Portable Machine Tool Research Articles

Portable Machine Tools by Small Piezoelectric Robots for Scalable and Waviness‐Adaptive Fabrication of Surface Microstructures

Surface functional microstructures exhibit extensive application requirements in an array of breakthrough areas. One critical problem that restricts their industrial application is the lack of scalable fabrication techniques due to the limitation of conventional machine tools. This study proposes a scalable surface texturing technique using a portable small (30 × 19 × 22 mm) three‐leg robot that walks and works on the workpiece surface. Due to the elliptical tool vibration, microgrooves can be created on the workpiece surface periodically; meanwhile, the machining force drives the robot to walk forward. Surface texturing experiments are conducted on aluminum and copper workpieces to explore the machining performance of the small robot. The robot can reach a maximum moving velocity of 6.3 mm s−1 and can produce microstructures with a spacing of 4–14 μm on workpiece surfaces. Owing to its unique working principle, the small robot can maintain a constant depth of cut, demonstrating its capacity to adapt to the surface waviness of the workpiece. Finally, the motion straightness of the robot is greatly improved by combining it with the auxiliary track, and multiline microstructures are obtained. In short, the developed small robot presents a promising solution to the challenge of scalable surface texturing.

ENSURING OF ACCURACY DURING PROCESSING OF HEAVY MACHINERY OBJECTS WITH PORTABLE MACHINES

The main layout features of portable machines with stationary machines of various groups are analyzed. The prospects and market trends for the growth in this class's equipment use in solving the problems of repair and modernization of various objects of heavy and power engineering, as well as in conventional engineering production, have been established. The main reasons that affect the accuracy of surface shaping during processing by portable machines are established, both from the side of the layout structure of the equipment and from the technological parameters of the shaping process. The issues of the relationship of layout solutions with basing a portable machine on the processing object and the kinematic scheme of shaping are considered. Based on this relationship, the factors affecting the accuracy of shaping were established and analyzed, which formed the basis of the proposed method for controlling accuracy at the early stages of creating portable machines, namely through the use of an aggregate-modular principle of equipment layout at the design stage of portable machines. This approach emphasizes the compliance of the proposed methodology with three modern concepts for the development of industrial production, namely, the widespread use of mechatronic systems, product lifecycle management through CALS technologies, and an integrated approach to creating technological systems through information technologies that form the basis of Industry 4.0. Based on the conducted research, a method for designing portable machine tools is proposed that provides control over the accuracy of processing, the layout of which is based on the aggregate-modular principle using the certification of technological modules. Keywords: mechanical processing, portable machine tools, layout, aggregate-modular principle, design, accuracy

DISSEMINATION OF APPLICATION OF COW FEED PRODUCTION MACHINERY EQUIPMENT IN KAYEE LEE VILLAGE, INGIN JAYA DISTRICT, ACEH BESAR

In this product-based community service activity, the service team offers several concrete and tangible solutions to overcoming the problem of difficulties in obtaining ruminant feed. The solution offered is to build a portable silage machine tool system. The installation of this machine tool is an application of bioprocess technology where this equipment system is not only equipped with a biomass chopping machine but is also equipped with a biofermentor installation that can produce silage which is animal feed from fermented biomass rich in nutrients that are needed for increasing cow weight. Thus the equipment and machines designed can be a targeted solution in overcoming the shortage of animal feed for ruminant animal breeders in one of the assisted villages of Syiah Kuala University, namely Kayee Lee Village, and can also improve the skills and knowledge of farmers in producing animal feed independently and sustainable.

Design of an Ultra-Light Portable Machine Tool

Designing machine tools for in situ machining is a challenging task due to their unique structures and restrictive functional requirements. Such a machine tool should be characterized by low mass, adequate machining accuracy and high machining stability. The paper presents the design of an ultra-light, axisymmetric, portable machine tool for in situ flange face milling. Due to a high compliance of the designed machine tool and a need of maintaining its low mass, structural modification aimed at stability increase were highly limited. Therefore, it was decided to select the spindle ensuring machining stability. The selection of the spindle was supported by finite element analysis. Based on numerical analyzes results a prototype with a proper spindle was build. Then, the accuracy of the finite element model and the predicted stability were experimentally verified, showing a good agreement with the real counterpart. Finally, two general conclusions were formulated: (i) in the case of machine tools characterized by high compliance and limited possibility of modifying their design a good choice may be the selection of a spindle that allows to obtain parameters that ensure stable machining, and (ii) it is possible to build low-dimensional, reliable finite element model without using substructuring or reduction methods, and a well-thought-out discretization and replacement elements of complex load bearing systems instead.

