Post Machining Multi-Step Material Working Treatment of Fluid End Housing

Abstract

A method for post machining treatment of the interior surfaces of the access, suction, and discharge bores within each fluid chamber of the fluid end housing of a plunger pump that includes a three (3) step cold and hot working process. The treatment processes include a first shot peening of selected sections of said interior surfaces of each fluid chamber; a quench-polish-quench process whereby an anticorrosion nitride surface layer is added to the interior surfaces of each fluid chamber; and a second shot peening of the selected sections of the interior surfaces of each fluid chamber.

What is claimed is: 
     
         1 . A post machining treatment process for a fluid end housing of a plunger pump with multiple fluid bore chambers having interior surfaces forming an inner volume, comprising the steps of:
 (a) a first shot peening of selected areas of said interior surfaces of each said fluid bore chamber;   (b) then treating said interior surfaces of each said fluid bore chamber by a quench-polish-quench process; and   (c) then a second shot peening of said selected interior surfaces of each said fluid bore chamber.   
     
     
         2 . The post machining treatment process for a fluid end housing of a plunger pump recited in  claim 1  wherein said first shot peening uses shot having a hardness in the range of 30 to 35 hardness on the Rockwell C scale. 
     
     
         3 . The post machining treatment process for a fluid end housing of a plunger pump recited in  claim 2  wherein second shot peening uses shot having a hardness in the range of 50 to 55 hardness on the Rockwell C scale size. 
     
     
         4 . The post machining treatment process for a fluid end housing of a plunger pump recited in  claim 3  wherein said step of treating said interior surfaces of each said fluid bore chamber by a quench-polish-quench process includes the step of carbonitiriding or nitrocarburizing. 
     
     
         5 . The post machining treatment process for the fluid end housing of a plunger pump recited in  claim 4  comprising the additional step of low intensity shot peening said interior chamber surfaces after said second shot peening. 
     
     
         6 . The post machining treatment process for the fluid end housing of a plunger pump recited in  claim 5  wherein said additional step of low intensity shot peening includes shot peening with glass beads at a minimum Almen Peening Intensity of 4N. 
     
     
         7 . A method for cold working and hot working the finish of machined internal surfaces of the fluid end housing of high-pressure plunger pumps comprising the steps of:
 (a) providing a plunger pump fluid end housing with a plurality of fluid chambers arranged in a common plane, each said fluid chamber having a machined interior surface;   (b) providing a first shot peening of selected sections of said interior surface of each said fluid chamber;   (c) then utilizing a quench-polish-quench process whereby an anticorrosion nitride surface layer is added to said interior surface of each said fluid chamber; and   (d) then providing a second shot peening of said selected sections of said interior surface of each said fluid chamber.   
     
     
         8 . The method recited in  claim 7  wherein said step of providing said first shot peening includes shot peening using a shot having a hardness in the range of 30 to 35 hardness on the Rockwell C scale. 
     
     
         9 . The method recited in  claim 8  wherein said step of providing said second shot peening includes shot peening using a shot having a hardness in the range of 50 to 55 hardness on the Rockwell C scale. 
     
     
         10 . The method recited in  claim 9  wherein said quench-polish-quench process will be at a temperature of at least 1000° F. 
     
     
         11 . The method recited in  claim 10  wherein said interior surface of each said fluid chamber has a roughness height Rz≦1.5 μm. 
     
     
         12 . The method recited in  claim 11  comprising the additional step of shot peening said interior surface of each said fluid chamber at a maximum Almen Peening Intensity of 4 A after said second shot peening. 
     
     
         13 . The method recited in  claim 12  comprising the additional step of shot peening said interior surface of each said fluid chamber with glass beads after said second shot peening. 
     
     
         14 . The method recited in  claim 13  wherein said step of shot peening said interior surface of each said fluid chamber with glass beads includes shot peening at a minimum Almen Peening Intensity of 4N. 
     
     
         15 . The method recited in  claim 14  comprising the additional step of masking selected sections of said interior surface of each said fluid chamber whereby shot peening is prohibited. 
     
     
         16 . The method recited in  claim 11  comprising the additional step of masking selected sections of said interior surface of each said fluid chamber whereby shot peening is prohibited. 
     
     
         17 . A method for cold working and hot working the finish of machined internal chamber surfaces of steel blocks comprising the steps of:
 (a) providing a steel block having a plurality of machined interior chamber surfaces;   (b) providing a first shot peening of selected sections of said interior chamber surfaces using a shot having a hardness in the range of 30 to 35 hardness on the Rockwell C scale;   (c) then utilizing a quench-polish-quench process at a temperature of at least 1000° F. whereby an anticorrosion nitride surface layer is added to said interior chamber surfaces; and   (d) then providing a second shot peening of selected sections of said chamber interior surfaces using a shot having a hardness in the range of 50 to 55 hardness on the Rockwell C scale.   
     
     
         18 . The method recited in  claim 17  comprising the additional step of shot peening said interior chamber surfaces with glass beads after said second shot peening. 
     
     
         19 . The method recited in  claim 18  comprising the additional step of masking selected sections of said interior chamber surfaces whereby shot peening is prohibited. 
     
     
         20 . The method recited in  claim 17  comprising the additional step of low intensity shot peening said interior chamber surfaces after said second shot peening at an Almen Peening Intensity of at least 4N and an Almen Peening Intensity of no more than 4 A.