z axis method and the equidistant path parallel to sheet metal are proposed in this paper. Both of the paths are generated by Visual C++ and OpenGL graphics library, the effect of the two kinds of forming paths to the forming quality of the sheet part with non-horizontal end face is researched using the finite element analysis method in this paper.

Abstract: In order to verify the correctness of the NC processing program which is generated by the post processing module of the Independently developed 5-axis micro-milling system, this article analyze the motion structure and obtained the topology relation between the feed shafts of the micro-milling system, established the milling simulation model of the micro-milling system by the VERICUT—the Virtual machining simulation platform. The milling process of an example part with a typical ellipsoid structure has been simulated by the milling simulation model and the correctness of the NC processing program and coordinate transforming relation have been verified by the simulation result.

Abstract: An FE model is established on the basis of ABAQUS software for simulating the closed cold rolling process of the high speed TRB (tapered roller bearing) with heavy load. The influences of the feed speed, main roll rotational ratio, and initial angle between two guide rolls on the stress uniformity of the formed bearing rings are studied by evaluating the standard deviation of the Von Mises on all elements in the FE model. The research shows that the stress uniformity of the formed bearing rings decreases with the increment of the feed speed; the stress uniformity increases with the increment of the main roll rotational ratio; and the stress uniformity increases with the increment of the angle between two guide rolls.