US 4,340,120 A · Annular casing hammer

Abstract

A casing hammer for simultaneously driving casing and drilling a water well comprises a housing having an annular pneumatic chamber with an annular piston that drives an annular anvil which seals the lower end of the chamber. The chamber is formed by outer and inner sleeves of which the inner sleeve is fixed to an end cap solely at its rear end and is thus cantilevered from the end cap, being free of connection at its forward end. The forward end of the inner sleeve is stabilized by means of a relatively small clearance between the anvil and the sleeves at the front end of the chamber. The cantilevered connection of the inner sleeve at its rear end provides a smooth and unobstructed bore through which extends a rotating drill string that also extends through casing while the casing is being driven by the annular hammer.

Claims14

Dependent claims

A pipe hammer comprising

an end cap,
an outer sleeve fixed to said end cap,
an inner sleeve having a rear end rigidly fixed to said end cap, said inner sleeve being concentric with and in radially spaced relation to said outer sleeve to define an annular chamber closed at one end by said end cap, the front end of said inner sleeve being free of connection to said end cap,
an annular piston slidably mounted in said chamber with a radial piston clearance between said piston and said chamber,
an annular anvil slidably mounted in and sealing the other end of said chamber and having radial anvil clearance between said anvil and said chamber that is less than said piston clearance, said anvil clearance being sufficiently small to cause said anvil to radially position said sleeves relative to each other at said other end of the chamber to maintain concentricity of said sleeves and to stabilize the free front end of said inner sleeve,
means for reciprocating said piston within said chamber to cause the piston to repetitively strike said anvil, and
means for receiving blows from said anvil and transmitting such blows to a pipe to be driven.

4 more elements

A pipe hammer for driving casing, said pipe hammer comprising

a rear cap having a bore,
an outer sleeve having a rear end seated on said rear cap and coaxial with said bore,
a front housing on the front end of said outer sleeve,
means for securing said front housing to said rear cap to fix said outer sleeve to said rear cap,
an inner sleeve positioned coaxially of said bore, and having a radially outwardly projecting portion,
means for rigidly fixing said projecting portion to said rear cap, said sleeves defining an annular chamber closed at the rear end of said sleeves by said rear cap,
an annular anvil positioned between said sleeves at the front ends thereof in sealing relation to said chamber, said anvil having a limited slidable motion within said chamber,
an annular piston slidably positioned within said chamber,
means for reciprocating said piston within said chamber and causing it to repetitively strike said anvil, and
means for transmitting blows from said anvil to casing to be driven by said hammer.

7 more elements

Dependencies are inferred from the claim text.

Annular casing hammer

Life of this patent

Annular casing hammer

Life of this patent

Abstract

Claims14