Research of Design and Simulation for the Small Modular Machine Tool

From 2010 to 2016, as part of the priority programme SPP1476 “Small Machine Tools for Small Workpieces” funded by the German Research Foundation (DFG) a new modular machine tools concept was scientifically established. The SPP1476 consisted of 13 projects from 18 leading institutes of Production Technology allocated to 13 German universities and research organisations. The objective of the priority programme was to solve the anomaly of an inappropriate machine tool size to workpiece size ratio. This was done by interdisciplinary and multidisciplinary development of new approaches for machine tools, which are used for manufacturing small parts, based on a methodical concept. By the consistent use of enablers which arise from miniaturisation, new allocation of machine elements to functions was possible. The individual project partners developed different modules for modular small machine tools. This includes various tools, feed units, a measurement system, machine frame, interface and other additional modules. Eventually, the generated methods have been validated by the realisation of prototypes and the configuration and assembling to functional machines tools.

The application of polymer composites to the table-top machine tool components for higher stiffness and reduced weight

Using a library of machine modules, modular machine tools are being developed by many machine tool manufacturers to reduce design lead time. To accommodate frequent changes in product design in a timely and cost-effective manner, the next generation of machine tools should be reconfigurable to process a family of products. This enables reduction not only in machine design lead time but more significantly a reduction in machine set-up and ramp-up time. The essential characteristics of Reconfigurable Machine Tools (RMTs) include modularity, convertibility, flexibility, and cost-effectiveness. Currently there is no systematic method of designing modular machines, let alone reconfigurable machines. This paper presents a methodology for kinematic synthesis of machine tools using screw theory. The motion characteristics of a set of desired machining tasks as well as stored library of machine modules are captured in a common representation scheme. A simple design example to illustrate the application of this methodology for systematic selection and synthesis of reconfigurable machine tools is presented. The proposed methodology can be extended to include the dynamic characteristics and control schemes to enable integrated design of machines and controllers.

Utilization of Thermal Energy to Compensate Quasi-static Deformations in Modular Machine Tool Frames

The lifecycle management issues of modular equipment, which mainly uses unified units and assemblies, are considered. The study touches upon modern trends in industrial production, which are associated with a reduction in the lifecycle of manufactured products due to the acceleration of its obsolescence and physical depreciation from the point of view of the modern competitive strategy of industrial enterprises. In the research process, the existing practice of design, production, and operation of modular machine tools was used to study the technical re-equipment of industrial enterprises in Ukraine. Based on modern information technology methods and CALS concepts, an enlarged model of the lifecycle of complex, knowledge-intensive technical systems has been developed to manage the lifecycle for such systems to establish the maximum period of use of unified units (modules). A new modular machine tools design model, which allows extending the lifecycle of machines, reducing the cost and timing of equipment design and manufacture, is proposed based on CALS technologies, the modular principle, and equipment certification. The model is based on using the modular principle and certification of equipment elements on the step-by-step information support of the technological system at all stages of the lifecycle. Particular attention is paid to reengineering and related processes during restoration work and machine tools modernization.KeywordsLifecycleCALS technologiesModular equipmentPower unitsUnified elementsMulti-tool machiningFlexible production systems

Taking the effect of geometric errors on machining accuracy into consideration in the design of small precision machine tools, the thermal errors become the main factor affecting the machining accuracy of machine tools. Currently, how to quickly and effectively evaluate the impact of thermal error on machining precision, in order to make effective thermal error prediction and compensation method, is needed to solve for small precision machining. Based on stepwise regression algorithm theory, combined with the DBB measured and analyzed on MATLAB in this paper, a better thermal error fitting regression formula is obtained. Meanwhile, this mathematical model approach is also applicable in a variety of other areas, such as machine tool thermal error analysis, compensation and testing etc.

In the early nineties, the global machine tool industry was struck by an economic downturn in most of its customers’ industries, especially the automotive industry and its suppliers. Consequently, a loss of more than 50% of production resulted in the German machine tool industry, see Figure 1 and the statistical reports published by the VDMA (1993, 1994b, 1995). German manufacturers were severely hit and many suffered losses that drove them out of business or forced them to merge with other manufacturers. Well known in the German industry are the Deckel merger with MAHO and afterwards the merger of Deckel-MAHO with Gildemeister in mid 1994. Overall, global competition between machine tool manufacturers has become fiercer. Recently, the German Machinery and Plant Manufacturers’ Association warned that it was almost impossible to generate profit by building machine tools in Germany, see VDMA (1991).

Industrial CNC machine tools are supplied as closed architecture systems. Their structure, kinematics and CNC controllers are designed to be used exclusively for their basic purpose, without any possibility of being changed. Reconfiguration is seen as the ability to add or remove modules from the machine, to be equipped with additional degrees of freedom (axes). For the concept to become a reality, it is necessary that the machine tool can be easily assembled and disassembled by an end-user and can adapt to changing projects or machining requirements. The approached of this research was to develop a 5-axis modular machine tool, with technological capabilities similar to industrial ones, at an affordable level of development costs and suitable to be used for teaching CAM techniques for future engineers.

