VIBRATION DAMPER

• US 3,774,731 A
• Filed: 09/19/1972
• Issued: 11/27/1973
• Est. Priority Date: 09/19/1972
• Status: Expired due to Term

• Current Assignee: Donald L. Zerb
• Original Assignee: Donald L. Zerb
• Inventors: Zerb, Donald L.
• Primary Examiner(s): Reger, Duane A.
• Application Number:
  US05/290,407
• Time in Patent Office: 434 Days
• Field of Search: 175/56 188/1B 267/141 408/143
• US Class Current: 188/268
• CPC Class Codes: E21B 17/07 Telescoping joints for varying drill string lengths; Shock absorbers
• CPC Class Codes: F16F 3/0876 and of the same shape
• CPC Class Codes: Y10T 408/76 Tool-carrier with vibration-damping means

Abstract

The invention provides an improved vibration damper primarily for use with a drill of the type used in drilling for oil and gas. The improved damper includes an elongated metallic sleeve assembly slidably housed in an outer casing assembly. The assemblies have co-operating longitudinally extending splines which prevent rotation of one assembly relative to the other but permit relative longitudinal motion. A plurality of rubber bushes are housed between the outer casing assembly and the sleeve assembly and separated by contoured rings which provide clearance for deformation on the bushes. The assemblies and bushes are arranged so that compressive shock forces deform the bushes thereby limiting the vibrations applied to the drill string and hence to the drilling rig.

Claims

1. A damper for damping longitudinal shocks in a drill string, said damper comprising:

a sleeve assembly having upper and lower ends;

a casing assembly co-axial with said sleeve assembly;

spline means slidably connecting said sleeve assembly and said casing assembly to permit relative longitudinal motion of said sleeve assembly and said casing assembly and to transmit torsional forces from one of said casing assembly and said sleeve assembly to the other of said casing assembly and said sleeve assembly, said sleeve assembly and said casing assembly defining an annular chamber;

resilient damping means positioned in said chamber and comprising at least one annular bush; and

means defining a face in contact with a portion of the bush adjacent an end of the bush, there being an annular cavity between said end of said bush and said face to permit deformation of said bush such that when a longitudinal shock forces said sleeve assembly axially into said casing assembly, said bush is deformed into said annular cavity to dissipate at least a part of the energy of said shock; and

means for limiting the relative longitudinal motion of said sleeve assembly and said casing assembly.

2. A damper as claimed in claim 1 in which said chamber terminates at its lower end in an upwardly exposed face of said sleeve assembly and at its upper end in a downwardly exposed face of said casing assembly, and in which said face in contact with said portion of said bush is concave and is fixed relative to one of said upwardly exposed face and said downwardly exposed face.

3. A damper as claimed in claim 2 in which said bush is one of a plurality of bushes and said damper further comprises a plurality of contoured rings, each of said rings being positioned in said chamber between adjacent bushes and having upper and lower faces in contact with portions of said adjacent bushes adjacent respective lower and upper ends of said adjacent bushes, each said contoured ring and said adjacent bushes defining further annular cavities into which said adjacent bushes may be deformed.

4. A damper as claimed in claim 3 in which said fixed face is formed on an upper end ring, said end ring being in contact with said downwardly-exposed face, and said damper further comprising:

a lower ring in contact with said upwardly-exposed face and having a concave upper face in contact with a portion of a lowermost one of said bushes adjacent an end of said lowermost bush, the lower ring and the end of the lowermost bush defining a further annular cavity into which said lowermost bush may be deformed.

5. A damper as claimed in claim 1 in which each said portion of said bushes is rounded to match the concave profile of a ring face in contact with said portion for smoother movement of said portions of said bushes over said ring faces.

6. A damper as claimed in claim 1 in which the sleeve assembly comprises:

a lower sleeve;

an upper sleeve; and

a connector for coupling said upper sleeve to said lower sleeve, said upwardly-exposed face being a part of said connector.

7. A damper as claimed in claim 1 in which said casing assembly comprises:

lower intermediate and upper members threadably connected in variation to present a relatively smooth cylindrical outer appearance, said downwardly exposed face being a lower end of said upper member.

8. A damper as claimed in claim 2 in which each said portion of said bushes is rounded to match the concave profile of a ring face in contact with said portion for smoother movement of said portions of said bushes over said ring faces.

9. A damper as claimed in claim 2 in which the sleeve assembly comprises:

a lower sleeve;

an upper sleeve; and

a connector for coupling said upper sleeve to said lower sleeve, said upwardly-exposed face being a part of said connector.

10. A damper as claimed in claim 2 in which said casiNg assembly comprises:

lower intermediate and upper members threadably connected in variation to present a relatively smooth cylindrical outer appearance, said downwardly exposed face being a lower end of said upper member.

11. A vibration damper tool having first and second ends and adapted for use in a drilling string said tool comprising:

telescopically arranged tubular parts comprising an outer barrel and an inner mandrel received in the barrel, said parts cooperating to define between them an annular packing-receiving chamber, said barrel and mandrel being movable longitudinally relative to each other between a collapsed position and an extended position;

said mandrel comprising, in sequence from the first end of the tool, coupling means for operatively connecting the mandrel to the drilling string, a spacer assemb-y, a first spline assembly, and means defining the inner wall of the packing-receiving chamber, said coupling means, spacer assembly and first spline assembly forming an integral unit;

said barrel comprising, in sequence from the first end of the tool, means for cooperating with the spacer assembly to provide a seal against the entry of drilling mud into the first spline assembly, a second spline assembly adapted to cooperate with the first assembly to lock the parts together with reference to rotational movement while enabling them to move longitudinally relative to each other, means defining the outer wall of the packing-receiving chamber, and coupling means adapted to operatively connect the barrel to the drilling string and provide second end closure means for the chamber;

resilient, compressible packing means almost filling the chamber, said means being adapted to be compressed by normal drilling shock thrusts without permitting the casing and mandrel to strike together and to return almost instantaneously substantially to its pre-compression state;

said mandrel having a radially extending shoulder, intermediate its ends, adapted to provide first end closure means for the chamber, whereby longitudinal movement of the parts toward the collapsed position will cause the shoulder to compress the packing means against the second closure means;

means, carried by the barrel, adapted to seal the second ends of the barrel and mandrel to prevent drilling mud entering between them.