Method for producing a helical body

Abstract

A method for producing a hollow, helical, electrically conducting body. The method comprising: producing a helical core made of a core material that can be at least one of liquefied and evaporated under the action of heat; coating the helical core with a first powder layer of an at least partially electrically conducting powder using a powder coating method; heating the helical core and the first powder layer to a first temperature, at which the helical core is at least one of liquefied and evaporated and at which the first powder layer is at least partially solidified in porous form, the core material exiting space surrounded by the first powder layer; and after the core material has exited the space surrounded by the first powder layer, sintering the first powder layer by heating the first powder layer to a second temperature, which is higher than the first temperature.

1 .- 17 . (canceled) 
     
     
         18 . A method for producing a hollow, helical, electrically conducting body, the method comprising:
 producing a helical core made of a core material that can be at least one of liquefied and evaporated under the action of heat;   coating the helical core with a first powder layer of an at least partially electrically conducting powder using a powder coating method;   heating the helical core and the first powder layer to a first temperature, at which the helical core is at least one of liquefied and converted into a gaseous state and at which the first powder layer is at least partially solidified in porous form, the core material exiting space surrounded by the first powder layer; and   after the core material has exited the space surrounded by the first powder layer, sintering the first powder layer by heating the first powder layer to a second temperature, which is higher than the first temperature.   
     
     
         19 . The method of  claim 18 , wherein after heating the helical core and the first powder layer to the first temperature, the first powder layer is solidified and remains porous, such that the core material that is at least one of liquefied and evaporated escapes through the solidified first powder layer. 
     
     
         20 . The method of  claim 18 , wherein after the sintering of the first powder layer at the second temperature, the first powder layer is compacted to become impermeable to liquids and gases. 
     
     
         21 . The method of  claim 18 , wherein the first powder layer is formed in the form of multiple consecutively applied sub-layers of the powder. 
     
     
         22 . The method of  claim 18 , comprising at least one second powder layer of a second powder applied to the first powder layer, prior to or after heating the helical core and the first powder layer to the first temperature. 
     
     
         23 . The method of  claim 22 , wherein the second powder is made of an electrically insulating material and forms an insulating layer after one or more of heating at the first temperature and heating at the second temperature. 
     
     
         24 . The method of  claim 18 , wherein the powder coating method includes one or more of spraying, dipping and using a fluidizing powder bed. 
     
     
         25 . The method of  claim 18 , wherein the powder coating method includes one or more of a powder slurry and a powder feedstock. 
     
     
         26 . The method of  claim 18 , wherein the helical core is produced in one or more of a casting process and a foaming process, such that the helical core is assembled from multiple parts. 
     
     
         27 . The method of  claim 26 , wherein the helical core is produced as a blank, and thereafter is brought into the shape of a helix by creating a helical recess. 
     
     
         28 . The method of  claim 27 , wherein the helical recess is created in the helical core using a tool that rotates about an axis extending through the helical core and, at the same time, is steadily advanced along the axis. 
     
     
         29 . The method of  claim 18 , comprising at least one interruption in powder coating of the first powder layer or a second powder layer to create an opening for a cavity defined by the helical core, the cavity being delimited by the powder coating. 
     
     
         30 . A helical body, comprising a cavity and being produced by the method of claim 
     
     
         18 . 
     
     
         31 . The helical body of  claim 30 , wherein the cavity is designed as a fluid channel and includes at least one opening. 
     
     
         32 . The helical body of  claim 30 , wherein outer dimensions of the helical body are between 3 cm and 1 m in each spatial direction. 
     
     
         33 . The helical body of  claim 30 , wherein a wall thickness of a material surrounding the cavity is between 1 mm and 20 mm. 
     
     
         34 . The helical body of  claim 30 , wherein a cross-section of the cavity designed as a fluid channel is one of polygonal and elliptical and has a cross-sectional surface area of between 10 mm 2  and 50 cm 2 .