What are the explosives used in explosive forming process?

Explosive forming – process description The workpiece is situated directly above the die and explosive material placed above that. The explosive material is typically Trinitrotoluene (TNT), a mixture of acetylene and oxygen or Nitroglycerine.

What are the advantages of explosive forming?

Explosive forming allows large, shaped, parts to be formed without an investment in machine tools and die sets, both of which are costly and time-consuming to produce. Thus for a decade, explosive forming exper- ienced a rapid growth.

How does metal forming work?

In any forming operation, the material must be exposed to tension, compression, or both, i.e., bending. The metal sheet is formed by placing it over a die block that punch-presses the material. The die does not actually punch a hole in the metal sheet but creates a bending force that shapes the metal to the die.

What is explosive hydroforming?

Explosive hydroforming, also known as HERF (High Energy Rate Forming), explosive forming, or exploform, is a striking alternative to the more traditional process of metal hydroforming. Although the charge is relatively small, it is capable of generating enough explosive energy to mold the associated metal into the die.

What are explosives made of?

Chemical composition A chemical explosive may consist of either a chemically pure compound, such as nitroglycerin, or a mixture of a fuel and an oxidizer, such as black powder or grain dust and air.

Can metal be stretched?

One of the most basic ways to stretch sheet metal is by using planishing hammers. Ultimately, the sheet metal is firmly placed on a hard surface and is beaten using the planishing hammer, forcing the metal to compress and stretch.

What is Herf process?

In some cases, electrical high energy rate forming (HERF), as it is called, enables shaping and forming operations to be carried out which would be impossible by other means. Shapes can be produced in metal using either one or the other of two established processes — electromagnetic or electrohydraulic forming.

What is hydroforming process?

Hydroforming is a metal forming technology based on the application of pressurized liquid media to generate defined workpiece shapes from tubular materials or sheet metals.

How is forming process done?

Forming is the process of obtaining the required shape and size on the raw material by subjecting the material to plastic deformation through the application of tensile force, compressive force, bending or shear force or combinations of these forces.

How does roll forming work?

A roll forming machine bends metal at room temperature using a number of stations where fixed rollers both guide the metal and make the necessary bends. As the strip of metal travels through the roll forming machine, each set of rollers bend the metal a little more than the previous station of rollers.

What is electro hydraulic forming process?

Electrohydraulic forming (EHF) is one of the high-speed forming process that uses high-voltage discharge in liquid. Shockwave resulting from the discharge is generated between two electrodes in liquid and it deforms the blank into the die.

In which method the explosive charge is held in direct contact with the workpiece while the detonation is initiated?

Contact Method:In this method, the explosive charge is held in direct contact with the workpiece while the detonation is initiated. The detonation produces interface pressures on the surface of the metal up to several million psi (35000 MPa).

What is an explosive forming?

An explosive forming is one of the techniques to form a metal plate using high shock pressure from the explosion. An explosive releases its energy instantly so that an extremely high pressure with short duration occurs at the instance of explosion. The underwater shock wave travels downstream and then it hits the metal plate to be formed.

What are the different types of metalworking done with explosives?

There are numerous types of metalworking done with explosives. This paper will focus only on explosive forming. However, some other metal working techniques are: Explosive forming can be separated into two different categories: contact operations and standoff operations. · Contact operations place the explosive in direct contact with the metal.

What happens after the detonation of an explosive?

After the detonation of explosive, a pressure pulse of high intensity is produced. A gas bubble is also produced which expands spherically and then collapses until it vents at the surface of the water. When the pressure pulse impinges against the workpiece, the metal is displaced into the die cavity.

How is the explosive charge placed in the workpiece?

The explosive charge is placed in position over the centre of the workpiece. The explosive charge is suspended over the blank at a predetermined distance. The complete assembly is immersed in a tank of water. After the detonation of explosive, a pressure pulse of high intensity is produced.