Well drilling pipe clamping apparatus

Abstract

A pipe clamping apparatus for an oil well in accordance with the present invention includes a body which is formed with an opening for receiving the pipe. Two cages are mounted to the body opposite the body opening from each other. Each cage includes a pair of spaced-apart guide plates which are formed with a cam slot. A cam follower pin is inserted into the cam slot and a pair of guide arms are attached to the cam follower pin at one end. At the other ends of the guide arms, a pair of slip assemblies and one end of a retractor arm are positioned between the guide arms and attached to the cage. The other end of the retractor arm is rotatably attached to the cage via a crankshaft. Rotation of the crankshaft cause the retractor arms to pivot. The pivoting of the retractor arm causes the guide arms to move toward the body opening along a predetermined path defined by the cam slot. A pair of slips are attached to each cage for selective engagement of the pipe, according to the position of the cam follower pin within the cam slot of the cage.

What is claimed is:  
     
         1 . An apparatus for clamping a pipe which comprises: 
 a body having an opening for receiving said pipe, said opening extending through said body;    a clamping means for selective engagement with said piping; and    a camming means defining a path of travel for said clamping means, said camming means being fixedly attached to said body, said camming means being movably attached to said camming means.    
     
     
         2 . The apparatus of  claim 1  wherein said camming means comprises at least one guide plate attached to said body proximate said opening, said guide plate projecting outwardly from said body and being formed with a cam slot.  
     
     
         3 . The apparatus of  claim 2  wherein said camming means includes a cam follower pin fixedly attached to said clamping means, said pin projecting into said cam slot and being movable therein.  
     
     
         4 . The apparatus of  claim 3  wherein said camming means further comprises: 
 a retractor arm having a first retractor end pivotally mounted to said guide plate and having a second retractor end; and,  
 at least one guide arm having a first guide arm end attached to said cam follower pin and having a second guide arm end attached to said second retractor end.  
 
     
     
         5 . The apparatus of  claim 4  wherein said cam slot is arch-shaped and has an outer point, an apex and an inner point, said outer point being located further from said body than said apex, said apex being located further from said body than said inner point.  
     
     
         6 . The apparatus of  claim 5  wherein said clamping means comprises at least slip assembly having an arcuate outer surface and an arched inner surface, said slip assembly being attached to said second retractor end and to said second guide arm end.  
     
     
         7 . The apparatus of  claim 6  wherein said opening defines a longitudinal axis and wherein said body has an outer surface and a frusto-conical inner surface co-extensive with said longitudinal axis, and further wherein said apparatus is in a closed position when said arcuate outer surface engages said frusto-conical surface.  
     
     
         8 . The apparatus of  claim 7  wherein said cam follower pin is located at said inner point when said apparatus is in said closed position.  
     
     
         9 . The apparatus of  claim 7  wherein said apparatus has an open position when said arcuate surface is spaced above and is spaced radially outward from said frusto-conical surface.  
     
     
         10 . The apparatus of  claim 9  wherein said cam follower pin is located at said outer point when said apparatus is in said open position.  
     
     
         11 . The apparatus of  claim 10  further comprising a biasing means for biasing said cam follower pin toward said outer point when said apparatus is in said open position.  
     
     
         12 . The apparatus of  claim 9  wherein said biasing means comprises at least one resilient member having a first resilient member end connected to said guide plate and having a second resilient member end attached to said cam follower pin.  
     
     
         13 . The apparatus of  claim 12  wherein said guide plate, said cam follower pin, said retractor arm, said guide arm and said resilient member define a first cage for said apparatus.  
     
     
         14 . The apparatus of  claim 13  further comprising two cage structures mounted opposite said opening from each other.  
     
     
         15 . The apparatus of  claim 14  further comprising: 
 a first crankshaft fixed to said first cage and rotatably mounted to said body;  
 a second crankshaft fixed to said second cage and rotatably mounted to said body; and,  
 a linkage for connecting said first crankshaft to said second crankshaft for simultaneously moving said first cage and said second cage between said open position and said closed position.  
 
     
     
         16 . An apparatus for clamping a pipe which comprises: 
 a body having an opening for receiving said pipe, said opening extending through said body;    at least one clamping means for selective engagement with said piping; and    at least one cage mounted external to said body for defining a path of travel for said clamping means, said clamping means being fixed to said cage.    
     
     
         17 . The apparatus of  claim 16  wherein said cage comprises two spaced-apart guide plates attached to said body to extend outwardly therefrom, each of said guide plates being oriented substantially parallel to each other and being formed with a corresponding cam slot.  
     
     
         18 . The apparatus of  claim 17  further comprising: 
 a cam follower pin extending from one of said guide plates to the other of said guide plates, said pin having a first pin end inserted into one of said cam slots and having a second pin end inserted into the other of said cam slots;  
 a first guide arm having a first guide arm end attached to said first pin end and having a second guide arm attached to said clamping means; and,  
 a second guide arm having a third guide arm end attached to said second pin end and having a fourth guide arm end attached to said clamping means.  
 
     
     
         19 . The apparatus of  claim 16  wherein said opening has a longitudinal axis and wherein said body is formed with a truncated frusto-conical surface co-extensive with said axis, and wherein said clamping means comprises: 
 a slip assembly, said slip assembly having an arcuate inner gripping surface, and arcuate outer surface, said apparatus being in a closed position when said arcuate outer surface is in contact with said frusto-conical surface.  
 
     
     
         20 . A method for raising and lowering a pipe for an oil rig which comprises the steps of: 
 A) providing a plurality of snubbing spiders, each spider including a body with an opening for receiving said pipe, said opening extending through said body, each spider also having a plurality of slip assemblies for selective engagement with said piping, each slip assembly being connected to a cam follower pin, each spider also having a guide plate attached to said body, said guide plate being formed with a cam slot, each cam follower pin being inserted into said cam slot;    B) engaging said piping with at least one of said spiders;    C) inverting another of said spiders;    D) gripping said piping with at least one of said inverted spiders; and,    E) selectively releasing said spider and said inverted spider according to the desired movement direction of said piping.