Journal of Mechanical Working Technology最新文献

In this paper a numerical solution of strip rolling based on finite element method is presented. The material behavior in the form of a stress-strain curve obtained from a plane-strain compression test and measured interfacial velocities as prescribed boundary conditions are used as input data to the numerical model of strip rolling. Numerical results such as distributions of roll pressure, frictional stress, and coefficient of friction in the contact region are presented.

In sheet metal working of large automobile parts, for the alignment of the upper and lower dies two types of guidance systems are used, namely the pillar guides and the heel block guides. The objective of the project is the determination of the angular deflection, the lateral offset and the angular spring constant of the die guidance systems with regard to the performance of the press slide under central and eccentric loading. The results of the experiments reveal that the heel blocks with brass plates produce optimal improvement with regard to die and slide tilting and lateral offset. The use of a combination of heel block guides and pillar guides produces only a small increase of angular stiffness.

Based on Kalman filter and probability theories, a failure detection model as well as a monitoring supporting system have been developed for machining process control and monitoring. Experimental results from computer simulations show that the model and the supporting system are effective and the average time in detecting typical failure signals is reduced about 20 percent when utilizing the supporting system.

This paper describes the computer-integrated design, fabrication and inspection of a 3-D curved surface as part of a wider study into the creation, machining and measurement of free-form surfaces. Using the CATIA solid modeller, a 3-D curve was first created using both a single arc and a spline followed by a surface patch. The surface generated by the two spline curves was faceted in appearance when machined, whereas that of the single arcs was smooth. An NC part program was generated interactively with dynamic, on-screen tool path display. However, because it was inconvenient to change the machining parameters, such as feedrate, within the NC program, a custom macro was written to make the NC program more readily modifiable. Machining tests carried out on aluminum and carbon steel test specimens yielded encouraging results. In the computer-assisted measurement of the surface on a CNC CMM, the VDA (Verband der Automobilindustrie Surface Data Communication Interface was adopted as the medium for data exchange between the CAD/CAM system and the CNC CMM. Instead of the SURF (surface) function, measurement was accomplished using a sequence of discrete measurement points, PSET.

The minimization of the workpiece surface damage due to randomly occurring arcing and the improvement in the process performance are the main objectives of the gap monitoring and control system incorporated with the state-of-the-art commercially available EDM units. This paper evaluates the effect of a recently developed control system based on monitoring of Radio Frequency signal on the surface integrity of components machined by EDM.

The experimental results of machining AISI 4130 steel and Titanium Carbide Adamas Titan 80 under the existing machine control, orbital motion and/or R.F. control indicate a substantial improvement in surface integrity with R.F. control. The effect of R.F. parameters on process performance and surface damage is further investigated by modelig and analyzing the surface profile characteristics using Data Dependent Systems methodology.

In this paper, a framework for automated mechanical assembly planning is discussed. The paper addresses three major issues: conceptual assembly design representation, assemblability analysis, and assembly plan generation. The objective of the study is to develop an effective way to model and plan for the assembly of a product. It is hoped that noty assembly planning can be automated, but also the feedback provided by the planning system can help to improve the design from a manufacturing point of view. Since the feasibility of automating the assembly plan generation depends on whether the assembly design is represented in a complete, unambiguous, and easy to use form, the design representation is the first issue addressed. In order to ensure the “manufacturability” of an assembly, the assemblability of the design must be analyzed at the early design stage. This analysis can be viewed as a rough planning. It provides the designer a quick feedback, thus the design can be changed before it is finalized. Before the actual assembly can be conducted, a detailed assembly plan must be prepared. Such an assembly plan is used for shop scheduling, and sometimes assembly system design.