Workspace analysis of reconfigurable parallel machine tool based on setting-angle of spherical joint

Workspaces of two plane-symmetry parallel machine tools whose limbs are composed of the revolute joint, the prismatic joint and the spherical joint were studied comparatively in this paper. Firstly, manipulators of the plane-symmetry 3-RPS parallel machine tool and the plane-symmetry 3-SPR parallel machine tool were introduced, and their simulation manipulators were given. Secondly, the workspaces of the plane-symmetry 3-RPS parallel machine tool and the plane-symmetry 3-SPR parallel machine tool were solved and expressed in the same figure on the basis of the computer aided geometric technique method, respectively. Lastly, indices measuring the workspace were defined, and workspaces of the plane-symmetry 3-RPS parallel machine tool and the plane-symmetry 3-SPR parallel machine tool were analyzed comparatively from two aspects: positional workspace and posture angle.

A 5-Degree of Freedom (DOF) 5-UPS/PRPU fully parallel machine tool (PMT) was introduced. Based on the original edition of CNC system, the concise motion control algorithm was deduced by analyzing the identical feature between two Euler angles of 5-UPS/PRPU PMT and two swing angles of conventional 5-axis cutter swing machine tool. Then by using the formula of the inverse kinematic solution of the PMT, the length of the driving axis in the joint space can be calculated. The new CNC system software based on this algorithm was developed and it has been applied successfully to the 5-DOF PMT in our laboratory.

A review of parallel kinematic machine tools: Design, modeling, and applications

Reconfigurable manufacture system is to list as one of key technologies which will first solve in the future manufacturing, this article will mainly solve research on theory of reconfigurable for NC machine tool. Reconfigurable machine tool has many merits that include modularization, integration, custom-made, convertibility and so on. That is the traditional machine tool cannot compare.This article has carried on the analysis from the deep hole components classification and the formed movement craft two aspects to the deep hole components race. The reconfigurable deep hole machine tool was to carry on the modular design based two aspects for the module partition and reconstructable analyze, solved the key technologies the machine tool modulation design. From the machine tool bed module, the head of machine tool module, the cutting tool auxiliary system and the numerical control system four aspects, to design and research on reconfigurable machine tool, solved the difficult design problem which the part reconfigurable designed. Finally uses the ultrasonic wave examination technology, has realized numerical control machine tool element level restructuring. (5 pages)

Reconfigurable Machines form a new class of machines that are designed around a specific part family of products and allow rapid change in their structure. They are designed to allow changes in production requirements by changes in the machine mechanical configuration and structure. Reconfigurable machines might be designed for various types of production operations such as machining, inspection and assembly. This paper introduces characteristics and design principles of reconfigurable machines, and describes their features using an example of our new full-scale industrial prototype of a Reconfigurable Bore Surface Inspection Machine (RBSIM). In addition, the paper also describes briefly other three prototypes of Reconfigurable Machines that were developed during recent years in our center: (1) the Reconfigurable Machine Tool (RMT), (2) the Reconfigurable Inspection Machine (RIM), and (3) the Reconfigurable Assembly Machine (RAM).

This paper took a 3-UPS Parallel Machine Tool (PMT) as the object of research; it mainly introduced the process of establishing the compensation strategy for this PMT. Firstly the kinematics equations on driving chain and constraint chain was established on the basis of kinematics analysis. Then according to the structural characteristics and the results of kinematics analysis, the error compensation strategy of feedback correction type with the semi-closed loop control mode was used in the error compensation for this PMT by the method of installing respectively the encoders on the each joint of parallelogram mechanism, namely the compensation way of “parallel driving and series feedback” was adopted. Finally this paper has also deduced the theoretical model of error compensation. The research results in this paper provided a theoretical basis for realizing error compensation of this PMT, and had important practical significance for improving machining precision of PMT

A novel 6-SSP parallel machine tool and a novel 4SPS+UPU parallel machine tool are presented, and a novel CAD approach is proposed to machine a 3D free-form surface in its normal direction by using the two parallel machine tools. First, by adopting the CAD geometry constraint and dimension-driving technique, the simulation mechanisms of a 6-SSP parallel manipulator with 6-DOF and a 4SPS+UPU parallel manipulator with 5-DOF are created. Second, a 3D free-form surface and a guiding plane of tool path are constructed above the moving platform of the two simulation mechanisms. Third, the tool axis of simulation parallel machine tool is retained perpendicular to the 3D free-form surface. In the light of two prescribed tool paths, the driving limbs and the pose of the moving platform of parallel machine tools are solved automatically and visualized dynamically.