In recent years, owing to the advent of mobile phones, product miniaturization and multifunctionalization have rapidly progressed. However, the large-sized machine tools for the manufacture of small products waste a considerable amount of space and power. The present study aimed at applying a magnetic-polishing method using a ball-end mill-type tool to examine the optimum processing conditions. This was done to apply a mirror finish for the integration of the cutting and polishing processes by using the small machine tool. The magnetic-polishing effect was evaluated from the point of view of the polishing amount, surface roughness, specimen shape, and mirror-surface condition. In addition, the movement of the paste during polishing was observed through images obtained through a high-speed camera. The movement of the paste is considered for effective polishing and other cases. Accordingly, various magnetic-polishing techniques were used for irregularities and step shapes. Various conditions were also examined, and a stable condition was determined. The results reveal that the amount of polishing paste significantly influences the polishing movement. In addition, a sufficient polishing effect could be obtained by duplicating the polishing course by using a sine wave course.

This paper outlines the design, specifications, and algorithms for a new modular self-reconfigurable robotic system; at its foundation is a novel modular magnetically geared linear actuator paired with a kinematic coupling connector. Motivating this work is the core idea that high performance actuators as well as inexpensive, precise and repeatable connectors are the key ingredients required for useful real-world self-reconfiguring machines. This work builds upon existing research in the areas of modular self-reconfigurable robots, magnetic lead screws, modular machine tools and kinematic couplings. Magnetic lead screws (MLS) have many desirable characteristics applicable to modular robots, including a tolerance for slight misalignments, high efficiency, zero backlash, robustness, inherent series elasticity, high force capability, and the ability to gracefully separate and reattach. Due to their high mechanical efficiency, MLS actuators are able to be combined in parallel to provide for increased forces and stiffness. Our system implements a MLS through two separable elements: brushless motor powered actuators called carts which pair with modular passive tracks which constrain the carts' movement to a line. This paper also explores the design for a connector which is able to precisely align modules through the use of a 4-way symmetric kinematic coupling.

Hierarchical Decision Making in Stochastic Manufacturing Systems

Among all the influential factors, the service quality of machine tools is the most important one for workers to decide their machine tools selection in process planning. This paper proposes an evaluation model for service quality of machine tools, aiming to help workers select machine tools on a reasonable basis. An evaluation indicator system of machine tools’ service quality is established based upon a thorough investigation into how the service quality of machine tools manifest themselves. The evaluation indicator system includes the following five aspects: processing cost, processing time, machining precision, green attributes and reliability. The least square method is used to establish an optimization model that determines the weight of indicators based on subjective weight-giving and objective Weight-giving. Finally, a grey relational analysis is conducted to evaluate the service quality of machine tools. Thus we provided an effective decision method for workers to decide their machine tools selection in process planning.

The massive data produced in real manufacturing processes provides a micro observation mechanism for managers and producers, which helps to analyze and grasp the manufacturing details, to form a macro decision-making mechanism, and finally to improve the manufacturing quality and production efficiency. This paper deeply investigates the real-time acquisition method of machine tool processing data and presents a general method of data analysis in different actual application scenarios to solve the general problem of insufficient and inappropriate utilization of machine tools. A framework of general machine tool monitoring system with four layers is proposed and several key stumbling blocks are researched, such as heterogeneous machine data acquisition, data analysis, and related application. These achievements are applied in a general cyber machine tools monitoring system based on MTConnect, which has greatly improved the utilization of machine tools and become a valuable unit in the framework of intelligent manufacturing and smart factory.

Scalability is one of six key characteristics found in reconfigurable manufacturing systems. Scalable systems satisfy changing capacity requirements efficiently through system reconfiguration, and in the flexible manufacturing literature this capability is called expansion flexibility. The development of modular scalable machine tools is a necessary precursor to achieving scalable systems. Unfortunately, there is little work describing the design of scalable machines. This paper establishes the need for scalable machines and a basis for evaluating and describing them. Applicable metrics are defined, and an architecture for scalable machines is presented. Two examples illustrate the scalable architecture. Finally, a design parameter based on a mathematical approach is presented to determine the optimal number of modules to be included on a modular scalable machine. This as a design parameter is important because it limits machine size and the number of module interfaces included in the base machine structure.

The flexibility and efficiency in parts production can be significantly increased through the technological cooperation of industrial robots and machine tools. The paper presents an approach in which a robot, in addition to the classic handling tasks, enhance machine tools by additional manufacturing technologies and thus beneficially supports workpiece machining. This can take place in various configurations, starting with pre- and final machining by the robot outside the machine, through sequential cooperative machining of the workpiece clamped in the machine, to parallel, synchronized machining of a workpiece in the machine. The approach results in a novel type of collaborative manufacturing equipment for matrix production that will improve the versatility, efficiency and profitability in production.