Fumio Obata

Prediction of cutting forces and machining error in ball end milling of curved surfaces -I theoretical analysis

This paper presents a theoretical model by which cutting forces and machining error in ball end milling of curved surfaces can be predicted. The actual trochoidal paths of the cutting edges are considered in the evaluation of the chip geometry. The cutting forces are evaluated based on the theory of oblique cutting. The machining errors resulting from force induced tool deflections are calculated at various parts of the machined surface. The influences of various cutting conditions, cutting styles and cutting modes on cutting forces and machining error are investigated. The results of this study show that in contouring, the cutting force component which influences the machining error decreases with increase in milling position angle; while in ramping, the two force components which influence machining error are hardly affected by the milling position angle. It is further seen that in contouring, down cross-feed yields higher accuracy than up cross-feed, while in ramping, right cross-feed yields higher accuracy than left cross-feed. The machining error generally decreases with increase in milling position angle.

Prediction of cutting forces and machining error in ball end milling of curved surfaces. II. Experimental verification

Abstract This paper presents the results of a series of experiments performed to examine the validity of a theoretical model for evaluation of cutting forces and machining error in ball end milling of curved surfaces. The experiments are carried out at various cutting conditions, for both contouring and ramping of convex and concave surfaces. A high precision machining center is used in the cutting tests. In contouring, the machining error is measured with an electric micrometer, while in ramping it is measured on a 3-coordinate measuring machine. The results show that in contouring, the cutting force component that influences the machining error decreases with an increase in milling position angle, while in ramping, the two force components that influence the machining error are hardly affected by the milling position angle. Moreover, in contouring, high machining accuracy is achieved in “Up cross-feed, Up cut” and “Down cross-feed, Down cut” modes, while in ramping, high machining accuracy is achieved in “Left cross-feed, Downward cut” and “Right cross-feed, Upward cut” modes. The theoretical and experimental results show reasonably good agreement.

Reversibility and disassembly time of part connection

Abstract The reversibility and disassembly time of part connections were experimentally examined through the actual disassembly work of some spent industrial products. The disassembly time for connections depends on the joining method, joining direction, length of product life and chemical and physical deformation. The strongest relation was observed between the joining method and disassembly time. The male–female joint (socket joint) and snap fitting had a relatively short disassembly time of

A discussion on the resource circulation strategy of the refrigerator

Abstract In order to discuss the optimal resource circulation strategy of refrigerators, actual resource recovery experiments and a life-cycle simulation were carried out. The combined processing of disassembly and shredding had the most high recovery rate, more than 80 wt.% of a refrigerator, while the disassembly can recover only 30 wt.% of components as a re-usable component. An alternative strategy, the elongation of life span, had a good performance in improving the resource circulation characteristics. The two-life scenario can decrease the environmental load by twice that of the conventional recycling scenario. However, the elongation of life span does not become a successful resource circulation strategy until the old refrigerator was up-graded to a low-energy consumption type after one life-span running.

A design for recycling technique for optimizing resource circulation characteristics of products

A design for recycling technique was developed for evaluating the disassembly and resource. circulation characteristics from the design data on CAD software. The product component tree, disassembly curve, reduction characteristics map and resource circulation index showed a good performance for evaluating the disassembly and resource circulation characteristics. An advanced product design support tool was also originated for improving the disassembly and. resource circulation characteristics. The case study on a notepad-type PC showed that the depletion of parts number by material unification had a better effect on improving the disassembly and resource circulation characteristics of the notepad-type PC than the parts number depletion by integration of UNIT components.

Regenerative Chatter Vibration in Ball End Milling of Curved Surfaces

This paper presents an analysis of chatter vibration in ball end milling of curved surfaces using time domain approach. A model for dynamic cutting process, which takes into consideration the variation of helix angle of the ball end mill along the cutting edge, is developed. The vibration of the tool is calculated by using a lumped-parameter model with two degrees of freedom. The chatter stability limit is indicated by the critical nominal depth of cut. The results show that chatter stability is very low for low spindle speeds. Also, the stability is lower for low and high milling position angles, and higher for intermediate milling position angles.

Effects of Microscopic Spherical Particles Mixed in Lubricating Oil on Frictional Characteristics of Linear Slide Guide

In order to develop a superior linear slide guide having friction coefficient independent of sliding velocity, the authors have proposed a method to supply microscopic spherical particles to hardened sliding surfaces finely finished by lapping. The frictional characteristics of a slide guide to which the method was applied were investigated using a model of machine tool’s slide guide. Experiments were carried out at the sliding velocity ranging from 1 to 6000 mm/min. Adding spherical particles with a 5 μm diameter to a vegetable lubricating oil having a viscosity of 215 mm2 /s leaded to a constant friction coefficient excluding ultra-low sliding velocity range.Copyright

Friction and Wear Characteristics of Natural Iron Sand Coating

Friction and wear characteristics of natural iron sand coating were experimentally examined in the absence of lubricant. The friction motion was not be continuous, but be intermittent and proceeded by a process of stick-slip. An oxide film, Fe2 O3 , was formed along the sliding marks, but the amount of coating worn away was slight. There is a striking similarity in the friction coefficient between the zinc/iron sand coating and MoS2 over a load range of 20N to 1000N. The iron sand coating has a spongy structure and the bonding strength between the iron sand particles is so small that the metallic junction formed between sliding surfaces may be weaker than the substrate. Consequently the amount of metal removed may be small. In addition, the oxide film formed on coating is so soft and fluid that it may in itself function as lubricants and may play little part in abrading the other surface.Copyright