Milling Head Research Articles

Application of industrial robot in 5-axis milling process

Present in machining creates constantly new requirements to increase economic efficiency, productivity and product quality. With this advancement, industry is no longer focusing only on commonly used machining technologies, but is paying increasing attention to the implementation of robots in the manufacturing process by machining. The paper describes the design of equipment for the implementation of 5-axis milling with the help of a robot arm ABB IRB 140. It describes the design of the milling head and deals with the creation of NC machining program in software Autodesk Fusion 360. The generated NC program is then used in RoboDK to create a robotic arm control program. At the end of the paper are described laboratory tests of machining using the designed prototype milling head.

Rice CR1009 Sub 1(IET 22187)-A new flood tolerant rice variety

CR1009 Sub 1 a new version of long duration short bold grain rice variety CR1009 with submergence tolerance was released by Department of Rice, Tamil Nadu Agricultural University, Coimbatore, to overcome submergence during samba season for flood prone areas of Tamil Nadu. CR1009 Sub1 is a product of Marker Assisted Selection of the cross CR 1009/FR 13 A and it was developed by IRRI in collaboration with NRRI, Cuttack. CR1009 Sub1 rice variety recorded a mean grain yield of 5759 kg/ha with 8.90 per cent increase over CR1009. The variety was tested over three years in station trial (2008–2010), one year in Multi location trial (2010–11), two years in Adaptive research trial (2011–12 and 2012–13), two years in OFT (2010–11, & 2011–12) and one year in AICRIP trial (2010–11). CR1009 Sub1 is moderately resistant to BPH, WBPH, Brown spot and Leaf Blast. CR1009 Sub1 has short bold grain type with good milling percentage (69.8%) and head rice recovery (62.5%), high amylose content (25.0) intermediate gelatinization temperature and soft gel consistency indicating its similarity to CR1009 and also suitable for idly making. This variety was released by TNAU during 2015 and notified during 2017.

THE INFLUENCE OF CUTTING CONDITIONS ON THE SELECTED PARAMETERS OF THE SURFACE INTEGRITY

The article deals with an investigation of residual stress in machined surface under conditions of high-feed milling and determination of the influence of machining conditions on the size and types of stress resulting from cutting into the machined surface. As a testing material, the hardened tool steel W. Nr. 1.2343 (CSN 19552) was used. For the realization of the experimental activity, a high-feed milling head was used with exchangeable cutting inserts marked H600 WXCU 070515T. All surfaces were machined under different cutting conditions (200, 300, 350, 400 and 500mmin−1 cutting speed) in regard to the recommended parameters and machine tool options. The evaluated residual stress was measured in the depth of 8 μm under the surface with the device PROTO iXRD working on the principle of the X-Ray diffraction. Monitoring was carried out using an analysis of occurrence of tensile or compressive residual stress, and from these results, a possible dependence of the residual stress on the cutting conditions during milling process was determined.

Design Optimization Approach of a Large-Scale Moving Framework for a Large 5-Axis Machining Center

The traditional machine tool design method with metal materials makes large-scale moving structures very heavy, which seriously impacts dynamic performance and results in significant energy consumption. Using sandwich structures of composite materials to replace metal materials is an important strategy for lightweight large-scale moving structures. However, this kind of substitution is generally believed to be difficult because foam-filled sandwich structures usually show nonlinear characteristics and must balance the moving mass, material costs, and structural stiffness. In the present study, we proposed a design optimization approach for a large-scale moving framework in a large 5-axis machining center (L5AMC) considering large dimensions in the x, y, and z work space and high machining speed with the aim of minimizing the displacements of the milling head. An improved approach, named the 3-step design optimization, was executed to obtain the optimum framework structures to solve the contradiction between the moving mass, material costs, and structural stiffness. This approach was based on multi-objective optimization and finite element analysis. The structural stiffness of the framework after optimization increased by 89% compared with before optimization although the mass increased by 6% and the material costs increased by 9%. A finite element simulation under four given operational loads showed that the displacements of the milling head were all less than the design requirement of 0.25 mm. The results indicated that the proposed 3-step design optimization approach for the optimal design of a large-scale moving framework was feasible and successful. A 40 m × 6 m × 4 m L5AMC prototype was manufactured, and the actual verification results indicated that the large-scale moving framework fully met the design requirements of the L5AMC and reduced energy consumption.

