Papers by Keyword: Machining Center

Abstract: To address global environmental challenges and mitigate bamboo-related ecological damage, this study focuses on the development of self-adhesive molded products utilizing solely bamboo fibers and powder obtained through machining center extraction. However, the mechanical properties of these molded products remain inadequate. This study utilizes Scanning Electron Microscope (SEM) and Fourier transform infrared spectrometer (FTIR) analyses to explore the disparities associated with chip size as raw materials for molded products. Bamboo fiber, characterized by its substantial cellulose content and high strength, is contrasted with bamboo powder, which contains significant amounts of lignin and exhibits potential adhesive properties. Building upon these findings, the powder was added to the conventional fiber alone, with results demonstrating that a predetermined ratio (20%) of the powder yields optimal mechanical properties. Moreover, employing a parameter representing the degree of lignin flow utilized in previous molding studies, the study establishes the optimum molding conditions (PD'=1.031) to maximize tensile strength (37.8 MPa) when incorporating a 20% powder mixture.

Abstract: The article deals with the methods of forming liquid rocket engines parts, in which sheet material is used as a blank. The analysis of the existing methods of processing workpieces with a variable surface profile allows us to conclude that the mechanical method is the most promising type of processing for hole perforation. The drilling holes technology in parts made of sheet blanks is presented. The features of processing non-rigid parts with unpredictable surface fluctuations are considered. The ways of ensuring the stability of the treatment process, increasing the technological indicators, which allowed expanding the area of dimensional machining, are shown. The results of the work contribute to improving the manufacturability of new generations products of equipment, which is important for mechanical engineering.

Abstract: A machining method of large-sized spiral bevel gears in cyclo-palloid system has been developed using a computer numerical control (CNC) machining center. As a result of trial machining, the tooth surfaces were rough and leprous tool mark occurred. Therefore, the tooth surfaces were polished using a poly-vinyl alcohol (PVA) elastic grindstone after machining in order to improve the surface roughness and the occurrence of leprous tool mark. However, the wear and clogging of the elastic grindstone occurred after polishing. In this paper, the tooth surfaces of the large-sized spiral bevel gears are polished using a radial bristle brush instead of a PVA elastic grindstone. The swarf cutting that was machined by the side of a tool was carried out in polishing in order to make the life of the radial bristle brush. After polishing, the tooth surface was observed and the surface roughness was measured. Afterwards, the surface roughness and the occurrence of leprous tool mark before and after polishing were compared. As a result, the surface roughness and the occurrence of leprous tool mark were improved.

Abstract: This paper describes possibilities of process and condition data acquisition on universal milling centers with Sinumerik 840D-sl control. The measurement and process data is gathered mostly with the present control system architecture of the machine tool. This internal data collection has been extended by additional sensors and an external measurement system to enable further and partially deeper analysis. This setup is also explained in this publication. The demonstrator together with the measuring system allows an investigation of the introduced components close to reality and the observation of the overall system at once. The latter is considered energetically on a comparative measurement to ascertain discrepancies in energy consumption between two different milling strategies for a pocket cycle.

Abstract: Currently, carbon fiber reinforced plastics (CFRP) are being increasingly adopted in various fields. Thus, machining CFRP with high accuracy and high efficiency is required. In addition, machining stack materials composed of CFRP and titanium alloys is required. Therefore, in this study, a novel end-mill electroplated with a cubic boron nitride (cBN) abrasive, which has high thermal resistance, is proposed. In order to evaluate the influence of the base metal shape of the proposed end-mill on the machining process, several cBN-electroplated end-mills with different rake angles or chamfers were fabricated and used to cut CFRP. In addition, in order to evaluate the abrasive shape, a blocky abrasive was also electroplated on the end-mill. The results indicate that the negative rake angle is useful to restrain the progression of tool wear. However, in order to obtain the element of cutting and grinding, it is required that the rake angle should be positive. Moreover, the reasonable width of chamfer is effective for restraining the increase in CFRP temperature. Further, a sharp shaped abrasive can more effectively generate a CFRP with a sharp edge compared with a blocky shape abrasive.

Abstract: Chatter vibration in end milling remains a serious problem for manufacturing engineers. Chatter vibration often leaves a characteristic pattern or chatter mark on the machined surface. Chatter marks are generated by the relative displacement of the tool and the workpiece. Closer observation of chatter marks may prove useful in understanding chatter vibration. In this study, we investigated chatter mark patterns on end-milled surfaces. Based on these observations, we proposed and demonstrated the effectiveness of an iterative analysis method to identify stable machining conditions and minimize chatter vibration in various operations without use of sensors under specific conditions.

Abstract: This paper described a methodology to simulate production activities by using object-oriented programming language. Simulation of production to be modeled are the production activities in a workshop. The first step of modelling was defining objects that constitute the main part of a machining center. The main part of machining-center which was being modeled are column spindle, pallet fixture, pallet changer and tool magazine. From these objects can be created a new object that was an object of machining center. The next step was modeling pallet stocker and stacker crane. Pallet Stocker is a container used to store the workpiece or product on the pallet. A stocker crane is a device used to move a workpiece from the pallet stocker to a machining center or vice versa. The final step was modeling a workshop in which there are some machining centers, pallet stocker and stocker crane. Object modeled can be used to simulate a workpiece transfer activity undertaken by stacker crane from the pallet stocker to the machining center.

Abstract: This paper investigates the software error compensation in CNC machining centers On-line inspecting system. Based on Windows 2000 operating system, compensation software is developed. It investigates modeling errors. The software can compensate probe errors, thermal and geometric errors. The software system is tested on MAKINO upright CNC machining centers, and the results verify the effectiveness of the method.

Abstract: Chatter vibration generated by coupling a work-piece, machine tools, and cutting tool is a serious problem for engineers. A regular pattern forms the machined surface when chatter vibration occurs. There must be a direct relationship between the relative displacement and machined surface. We propose a method for controlling chatter vibration of end-milling from a machined surface. Hammering tests were first carried out to determine the natural frequencies of machine tools and the tool system, which are likely to be the cause of vibration. We also propose a technique of applying reverse analysis to end-milling surfaces. The machined surface is assumed to include an essential index to easily control chatter vibration at the factory. We found that chatter vibration occurs near the frequency of the cutting tool, tool holder, and their coupling, not at the natural frequency, and the chatter vibration frequency can be calculated by analyzing the surface pattern and cutting conditions. Moreover, the proposed method was effective in analyzing chatter vibrations including more than two kinds of natural frequencies at the same time.

Abstract: One of the objectives of process planning optimization is to diminish machining time. Nowadays a lot of research papers presented different algorithms to solve this classic problem. Thus, the optimal sequence of parts in the machining operations by considering fixture faces, part faces, number of operations and number of tools is presented in this paper. The mathematical model based on the integer linear programming is developed to minimize the total production time of the prismatic parts manufactured on a CNC machining center equipped with the tombstone-type fixture. The time required for machining, tool traveling and tool changing is taken into consideration under relevant constraints such as precedence, fixture and available cutting tools. The optimal process plan can be obtained from the mathematical model and it is considered practical and acceptable.