Toshio Yokoyama

Production of electrodeposited diamond wheels and grinding performance for hard metals and ceramics

Abstract Influence of material properties and electrodepositing condition on occurence of the detriminal phenomena, ‘over plating’ and ‘nodule’, were investigated for eighteen kinds of synthetic diamond abraisive grains. Grinding performance of a electrodeposited wheel for hard metals, ceramics, and cermet were tested. Grinding tests were carried out at constant thrust pressure. Some patterns of growth of ‘over plating’ and ‘nodule’ were observed and their photographs were taken with a SEM microscope. Ratios of number of over plated abrasive grains and nodules to total numbers of electrodeposited abrasive grains were smaller than 2% under the current density of 6 A/dm 2 for all kinds of tested grains. These ratios were abruptly increased for the abrasive grains with high friability in current density of 10 A/dm 2 . Grinding performance for the high friability abrasive grains was good for a hard metal and a TiN cermet. On the contrary, abrasive grains with low friability were suitable for grinding of ceramics, as Al 2 O 3 and Si 3 N 4 .

Some problems in the manufacturing of an electro-deposited diamond wheel

Abstract “Variation” is a phenomenon in which an electro-deposited layer thickness is not uniform on a surface, and is an undisirable phenomenon for a formed wheel. In this paper, the mechanism for the occurrence of variation and the effect of an auxiliary anode and cathode on the prevention of variation are made clear.

Factors affecting stretching limits of Aluminum sheet

The purpose of the present paper is to study methods to improve the stretching limit of metal sheet. The factors affecting the stretching limit were sheet thickness, blank diameter, blank holding pressure, and forming rate. Punch radius, die radius, and clearance between a punch and a die were retained constant. Tested materials were softened and half hardened types of aluminum sheet. The effect of lubrication was also studied. Lubricants used were a press working oil and graphite. Stretching by two types of punch shape, a spherical head punch and a truncated cone one, was tried in order to research the effect of punch shape. The half hardened aluminium, which has a larger n-value, showed the larger stretching limit. The larger thickness gave rise to the larger stretching limit. Flow characteristic of materials was poorer in larger diameter of a blank, so its stretching limit was lower. A bit lower holding pressure, which allows drawing of materials to some extent, yielded larger stretching limit than rigid holding. The forming rate did not so much affect stretching limit. Concerning the effect of lubrication, applied position of lubricants was important.

Effect of lubrication in upsetting of aluminum alloy columns.

A concentric circular groove is on the both end surfaces of aluminum alloy column to retain lubricant. The columns are compressed by appling lubricant oozed from a groove and its barreling forms are measured. Effects of diameter and depth of concentric groove on the lubricating ability are studied in the compressibility of 10 to 40%. Effective geometric conditions of a groove are obtained from these experiments. Material flow patterns in the cross section of compressed columns with a concentric groove is shown in the comparison with a compressed column without a groove.

Sprinkling of Diamond Grit for Electrodeposited Wheel.

Grit sprinkling is important for the effective working process of a product with a diamond wheel. However, to date this working process is still carried out manually. Hence, development of a mechanical method is expected. In the present paper, sprinkling method utilizing a jet issuing from a nozzle is proposed and studied. Influences of diameter of diamond grits, jet velocity at the nozzle exit, depth of liquid in an electrodepositing bath and the distance between a nozzle and wall of a bath on the grit distribution are experimentally investigated. Dimensionless variables determining the mean position and standard deviation of the distribution are obtained by a method of dimensional analysis, and the empirical formulas for these values are presented. The uniformity of grit distribution on a nozzle sprinkle method are examined, and superiority of this method with the uniformity of distribution is confirmed.