Search

Setup planning is an important function in CAPP systems for determining the setups, sequencing these setups and their constituent machining features, and planning the jig or fixture required for each setup. The remedial or preventive measures required to resolve the problem of cycles commonly arisen between the setups are considered as a major challenge in setup planning procedures. In the present study, a permutation-based approach is introduced to setup planning which, in addition to its flexibility and ease of use, precludes the cycles. For this purpose, new rules have had to be introduced for the geometrical machining rules and an algorithm for automated application of these rules. The proposed procedure for the setup planning and application of the machining rules have been developed in Python OCC and verified by a detailed example. [ABSTRACT FROM AUTHOR]

Prior knowledge of the free-vibration responses of a hexapod is strongly needed to avoid resonance occurring in the prevailing complicated machining situations. A comprehensive study has been conducted by the authors on the free vibration of machine tools’ hexapod table, taking account of the whole kinematic chains. The results have been compared with those obtained from the vibration equations of the moving platform. The second approach entailing fewer equations can yield sufficiently accurate results for vibrations occurring in horizontal planes. The theoretical and finite element method (FEM) results exhibit similar trends of changes and are close to each other. The discrepancies between the results arise mainly from the rotational modes of vibration occurring in vertical planes, which are attributable to the dynamic nature of contact models. A hexapod table possesses distinct vibration modes, including linear vibrations in horizontal planes prevailing in lower modes and rotational vibration in higher modes. [ABSTRACT FROM AUTHOR]

Parallel mechanisms have found new applications in machine tool’s as the end effector carrying the spindle or used as the table of the machine. Investigations on the dynamics and especially the vibration behavior of these mechanisms are in the initial stage. The authors developed a vibration model for the hexapod table of milling machines and machining centers and derived the relevant explicit equations. The eigenvalue problem of the upper platform of hexapod was solved to obtain the natural frequencies of the platform. The results have been verified with FEM simulation. The distinguishing features of the hexapod tables from the view point of dynamic behavior have also been concluded. [ABSTRACT FROM AUTHOR]

The design of gripper jaws for the concentric handling of tapered components is investigated. The jaws have specially shaped profiles made up of a series of curves resembling the Greek character 'v', stacked one on top of another. The equations for the profiles are derived. The geometrical parameters affecting their dimensions and shapes are identified. The selection of values for the parameters to yield optimum profiles is discussed. [ABSTRACT FROM AUTHOR]

The state of the art in the technology of jigs and fixtures is reviewed. Heuristic and analytical principles of jig and fixture design are summarised. An interactive knowledge-based program for assisting designers of jigs and fixtures is described. The program incorporates design principles in the form of explicity declared facts and rules as well as numerical procedures. The declarative part of the program is implemented in an expert system shell with a powerful inference engine and comprehensive explanation and trace facilities. Details of these are given, together with a simplified example of a design session using the program. [ABSTRACT FROM AUTHOR]