Analysis of Physical Quality and Nutrition of Two Rice Varieties With the Implementation of Various Planting Systems

As an effort to overcome problems in rice cultivation system, it is necessary to use new technologies and innovations. This study aims to determine the physical and nutritional quality of grain and milled rice from 2 varieties of rice using several planting systems. The research was conducted using a Completely Randomized Design of factorial pattern, consisting of 2 factors with 3 replications. The factors were: a) Planting system (S1 = Cubic S2 = Double row 2: 1, and S3 = Twin seed) and b) Rice varieties (V1 = Ciherang; V2 = Inpari 10). The observation parameters include: physical quality of grain, rice milled quality, physical quality of rice and rice nutrition. The results showed that the cubic planting system produced a higher empty grains than the double row and twin seed planting system. The twin seed planting system, yielding lime green grains and yellow broken grains lower than other planting systems, both on rice varieties of Ciherang and Inpari 10. Grains from Ciherang variety had a thinner shell and a higher hardness level of rice compared to grain of Inpari 10 variety, resulting in higher milled rice and head rice, but lower in broken rice and rice groats contents. It can be concluded that: a) the physical quality of rice was not affected by the planting system, but it was significantly affected by the rice varieties; b) the planting system and rice varieties used in this study did not have significant effect on the nutritional quality of the rice produced.

Experimental Analysis on Effect of Tool Transverse Feed, Tool Rotational Speed And Tool Pin Profile Type on Weld Tensile Strength of Friction Stir Welded Joint of AA 6061

Friction stir welding is an emerging solid state joining process which is used to join metals and alloys having low weldability. In this research work experimental analysis has been performed on FSW for AA 6061. Effect of FSW parameters like tool rpm, tool transverse speed and tool pin profile are investigated. A vertical milling head is used to produce FSW joints. Hot work tool steel (H13) is used as a tool material and total 3 number of tools are manufactured namely as cylindrical pin, tapered pin and square pin. Tool transverse feed of 10, 15 and 20 mm/min and tool rotational speed of 2250, 2500 and 2750 rpm are taken for the study. A full factorial method is used for three numbers of parameters and their three levels and total 27 numbers of experiments are conducted keeping all other parameters constant. As a response weld tensile strength of joint is tested according to ASME-IX. Response surface method (RSM) and Analysis of variance (ANOVA) is adopted for the statistical analysis. As a conclusion it has been derived that feed of 15 mm/min, tool rotational speed of 2750 rpm and tapered pin profile gives better weld strength for the given experimental conditions.

Model for surface topography prediction in mirror-milling of aircraft skin parts

As a new technology of aircraft skin processing, mirror-milling is an efficient and green processing technology, which is a gradually developmental substitute for chemical milling. The purpose of this research aims to study surface topography forming mechanism and the effect of support location on the surface topography forming in mirror-milling of aircraft skin parts. A new iterative workpiece deformation prediction model is proposed for mirror-milling error prediction of low-rigidity parts. In addition, the workpiece surface topographies are predicted and verified at different support locations. The results of the study are summarized: under the same processing parameters, the machined surface topographies with different characteristics are obtained only by changing the relative position between the support head and the milling head. The support location is the key parameter of reducing the workpiece deformation error.

A Study on the Application of Machine Simulation and Angle Milling Head of a 6-Axis Parallel Kinematic Machine

A Study on the Application of Machine Simulation and Angle Milling Head of a 6-Axis Parallel Kinematic Machine

Identification of milling inserts in situ based on a versatile machine vision system

This paper proposes a novel method for in situ localization of multiple inserts by means of machine vision techniques, a challenging issue in the field of tool wear monitoring. Most existing research works focus on evaluating the wear of isolated inserts after been manually extracted from the head tool. The method proposed solves this issue of paramount importance, as it frees the operator from continuously monitoring the machining process and allows the machine to continue operating without extracting the milling head for wear evaluation. We use trainable COSFIRE filters without requiring any manual intervention. This trainable approach is more versatile and generic than previous works on the topic, as it is not based on, and does not require, any domain knowledge. This allows an automatic application of the method to new machines without the need of specific knowledge on machine vision. We use an experimental dataset that we published to test the effectiveness of the method. We achieved very good performance with an F1 score of 0.9674, in the identification of multiple milling head inserts. The proposed approach can be considered as a general framework for the localization and identification of machining pieces from images taken from mechanical monitoring systems.