The objective of this research was to integrate an Electrical Discharge Machining module onto an existing reconfigurable CNC machine tool, using a modular approach, which potentially would enable conventional milling and EDM to be conducted in a co-ordinated fashion on the same machine tool. Ideally, multi-axis EDM is desired; however, single axis investigations were first done, as a step towards this ideal. The investigations determined which possible integration options should be pursued. This paper considers these single-axis investigations. The integration strategies implemented and evaluated in this research were (a) using the EDM machine's servo-drive output to drive the Reconfigurable Machine Tool's Z axis servo motor, via an external amplifier, (b) using a control signal from the EDM machine to communicate with the PC-based CNC control program (Mach3) to achieve advancement and retraction of the electrode using the RMT's Z axis servo motor, but governed by the EDM process, and (c) using an external controller, effectively replacing the EDM machine's controller and the CNC controller, while providing actuation of the electrode by means of a moving coil linear actuator mounted on the (now fixed) Z axis of the CNC machine. The external controller was implemented in LabVIEW, using a data acquisition device. The third strategy required that a voltage monitoring circuit be implemented to sense conditions at the EDM process spark gap. Single axis EDM was implemented using this method, but a version of the controller for potential 2-dimensional machining was also developed. PC simulation models of the linear actuator, controller, and EDM process were produced.

Firstly, structure component of the 6PUS-UPS PMT (Parallel Machine Tool) was introduced. Secondly, errors during the machine tool debugging were analyzed and measured, and those determined by the 6PUS-UPS PMT structure character were focused on, including the clearance error between the slider and the guide way, the vibration error and the verticality error and so on. Lastly, the verticality error was measured using the digital display micrometer and the frame level, which has great influence on the 6PUS-UPS PMT precision

In the development of robots and machine tools, in addition to conventional and serial structures, parallel mechanism-based kinematic structures have been used over a longer period of time. Aside from a number of advantages, the irregular shape and relatively small dimensions of the workspace formed by parallel mechanisms rank among the major weaknesses of their application. Accordingly, this fact has to be taken into consideration in the process of designing parallel mechanism-based robots or machine tools. This paper describes the categorization of criteria for the conceptual design of parallel mechanism-based robots or machine tools, resulting from workspace analysis as well as the procedure of their defining. Furthermore, it also presents the designing methodology that was implemented into the program for the creation of a robot or machine tool space model and the optimization of the resulting solution. For verification of the criteria and the programme suite, three common (conceptually different) mechanisms with a similar mechanical structure and kinematic characteristics were used.

The manipulator workspace denotes the work area of a manipulator and it is an important foundation of designing a robot. The workspace of a novel symmetrical 4-DOF 3-RRUR parallel manipulator is researched here based on the inverse solution. Five essential conditions of a point within the workspace of the manipulator are presented and the cause of the existence of each condition is given. According to the characteristics of this parallel mechanism and the geometrics, and based on the inverse kinematical solution of the mechanism, the reachable workspace under the five conditions is ascertained. The three-dimensional graph and its section graphs of the workspace are obtained. The thoroughness of the workspace of the manipulator is proved. The mechanism with the advantages of simple symmetric structure and large stiffness can be applied to the developments of four-dimensional force sensors, NC positioning platforms, parallel machine tools and micro-positional parallel manipulators. This work is with great significance to the practical application of the manipulator.

Cooperative optimization of reconfigurable machine tool configurations and production process plan

Integrated Lot-sizing and Job Shop Scheduling Benefiting From Reconfigurable Machine Tools

Due to the rigidness of cellular manufacturing system (CMS), it lacks adaptability which is the ability to respond to changing products, product mix and production capacity, hence loosing competency in dynamic manufacturing environment. Reconfigurable machine tools (RMTs) are the great means to propel flexibility in CMS to enable a high degree of system responsiveness to frequentchanges in cost effective way. In this paper, RMTs are used to exert lean characteristics in CMS by inheriting the desirable properties of RMTs. A heuristic is developed for embedding lean characteristics into machine cell design. The emphasis of this research is the formation of machine cells driven by specific product mix. An application example is included to illustrate the cellular model.

A deformation model of a parallel kinematic machine tool