Parametric vibration analysis and validation for a novel portable hexapod machine tool attached to surfaces with unequal stiffness

The Free-Leg Hexapod (Free-Hex) machine tool is an advancement from the conventional Stewart platform, which has the fixed base platform removed to enable the limbs to be attached to a wider range of surfaces (e.g. non-flat and curved). However, in some scenarios (e.g. in-situ repair of industrial installations), the limbs of the Free-Hex need to be attached to the surfaces with unequal stiffness, which brings the challenge of predicting the dynamics of the system for conducting machining operations under dynamically stable conditions. In this paper, after introducing the attachment stiffness (i.e. feet attached to the environment with different materials) in the conventional dynamic model of the parallel manipulator, the dynamic behavior of the Free-Hex machine tools devoted to the in-situ operation environments was studied. Then, the experimental validation was conducted to prove the dynamic model developed in this paper. It was found that the errors of the proposed model are under 6% (i.e. 5.1% at symmetrical limb configuration and 5.8% at the arbitrary configuration) when the limbs are attached to the surfaces with unequal stiffness. Further, by applying the validated model, the dynamic performance of the Free-Hex with a wider range of attachment stiffness was analyzed. Overall, it was found that the attachment stiffness has a remarkable influence on the natural frequencies of the machine tool (e.g. the frequency of mode 4 at the symmetrical configuration is increased by 36.8% when the attachment stiffness of one limb changes from 0 to 1e+12 N/m). Thus, the work discussed in this paper can be utilized to avoid the dynamically unstable configurations of parallel kinematic machine tools (e.g. Free-Hex) when mounting on the surface with unequal stiffness in the in-situ operation environments.

Offline tool trajectory compensation for cutting forces induced errors in a portable machine tool

Portable machine tools are designed to reduce costs and resources necessary to perform dedicated tasks, such as milling of large components like wind turbine hubs. Such machines however lack in performance (e.g. stiffness, accuracy, thermal stability) with respect to conventional machine tools and may require compensation strategies to guarantee adequate accuracy. An offline compensation methodology, involving tool trajectory modification, based on the calculation of tool center point displacements from prediction of cutting forces and static stiffness characterization was implemented on a portable machine tool. The offline compensation was validated through a posteriori comparison with the nominal cutting conditions.

Assessment of the safety of use of portable machine tools

The article presents safety issues related to on-site machining with the use of portable machine tools. Their advantage is the possibility of machining elements at places in which they are used. This especially refers to large-size constructions, welded elements and any items whose disassembly is technically difficult. The authors present tasks performed by the operators of portable machining equipment, working conditions, construction and characteristic features of portable machine tools on the example of a portable boring machine, milling machine and flange facing machine. The presented characteristics can influence the safety of work with these machines. The information given in the article were used to asses risk at the position of a portable machine tool operator. The assessment was conducted using the Risk Score method taking into account four stages of using portable machine tools, i.e. transport, assembly/disassembly, machining and maintenance. The result of the conducted risk analysis is the proposal of possible risk reducing actions. Due to the specificity of the operation of portable machine tools which significantly impedes the development of a machine tool which would be safe in and of itself, the proposed actions refer mainly to organisational solutions. The work presents also the thesis that it is possible to decrease the risk at this position thanks to the use of numerical control in a portable machine tool. Such a solution may reduce exposure to some identified threats. The issue is presented on the example of a prototype of a portable flange facing machine developed in the Institute of Mechanical Technology ZUT in Szczecin.

Achievable tolerances in robotic feature machining operations using a low-cost hexapod

Portable robotic machine tools potentially allow feature machining processes to be brought to large parts in various industries, creating an opportunity for capital expenditure and operating cost reduction. However, robots lack the machining capability of conventional equipment, which ultimately results in dimensional errors in parts. This work showcases a low-cost hexapod-based robotic machine tool and presents experimental research conducted to investigate how the widely researched robotic machining challenges, e.g. structural dynamics and kinematics, translate to achievable tolerance ranges in real-world production to highlight currently feasible applications and provide a context for considering technology improvements. Machining trials assess the total dimensional errors in the final part over multiple geometries. A key finding is error variation which is in the sub-millimetre range, although, in some cases, upper tolerance limits < 100 μ m are achieved. Practical challenges are also noted. Most significantly, it is demonstrated that dimensional machining error is mainly systematic in nature and therefore that the total error can be dramatically reduced with in situ measurement and compensation. Potential is therefore found to achieve a flexible, high-performance robotic machining capability despite complex and diverse underlying scientific challenges. Overall, the work presented highlights achievable tolerances in low-cost robotic machining and opportunities for improvement, also providing a practical benchmark useful for process selection.

