From the calculated motion diagrams of a sewing machine (H-B-1-type), we see that the maximum velocity and the maximum acceleration of the " eye of thread take-up lever " of this machine become 5 m/sec and 680 m/sec² respectively at 800 r. p. m.. The respective maximum values of the angular velocity and the angular acceleration of the " shuttle " become 140 rad/sec and 13, 000 rad/sec² at the same speed of rotation.
These calculated results show that some undesirable vibrations may be excited in the machine for these great velocities and accelerations.
Now the calculated value of the acceleration of the " feed-teeth " of the machine becomes small compared with those of other parts, but its time variation becomes discontinuous, and therefore it may induce some impacts and vibrations on the machine.

View full abstract

It is the object of our research whether electrolytic polishing can be applied to the precision finishing of gauges or machine parts. Our experiments were begun with measurement of polishing rate at the different points of the objects which had been polished and had acted as the anode.
First we observed the mean polishing rate at both the fore and back surfaces of the specimen plate which was placed in parallel to the cathodic plate under different conditions.
Secondly we also determined the characteristic polishing rate at the extreme parts of them in case that they were placed perpendicularly to the cathode. Lastly the discussion.were given. In our experiments, there were adopted the special methods in which two identical plates were put together and the side beam of them was kept off the intruding electrolytic liquid by paraffin.
We must add that copper plate was used as the specimen and phosphoric acid as the liquid. The research should be continued in order to so design the form of the cathodic plate as to finish plug gauges precisely.

View full abstract

We treat the frequency of the natural horizontal bending vibrations when a symmetrical trapezidal girder bent supports a load, neglecting self-mass of girder bent in 2 cases, i. e. one is girder bent with fixed-end columns and another with pin-end columns. Then changes of frequency due to the change of the angle of columns and the ratio of the height to the length of horizontal beam, etc. are discussed.
Moreover we calculate the effect of the self-mass of the trapezidal girder bent on the frequency.

View full abstract

In this research, it is not a gear of circular arc tooth profile, but a gear of circular arc tooth line that we named a circular arc gear. Therefore the profile has an involute curve as ordinary ones. Such a circular arc gear can be used as a double helical gear which transmits the power smoothly without thrust force. There are some kinds of double helical gear planers or shapers of heavy type. But the tooth profile of the double helical gear can not be ground, as its tooth line is not suitable for grinding. With the gear generator, which the writer, K. Hasegawa invented ten years ago, we can cut a tiny arc gear, a precision type gear, which can be ground, although it has some points to be improved. The writers studied the characteristics of trial arc gear.

View full abstract

Recently, the study on grinding practice has become active year by year, and some excellent reports have been published.
But the studies on the wheels, particularlly on its grinding action and grinding ability are so rare that I studied the grinding mechanism of wheels, the grinding ability and the relation between the wheel constitute elements such as abrasive, grain size, grade (bonding strength), structure and bond through the cylindrical grinding experiment.
I obtained the conclusions from practical and theoretical study which were summarized as follows;
1) In the grinding mechanism there are four types, such as "torn off", . "normal", "loading", and "glazing".
The characteristics of these four types have a fundamcntal relation to the grinding action and ability of wheels.
2) Grinding force is decided by the sharpness of abrasive edges and the number participant of grinding.
3) Wheel wear is decided by the cutting force exerting on the wheel surface and the break strength(bonding strength, crush and abrasion strength of edges) of wheels.
4) Accuracy and surface roughness of finish are decided by the abrasive edge number participant of finishing.
5) Grinding temperature is nearly in proportion to the grinding force.
6) But the results 2)5) are established only in "normal" grinding type, and in other types the results become more complex.

View full abstract