Predicting Milling Yields of Long-Grain Rice Using Select Physical Parameters

Abstract. Milling yields of long-grain rice were successfully predicted using multi-parameter linear modeling, although the data was limited to lots of only two cultivars (Grigg and Siebenmorgen, 2015). Thus, modeling was expanded to include six currently-produced long-grain cultivars. For unfractioned rice, milling yields [milled rice yield (MRY) and head rice yield (HRY, adjusted to account for degree of milling variations)] were regressed to combinations of physical parameters comprising bulk density (Ib) of rough rice, and fissured-kernel percentage (FKP), chalkiness, and average kernel thickness of brown rice. The resulting models for prediction of milling yields were cross-validated with equivalent data of thickness-fractioned rough rice of the same cultivar lots. Thickness fractions comprised ( 2.05 mm). Milling yields were first predicted using Ib, FKP, and chalkiness parameters (Model I). The adjusted coefficient of determination (R 2 ) value indicates that Model I effectively predicted HRY (R 2 = 0.90); however prediction of MRY was poor (R 2 = 0.22), and related model cross-validations (Valid. R 2 = 0.67 and 0.59, MRY and HRY, respectively) were marginal. Adding the kernel thickness parameter in Model II improved milling yield predictions and cross-validations (R 2 = 0.72 and 0.94, and Valid. R 2 = 0.82 and 0.74, for MRY and HRY, respectively). As the chalkiness parameter estimates in Models I and II were statistically insignificant, Model III considered only the Ib, FKP, and thickness parameters. Model III maintained effectiveness in predictions and cross-validations of milling yields (R 2 = 0.71 and 0.95, and Valid. R 2 = 0.83 and 0.72, for MRY and HRY respectively). The Ib, FKP, and thickness parameters of Model III effectively predicted MRYs and HRYs of both unfractioned and thickness-fractioned long-grain rice of this set of cultivar lots.

Composite Framework Design Method for Large 5-axis Machining Center Based on Finite Element Analysis

The subject of this study is to find a best solution to design and manufacture a composite framework for large 5-axis machining center to meet the large dimensions in x, y and z working space, high accuracy for position of machine tool, lightweight design for good dynamic drive performance and cost effective design. A series of parameter studies and finite element analyses were carried out for this purpose. The goal of optimization design is to minimize the displacements in the milling head while a lightweight design, a reliable fabrication processes and a low material cost. A two-step approach was presented to find out the optimum structure of composite framework using finite element analysis method for a low-stiffness-case and a high-stiffness-case to analyze the maximum deformation of milling head under operational loads, including the gravity and maximum acceleration in each axis for starting and stopping. The results show that, after optimization design for composite framework, the deformations in the milling head were below 0.21 mm in high-stiffness-case and the stress inside the laminate was much lower than allowable material limits, it means that the optimal design of composite framework is feasible and successful. The prototype of 40m×6m×4m large 5-axis machining center was also manufactured and the actual verification results indicate that the composite framework can fully satisfy the design requirements of large 5-axis machining center based on the approach proposed by this work, which can provide a technical guidance for design of large structure to improve its precision.

Design and Manufacturing of Spindle of Universal Milling Head

Design and Manufacturing of Spindle of Universal Milling Head

3D Printed Real-Time PCR Machine for Infectious Disease Diagnostics

Diagnosing infectious diseases is a complex task with many different techniques to obtain the results. According to the World Health Organization some diseases such as Malaria and HIV, Polymerase Chain Reaction (PCR) must be used to obtain results and to determine the proper treatment. Ideally, PCR would be used as often as possible because it gives increased reliability and accuracy, but the cost and the difficulty to obtain equipment used for PCR diagnostics outside of a lab environment effectively forces the use of an inferior method of a more accessible nature or treatment without proper diagnosis. The main goal of this research is to develop a system to perform PCR diagnostics that can be manufactured using simple tools, off-the-shelf parts, and a 3D printer. Using a 3D printer allowed for the manufacture of complex parts that would otherwise have to be machined or injection molded, both processes that are out of reach for many. In keeping with this theme, the printed circuit boards were also routed and drilled using the milling tool head of the 3D printer. This was to avoid the complexity of a photochemical process or the poor reliability of a heat transfer method. Few challenges, including difficulty decreasing cycle times, which required designing a heating block that satisfied light-path and thermal requirements, and reading of real-time fluorescence data, were addressed. The resulting device is battery-operated and can perform a complete 40-cycle PCR with real-time fluorescence reading of intercalating dyes. Ultimately, the files for the 3D printed parts can be published and printed out on any 3D printer. This will enable the construction and use of this device in all corners of the globe and without the need for a complex manufacturing process and only standard tools.

