Kazumasa Shiramoto

Explosive Welding Using Underwater Shock Wave Generated by the Detonation of the Detonating Code

Detonating code is a flexible code with an explosive core. It is used to transmit the ignition of explosives with high detonation velocity in the range of 5.5 to 7 km/s. However, it is difficult to use detonating code for the explosive welding of common metals since the horizontal point velocity usually exceeds the sound velocity. Hence, in the present work, a new method using underwater shock wave generated by the detonation of detonating code was tried. The details of the experimental parameters and the results are presented. From the results it is observed that the above technique is suitable to weld thin metal plates with relatively less explosives.

Effects of Experimental Parameters in the Explosive Welding Process Using Reflected Underwater Shock Wave

The authors have proposed an explosive welding process using reflected underwater shock wave to accelerate a thin plate. In this process, an explosive attached on a surface of a steel block is set vertical to the specimen to be welded (a pair of a flyer and a parent plates), and a reflector is placed over the specimen at an angle. The explosive is ignited in the whole set up is submerged in water. When underwater shock wave propagates through the specimen from explosive side to the other side, the shock wave is amplified by the reflector to derive sufficiently high pressure to satisfy the requirements of explosive welding. As the important parameters in this process considered are the inclination of the reflector and other dimensions of the assembly, the experimental results can be changed by varying the dimensional parameters of the assembly. Introduction Explosive welding is well known as one of the techniques for bonding dissimilar metal plates, and various explosively-welded clads have been industrialized widely due to the high bonding strength at the welded interface [1]. As a purpose of increasing the applications of the explosive welding technique, a method utilizing underwater shock wave to weld a thin metal plate to a base plate is proposed [2]. Fig.1 shows the widely practiced the explosive welding method using underwater shock wave. In this method, the explosive covering the area of the flyer plate, was set with a suitable inclined angle against the flyer plate. Anvil(steel) Seal

A Method of Explosive Forming Process for Making a Palm and a Back of Human Hand

t is well known as an important merit of the explosive forming process that the delicate figure of the die surface is precisely transferred onto the specimen of a thin metal plate, because the plate is strongly pressed against the die by the very high pressure of underwater shock wave. However, we cannot find any examples of work pieces making the best use of the merit in literatures until now. We tried to form explosively a thin copper plate into shapes of a palm and a back of human hand, as a work piece making the best use of the merit. The palm has many small delicate lines such as fingerprints and the back has interesting figures such as loose skin at the joints of fingers and the borders of fingernails. The object of the present investigation is to make work pieces just like to a real hand. In this investigation, the following process is adopted in order to perform successfully explosive forming ; real hand plaster concave model convex model of Duplicone (material for dental impression) die of Ren Cast (a kind of epoxy resin) explosive forming. Annealed copper plates of 0.3 mm thick were used in the experiments. Since the extension limit of the plate is not so large, the plate is apt to be broken. If the plate is broken, the die is modified not to break the plate. Though the die made of epoxy resin is too hard to be modified, the plaster model can be easily modified with a cutter knife or a chisel. The modified die is obtained through model of Duplicone made by using the modified plaster model. After a few times of repeating modification, the breakage of plate was scarcely produced. On the work piece of palm, a lot of small lines including finger prints clearly appeared and the work piece of the back showed the shape just like to real human hand.

An Investigation on Deburring Technology Using Concentrated Underwater Shock Wave

When a few branched holes are made in order to cross a main hole at right angle, burrs are produced on the sidewall of the main hole at end of each branched hole. The principle of the process is as follows. After the specimen of which all holes are closed by using sealing tape is submerged, explosive set at the position a little apart from the entrance of the main hole is detonated. As soon as the generated underwater shock wave is arrived at the entrance of the main hole, the sealing tape is broken and the water stream with very high velocity flows into the main hole. The deburring is performed by the action of the water stream with very high velocity. The deburring is sufficiently succeeded in most case. When the main hole is closed, however, the deburring could not be succeeded at the branched hole very near closed position. In order to improve the insufficiency of the process, we designed new equipment in order that underwater shock wave may be concentrated at the entrance of main hole and the water stream with very high velocity, which is caused by the shock wave, may flow along sidewall on which burr is generated. In the present report, we propose the new method and give full account of the experimental results for deburring obtained by using the equipment.

Underwater Explosive Welding Using Detonating Code

Detonating code, which is a flexible code with an explosive core, is normally used to transmit the ignition of explosives with high detonation velocity 6 km/s. Therefore it is difficult to use detonating code for the explosive welding of common metals toward the detonating direction since the welding velocity exceeds the sound velocity of metals. Hence, an explosive welding method using underwater shock wave generated by the detonation of detonating code was tried. In the present investigation, the details of the experimental setup and results are reported. And the welding conditions are discussed through numerical simulation. From these results it is observed that the above technique is suitable to weld thin metal plates with relatively less explosives.

A Deburring Process Performed by Underwater Shock Wave

A burr is most commonly created after machining operations, such as drilling. Drilling burrs, for example, are common when drilling almost any material. When burrs are broken during the operation of a machine including the parts with the created burrs, the broken piece is in fear of disturbing normal operation or damaging the parts of the machine, so that the sufficient deburring is requested because it can affect equipment performance, reliability, and durability. Several deburring method have been developed up to date. In the present report, we proposed a deburring method by means of applying underwater shock wave. The method is as follows: after all entrance of holes is closed with seal tape, the equipment is submerged, so that all passages for running fluid are filled with air. The explosive is set under water near the entrance of the main hole. As soon as the explosive is detonated, the underwater shock wave generated at the detonation point arrives at the entrance of the hole and breaks through the tape. The water flows into the hole with a high speed. The burr is broken by water hummer action of high speed. In the present investigation, the experiments of deburring are performed under some setting conditions of explosive. It is found by experimental results, that the burr is sufficiently removed with the newly proposed method. When the shock pressure is sufficiently high at the entrance of hole, the burr is broken surface is smooth as polished one. When the shock pressure is not sufficiently high, the broken surface of the burr is notched.

Numerical Simulation on Explosive Welding Process Using Reflected Underwater Shock Wave

The paper describes a numerically simulated result for the explosive welding using reflected underwater shock wave. Through the numerical simulation, the effective use of reflected underwater shock wave was clearly suggested and the method to improve the assembly was demonstrated.

A New Method of Explosive Welding Performed by Effective Application of Reflected Underwater Shock Wave

In this report, we propose a new explosive welding method, and the welding is performed at employing underwater shock pressure produced by the underwater explosion of an explosive placed at one side almost vertical to the specimen to be welded. In order to prevent the reduction of the shock pressure with the distance away from explosive, a steel reflector is placed over the area of the specimen. The effects of the reflector are investigated based on the experimental results and the process is numerically analyzed results.Copyright