The authors carried out experiments on underwater explosive free forming with a cylindrical air-layer established over the specimen. When the size of the cylindrical air-layer has been properly selected, the efficiency of deformation will be much improved. This fact seems to offer a suggestion about the effect of gas bubble expansion. That is, the effect of gas bubble expansion is one of the important factors in deforming metals, and this effect will be seriously affected by the acting conditions of explosive forces.

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Metal oxide powder packed into metal tube was explosively pressed, by means of blowing up with explosive which was charged around the tube, simultaneously with detonating at the upper part of the tube.
By this method,
1) metal oxide powder was formed to a tightly compressed piece in bar.
2) the obtainable pieces were not exactly uniformly compacted, but some of them had over 80% density of sintering materials.
3) there were well-compacted as well as badly-compacted powders, and in bad cases, although binder was added to oxides (CdO, TiO₂, BaTiO₃, etc.), they were not formed.
4) centric pores in longitudinal direction, or radial or concentric cracks in radial direction occurred in some compacted oxides.
5) considerably high temperatures are estimated in explosion, but X-ray diffraction did not show that powder particles had reacted each other chemically.

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We have succeeded in fabrication of metal lined chemical equipments using the HABW explosive welding process, instead of the conventionals such as fusion welding or using claded plates.
By means of HABW process, metal plates and sheets can be welded in spot type or in seam type. The superior features in this new method are idicated that this process enables to join not only several corrosion resistant metal to ferrous metal but also any metal to another, e. g. Al, Cu, Ni, Ti, Zr, Ta, etc.
In this paper, the properties of explosively welded metal and the manufacturing process of metal lined equipments are presented, and the merits and applications of this method are discussed.

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Summarizing results on recent experimental and analytical investigations for hydrospark forming reported hitherto, in this paper, mechanism of generation of output energy by hydrospark, process of increase of output for the same electrical discharge energy by using explosive powder between electrodes, method of increase of forming efficiency by utilizing powder explosion, etc., are described.

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Here we offer a type of gear which has three parts of structure being composed of an outer shell, a shaft part and a part being filled into the part enclosed by the outer shell and the shaft. These three parts are to be manufactured independently, by using adaptable materials and processes for gear. Then these parts are combined as one gear. We nominate it as a case gear.
In this report we explain the manufacturing process of the outer shell which is the main subject in case gear making.
We have completed the outer shell of steel plate by liquid spark forming method.

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Electromagnetic forming is a typical method of high energy rate forming. This is the newest-and also one of the most spectacular-of the H.E.R.F. techniques along with spark discharge forming.
Electrical energy stored in a capacitor bank is discharged rapidly through a coil, establishing a changing high-intensity magnetic field. The metal plate in the magnetic field is flyed up by the magnetic force.
Magnitude of the magnetic force is estimated by measuring by maximum flying height.
In this experiment disk materials are copper, Aluminum, Magnesium, Zinc, Cadmium, Iron and Tin.
The following experimental results have been obtained.
1) Maximum flying height is depend on resistance of disk material, increasing resistance decreases maximum height.
2) Maximum value of magnetic force exists being due to thickness of disk and frequency of discharging current.
The experimental formula is introduced as following.
t=kf^-0.9
Where t is the thickness of disk, f is the frequency of the discharging current and k is constant.
Relationship between resistance of these materials and forming difficulty of each metals is shown in table 1.

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