Nonlinear dynamics of the milling head drive mechanism in five-axis CNC machine tools

As an essential assembly in five-axis CNC machine tools, the milling head with high-power and high-torque is used in processing the titanium, superalloy, and other high hardness materials. However, nonlinear friction, structural flexibility, and other factors affect the positioning precision and dynamic characteristics of the milling head seriously. To achieve perfect performance, dynamics investigation is necessary in the initial design. Firstly, considering the nonlinear friction and structural flexibility, a nonlinear dynamics model is established. Secondly, based on least squares method and genetic algorithm, static and dynamic parameters are identified for the LuGre friction model, and the axial elastic coefficients are calculated by the pressure tests. Finally, the dynamics model is solved by Newton-Simpson algorithm and Newmark-β algorithm. Additionally, influences of related parameters on dynamics performance of the milling head drive mechanism are investigated. The theoretical model and experimental results derived in this paper provide basis for the optimal design and error compensation control of the milling head drive system.

Machine-vision-based identification of broken inserts in edge profile milling heads

This paper presents a reliable machine vision system to automatically detect inserts and determine if they are broken. Unlike the machining operations studied in the literature, we are dealing with edge milling head tools for aggressive machining of thick plates (up to 12 centimetres) in a single pass. The studied cutting head tool is characterised by its relatively high number of inserts (up to 30) which makes the localisation of inserts a key aspect. The identification of broken inserts is critical for a proper tool monitoring system. In the method that we propose, we first localise the screws of the inserts and then we determine the expected position and orientation of the cutting edge by applying some geometrical operations. We compute the deviations from the expected cutting edge to the real edge of the inserts to determine if an insert is broken. We evaluated the proposed method on a new dataset that we acquired and made public. The obtained result (a harmonic mean of precision and recall 91.43%) shows that the machine vision system that we present is effective and suitable for the identification of broken inserts in machining head tools and ready to be installed in an on-line system. HighlightsA novel machine-vision-based method that detects broken inserts in milling heads.Unlike other methods, this approach does not require comparison to reference images.We demonstrate its effectiveness on a new data set of 144 images with 180 inserts.It is very efficient and it can be used without delaying any machining operations.

A formulation of tooth deformation and its error compensation for worm gear transmission mechanisms

Milling head and rotary table are the key components in five-axis CNC machine tools. However, tracking and positioning precision of these rotary axes based on worm gear mechanisms are affected by the backlash, friction, elastic deformation, and other nonlinearities. Therefore, finding out a simple and universal principle to predict the tooth deformation in an initial design is quite significant. A novel deformation calculation and compensation method with finite element analysis and circular plate theory is proposed for the worm gear transmissions. When the relationship (form factor) between the solutions of circular plate theory and finite element analysis is derived, deformation calculation with finite element analysis can be replaced by multiplying the solution of circular plate theory and the form factor. Analysis and calculation results show that the presented method can provide a reference for the compensation control of the positioning errors.

Improved open-sun drying method for local swamp rice in Uganda

“Kaiso” and “Supa” are the main local swamp-rice (Oryza Sativa) varieties currently grown in Uganda mainly by smallholder farmers on small gardens (0.5 – 2ha). Due to lack of mechanized drying equipment and owing to the low volumes of their harvests, these farmers use open-sun drying methods, where the paddy is spread on tarpaulins, cemented floors or bare ground. In most cases the paddy is badly dried and is highly fissured. Such paddy on milling contributes to low levels of mill recovery and head rice count of the milled rice. Compared to other varieties and countries, the mill recovery and head rice levels are ostensibly low. The study aimed to improve the above method under the Ugandan weather conditions with a view to increase the mill recovery and head rice levels. Paddy of the predominant “Kaiso” variety was dried in sun on cemented floor at ten depths: control (farmers’ method), 30, 40, 50, 60, 70, 80, 90, 100 and 110 mm. The results showed that the best paddy drying depth was between 70 and 80 mm. However at these depths, the paddy takes 7 – 8 days to dry. To reduce the drying time, the paddy was first set to dry at 80 mm depth for two days; after which time, it was divided into three different potions that were further dried at different depths of 80, 40 and 30 mm. The results showed that samples whose drying depths were reduced to 40 mm and 30 mm took four days to dry while samples whose depths remained at 80 mm took 7-8 days. There were no significant differences in mill recovery values (p = 0.2968) and head rice levels (p = 0.5890). Improvement index in mill recovery was 1.14 and that of head rice was 1.24. Average aflatoxin level in the samples whose depth was reduced to 40mm was 4.8ppb and that reduced to 30 mm was 2.3ppb. From these results, it was recommended that “Kaiso” variety should be dried at 80 mm depth for two days and drying depth should be reduced between 30 and 40 mm for subsequent drying. It was further recommended that the method be tested with other swamp varieties before general conclusion is drawn that it can work for all swamp varieties.Keywords: Head rice, mill recovery

