Cooler pipe and method of forming

Abstract

A method of forming a cooler pipe includes filling a cavity of a workpiece with a backing material, roll-forming at least one helical groove along an axial length of the workpiece to define a cooling portion, and removing the backing material from the workpiece to provide a cooler pipe. The backing material may be an aggregate or granular material such as sand, which fills the cavity to provide a supportive force to the workpiece during roll-forming of the groove. The cooling portion of the cooler pipe includes an exterior recess and an interior protrusion defined by the groove which each increase the conductive surface area of the cooling portion relative to the workpiece surface area. The backing material is removable from the cooler pipe and may be recycled for use in forming a subsequent cooler pipe.

1 . A method of forming a cooler pipe from a workpiece including a wall having cylindrical outer and inner surfaces concentrically disposed about a longitudinal axis of the workpiece, the inner surface defining a hollow portion, the method comprising:
 filling the hollow portion with a backing material;   roll-forming a helical groove extending axially along the wall to form the cooler pipe using a rolling tool configured to exert a rolling force on the outer surface of the wall;   wherein:
 the backing material is configured to exert a supportive force opposing the rolling force; and 
 the helical groove defines:
 a helical recess in the outer surface of the wall; and 
 a helical protrusion extending radially from the inner surface of the wall and into the backing material. 
 
   
     
     
         2 . The method of  claim 1 , wherein the supportive force is sufficient to prevent collapse of the wall during roll-forming. 
     
     
         3 . The method of  claim 1 , further comprising:
 removing the backing material from the cooler pipe after roll-forming the workpiece to form the cooler pipe;   wherein the backing material includes a granular material.   
     
     
         4 . The method of  claim 1 , wherein the backing material includes sand. 
     
     
         5 . The method of  claim 1 , wherein the helical protrusion extending from the inner surface of the wall and into the backing material one of displaces and compresses the backing material adjacent the helical protrusion within the hollow portion. 
     
     
         6 . The method of  claim 1 , further comprising:
 compacting the backing material in the hollow portion of the workpiece prior to roll-forming the helical groove.   
     
     
         7 . The method of  claim 1 , further comprising:
 removing the backing material in portions from the cooler pipe, by one of shaking, vibrating, and gravitating each of the portions of the backing material from the cooler pipe.   
     
     
         8 . The method of  claim 1 , wherein the backing material is a suspension including a granular material. 
     
     
         9 . The method of  claim 1 , further comprising:
 removing the backing material from the cooler pipe after roll-forming by rinsing the backing material from the hollow portion using one of a fluid and a gas.   
     
     
         10 . The method of  claim 1 , wherein:
 the rolling tool is configured to form a plurality of helical grooves; and   each of the plurality of helical grooves is spaced at an interval from another of the helical grooves along the axial length of the workpiece.   
     
     
         11 . The method of  claim 1 , wherein the workpiece is made from stainless steel. 
     
     
         12 . The method of  claim 1 , wherein the wall of the workpiece is characterized by a thickness of between 0.6 mm and 0.7 mm. 
     
     
         13 . The method of  claim 1 , wherein:
 the wall of the workpiece is characterized by a first radial thickness and the helical groove is characterized by a second radial thickness; and   the first thickness and the second thickness are substantially the same.   
     
     
         14 . A cooler pipe including a tubular cooling portion defining a longitudinal axis, the cooler pipe comprising:
 a helical groove defined by the tubular cooling portion concentrically disposed about the longitudinal axis including:
 a helical recess defined by an outer surface of the tubular cooling portion; 
 a helical protrusion projecting from an inner surface of the tubular cooling portion; 
   wherein the helical recess is characterized by a continuous extruded grain flow extending the axial length of the helical groove.   
     
     
         15 . The cooler pipe of  claim 14 , wherein:
 the helical groove is one of a plurality of helical grooves defined by the tubular cooling portion;   wherein each respective one of the plurality of helical grooves is:
 characterized by a continuous extruded grain flow extending the axial length of the helical recess of the respective helical groove; and 
 non-intersecting with each other one of the plurality of helical grooves. 
   
     
     
         16 . The cooler pipe of  claim 14 , further comprising:
 a wall portion adjacent the helical groove and concentric to the longitudinal axis;   wherein:
 the wall portion is characterized by a first radial thickness and the helical groove is characterized by a second radial thickness; and 
 the first thickness and the second thickness are substantially the same. 
   
     
     
         17 . The cooler pipe of  claim 14 , wherein the cooler pipe is configured as an exhaust gas recirculating (EGR) pipe for use with an engine. 
     
     
         18 . A method of forming an exhaust gas recirculating (EGR) pipe from a stock pipe defining inner and outer surfaces concentrically disposed about a longitudinal axis of the stock pipe, the method comprising:
 compacting a backing material in the stock pipe such that the compacted backing material conforms to the inner surface of the stock pipe and exerts a supportive force on the inner surface;   forming the EGR pipe by concurrently:
 contacting the outer surface of the stock pipe using a roller configured to define a recess of a helical groove and exert an extruding force against the outer surface of the stock pipe; 
 advancing the stock pipe axially and radially relative to the roller and with the stock pipe in interfering contact with the roller; 
 exerting the extruding force against the outer surface of the stock pipe and in opposition to the supportive force of the compacted backing material to extrude the helical groove along an axial length of the stock pipe by forming a helical recess defined by the outer surface of the EGR pipe and a helical protrusion defined by the inner surface of the EGR pipe; 
 compressing the compacted backing material proximate to the helical protrusion during forming of the helical protrusion such that the helical protrusion extends radially into the compacted backing material; and 
   removing the backing material from the EGR pipe by decompacting the backing material.   
     
     
         19 . The method of  claim 18 , wherein the supportive force exerted by the backing material is sufficient to prevent collapse of the EGR pipe by exertion of the extruding force. 
     
     
         20 . The method of  claim 18 , wherein the backing material is an aggregate material; the method further comprising:
 recycling the backing material after removing the backing material from the EGR pipe; and   reusing at least a portion of the backing material as backing material during forming of a subsequent EGR pipe.