Prijenosni stroj za graviranje kamena

Iako je ručni način klesanja kamena danas još uvijek dosta zastupljen, pojavila se u modernom svijetu potreba za bržom i preciznijom izradom gravura i natpisa na kamenim površinama. Drugi problem u kamenorezačkoj struci predstavljaju velike površine i komadi kamena koji se zbog svojih dimenzija i mase ne mogu tako jednostavno postaviti kao obradak na alatni stroj. Upravo će iz tih razloga prijenosni stroj za graviranje kamena doći do izražaja, jer će se njime smanjiti vrijeme izrade i povećati produktivnost

Konstrukcija glodačeg obradnog centra za obradu kamena

U današnjem modernom svijetu sve je učestalija potreba za bržom i preciznijom izradom trodimenzionalnih i kompleksnih kamenih proizvoda. Upravo takvi kameni proizvodi koji iziskuju puno vremena i rada donedavno su se radili ručnom obradom. Razvojem i uvođenjem u rad modernih numerički upravljanih strojeva vrijeme obrade i mogučnost za pogreškom puno se smanjila. Obradni centri za glodanje kamena koji to mogu i postoje na tržištu imaju dosta visoku cijenu pa se zbog tog razloga slabo koriste. S obzirom da ovdje nisu prisutni pretjerani zahtjevi za točnošću, ideja je da se od postojećih gotovih kupovnih modula napravi alatni stroj koji udovoljava zahtjevima, ali nije pretjerano skup

On-Line Workpiece Hardness Monitoring in Stone Machining

The application of four types of process signals in the indirect on-line monitoring of stone hardness has been analysed in this paper. Cutting forces, servomotor currents, vibration and acoustic emission signals were measured during the drilling of three types of stones characterised by different hardness and heterogeneity values. A group of features were extracted from each signal from the time and frequency domain. Their capacity to correctly classify stone hardness was analysed using an artificial neural network classifier. Stone samples were drilled with new drill bits and drill bits worn to three different wear levels in order to analyse the influence of tool wear on the hardness classification process. Nine combinations of cutting parameters were applied for each drill wear level and stone type. Features extracted from the vibration signals obtained the best results in the stone hardness classification. The results indicate their potential industrial application, since they have achieved a high classification precision regardless of the drill bit wear level

Calibration of a 5-Axis CNC Machine for Making Orthoses by Means of a Vision System

Orthoses are aids that compensate for the loss of function of a particular part of the locomotor system, while prostheses are devices that compensate for the loss of a part of the body. Digital technologies have enabled the measurement and the production of such aids. The production technology is a CNC or robotics arm-based system comprising several modules that are relatively positioned with a submillimetre precision. In practice, the implementation and calibration of such systems are challenging, especially in cases of adapting already used hardware or when the control unit is undocumented or closed to outside interventions. Our approach responds to several challenges, resulting in a unique visual solution for fast and affordable calibration. This approach enables reading the machine positions from an external computer without a physical connection to the control unit, tracking the movement of the machine in near real-time, and finally calculating calibration parameters of the observed system

Tool wear classification using decision trees in stone drilling applications: A preliminary study

AbstractProcess parameters of stone drilling with a small diameter twist drill were used to predict tool wear by means of a machine learning decision tree algorithm. The model links tool wear with features extracted from the force sensor and the main and feed drive current sensors signals recorded under different cutting conditions and different tool wear states. Signal features extracted from both the time and frequency domain were used as input parameters for construction of a decision tree which classifies the tool state into sharp or worn. The model was refined by selecting only the feature sources most important for classification. The best model achieves 90% accuracy in classification and relies only on features of the current signals, which simplifies its implementation in a CNC system for industrial applications

Application of Machine Tools in Orthoses Manufacture

CNC technology is widely used in the manufacture of medical products. An area in which CNC technology has proven to be extremely useful and innovative is Orthotics and Prosthetics (O&P). O&P laboratories are engaged in the manufacture of individual orthoses and prostheses. The usual manual manufacture of such products takes a long time and requires tremendous experience and skill. In this regard, any engineering solution that improves the quality of the production process; reduces production time, production costs, and physical human labor; and at the same time improves the environmental conditions of the production environment will be desirable. Various designs of CNC machine tools for the manufacture of orthoses or molds for their production are in use today. In most cases, customized commercially available numerical control lathes and milling machines are used, as well as industrial robotic arms, but there are also highly specialized designs. For the mentioned purpose, we also encounter the application of additive manufacturing (AM) devices. Due to the fact that issuing of orthoses is often the subject of cost reduction in healthcare systems, the pursuit of production systems that will be cost-effective and functional, easily implemented, and used primarily in small manufacturing practices is imperative

Automation Systems Design and Laboratory Prototyping Aimed at Mature Petroleum Drilling Rig Retrofitting

This paper presents a control system design methodology for the drill-string rotary drive and draw-works hoist system aimed at mature drilling rig retrofitting. The rotary drive is equipped with an active damping speed control system featuring a proportional-integral speed controller readily available within modern controlled electrical drives, extended with drill-string back-spinning prevention scheme for the case of stuck tool. The draw-works hoist system features a tool normal force (Weight-on-Bit) controller with tool longitudinal speed (Rate-of-Penetration) limiting functionality. The design of proposed control systems has been based on suitable control-oriented process models and damping optimum criterion which guarantees a desired level of closed-loop system damping. The proposed drilling control systems have been verified on a downscaled laboratory experimental setup, which represents a necessary pre-requirement before these systems are tested in the field

Virtual Modelling and Simulation of a CNC Machine Feed Drive System

This paper deals with the virtual modelling and simulation of a complex CNC machine tool feed drive system. The first phase of the study was the modelling of a very complex structure of the feed drive which consists of many elements (position, velocity and current control regulators, actuators, mechanical transmission elements, etc.). All these elements have great influence on important parameters of the machine tool such as movement stability, positioning accuracy and dynamic stiffness. For the modelling of the system the Matlab-SIMULINK and Matlab-Sim Scape Toolbox software was used. The Matlab-Sim Scape Toolbox allowed us to use the complete CAD model of the geometry of the machine tool, automatically calculating the selected properties. The influence of changing and optimizing several feed drive parameters (position loop gain Kv, proportional gain Kp of the velocity controller, integral gain of velocity controller-Tn, electrical drive time constant Te, total moving mass m, sampling period Ts, etc.) on the positioning accuracy and the dynamic stiffness was simulated, tested and validated. The finished Matlab-Simulink and Sim Scape models were initially visualized in the Matlab program. They were very simplified, comparing with their later visualization in the Virtual Reality EON Studio program

Portable stone carving machine

Iako je ručni način klesanja kamena danas još uvijek dosta zastupljen, pojavila se u modernom svijetu potreba za bržom i preciznijom izradom gravura i natpisa na kamenim površinama. Drugi problem u kamenorezačkoj struci predstavljaju velike površine i komadi kamena koji se zbog svojih dimenzija i mase ne mogu tako jednostavno postaviti kao obradak na alatni stroj. Upravo će iz tih razloga prijenosni stroj za graviranje kamena doći do izražaja, jer će se njime smanjiti vrijeme izrade i povećati produktivnost