Oil well polish rod clamp for use with a rotator on a beam pumping unit

Abstract

An oil well polish rod clamp includes unitary metallic cylindrical housing and a plurality of setscrews. A textured inner surface of the housing increases longitudinal gripping capacity on a rod rotated inside an oil well by a rod rotator and reciprocated by a beam pumping unit to actuate a downhole pump. The inner housing surface may include a plurality of axially short cylindrical portions with annular gaps between upper and lower portions to increase gripping pressure by reducing the contact area with the rod.

1 . An oil well polish rod clamp, comprising:
 a unitary, generally cylindrical housing;   the housing having a radially inner surface for engagement with a polish rod, and a plurality of grooves in the inner surface for decreasing the contact area between the rod and the housing, the inner surface engaging the rod comprising a plurality of generally arcuate inner surfaces with recesses between the inner surfaces; and   at least one force applying member passing through the housing for engagement with the sucker rod to force the sucker rod into gripping engagement with the inner surface of the housing.   
   
   
       2 . A polish rod clamp as defined in  claim 1 , wherein a plurality of recesses collectively occupy 25% or more of the interior surface of the housing between an uppermost inner surface and a lowermost inner surface. 
   
   
       3 . A polish rod clamp as defined in  claim 1 , wherein the recesses on the inner surface are axially spaced grooves. 
   
   
       4 . A polish rod clamp as defined in  claim 1 , wherein the force applying member is one or more bolts for threaded engagement with the housing. 
   
   
       5 . A polish rod clamp as defined in  claim 1 , wherein the force applying member comprises at least two circumferentially spaced force applying members. 
   
   
       6 . A polish rod clamp as defined in  claim 5 , wherein the force applying member comprises at least two axially spaced force applying members. 
   
   
       7 . An oil well polish rod clamp, comprising:
 a unitary, generally cylindrical housing;   the housing having a radially inner surface for engagement with a polish rod, and a plurality of grooves in the inner surface for decreasing the contact area between the rod and the housing, the inner surface engaging the rod comprising a plurality of generally arcuate inner surfaces with recesses between the inner surfaces; and   a plurality of circumferentially spaced and axially spaced force applying members passing through the housing for engagement with the sucker rod to force the sucker rod into gripping engagement with the inner surface of the housing.   
   
   
       8 . A polish rod clamp as defined in  claim 7 , wherein a plurality of recesses collectively occupy 25% or more of the interior surface of the housing between an uppermost inner surface and a lowermost inner surface. 
   
   
       9 . A polish rod clamp as defined in  claim 7 , wherein the plurality of recesses on the inner surface are axially spaced grooves. 
   
   
       10 . A polish rod clamp as defined in  claim 7 , wherein the force applying members are a plurality of bolts for threaded engagement with the housing. 
   
   
       11 . An oil well polish rod clamp, comprising:
 a unitary, generally cylindrical housing;   the housing having a radially inner surface for engagement with a polish rod, and a plurality of grooves in the inner surface for decreasing the contact area between the rod and the housing, the inner surface engaging the rod comprising a plurality of generally arcuate inner surfaces with recesses between the inner surfaces, the plurality of recesses collectively occupying 25% or more of the interior surface of the housing between an uppermost inner surface and a lowermost inner surface; and   a plurality of force applying members each passing through the housing for engagement with the sucker rod to force the sucker rod into gripping engagement with the inner surface of the housing.   
   
   
       12 . A polish rod clamp as defined in  claim 11 , wherein the plurality of recesses on the inner surface are axially spaced grooves. 
   
   
       13 . A polish rod clamp as defined in  claim 11 , wherein the plurality of force applying members are bolts for threaded engagement with the housing. 
   
   
       14 . A polish rod clamp as defined in  claim 11 , wherein the plurality of force applying members comprise at least two circumferentially spaced force applying members. 
   
   
       15 . A polish rod clamp as defined in  claim 14 , wherein the plurality of force applying members comprise at least two vertically spaced force applying members.