A fine mechanical machining treated in this paper may be called by the name of Vibration Machining, through which hard and brittle materials are able to be rapidly machined, as in the case of ultrasonic mechanical machining, by the energy of free abrasive grains given through the action of an elastically suspended tool vibrated by electro-magnetic force of time with sonorous frequency of about from 10 to 10⁴ c/s.
Concerning to the sonorous vibration system of the present vibration machining apparatus, is studied elementarily under some assumption the tool motion occured in its vibration states, in which the tool end collides with the material to be worked before the vibration displacement of the tool becomes its maximum amplitude.
Some of the theoretical results thus obtained are as follows, and they are also confirmed by experimental study in the paper.
1) The tool motion becomes more stable at its resonance condition than non-resonance, in which it keeps almost harmonic displacement vibration expressed by x=a₀ cos nt
where a₀ shows the distance between neutral position of tool vibration and contact point of tool and work. Therefore, we can see that it is advantageous to excercise the Vibration Machining at the resonance condition of tool vibration.
2) The velocity υ₀ at which the tool comes into collision with the material to be worked is given by
υ₀=-1/1+α F₀√1-r²/2mf
3) The relation between amplitude ratio r and machining force F_w is expressed by
F_w/F₀=1/2√1-r²

View full abstract

This newly devised drill has four edges.
In this cutting tool, two edges for heavy cutting are followed by other two edges for fine cutting. The cutting temperature is compartively low, and the cutting surface is good.
The edges for fine cutting is flat, the roughness of cutting surface is constant, being not effected by the feed.

View full abstract

A new stylus-type electrical roughness measuring instrument has been developed by the authors. The instrument was designed in conformity with the definition of center line average height prescribed in ASA, B. S and JIS (Japanese Industrial Standard). Before its development electrical and mechanical problems of the instrument were discussed, that is, dynamic characteristics of a mechanical system of a stylus, frequency characteristics of electrical circuits, cutoff method of waviness and stylus driving systems. As a ceramic transducer is used for the roughness pick-up and all the recording circuits are transisterized, the instruments is designed very compact.
Main specification of the instrument are as follows :
1. Pick-up
Stylus……diamond, 5 μ (or 12.5 μ) tip radius.
Stylus pressure……1 gram (approx.)
2. Amplifier
Range……0.075, 0.25, 0.75, 2.5 and 7. 5 μ.
Roughness width cutoffs……0.075, 0.25, 0.75 mm
Outputs……profile, average.
3. Motor Driver
Traverse speeds
(for continuously-averaging) ……3mm/s
(for recording) ……0.3 mm/s
Reversing time……0.01 second (approx.)
Length of stroke adjustable from 75 mm to less than 1.5 mm.

View full abstract

The poor machinability of austenitic stainless steel is emphasized to the largest extent in the operation of milling with carbide blades. The difficulty can be attributed solely to chipping due to welding at the cutting edge.
The object of this study is to investigate the factors to affect welding and to enable the operation of carbide milling possible from a practical point of view.
The conclusion is that for milling an austenitic stainless steel carbide blades are not applicable unless a special technique which has been newly introduced and named “bicutting” by the authors is used, whereas high speed steel blades perform satisfactorily at speeds not so much lower than with carbides.

View full abstract

The relations between tool life, cutting temperature, mechanical properties of the work materials are experimentally analyzed.
Annealed and normalized plain carbon steels, of which carbon contents are varied from 0.15 % to 0.55 % are turned with carbide tools.
For the aforementioned purpose, only normal or regular type of tool wear is taken into consideration for the tool life criteria.
The major findings are as follows.
(1) Under the fixed condition of work material and tool, the tool life can be defined by one variable function of cutting temperature.
(2) Under the fixed cutting condition of cutting speed, feed per revolution and depth of cut, the tool life is closely related with Brinell hardness H_B, and ultimate strain of the shear test γ_u.
(3) The relationships between tool life equation and mechanical properties of the work materials are as follows.
V·Tⁿ exp (δ·f) d^β=C
n∝H_B^0.23·γ_u^0.22
δ∝H_B^-1.01·γ_u^-0.29
C∝H_B-^1·36·γ_u-^0.145
where, V= cutting speed, m/min,
f=feed per revolution, mm/rev,
d=depth of cut, mm.
Because, it is very difficult to vary said variables independently each other, they are not independent from a physical point of view.
However, the relationships can be derived mathematically, by means of a unique analytical method.

View full abstract

In order to clear the electrolytic reaction of cemented carbide and to determine the Faraday efficiency, some preliminary experiments were performed. Conclusions obtained are as follows.
(1) The mass loss in electrolytic grinding of cemented carbide with or without titanium carbide, is about 1213 mg/amp. min. when 10 % solusion of NaNO₃ or NaNO₂ is used as electrolyte.
(2) In elcetrolysis of cemented carbide, tungsten carbide oxidizes to WO₃, remaining free carbon and in part CO and CO₂. WO₃ changes chemically in alkalized water to Na₂(WO₄), which is soluble in water. Titanium carbide also oxidizes to TiO₂ then hydrates to Ti(OH)₄ forming colloidal solution.
(3) Anode gas by electrolysis with NaNO₃ is mainly oxygen, but with NaNO₂ it is mostly NO gas.
(4) Faraday efficiency in electrolysing cemented carbide is about 80 %, the remains are the excess electrolysis of water and pure loss.
(5) Even when NaNO₂ is used as electrolyte, the rate of oxidization by dissolution of NO₂ is about 20 %. Oxidization of carbide is performed mostly by oxygen generated from the electrolysis of water.

View full abstract