Known in the art are high-speed explosion hammers having a stationary bed incorporating a load-bearing frame supporting a lower die to receive a blank, and, mounted in the upper portion of the frame, a piston having a piston rod supporting an upper die coaxial with the lower die and an explosion device arranged over the piston in such a manner that the upper piston chamber defines the explosion chamber.
The explosion device of prior art hammers is made in the following manner. A sleeve is rigidly fixed to the upper portion of the load-bearing frame to receive a cartridge with a powder charge and an igniter pellet. The cartridge is locked in the sleeve by means of a wedge arrangement. A trigger and percussion assembly is provided for firing impression of the pellet and for igniting the powder charge of the cartridge. The explosion device is also provided with a cartridge magazine.
In order to provide optimum conditions for the manufacture of high-grade parts, the upper die should be given pre-set velocity and impact energy. These values depend on strength and ductility of the material of the blank being treated, as well as on the shape and size of a part.
Impact energy required at a given impact velocity may be achieved by selecting appropriate amount of powder charge and volume of the explosion chamber. It is, however, practically impossible to substantially change the amount of charge in prior art hammers since the charge is of a predetermined size. A change in size of the cartridge for changing the amount of charge requires replacing a number of parts and assemblies of the explosion device, such as the sleeve, the wedge arrangement, the cartridge magazine. Therefore, prior art hammers are designed for a pre-set size of blanks so that the manufacturing capabilities of a hammer are limited.
Besides, an increase in air humidity may result in the igniting pellet and powder becoming damp thus leading to the failure of the explosion device to operate and making the hammer unreliable in operation.
For charging the cartridges with powder, wads, such as cardboard wads are used which remain in the explosion chamber after the blow-up to contaminate it. Removing the wads presents certain problems.
USPTO Backgrounds
USPTO Backgrounds