A performance evaluation methodology for robotic machine tools used in large volume manufacturing

The manufacture of large components in various industries can create health, safety and economic challenges as a result of machining operations. A potential solution is the replacement of conventional large machine tools with low-cost and portable robotic machine tools, although these lack accuracy and precision in comparison. Effort is therefore required to develop robotic machining technology to a state where it can be implemented in high tolerance applications using a variety of materials. A barrier to implementation is that there is not a standardised procedure available to robustly assess current robotic machining performance, which makes it challenging to assess the impact of technological developments. This paper develops a methodology to determine robotic machining performance based upon reviews of standards available that currently specify such guidelines for robotics and machine tool technologies used independently. It is found that useful elements from each theme can be combined and applied to robotic machine tool performance evaluation. These are presented here with the aim of forming a conceptual foundation on which the technology can be developed for large volume manufacturing.

Analysis of Portable Machine Tool Construction Containing Modular Components

Summary The article presents the issue of designing portable machine tools in which module components are applied. Portable machine tools are mainly designed for machining of elements at the place of their final installation. Experience has shown that achieving high efficiency in the design of portable machine tools can only be reached through the use of mechatronic approach with the use of ready-made modular components (for example: ballscrew mechanisms, bearing units, linear guide systems). The designer of a machine tool must be aware of lack of information on selected parameters of these components. It is recommended to use simplified replacement models of these components and implement them to the model of entire machine tool to achieve desired static and dynamic characteristics. Authors of the article present an example of a modular component and its replacement model. They also present the results of calculations performed with the use of this.

Research and Application of NC Machine Tool Energy Consumption Control Optimization

The numerical control machine tool, which is a typical energy-using product, because there are all sorts of energy loss and auxiliary functions, has low efficiency in machining process. Author makes a study of NC machine tool energy consumption controlling. With simens840Dsl numerical control system as an example, based on the analysis of CNC system control principle, according to processing characteristic of the part, the macro program is wrote to optimize dynamic characteristics of NC machine tool. According to the machine idle time in different work condition, three energy-saving control profiles are formulated, including machine standby, NC standby, auto shut off. By the formulation of the corresponding PLC control logic, low energy consumption of intelligent control of NC machine tool is realized. Integrate PAC3200/4200 multi-function meter in NC machine tools, quantitative measurement and analysis of energy consumption for numerical control system and ancillary equipment can be implemented, and machine tool real-time energy data can be obtained. This scheme has been successfully applied in long-men portable CNC machine tools, and obtained the ideal effect: to realize the optimize control of energy consumption, improve the performance of the machine tool, become more market competitiveness.

Vibrating Portable Machine‐Tools Acting on Human Operator

AbstractThis paper will be a short presentation of the specialized literature and international standards about the importance of vibration action of portable machine tools on human body and particularly on the hand‐arm system. Exposure to harmful vibrations can lead to health problems and disorders, especially in the upper joints and dorsal region of the human body. A detailed understanding of the undesirable effects of vibration on the human body is essential to achieve administrative and technical prevention. In modern times, vibration studies become more frequent, decisive for the many machines, vehicles and construction. (© 2012 Wiley‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

A Simulation System to Analyze Effects of Relocation of Machine Tools on Supply Chain Robustness

Supply chains of modern complex systems need to keep up with the globalization of module and component suppliers to cope with resource restrictions, economic disparities, and rigorous environmental legislations. Robustness against variations in manufacturing tasks under undesirable situations is a crucial capability of global supply chains. Flexible and portable facilities can be shared among suppliers to increase supply chain robustness. This study proposes a system for modeling and simulating a supply chain in which portable machine tools are shared among the suppliers and relocated in order to adapt to machine tool breakdowns and manufacturing volume excesses. The system supports complex decision making in terms of the logistics of these machine tools with a view to decreasing the average completion time of manufacturing tasks without adding machine tools into the supply chain as a whole.

Selection of kinematic structure for portable machine tool

Selection of kinematic structure for portable machine tool The article presents the problem of selecting kinematic structures for the proposed portable machine tool. Developed methodology of selection has been based on the detailed design requirements and elimination conditions formulated thanks to them. The paper describes the program developed to assist the process of selecting the kinematic structures for the portable machine tool and the results achieved.

Flange facers provide precise, on-site machining

Climax Portable Machine Tools Inc has introduced a line of flange facers for in-situ repair and on-site machining of flange surfaces.

4523504 Portable machine tool having an operating unit mounted on a column : Lorenzo E Alessio, Lecco, Italy assigned to Black & Decker Inc

4523504 Portable machine tool having an operating unit mounted on a column : Lorenzo E Alessio, Lecco, Italy assigned to Black & Decker Inc