Recently mechanical seals are replacing grand packings for sealing of rotating shaft. But there are many unknown things about the seal performance of the mechanical seal used in high pres-sure. This paper describes the results of some experiments on the thrust force and on the friction torque which relate to very important properties of seal characteristics of the mechanical seal. In these experiments a metallic seal is used and the sealing pressure covers the range from 0.5 to 100kg/cm².
The obtained results are as follows.
1) The necessary thrust force to seal the fluid pressure consists of the oil film pressure which acts between the sliding surfaces and the actual thrust pressure the value of which is less than 4kg/cm².
When the thrust force is larger than the force due to the oil film pressure the fluid pressure can be sealed satisfactorily.
2) At the perfect balanced point friction torque causes mainly by the shearing force of the oil film and at the perfect seal condition the force due to the actual thrust pressure predominates over the others.
3) The sliding surface breadth is wider, the shape of the actual distribution of the oil film pressure becomes more disadvantageous than the theoretical one in which the mechanical seal is considered as a parallel plane hydrostatic thrust bearing. This fact may be caused by the throttle effect of flow path due to the deformation of the sliding surfaces.

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In the case where screws are used for leadscrews on machine tools, ruling engine and so on the lead error is very important. But its measurement due to the conventional methods requires the long time and troublesome treatment. From the viewpoint of production, the lead error of workcd screws must be measured readily at the workshop, that is, on screw cutting lathe itself. In this paper a new method of measurement suitable for these purposes is reported. The measured values by this method are compared with the results obtained by the same method as the lead-screw measuring machine with automatic recording equipment (see Bulletin of JSPE, Vol. 1, No. 1). According to this new method, the lead error of lathe is cancelled even if the leadscrew of lathe has any error, and the error of worked screws alone can be measured simply and immedia-tely. The measurement has been done with the automatic accumulating device made on trial. The results obtained are as follows; (1) the new method is more handy and ready than the handy lead tester for leadscrews (see J. JSPE, Vol. 32, No. 7). (2) the measured values are accurate enough for the measurement at workshop.

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Most studies on the honing relate mainly to its practical phase, and even such fundamental matters as the mechanism of abrasive grain wear and that of chip formation are not clear. Report 1 describes the cutting mechanism of abrasive grains that has been corroborated experimentally on a horizontal honing machine. The following matters have been clarified;
1. The cutting edge of the abrasive grain, which undergoes considerable thermal effect in the process of wear, seems to have the following life cycle; New cutting points→wear→chipping off, nicking off, flaking off→disappearing.
2. As chips formed by the honing there are two types; continuous chip and discontinuous chip. The latter is frequently mass-like, and interference of the swell-up plays a large part in its formation.
3. The honed surface is a surface made brittle by repeated plastic deformations.

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Cutting temperature distribution in the workpiece was investigated. From the temperature distribution measured by the thermocouple constructed with work-material and the inserted constantan wire (0.08mm dia.), the following conclusions were drawn :
Maximum temperature in the workpiece was observed around the cutting edge and it was proportional to the 1/2 power of the cutting speed.
Isothermal lines far beyond the cutting edge were almost parallel to the shear plane, while those far behind the cutting edge were parallel to the machined surface.
At a higher cutting speed the temperature of the surface layer in the instance of cutting was higher, but that of inner layer was lower than at a lower cutting speed.

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In this paper, the theoretical analysis on the frictional vibrations which occur on the machinetool slide-way are described. To the contrary the past theoretical analysises in which the steady state frictional characteristics of slide-way are used, a new analysis in which the time effects are considered to the frictional characteristics of slide-way, is presented and both results are com-pared. In the results on the amplitude characteristic it is made clear that there are remarkable difference between the new analysis and the past ones. And a new point of view to the limit of the frictional vibrations in which the effects are considered is presented. By taking the new analysis the limit of the frictional vibrations can be more clearly explained than the past analysses in which the steady state frictional characteristics of the slide-way are used.

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The influence of the increase of wheel speed on the grinding results has been studied experi-mentally. In this cylindrical grinding tests, the wheel speed was increased up to 3500m/min from 1300m/min. The following results are obtained :
1. As the wheel speed is increased, the ground volume per unit time increases and so the practical reduction of work radius versus the theoretical reduction of work radius increases.
2. The relation between the grinding force (P) and the wheel speed (V) is Poc (1/V) ^0.791.47. And as the grain size of wheel is smaller, the value of the index of this formula is larger.
3. The other result of higher wheel speed is the improvement of the surface finishing of the workpiece by decreasing the thickness of chip.
4. The influence of the higher wheel speed is smaller to the heat resisting steel as like the high vanadium high speed steel than to the carbon steel.
5. At the high speed grinding, an inclined metal sheet must be fixed against the wheel in order to deflect the air-flow on the rotating grinding wheel which prevents the coolants from penetrating into the grinding zone.

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In this paper, a new method of determining three-dimensional distribution of cutting edges in the grinding wheel is discribed. On the basis of its results, a wheel model is made that has the three-dimensional random destribution of cutting edges. Next, the attempt to analytically determine whether a cutting edge is able to effectively cut the work is made.
The principal results obtained are summarized as follows:
(1) The rate of effective cutting edges to all is determined in terms of H_m, Δ, n.
(2) The distance from the outermost surface of wheel to the lowest cutting edges which are able to cut the work, effective wheel depth δ_m, is calculated in terms of H_m, Δ.
(3) Effective cutting edge spacing we is defined and calculated analogously to grain spacing w.
(4) Analytical consideration is given on the concept of successive cutting edge spacing.

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