Investigation and Correction of Actual Microphone Response for Chatter Detection in Milling Operations

Integrating sensors in machine tools for monitoring purpose entails dealing with different issues, not only related to accessibility and safety but also to measureable bandwidth and linearity of the sensors. Those factors could be related to the sensor itself but also to sensor–machine interaction that could drastically affect sensor performances and reliability. This paper presents a dedicated experimental investigation of the actual response of microphone transducer inside the machine-tool chamber, highlighting the effects of the machine-tool chamber in altering response linearity. The identified response is then processed with specifically developed equalization filters to correct the measured response and rescale the amplitude of frequency contributions, as required by most chatter detection techniques. The main aspect of both the experimental identification procedure and the development of an effective correction approach are presented and discussed. Finally, the technique is tested in processing signals acquired in experimental chatter tests to estimate the achievable improvements

Intelligent Fixtures for Active Chatter Control in Milling

AbstractThe mitigation of chatter vibrations in milling has collected the interest of several researches in the last decades. One of the most industrially oriented alternatives is represented by active fixtures, complex mechatronic devices capable of actuating the workpiece during machining operations, with the purpose of stabilizing the process by generating counteracting vibrations. Most of the previous works show different fixture architecture and model based control techniques. This paper deals with the development and testing of such an active fixture, presenting the main design aspects and the features of the black-box control-logic used. Experimental tests are presented to show the achievable chatter mitigation

Few-body precursors of topological frustration

Quantum spin chains - the prototypical model for coupled two-level systems - offer a fertile playground both for fundamental and technological applications, ranging from the theory of thermalization to quantum computation. The effects of frustration induced by the boundary conditions have recently been addressed in this context. In this work, we analyze the effects of such frustration on a few spin system and we comment the strong even-odd effects induced in the ground state energy. The purpose of this work is to show that such signatures are visible on current quantum computer platforms

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Forces Shapes in 3-Axis End-Milling: Classification and Characteristic Equations

In 3-axis milling, cutting force analysis represents one of the main methods to increase the quality and productivity of the process. In this context, cutting force shape gives information of both monitoring and prediction of the cutting process. However, the cutting force shape is not unique, and it changes according to the cutting strategy, tool geometry, and cutting parameters. This paper presents a comprehensive approach to predict and classify cutting force shapes in 3-axis milling operations. In detail, the proposed approach starts by classifying the cutting force shapes for a single fluted endmill (i.e., single flute force shape), and, considering how the single flute force shapes may overlap one another, it extends the classification to a general multiple-fluted endmill. Moreover, the method provides, through analytical equations, angles, and magnitude dimensionless parameters of each key point, describing each shape classified. Finally, the proposed approach was experimentally validated through several milling tests in different cutting conditions

A Non-Uniform Offset Algorithm for Milling Toolpath Generation Based on Boolean Operations

In milling, the advancement of CAM strategies has increased the need for tailored algorithms for semi-finished phase computation. In some cases (e.g., thin-wall milling), variable radial engagement of the tool during the toolpath is desired, leading to the need of non-uniform machining allowance on the component that could be achieved only with a non-uniform offset algorithm, i.e., offset where the distance to the initial contour varies along that input. This work presents a general algorithm for non-uniform offset of polyline curves. The approach is based on 2D polygons and Boolean union operation, following these steps: (i) projection segments are generated, (ii) polygons (trapezoids and circular sectors) are created, (iii) Boolean union of all the polygons is performed, (iv) boundary of interest is extracted. The proposed algorithm is able to handle both internal and external offset and is robust for complexity of both the polyline and variable offset magnitude along that line, as proven by several examples and two applications to thin-wall milling provided

Design and Testing of a WAAM Retrofit Kit for Repairing Operations on a Milling Machine

Repairing, remanufacturing, and refurbishing high value metal components are crucial to move towards a more sustainable economy. Nowadays, repairing operations on high value parts, such as dies, are generally performed using time-consuming manual approaches that rely on the operator’s expertise. The research idea of this paper is to develop a retrofit kit to provide additive capabilities to an existing milling machine, allowing automatic repairing of components thanks to a fast switch between additive and machining operations without a relevant economic investment such the acquisition of a brand-new machine: the final cost of the solution is lower than 10% with respect to the mean cost of a 5-axis milling machine. The additive technology used in this work is Wire Arc Additive Manufacturing (WAAM) that is characterized by a higher deposition rate and a simpler and cost-effective equipment with respect to other techniques (e.g., laser cladding). The design of the system is illustrated in the paper together with the analysis of the results achieved repairing a test case: a die casting mold made of AISI H13 tool steel

IoT-Based Home Monitoring: Supporting Practitioners’ Assessment by Behavioral Analysis

This paper introduces technical solutions devised to support the Deployment Site - Regione Emilia Romagna (DS-RER) of the ACTIVAGE project. The ACTIVAGE project aims at promoting IoT (Internet of Things)-based solutions for Active and Healthy ageing. DS-RER focuses on improving continuity of care for older adults (65+) suffering from aftereffects of a stroke event. A Wireless Sensor Kit based on Wi-Fi connectivity was suitably engineered and realized to monitor behavioral aspects, possibly relevant to health and wellbeing assessment. This includes bed/rests patterns, toilet usage, room presence and many others. Besides hardware design and validation, cloud-based analytics services are introduced, suitable for automatic extraction of relevant information (trends and anomalies) from raw sensor data streams. The approach is general and applicable to a wider range of use cases; however, for readability’s sake, two simple cases are analyzed, related to bed and toilet usage patterns. In particular, a regression framework is introduced, suitable for detecting trends (long and short-term) and labeling anomalies. A methodology for assessing multi-modal daily behavioral profiles is introduced, based on unsupervised clustering techniques. The proposed framework has been successfully deployed at several real-users’ homes, allowing for its functional validation. Clinical effectiveness will be assessed instead through a Randomized Control Trial study, currently being carried out