Development of Methods for Determining Differentiated Rates of Mineral Extraction Tax in Recovery of Solid Commercial Components from Technogenic and Natural Fields

Background: The article presents differential methods to determine ad valorem Mineral Extraction Tax (MET) rates for commercial components extracted from technogenic raw materials and from secondary mineral resources. Methods: Proposed objectives include restrictions on the minimum level of MET rates. MET is calculated by reference to stock exchange prices for finished products in formulas 1 and 2. This tax is calculated relying on the estimated value of extracted minerals in formulas 4 and 5. The forecasted MET potential is estimated as present value of expected payments to the budgets of the RF budget system. Findings: Increasing the complexity of the use of mineral resources through the development of state regulation of economic measures aimed at stimulating subsoil usage involves determining the optimal ad valorem tax rates on mining operations, which provide cost-effectiveness of the investment project organization engaged in the development of technogenic deposits. For this purpose, the study has developed and scientifically validated methods in terms of mining rent, where mining-and-geological (mill head grade) and technological (the value of throughout recovery of the component to the finished product) criteria have been highlighted in its structure which are prerequisite to establish economically justified level of tax exemptions of mineral extraction tax. Frequency of revision of MET rates is still debatable, whether it will be a period of development of the deposit or another period of imposing the tax rate. Improvements: The presented methods can be used in working out the directions of Russian tax system development, as well as the implementation of regional investment projects aimed at developing, in the first place, technogenic deposits under a separate license.

A parametric modeling method for the pose-dependent dynamics of bi-rotary milling head

Bi-rotary milling head is one of the core components of five-axis machining center, and its dynamic characteristics directly affect the machining stability and accuracy. During the sculptured surface machining, the bi-rotary milling head exhibits varying dynamics in various machining postures. To facilitate rapid evaluation of the dynamic behavior of the bi-rotary milling head within the whole workspace, this article presents a method for parametrically establishing dynamic equation at different postures. The rotating and swing shafts are treated as rigid bodies. The varying stiffness of the flexible joints (such as bearings and hirth coupling) affected by gravity and cutting force at different swing angles is analyzed and then a multi-rigid-body dynamic model of the bi-rotary milling head considering the pose-varying joint stiffness is established. The Lagrangian method is employed to deduce the parametric dynamic equation with posture parameters. The static stiffness, natural frequencies and frequency response functions at different postures are simulated using the parametric equation and verified by the impact testing experiments. The theoretical and experimental results show that the dynamics of the bi-rotary milling head vary with the machining postures, and the proposed method can be used for efficient and accurate evaluation of the pose-dependent dynamics at the design stage.

Nonlinear dynamic modeling and adaptive sliding control of the milling head for efficient and powerful machining

Milling head is an essential assembly in the five-axis computer numerical control machine tools, positioning precision of which directly affects the machining accuracy and surface quality of the processed parts. Considering the influence of nonlinear friction in the transmission mechanism and the uncertain cutting force disturbance on the control precision of the milling head, the static and dynamic performances of the milling head are analyzed; relationships among the drive torque, load torque, motion direction and system parameters are discussed; and, finally, nonlinear dynamic model of the milling head is established. A novel adaptive sliding mode control scheme based on the variable switching gain and the adjustable boundary thickness is proposed for this nonlinear dynamic model; the stability of the closed-loop system is guaranteed by the Lyapunov theory. Experimental results show that the proposed adaptive sliding mode control can reduce the chattering in the traditional sliding mode control and can achieve high control precision without knowing the boundaries of uncertainties in advance.