Patent Application
20080073091
The preferred embodiment of the present invention is a non-filled impact piston made from a material with more density than 12 grams per cubic centimeter which will impact against an anvil within a bore of a pneumatic hand held impact power tool such as disclosed in U.S. Pat. Nos. 6,095,256, 6,488,102, 6,530,435, 6,691,798, 3,393,755, 4,694,912, 4,903,784, 5,203,417, and 5,515,930.
Applicant has discovered that making such a piston from a tungsten alloy or a carbide alloy will provide these types of impact power tools much more impact power. It is a benefit to users to provide additional power to these types of tools and yet keep the tools at the size of an original palm push sized graver. A heavy tungsten or carbide piston that is the same physical size as a lighter steel piston provides this benefit. In other words, by providing a heavy tungsten or carbide piston the inertia of each impact is much more than that of a steel or stainless steel piston made at the same size.
The following are the densities of various materials:
Pure Tungsten 18.8 g/cc
Tungsten Alloys 17.1 g/cc to 18.5 g/cc (90% to 97% Tungsten)
Carbide Alloys 13 g/cc to 15.1 g/cc (75% to 96% Carbide)
Platinum 21.3 g/cc
Iridium 22.1
Rhodium 12.4 g/cc
Pure Gold 19.3 g/cc
Lead 11.3 g/cc
Molybdenum 10 g/cc
Cobalt 8.9 g/cc
Pure Copper 8.9 g/cc
Nickel 8.5 g/cc
Brass 8.5 g/cc
Stainless Steel 8 g/cc
Steel 7.8 g/cc
High Speed Tool Steel 8.75 g/cc
Carbon Tool Steel 7.7 g/cc
Titanium 4.6 g/cc
Applicant has also discovered that a nylon or plastic type material on the face of a piston used in the hand engraving pneumatic tools will give more delicate impacts. This is useful for fine engraving done using a microscope and/or to quiet the impacts. This nylon or plastic material can be utilized on a lighter titanium piston, medium weighted stainless or steel piston or heavy weight tungsten or carbide piston. One way the nylon or plastic can be attached to the front end of the piston is by drilling a hole in the front end of the piston approx 0.125′ in depth and to a size to provide a drive fit to the diameter of a short piece of nylon or plastic rod. The rod is driven in the hole and trimmed to length, leaving around 0.010′ to 0.050′ of it exposed out from metal piston end face.
Accordingly, the reader will see that the invention provides an improved non-filled piston for an impact power tool providing additional power which an engraver, jeweler or artist can utilize for his or her work. It also provides a soft faced piston for more delicate impacts.
Although the invention has been described with reference to the preferred embodiment, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims. For example other materials with densities greater than 12 g/cc can be substituted for those disclosed. Accordingly, the scope of the invention should be determined not by the embodiment disclosed and described, but by the appended claims and their legal equivalents.
